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BY

The Norman W. Henley Publishing Co.

PRINTED IN U. S. A.

THIRD IMPRESSION

ALL ILLUSTRATIONS IN THIS BOOK HAVE BEEN SPECIALLYMADE BY THE PUBLISHERS, AND THEIR USE, WITHOUTPERMISSION, IS STRICTLY PROHIBITED

pRCSs or

BRAUNWORTH * CO. BOOK MAKUFACTUMM •nOOKLVM. N« V> -

PREFACE

In presenting this treatise on **Aviation Engines/^

5 writer realizes that the rapidly developing art makes

difficult to outline all latest forms or describe all

rrent engineering practice. This exposition has been

spared primarily for instruction purposes and is adapted

r men in the. Aviation Section, Signal Corps, and

idents who wish to become aviators or aviation mech-x

icians. Every effort has been made to have the engi-

ering information accurate, but owing to the diversity

authorities consulted and use of data translated from

reign language periodicals, it is expected that some

ght errors will be present. The writer wishes to ac-

owledge his indebtedness to such firms as the Curtiss

iroplane and Motor Co., Hall-Scott Company, Thomas-

)rse Aircraft Corporation and General Vehicle Com-

ny for photographs and helpful descriptive matter.

fecial attention has been paid to instructions on tool

aipment, use of tools, trouble **shooting^' and engine

pairs, as it is on these points that the average aviation

ident is weakest. Only such theoretical consideration

thermo-dynamics as was deemed absolutely necessary

secure a proper understanding of engine action after

fisulting several instructors is included, the writer's

orts having been confined to the preparation of a

actical series of instructions that would be • of the

eatest value to those who need a diversified knowledge

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internal-combustion engine operation and repair, and

who must acquire it quickly. The engines described and illustrated areall practical forms that have been fitted to airplanes capable of makingflights and may be considered fairly representative of the present stateof the art.

Victor W. Pagi^, \si Lieut. A. 8. S. C, U. 8. B.

MlNEOLA^ L. I.,

March, 1918.

CONTENTS

CHAPTER I

PAGES

Brief Consideration of Aircraft Types—^Essential Bequirements ofAerial Motors—^Aviation Engines Must Be Light—^Factors Influen-cing Power Needed—Why Explosive Motors AreBest—Historical—Main Types of Internal Combustion Engines 17-36

CHAPTER II

Operating Principles of Two- and Four-Strgke Engines—^Four-cycleAction—^Two-cycle Action—Comparing Two- and Four-cycle Types—^Theory of Gas and Gasoline Engine—^Early Gas-Engine Forms—Isothermal Law—Adiabatic Law—^Temperature Computations— Heatand Its Work—Conversion of Heat to Power—Bequisites for BestPower Effect 37-59

CHAPTER III

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Efficiency of Internal Combustion Engines—^Various Measures of Ef-ficiency—^Temperatures and Pressures—^Factors GoverningEconomy —^Losses in Wall Cooling—^Value of IndicatorCards—Compression in Explosive Motors—^Factors Limiting Com-pression—Causes of Heat Losses and Inefficiency—^Heat Losses toCooling Water 60-79

CHAPTER IV

Engine Parts and Functions—Why Multiple Cylinder Engines Are Best—^Describing Sequence of Operations—Simple Engines—^Four andSix Cylinder Vertical Tandem Engines—Eight' and Twelve Cylinder VEngines—^Badial Cylinder Arrangement—Botary Cylinder Forms80-109

CHAPTER V

Properties of Liquid Fuels—^Distillates of Crude Petroleum—^Prin-ciples of Carburetion Outlined—Air Needed to Bum Gasoline—^Whata Carburetor Should Do—Liquid Fuel Storage and Supply—^VacuumFuel Feed — Early Vaporizer Forms — Development of Float

PAa

Feed Carburetor—^Maybach's Early Design—Concentric Float and JetType — Schebler Carburetor — Claudel Carburetor — Stewart Meter-ing Pin Type—Multiple Nozzle Vaporizers—Two-Stage Carbur-etor—Master Multiple Jet Type—Compound Nozzle Zenith Carbur-etor—Utility of Gasoline Strainers—Intake Manifold Design and Con-struction—Compensating for Various Atmospheric Conditions— HowHigh Altitude Affects Power—The Diesel System—Notes on CarburetorInstallation—Notes on Carburetor Adjustment . 110-JLS

CHAPTER VI

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•

Early Ignition Systems—Electrical Ignition Best—^Fundamentals ofMagnetism Outlined—Forms of Magneto—Zones of Magnetic Influ-ence—How Magnets are Made—Electricity and MagnetismBelated—^Basic Principles of Magneto Action—Essential Parts ofMagneto and Functions—^Transformer Coil Systems—^True HighTension Type—The Berling Magneto—Timing and Care—^The DixieMagneto—Spark-Plug Design and Application—^Two-Spark IgnitionSpecial Airplane Plug 155-£0

CHAPTER VII

Why Lubrication Is Necessary—^Friction Defined—Theory of Lubriea-tion—^Derivation of Lubricants—^Properties of Cylinder Oils—Fact-ors Influencing Lubrication System Selection—Qnome Type EnginesUse Castor Oil—^Hall-Scott Lubrication System—Oil Supply by Con-stant Level Splash System—^Dry Crank-Case System Best for AirplaneEngines—Why Cooling Systems Are Necessary—Cooling Systems Gen-erally Applied—Cooling by Positive Pump Circulation ^ Thermo-Syphon System — Direct Air-Cooling Methods — Aip-Cooled EngineDesign Considerations 201-231

CHAPTER VIII

Methods of Cylinder Construction—^Block Castings—^Influence onCrank-Shaft Design—Combustion Chamber Design—^Bore and StrokeBatio —^Meaning of Piston Speed—Advantage of Off-Set Cylinders—Valve Location of Vital Import—^Valve Installation Practice—^ValveDesign and Construction—Valve" Operation—Methods of DrivingCam-Shaft—Valve Springs—Valve Timing—^Blowing Back—^LeadGiven Exhaust Valve—Exhaust Closing, Inlet Opening—Closing the In-let Valve—Time of Ignition—How an Engine is Timed—Gnome "

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Monosoupape" Valve Timing—Springless Valves—^Four Valves perCylinder 233-28i

CHAPTER IX

lonstmctional Details of Pistons—Aluminum Cylinders and Pistons—Piston Ring Construction—Leak Proof Piston Bings—Keeping Oil Outof Combustion Chamber—Connecting Rod Forms—Connecting Rodsfor Yee Engines—Cam-Shaft and Crank-Shaft Designs—^Ball BearingCrank-Shafts—Engine Base Construction .... 287-323

CHAPTER X

ower Plant Installation—Curtiss OX-2 Engine Mounting and Operat-ing Boles — Standard S. A. E. Engine Bed Dimensions — Hall-ScottEngine Installation and Operation—^Fuel System Rules—^IgnitionSystem—^Water System—Preparations to Start Engine—MountingBadial and Rotary Engines — Practical Hints to Locate EngineTroubles—^All Engine Troubles Summarized—^Location of EngineTroubles Made Easy 324-375

CHAPTER XI

ools for Adjusting and Erecting—Forms of Wrenches—Use and Care ofFiles—Split Pin Removal and Installation—Complete Chisel Set—^Drilling Machines—Drills, Reamers, Taps and Dies—MeasuringTools—Micrometer Calipers and Their Use—Typical Tool Outfits—Special Hall-Scott Tools—Overhauling Airplane Engines—TakingEngine Down—^Defects in Cylinders—Carbon Deposits, Cause andPrevention—^Use of Carbon Scrapers—Burning Out Carbon with Oxy-gen—Repairing Scored Cylinders—^Valve Removal and Inspec-tion—Reseating and Truing Valves—^Valve Grinding Processes— De-preciation in Valve Operating System—Piston Troubles—Piston RingManipulation—^Fitting Piston Rings—Wrist-Pin Wear—Inspection

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and Refitting of Engine Bearings—Scraping Brasses to Fit —FittingConnecting Rods—Testing for Bearing Parallelism—Camshafts andTiming Gears—Precautions in Reassembling Parts . 376-456

CHAPTER XII

.viatioB Engine Types—Division in Classes—Anzani Engines—Cantonand Unn6 Engine—Construction of Gnome Engines—^'Monosou-pa-pe" Gnome—German **Gnome" Type—Le Rhone Engine— RenaultAir-Cooled Engine—Simplex Model "A" Hispano-Suiza— Curtiss Avi-ation Motors—Thomas-Morse Model 88 Enginep-Duesen-berg Engine— Aeromarine Six-Cylinder — Wisconsin Aviation Engines — Hall-Scott Engines — Mercedes Motor — Benz Motor — Austro-DaimlerEngine—Sunbeam-Coatalen—Indicating and Measuring Instru-ments—Ait Starting Systems—Electric Starting—Battery Ignition457-571

NDEX 573

AVIATION ENGINES

DESIGN—CONSTRUCTION-REPAIR

CHAPTER I

Brief Consideration of Aircraft Types—Essential Requirements of Aeri-al Motors—Aviation Engines Must Be Light—Factors InfluencingPower Needed—Why Explosive Motors Are Best—Historical—^MainTypes of Internal Combustion EiUgines.

BRIEF CONSIDERATION OF AIRCRAFT TYPES

The conquest of the air is one of the most stupendous achievements ofthe ages. Human flight opens the sky to man as a new road, and

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because it is a road free of all obstructions and leads everywhere, af-fording the shortest distance to any place, it offers to man the prospectof unlimited freedom. The aircraft promises to span continents likerailroads, to bridge seas like ships, to go over mountains and forestslike birds, and to quicken and simplify the problems of transportation.While the actual conquest of the air is an accomplishment just beingrealized in our days, the idea and yearning to conquer the air are old,possibly as old as intellect itself. The myths of different races tell ofwinged gods and flying men, and show that for ages to fly was thehighest conception of the sublime. No other agent is more responsiblefor sustained flight than the internal combustion motor, and it wasonly when this form of prime mover had been fully developed that itwas possible for man to leave the ground and alight at will, not de-pending upon the caprices of the winds or lifting power of gases aswith the balloon. It is safe to say that the solution of the problem offlight would have been attained many years ago if the proper source ofpower had been available as all the essential

m

elements of the modern aeroplane and dirigible balloon, other thanthe power plant, were known to early philosophers and scientists.

Aeronautics is divided into two fundamentally differentbranches—aviatics and aerostatics. The first comprises all types ofaeroplanes and heavier than air flying machines such as the heli-copters, kites, etc.; the second includes dirigible balloons, passive bal-loons and all craft which rise in the air by utilizing the lifting force ofgases. Aeroplanes are the. only practical form of heavier-than-air ma-chines, as the helicopters (machines intended to be lifted directly intothe air by propellers, without the sustaining effect of planes), and or-nithoptersj or flapping wing types, have not been thoroughly de-veloped, and in fact, there are so many serious mechanical problems

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to be solved before either of these types of air craft will function prop-erly that experts express grave doubts regarding the practicability ofeither. Aeroplanes are divided into two main types—^monoplanes orsingle surface forms, and bi-planes or machines having two sets of lift-ing surfaces, one suspended over the other. A third type, the triplane,is not very widely used.

Dirigible balloons are divided into three classes: the rigid, the semi-ri-gid, and the non-rigid. The rigid has a frame or skeleton of eitherwood or metal inside of the bag, to stiffen it; the serai-rigid is rein-forced by a wire net and metal attachments; while the non-rigid is justa bag filled with gas. The aeroplane, more than the dirigible and bal-loon, stands as the emblem of the conquest of the air. Two reasons forthis are that power flight is a real conquest of the air, a'real victoryover the battling elements ; secondly, because the aeroplane, or anyflying machine that may follow, brings air travel within the reach ofeverybody. In practical development, the dirigible miay be the steam-ship of the air, which will render invaluable services of a certain kind,and the aeroplane will be the automobile of the air, to be used by themultitude, perhaps for as many purposes as the automobile is now be-ing used.

ESSENTIAL REQUIBEBiENTS OF AERIAL MOTORS

One of the marked features of aircraft development has been the effectit has had upon the refinement and perfection of the internal combus-tion motor. Without question gasoline-motors intended for aircraft arethe nearest to perfection of any other type yet evolved. Because of thepeculiar demands imposed upon the aeronautical motor it must pos-sess all the features of reliability, economy and efficiency now presentwith automobile or marine engines and. then must have distinctivepoints of its own. Owing to the unstable nature of the medium throughwhich it is operated and the fact that heavier-than-air machines can

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maintain flight only as long as the power plant is functioning properly,an airship motor must be more reliable than any used on either landor water. While a few pounds of metal more or less makes practicallyno difference in a marine motor and has very little effect upon thespeed or hill-climbing ability of an automobile, an airship motor mustbe as light as it is possible to make it because every pound counts,whether the motor is to be fitted into an aeroplane or in a dirigibleballoon.

Airship motors, as a rule, must operate constantly at high speeds in or-der to obtain a maximum power delivery with a minimum piston dis-placement. In automobiles, or motor boats, motors are not required torun constantly at their maximum speed. Most aircraft motors mustfunction for extended periods at speed as nearly the maximum as pos-sible. Another thing that militates against the aircraft motor is themore or less unsteady foundation to which it is attached. The neces-sarily light framework of the aeroplane makes it hard for a motor toperform at maximum efficiency on account of the vibration of itsfoundation while the craft is in flight. Marine and motor car engines,while not placed on foundations as firm as those provided for station-ary power plants, are installed on bases of much more stability thanthe light structure of an aeroplane. The aircraft motor, therefore, mustbe balanced to a nicety

and must run steadily under the most unfavorable conditions.

AERIAL MOTORS MUST BE LIGHT

The capacity of light motors designed for aerial work per unit of massis surprising to those not fully conversant with the possibilities that athorough knowledge of proportions of parts and the use of specialmetals developed by the automobile industry make possible. Activityin the development of light motors has been more pronounced in

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France than in any other country. Some of these motors have beencomplicated types made light by the skillful proportioning of parts,others are of the refined simpler form modified from current auto-mobile practice. There is a tendency to depart from the freakish or un-conventional construction and to adhere more closely to standardforms because it is necessary to have the parts of such size that everyquality making for reliability, efficiency and endurance are incorpor-ated in the design. Aeroplane motors range from two cylinders toforms having fourteen and si;cteen cylinders and the arrangement ofthese members varies from the conventional vertical tandem and op-posed placing to the V form or the more unusual radial motors havingeither fixed or rotary cylinders. The weight has been reduced so it ispossible to obtain a complete power plant of the revolving cylinder air-cooled type that will not weigh more than three pounds per actualhorse-power and in some cases less than this.

If we give brief consideration to the requirements of the aviator it willbe evident that one of the most important is securing maximum powerwith minimum mass, and it is desirable to conserve all of the goodqualities existing in standard automobile motors. These are certaintyof operation, good mechanical balance and uniform delivery ofpower—fundamental conditions which must be attained before apower plant can be considered practical. There are in addition, sec-ondary considerations, none the less desirable, if not nhsohitHy essen-tial. These are min-

inmm consumption of fuel and lubricating oil, which is really a factorof import, for upon the economy depends the capacity and flying radi-us. As the amount of liquid fuel must be limited the most suitable mo-tor will be that which is powerful and at the same time economical.Another important feature is to secure accessibility of components inorder to make easy repair or adjustment of parts possible. It is pos-sible to obtain sufficiently lightweight motors without radical

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departure from established practice. Water-cooled power plants havebeen designed that will weigh but four or five pounds per horse-powerand in these forms we have a practical powfer plant capable of exten-ded operation.

FACTORS INFLUENCING POWER NEEDED

Work is performed whenever an object is moved against a resistance,and the amount of work performed depends not^only on the amountof resistance overcome but also upon the amount of time utilized inaccomplishing a given task. Work is measured in horse-power for con-venience. It will take one horse-power to move 33,000 pounds onefoot in one minute or 550 pounds one foot in one second. The samework would be done if 330 pounds were moved 100 feet in one!minute. It requires a definite amount of power to move a vehicle overthe ground at a certain speed, so it must take power to overcome res-istance of an airplane in the air. Disregarding the factor of air density,it will take more power as the speed increases if the w^eight or resist-ance remains constant, or more power if the speed remains constantand the resistance increases. The airplane is supported by air reactionunder the planes or lifting surfaces and the value of this reaction de-pends upon the shape of the aerofoil, the amount it is tilted and thespeed at which it is drawn through the air. The angle of incidence ordegree of wing tilt regulates the power required to a certain degree asthis affects the speed of horizontal flight as well as the resistance.Eesistance may be of two kinds, one that is

necessary and the other that it is desirable to reduce to the lowestpoint possible. There is the wing resistance and the sum of the resist-ances of the rest of the machine such as fuselage, struts, wires, landinggear, etc. If we assume that a certain airplane offered a total resistanceof 300 pounds and we wished to drive it through the air at a speed of

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sixty miles per hour, we can find the horsepower needed by a verysimple computation as follows: The product of

300 pounds resistance times speed of 88 feet

per second times 60 seconds in a minute

= H.P. needed.

divided by 33,000 foot pounds per minute

in one horse-power

The result is the horse-power needed, or

300 X 88 X 60

= 48 H.P.

33,000 •

Just as it takes more power to climb a hill than it does to run a car onthe level, it takes more power to climb in the air with an airplane thanit does to fly on the level. The more rapid the climb, the more power itwill take. If the resistance remains 300 pounds and it is necessary todrive the plane at 90 miles per hour, we merely substitute proper val-ues in the above formula and we have

300 pounds times 132 feet per second times 60

seconds in a minute ^^ „^

: = 72 H.P.

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33,000 foot pounds per minute in one

horse-power

The same results can be obtained by dividing the product of the resist-ance in pounds times speed in feet per second by 550, which is thefoot-pounds of work done in one second to equal one horse-power.Naturally, the amount of propeller thrust measured in pounds neces-sary to drive an airplane must be greater than the resistance by a sub-stantial margin if the plane is to fly and climb as well-

! following formulse were given in **The Aeroplane'* jondon and canbe used to advantage by those desiring nake computations to ascertainpower requirements: The thrust of the propeller depends on the powerof

L= Lift'- Weighi=-W

D = Drift

R- Reaction

B^ Angle of Incidence

Tana ^j^tD^ TanccL

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6

Pr ^ Momenfum^ M

O Pr2:Jt^ Work

Pr 2%^ Work Km,

60x75 ~^' ^' ^'' '" English

PrZTCR 33.000

^H.P.

B

1«—DUgrasiB Illiistratliig Computatioiw for Hone-Power Required for

Airplane Flight.

the motor, and on the diameter and pitch of the propeller. If the re-quired thrust to a certain machine is known, the calculation for thehorse-power of the motor should be an easy matter.

The required thrust is the sum of three different ** resistances.'' Thefirst is the **drift'' (dynamical head resistance of the aerofoils), i.e.,tan a x lift (L), lift being equal to the total weight of machine (W) forhorizontal flight and a equal to the angle of incidence. Certainly wemust take the tan a at the maximum Ky value for minimum speed, asthen the drift is the greatest (Fig. 1, A).

Another method for finding the drift is D = K X AV^, when we take thedrift again so as to be greatest.

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The second ** resistance'' is the total head resistance of the machine,at its maximum velocity. And the third is the thrust for climbing. Thehorse-power for climbing can be found out in two different ways. Ifirst propose to deal with the method, where we find out the actualHorse-power wanted for a certain climbing speed to our machine,where

climbing speed/sec. X W

H.P. = —

550

In this case we know already the horse-power for climb-ing, and wecan proceed with our calculation.

With the other method we shall find out the *Hhrusf in pounds orkilograms wanted for climbing and add it to drift and total head resist-ance, and we shall have the total ^Hhrusf of our machine and we shalldenote it with T; while thrust for climbing shall be Tc.

The following calculation is at our service to find out

VcXW

this thrust for climbing = H.P.,

550

H.P. X 550

thence Vc = (1)

W

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TcXV

H.P. = , then from

550

TcXV

X 550

550 TcXV VcXW

(1) Vc = = , thence, Te =

WW V

Whether T means drifts, head resistance and thrust for climbing, ordrift and head resistance only, the following calculation is the same,only in the latter case, of course, we must add the horse-power re-quired for climbing to the result to obtain the total horse-power.

Now, when we know the total thrust, we shall find the horse-power inthe following manner:

Pr2xiJ

We know that the H.P. = in kilograms, or in

75 X 60

Pr2xiJ

English measure, H.P. = (Fig. 1, B)

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33,000

where P = pressure in klgs. or lbs.

r = radius on which P is acting.

R = Rfevolution/min.

P M.R. 2 X

When lBXr = M, then H.P. = , thence,

^ 4,500

H.P. X 4,500 71&.2H.P.

M = = in meter kilograms,

R2% R

H.P. 33,000 5253.1 H.P.

or in English system M = = in foot

it 2 X R

pounds.

Now the power on the circumference of the propeller

M will be reduced by its radius, so it will be — = p. A part

of p will be used for counteracting the air and bearing friction, so thatthe total power on the circumference of the

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M

propeller -will be — Xfi = p where tj is the mechanical

r

efficiency of the propeller. Now = T, where « is taken

tan <x

on the tip of the propeller.

I take ot at the tip, but it can be taken, of course, at any

M point, but then in equation p = —, r must be taken only up

r

to this point, and not the whole radius; but it is more corn-Pitch

fortable to take it at the tip, as tan « = (Fig, 1, C).

r 2«

Now we can write up the equation of the thrust:

716.2 H.P. t) 5253.1 H.P. n

T = , or in English measure

R r tan a Rr tan «

T xRXrtana

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thence H.P. = , or in English measure

716.21)

T xRXrtanot

5253.11)

The computations and formulae given are of most value to the studentengineer rather than matters of general interest, but are given so that ageneral idea may be secured of how airplane design influences powerneeded to secure sustained flight. It will be apparent that the resist-ance of an airplane depends upon numerous considerations of designwhich require considerable research in aerodynamics to determine ac-curately. It is obvious that the more resistance there is, tTie morepower needed to fly at a given speed. Light monoplanes have beenflown with as little as 15 horse-power for short distances,

but most planes now built nse engines of 100 horse-power or more.Giant airplanes have been constnictegl having. ; 2,000 horse-powerdistributed in four power units. The amount of power provided for anairplane of given design varies widely as many conditions govern this,but it will range from approximately one horse-power to each Spounds weight in the case of very light, fast machines to one horse-power to 15 or 18 pounds of the total weight. in the case of mediumspeed machines. The development in airplane and power plant designis so rapid, however, that the figures given can be considered only inthe light of general averages rather than being typical of currentpractice.

WHY EXPLOSIVE MOTORS ARE BEST

Internal combustion engines are best for airplanes and all types of air-craft for the same reasons that they are universally used as a source of

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power for automobiles. The gasoline engine is the lightest known formof prime mover and a more efficient one than a steam engine, espe-cially in the small powers used for airplane propulsion. It has beenstated that by very careful designing a steam plant and engine could bemade that would be practical for airplane propulsion, but even withthe latest development it is doubtful if steam power can be utilized inaircraft to as good advantage as modem gasoline-engines are. Whilethe steam-engine is considered very much simpler than a gas-motor,the latter is much more easily mastered by the non-technical aviatorand certainly requires less attention. A weight of 10 pounds per horse-I)ower is i)ossible in a condensing steam plant but this figure is nearlydouble or triple what is easily secured with a gas-motor which mayweigh but 5 pounds per horsepower in the water cooled forms and but2 or 3 pounds in the air-cooled types. The fuel consumption is twice asgreat in a steam-power plant (owing to heat losses) as would be thecase in a gasoline engine of equal power and much Iass weight.

The internal-combustion engine has come seemingly like an avalancheof a decade; but it has come to stay, to take its well-deserved positionamong the powers for aiding labor. Its ready adaptation to road, aerialand marine service has made it a wonder of the age in the develop-ment of speed not before dreamed of as a possibility; yet in so short atime, its power for speed has taken rank on the conmion road againstthe locomotive on the rail with its century's progress. It has made aeri-al navigation possible and practical, it furnishes power for all marinecraft from the light canoe to the transatlantic liner. It operates the ma-chine tools of the mechanic, tills the soil for the farmer and provideshealthful recreation for thousands by furnishing an economical meansof transport by land and sea. It has been a universal mechanical edu-cation for the masses, and in its present forms,represents the great re-finement and development made possible by the concentration of theworld's master minds on the problems incidental to internal combus-tion engineering.

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HISTORICAL

Although the ideal principle of explosive power was coneeived sometwo hundred years ago, at which time e^pferirpents were made withgunpowder as the explosive elfettieiit, it was not until the last years ofthe eighteenth ' ceiitury that the idea took a patentable shape, and notuntil about 1826 (Bro\\Ti's gas-vacuum engine) that a further pro-gress was made in England by condensing the products of combustionby a jet of water, thus creating a partial vacuum.

Bro^Ti's was probably the first explosive engine that did real work. Itwas clumsy and unwieldy and was soon relegated to its place amongthe failures of previous experiments. No approach to active explosiveeffect in a cylinder was reached in practice, although many ingeniousdesigns were described, until about 1838 and the folloAving years.Barnett's engine in England w^as the first attempt to compress thecharge before exploding. From this -^Ime

on to about 1860 many patents were issued in Europe and a few in theUnited States for gas-engines, but the progress was slow, and its prac-tical introduction for power came with spasmodic effect and low effi-ciency. From 1860 on, practical improvement seems to have beenmade, and the Lenoir motor was produced in France«and brought tothe United States. It failed to meet expectations, and was soon fol-lowed by further improvements in the Hugon motor in France (1862),followed by Beau de Rocha's four-cycle idea, which has been slowlydeveloped through a long series of experimental trials by different in-ventors. In the hands of Otto and Langdon a further progress wasmade, and numerous patents were issued in England, France, andGermany, and followed up by an increasing interest in the UnitedStates, with a few patents.

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From 1870 improvements seem to have advanced at a steady rate, andlargely in the valve-gear and precision of governing for variable load.The early idea of the ne-cessity of slow combustion was a great draw-back in the advancement of efficiency, and the suggestion of de Rochain 1862 did not take root as a prophetic truth until many failures andyears of experience had taught the fundamental axiom that rapidity ofaction in both combustion and expansion was the basis of success inexplosive motors.

With this truth and the demand for small and safe prime movers, the.manufacture of gas-engines increased in Europe and America at amore rapid rate, and improvements in perfecting the details of thischeap and efficient prime mover have finally raised it to the dignity ofa standard motor and a dangerous rival of the steam-engine for smalland intermediate powers, with a prospect of largely increasing its indi-vidual units to many hundred, if not to the thousand horse-power in asingle cylinder. The unit size in a single cylinder has now reached toabout .700 horse-power and by combining cylinders in the same ma-chine, powers of from 1,500 to 2,000 horse-power are now availablefor-large power-plants.

MAIN TYPES OF INTERNAL-COMBUSTION ENGINES

This form of prime mover has been built in so many different types, allof which have operated with some degree of success that the diversityin form will not be generally appreciated unless some attempt is madeto classify the various designs that have received practical application.Obviously the same type of engine is not universally applicable, be-cause each class of work has individual peculiarities which can best bemet by an engine designed with the peculiar conditions present inview. The following tabular synopsis will enable the reader to judgethe extent of the development of what is now the most popular primemover for all purposes.

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A. Internal Combustion (Standard Type)

1. Single Acting (Standard Type)

2. Double Acting (For Large Power Only)

3. Simple (Universal Form)

4. Compound (Rarely Used)

5. Reciprocating Piston (Standard Tyi>e)

6. Turbine (Revolving Rotor, not fully devel-

oped)

Al. . Two-Stroke Cycle

a. Two Port

b. Three Port

c* Combined Two and Three Port

d. Fourth Port Accelerator

e. Differential Piston Type

f. Distributor Valve System

A2. Four-Stroke Cycle

a. Automatic Inlet Valve

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b. Mechanical Inlet Valve

c. Poppet or Mushroom Valve

d. Slide Valve

d 1. Sleeve Valve

d 2. Reciprocating Ring. Valve

d 3. Piston Valve

e. Rotary Valves

e 1. Disc

e 2. Cylinder or Barrel

e 3. Single Cone

e 4. Double Cone

f. Two Piston (Balanced Explosion)

g. Rotary Cylinder, Fixed Crank (Aerial)

h. Fixed Cylinder, Rotary Crank (Standard Type)

l3. Six-Stroke Cycle

\. External Combustion (Practically Obsolete) a. Turbine, RevolvingRotor b* Reciprocating Piston

CLASSIFICATION BY CYLINDER ARRANGEMENT

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c. Horizontal (Two Pairs Opposed)

d. 45 to 90 Degrees V

e* Twin Tandem (Double Acting)

Five Cylinder

a. Vertical (Five Throw Crankshaft)

b. Radially Spaced at 72 Degrees (Stationary

c. Radially Placed Above Crankshaft (Static

ary)

d. Placed Around Rotary Crankcase (72 Degr<

Spacing)

Six Cylinder

a. Vertical

b. Horizontal (Three Pairs Opposed)

c. 45 to 90 Degrees V

Seven Cylinder

a. Equally Spaced (Rotary)

m

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Eight Cylinder

a. Vertical

b. Horizontal (Four Pairs Opposed)

c. 45 to 90 Degrees V

Nine Cylinder

a. Equally Spaced (Rotary)

Twelve Cylinder

a. Vertical

b. Horizontal (Six Pairs Opposed)

c. 45 to 90 Degrees V

•

Fourteen Cylinder a. Rotary

Sixteen Cylinder

a. 45 to 90 Degrees V

b. Horizontal (Eight Pairs Opposed)

Eighteen Cylinder a. Rotary Cylinder

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)-Cylmder. Double Acling,Tour Cycle Enginefor Blast Furnace &asFuel

ry slow speed, made In siios upto ^000 Horsepower. 6O+0 100R.P.M,

Stationary Gas Engine

Four Cycle-Two Cylinder iOOPoi.ndB perHorsepower

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2. —^Plate Sbowlng Heavy, fflow SpMd Intenial Oomlmstlaii EnginesUsed Onlr foi Statlonu; Power fn Large InstalUtloiu OlTliig Weight toHone-Fowei Satio.

'wo Cyfinaer Tour Cycle Tractor DiQi»( BOO Is 1000 ff.P.M .

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Four tylindcr FourCvclcfli/tomobilcPDwerPlcint. WeighiObout 15Pounds per Horseoower IZOO to 2000 R P, M,

Fig. 3-— Vucioaa Forms of InteniBl Coroliniitloii Eiigin«B ShowingDeerim in Welgbt to Hone-Power BaUo with AoKmaDtiiig Speed ofBotettoB.

htCylinder'Vee'AutomobileEngi

15 to IB Poundi per Horta power

Speed) ISOO to 1000 R P.N

Two Cylinder A'r Cooled MotoreycU

Engine weiflHtB'IORogrids Horsepower

5p«*diO0OR.RM.

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■ix.Eight or Twelve Cylinder Worf«r Cooled AvioVion Engine,Tande-morV Form 4 to 6 Pounds per Horsepower Speed ISOO R.P. H. DirectCoupled - ZOOO R P.M. 6eored Drive

. 4.—Intanul Oom^naUoii Engine Types of ExtremelT Fine ConBt-nictlon and Befinad Design, ffliowlng Oieat Power Ontpnts for VerySmmll Welgli^ ft Feature Very Uncli Desired in Airplane FowerFlants.

Of all the types enumerated above engines having less than eight cylin-ders are the most popular in everything but aircraft work. The four-cylinder vertical is without doubt the most widely used of all types ow-ing to the large number employed as automobile power plants. Sta-tionary engines in small and medium powers are invariably of thesingle or double form. Three-cylinder engines are seldom used at thepresent time, except in marine work and in some stationary forms.Eight- and twelve-cylinder motors have received but limited applica-tion and practically always in automobiles, racing motor boats or inaircraft. The only example of a fourteen-cylinder motor to be used to

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any extent is incorporated in aeroplane construction. This is also trueof the sixteen- and eighteen-cylinder forms and of twenty-four-cylin-der engines now in process of development.

The duty an engine is designed for determines the weight per horse-power. High powered engines intended . for steady service are alwaysof the slow speed type and, consequently are of very massive construc-tion. Various forms of heavy duty type stationary engines are shown atFig. 2. Some of these engines may weigh as much as* 600 pounds perhorse-power. A further study is possible by consulting data given onFigs. 3 and 4. As the crankshaft speed increases and cylinders are mul-tiplied the engines become lighter. While the big stationary po#erplants may run for years without attention, airplane engines requirerebuilding after about 60 to 80 hours air service for the fixed cylindertypes and 40 hours or less for the rotary cylinder air-cooled forms.There is evidently a decrease in durability and reliability as the weightis lessened. These illustrations also permit of obtaining a good idea ofthe variety of forms internal combustion engines are made in.

CHAPTER II

Operating Principles of Two- and Four-Stroke Engines—Four-cycleAction—Two-cycle Action—Comparing Two- and Four-cycle Types—Theory of Gas and Gasoline Engine—Early Gas-Engine Forms— Iso-thermal Law—^Adiabatic Law—Temperature Computations—

Heat and Its Work—Conversion of Heat to Power—Requisites for BestPower Effect.

OPERATING PRINCIPLES OF TWO- AND FOUR-STROKE

CYCLE ENGINES

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Before discussing the construction of the various forms of internalcombustion engines it may be well to describe the operating cycle ofthe types most generally used. The two-cycle engine is the simplest be-cause there are no valves in connection with the cylinder, as the gas isintroduced into that member and expelled from it through ports coredinto the cylinder walls. These are covered by the piston at a certainportion of its travel and uncovered at other parts of its stroke. In thefour-cycle engine the explosive gas is admitted to the cylinder througha port at the head end closed by a valve, while the exhaust gas is ex-pelled through another port controlled in a similar manner. Thesevalves are operated by mechanism distinct from the piston.

The action of the four-cycle type may be easily understood if one refersto illustrations at Figs. 5 and 6. It is called the **four-stroke engine"because the piston must make four strokes in the cylinder for each ex-plosion or power impulse obtained. The principle of the gas-engine ofthe internal combustion t>T)e is similar to tliat of a gun, i.e., power isobtained l)y the rapid coml)ustion of some explosive or other quickburning substance. The bullet is driven out of the gun barrel by thepressure of the gas evolved when the charge of powder is ignited. Thepiston or movable element of the gas-engine is driven

from the closed or head end to the crank end of the i cylinder by a sim-ilar expansion of gases resulting from combnstion. The first operationin firing a gun or securing an explosion in the cylinder of the gas-en-gine is to

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/. Powdar Insttttd.

2. Powder Comprtsstd.

Fig. 6.—OntllnluK First Two Strokes of Piston in Foor-OycU

fill the combustion space with combustible materia!. This is done by adown stroke of the piston during which time the inlet valve opens toadmit the gaseous charge to the cylinder interior. This operation isshown at Fig. 5, A. The second operation is to compress this gas whichis done by an upward stroke of the piston as shown at Fig.

5, B. When the top of the compression stroke is reached, the gas is ig-nited and the piston is driven down toward the open end of the cylin-der, as indicated at Fig. 6, C. The fourth operation or exhaust stroke isperformed by the

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a. Compnuud Ooa fip/erf*/.

4. Intrt floM* frAoMtfA

M* </alia CKM-

3. foiudti explvttd.

4. Powdar Oat Exhautfti.

Fig. 6.—OntUning Second Two Strokes of Piaton in Fonr-OyclBEngine.

return upward movement of the piston as sho\\Ti at Fig. 6, D duringwhich time the exhaust valve is opened to permit the burnt gases toleave the cylinder. As soon as the piston reaches the top of its exhaust

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stroke, the energy stored in the fly-wheel rim during the po^^er strokecauses that member to continue revolving and as tlie piston

Aviation Engines

C- Power Stroke

D-Exhaust Stroke

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Fig. 7.—B«ctional Vlow of I> Head Qaaollue Engiiie Cylinder ShowingPiston Morements Daring Four-Stroke Cycle,

again travels on its down stroke the inlet valve opens and admits acharge of fresh gas and the cycle of operations is repeated.

The illustrations at Fig. 7 show how the. various cycle functions takeplace in an L head type water cooled cylinder engine. The sections at Aand C are taken through the inlet valve, those at B and D are takenthrough the exhaust valve.

The two-cycle engine works on a different principle, as while only thecombustion chamber end of the piston is employed to do useful workin the four-cycle engine, both upper and lower portions are calledupon to perform the functions necessary to two-cycle engine opera-tion. Instead of the gas being admitted into the cylinder as is the casewith the four-stroke engine, it is first drawn into the engine basewhere it receives a preliminary compression prior to its transfer to theworking end of the cylinder. The views at Fig. 8 should indicate clearlythe operation of the two-port two-cycle engine. At A the piston is seenreaching the top of its stroke and the gasjtbove the piston is beingcompressed ready for ignition, while the suction in the engine basecauses the automatic valve to open and admits mixture from the car-buretor to the crank case. When the piston reaches the top of itsstroke, the compressed gas is ignited and the piston is driven down onthe power stroke, compressing the gas in the engine base.

When the top of the piston uncovers the exhaust port the flaming gasescapes because of its pressure. A downward movement of the pistonuncovers the inlet port opposite the exhaust and permits the fresh gasto bypass through the transfer passage from the engine base to the cyl-inder. The conditions with the intake and exhaust port fully openedare clearly shown at Fig. 8, C. Tlie deflector plate on the top of the

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piston directs the entering fresh gas to the top of the cylinder and pre-vents the main portion of the gas stream from flowing out through theopen exhaust port. On the next upstroke of the piston

Aviation Engines

i! iM

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the gas in the cylinder is compressed and the inlet valve opened, asshown at A to permit a fresh charge to enter the engine base.

The operating principle of the three-port, two-cycle engine is practic-ally the same as that previously described with tlie exception that tliegas is admitted to the. crank-case through a third port in the cylinderwall, which is imcovered by the piston when that member reaches tlieend of its upstroke. The action of the three-port form can be readilyascertained by studying the diagrams given at Fig. 9. Combination

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two- and three-port engines have been evolved and other modifica-tions made to improve the action.

THE TWO-CYCLE AND FOUR-CYCLE TYPES

In the earlier years of explosive-motor progress was evolved the twotypes of motors in regard to the cycles of their operation. The early at-tempts to perfect the two-cycle principle were for many years held inabeyance from the pressure of interests in the four-cycle type, until itssimplicity and power possibilities were demonstrated by Mr. DugaldClerk in England, who gave the principles of the two-cycle motor abroad bearing leading to immediate improvements in design, whichhas made further progress in the United States, until at the presenttime it has an equal standard value as a motor-powder in some applic-ations as its ancient rival the four-cycle or Otto type, as demonstratedby Beau de Rocha in 1862.

Therniodynaniically, the methods of the two types are equal as far ascombustion is concerned, and compression may favor in a small de-gree the four-cycle type as well as the purity of the charge. The cylin-der volume of the two-cycle motor is much smaller per unit of power,and the enveloping cylinder surface is therefore greater per unit ofvolume. Hence more heat is carried off bv the jacket water duringcompression, and the higher compression available from this tends toincrease the economy during conijiression which is lost duringexpansion.

From the above considerations it may be safely stated hat a lower tem-perature and higher pressure of charge t the beginning of compressionis obtained in the two-ycle motor, greater weight of charge and greaterspecific ►ower of higher compression resulting in higher thermal ffi-ciency. The smaller cylinder for the same power of he two-cycle motorgives less friction surface per impulse han of the other type; although

45/821

the crank-chamber pres-ure may, in a measure, balance the friction ofthe four-ycle type. Probably the strongest points in favor of the wo-cycle type are the lighter fly-wheel and the absence f valves and valvegear, making this type the most simple a construction and the lightestin weight for its developed »ower. Yet, for the larger power units, thefour-cycle vpe will no doubt always maintain the standard for fficiencyand durability of action.

The distribution of the charge and its degree of mix-are with the re-mains of the previous explosion in the learance space, has been a mat-ter of discussion for both ypes of explosive motors, with doubtful res-ults. In Fig. 0, A we illustrate what theory suggests as to the distribu-lon of the fresh charge in a two-cycle motor, and in Fig. 0, B what isthe probable distribution of the mixture when he piston starts on itscompressive stroke. The arrows how the probable direction of flow ofthe fresh charge nd burnt gases at the crucial moment.

In Fig. 10, C is shown the complete out-sweep of the products of com-bustion for the full extent of the piston troke of a four-cycle motor,leaving only the volume of he clearance to mix with the new chargeand at D the iianner by which the new charge sweeps by the ignitionle\dce, keeping it cool and avoiding possibilities of pre-^ition by un-due heating of the terminals of the sparking levice. Thus, by envelop-ing the sparking device with he pure mixture, ignition spreads throughthe charge with ts greatest possible velocity, a most desirable condi-tion n high-speed motors with side-valve chambers and igni-ers withinthe valve chamber.

Aviation Enginet

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THEORY OF THE GAS-AND GASOLINE ENGINE

The laws controlling the elements that create a power by their expan-sion by heat due to combustion, when properly understood, become amatter of computation in regard to their vajue as an agent for generat-ing power in the various kinds of explosive engines. The method ofheating the elements of power in explosive engines greatly widens thelimits of temperature as available in other types of heat-engines. It dis-poses of many of the practical troubles of hot-air, and even of steam-engines, in the simplicity and directness of application of the elements

47/821

of power. In the explosive engine the difficulty of conveying heat forproducing expansive effect by con-vection is displaced by the genera-tion of the required heat within the expansive element and at the in-stant of its useful work. The low conductivity of heat to and from airhas been the great obstacle in the practical development of the hot-airengine; while, on the contrary, it has become the source of economyand practicability in the development of the internal-combustionengine.

The action of air, gas, and the vapors of gasoline and petroleum oil,whether singly or mixed, is affected by changes of temperature prac-tically in nearly the same ratio; but when the elements that producecombustion are interchanged in confined spaces, there is a markeddifference of effect. The oxygen of the air, the hydrogen and carbon ofa gas, or vapor of gasoline or petroleum oil are the elements that bycombustion produce heat to expand the nitrogen of the air and the wa-tery vapor produced by the union of the oxygen in the air and the hy-drogen in the gas, as well as also the monoxide and carbonic-acid gasthat may be formed by the union of the carbon of gas or vapor withpart of the oxygen of the air. The various mixtures as between air andgas, or air and vapor, with the proportion of the products of combus-tion left in the cylinder from a previous combustion, form the ele-ments to be considered in estimating the amount of

pressure that may be obtained by their combustion and expansiveforce.

EARLY GAS ENGINE FORMS

The working process of the explosive motor may be divided into threeprincipal types: 1. Motors with charges igniting at constant vohunewithout compression, such as the Lenoir, Hugon, and other similartypes now abandoned as wasteful in fuel and effect. 2. Motors with

48/821

charges igniting at constant pressure with compression, in which a re-ceiver is charged by a pump and the gases burned while being admit-ted to the motor cylinder, such as types of the Simon and Brayton en-gine. 3. Motors with charges igniting at constant volume with variablecompression, such as the later two- and four-cycle motors with com-pression of the indra^^^l charge; limited in the two-cycle tjrpe andvariable in the four-cycle type with the ratios of the clearance space inthe cylinder. This principle produces the explosive motor of greatestefficiency.

The phenomena of the brilliant light and its accompanying heat at themoment of explosion .have been witnessed in the experiments ofDugald Clerk in England, the illumination lasting throughout thestroke; but in regard to time in a four-cycle engine, the incandescentstate exists only one-quarter of the running time. Thus the time inter-val, together with the non-conductibility of the gases, makes the phe-nomena of a high-temperature combustion 'iVithin the comparativelycool walls of a cylinder a practical possibility.

THE ISOTHERMAL LAW

The natural laws, long since promulgated by Boyle, Gay Lussac, andothers, on the subject of the expansion and compression of gases byforce and by heat, and their variable pressures and temperatures whenconfined, are conceded to be practically true and applicable to allgases, whether single, mixed, or combined.

The law formulated by Boyle only relates to the compression and ex-pansion of gases without a change of temperature, and is stated inthese words:

// the temperature of a gas be kept constant, its pressure or elasticforce ivill vary inversely as the volume it occupies.

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It is expressed in the formula P X V = C, or pressure

C C

X volume = constant. Hence, — = V and — = P.

P V

Thus the curve formed by increments of pressure during the expan-sion or compression of a given volume of gas without change of tem-perature is designated as the isothermal curve in which the volumemultiplied by the pressure is a constant value in expansion, and in-versely the pressure divided by the volume is a constant value in com-pressing a gas.

But as compression and expansion of gases require force for their ac-complishment mechanically, or by the application or abstraction ofheat chemically, or by convection, a second condition becomes in-volved, which wa-s formulated into a law of thermodynamics by GayLussac under the following conditions: A given volume of gas under afree piston expands by heat and contracts by the loss of heat, itsvolume causing a proportional movement of a free piston equal to ^73part of the cylinder volume for each degree Centigrade difference intemperature, or /492 part of its volume for each degree Fahrenlieit.With a fixed piston (constant volume), the pressure is increased or de-creased by an increase or decrease of heat in the same proportion of^73 part of its pressure for each degree Centigrade, or ^92 part of itspressure for each degree Fahrenheit change in temperature. This is thenatural sequence of the law of mechanical equivalent, which is a ne-cessary deduction from the principle that

nothing in natnre can be lost or wasted, for all the heat that is impar-ted to or abstracted from a gaseous body must be accounted for, eitheras heat or its equivalent transformed into some other form of energy.

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In the case of a piston moving in a cylinder by the expansive force ofheat in a gaseous body, all the heat expended in expansion of the gas isturned into work; the balance must be accounted for in absorption bythe cylinder or radiation.

THE ADIABATIC LAW

This theory is equally applicable to the cooling of gases by abstractionof heat or by cooling due to expansion by the motion of a piston. Thedenominators of these heat fractions of expansion or contraction rep-resent the ab^ solute zero of cold below the freezing-point of water,and read —273° C. or — 492.66° =—460.66° F. below zero; and theseare the starting-points of reference in computing the heat expansion ingas-engines. According to Boyle's law, called the first law of gases,there are but two characteristics of a gas and their variations to beconsidered, viz.y volume and pressure: while by the law of Gay Lussac,called the second law of gases, a third is added, consisting of the valueof the absolute temperature, counting from absolute zero to the tem-peratures at which the operations take place. This is the Adiahatic law.

The ratio of the variation of the three conditions — volume, pressure,and heat — from the absolute zero temperature has a certain rate, inwhich the volume multiplied by the pressure and the product dividedby the absolute temperature equals the ratio of expansion for each de-gree. If a volume of air is contained in a cylinder having a piston andfitted with an indicator, the piston, if moved to and fro slowly, will al-ternately compress and expand the air, and the indicator pencil willtrace a line or lines upon the card, which lines register the change ofpressure and volume occurring in the cylinder. If the piston is per-fectly free from leakage, and it be supposed

Adiabatic Law

51/821

51

fhat the temperature of the air is kept qnite constant, then the line sotraced is called an Isothermal line, and the pressure at any point whenmultiplied by the volume is a constant, according to Boyle's law,

pv = & constant.

If, however, the piston is moved very rapidly, the air will not remain atconstant temperature, but the temperature will increase because workhas been done upon the air,

0 to JO 30 « so 60 70 30 SO 100 VOLUME

FlC. 11.—Dlngtam IsotlieimAl and Adiftbatlc Unea.

and the heat has no time to escape by conduction. If no heat whateveris lost by any cause, the line \\ill be traced over and over again by theindicator pencil, the cooling by expansion doing work preciselyequalling the heating by compression. This is the line of no transmis-sion of heat, therefore known as Adiabatic.

The expansion of a gas Ht3 of its volume for every degree Centigrade,added to its temperature, is equal to the decimal .00366, the coeffi-cient of expansion for Centigrade units. To any given volume of a gas,its expansion may be computed by multiplying the coeflRcient by the

number of degrees, and by reversing the process the degree of ac-quired heat may be obtained approximately. These methods are notstrictly in conformity with the absolute mathematical formula, becausethere is a small increase in the increment of expansion of a dry gas,and there is also a slight' difference in the increment of expansion dueto moisture in the atmosphere and to the vapor of water formed by the

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imion of the hydrogen and oxygen in the combustion chamber of ex-plosive engines.'

TEMPERATURE COMPUTATIONS

The ratio of expansion on the Fahrenheit scale is da-rived from the ab-solute temperature below the freezing-point of water (32°) to corres-pond with the Centigrade

1

scale; therefore = .0020297, the ratio of expansion

492.66

from 32° for each degree rise in temperature on the Fahrenheit scale.As an example, if the temperature of any volume of air or gas at con-stant volume is raised, say from 60° to 2000° F., the increase in tem-perature will be

1

1940°. The ratio will be = .0019206. Then by the

520.66

formula:

Ratio X acquired temp. X initial pressure = the gauge pressure; and.0019206 X 1940° X 14.7 = 54.77 lbs.

Bv another formula, a convenient ratio is obtained bv

absolute pressure 14.7

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or = .028233; then, using the dif-

absolute temp. 520.66

ference of temperature as before, .028233 X 1940° = 54.77 lbs.pressure.

By another formula, leaving out a small increment due to specific heatat high temperatures:

Atmospheric pressure X absolute temp. J + acquired temp.

Absolute temp. + initial temp.

absolute pressure due to the acquired temperature, from

which the atmospheric pressure is deducted for the

gauge pressure. Using the foregoing example, we have

14.7 X 460.66° + 2000°

= 69.47 —14.7 = 54.77, the gauge

460.66 + 60°

pressure, 460.66 being the absolute temperature for zero Fahrenheit.

For obtaining the volume of expansion of a gas from a given incrementof heat, we have the approximate formula:

Volume X absolute temp. + acquired temp.

II. — heated

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Absolute temp. + initial temp.

volume. In applying this formula to the foregoing example, the figuresbecome:

460.66° + 2000°

I. X = 4.72604 volumes.

460.66 + 60°

From this last term the gauge pressure may be obtained as follows:

III. 4.72604 X 14.7 = 69.47 lbs. absolute —14.7 lbs. atmospheric pres-sure = 54.77 lbs. gauge pressure; which is the theoretical pressure dueto heating air in a confined space, or at constant volume from 60° to2000° F.

By inversion of the heat formula for absolute pressure we have the for-mula for the acquired heat, derived from combustion at constantvolume from atmospheric pressure to gauge pressure plus atmospher-ic pressure as derived from Example I., by which the expression

absolute pressure X absolute temp. + initial temp.

initial absolute pressure

= absolute temperature + temperature . of combustion, from whichthe acquired temperature is obtained by subtracting the absolutetemperature.

69.47 X 460.66 + 60

Then,, for example, = 2460.66, and

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14.7

2460.66 — 460.66 = 2000% the theoretical heat of combustion. Thedropping of terminal decimals makes a small decimal difference in theresult in the different formulas.

HEAT AND ITS WORK

By Joule's law of the mechanical equivalent of heat, whenever heat isimparted to an elastic body, as air or gas, energy is generated andmechanical work-produced by the expansion of the air or gas. Whenthe heat is imparted by combustion within a cylinder containing amovable piston, the mechanical work becomes an amount measurableby the observed pressure and movement of the piston. The heat gener-ated by the explosive elements and the expansion of the non-combin-ing elements of nitrogen and water vapor that may have been injectedinto the cylinder as moisture in the air, and the water vapor formed bythe union of the oxygen of the air with the hydrogen of the gas, all addto the energy of the work from their expansion by the heat of internalcombustion. As against this, the absorption of heat by the walls of thecylinder, the piston, and cylinder-head or clearance walls, becomes amodifying condition in the force imparted to the moving piston.

It is found that when any explosive mixture of air and gas or hydrocar-bon vapor is fired, the pressure falls far short of the pressure com-puted from the theoretical effect of the heat produced, and fromgauging the expansion of the contents of a cylinder. It is now wellknown that in practice the high efficiency which is promised by theor-etical calculation is never realized; but it must always be

remembered that the heat of combustion is the real agent, and that thegases and vapors are but the medium for the conversion of inert ele-ments of power into the activity of energy by their chemical union. The

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theory of combustion has been the leading stimulus to large expecta-tions with inventors and constructors of explosive motors; its entan-glement with the modifying elements in practice has delayed the bestdevelopment in construction, and as yet no really positive design ofbest form or action seems to have been accomplished, although greatprogress has been made during the past decade in the development ofspeed, reliability, economy, and power output of the individual unitsof this comparatively new power.

One of the most serious difficulties in the practical development ofpressure, due to the theoretical computations of the pressure value ofthe full heat, is probably caused by imparting the heat of the freshcharge to the balance of the previous charge that has been cooled byexpansion from the maximum pressure to near the atmospheric pres-sure of the exhaust. The retardation in the velocity of combustion ofperfectly mixed elements is now well known from experimental trialswith measured quantities; but the principal difficulty in applying theseconditions to the practical work of an explosive engine where a neces-sity for a large clearance space cannot be obviated, is in the inability toobtain a maximum effect from the imperfect mixture and the minglingof the products of the last explosion with the new mixture, which pro-duces a clouded condition that makes the ignition of the mass irregu-lar or chattering, as observed in the expansion lines of indicator cards;but this must not be confounded with the reaction of the spring in theindicator.

Stratification of the mixture has been claimed as taking place in theclearance chamber of the cylinder; but this is not a satisfactory explan-ation in view- of the vortical effect of the violent injection of the airand gas or vapor mixture. It certainly cannot become a perfect mixturein the time of a stroke of a high-speed motor of the two-

Aviation Engines

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cycle class. In a four-cycle engine, making 1,500 revolutions perminute, the injection and compression in any one cylinder take placein one twenty-fifth of a second— formerly considered far too short atime for a perfect infusion of the elements of combustion but now veryeasily taken care of despite the extremely high speed of numerous avi-ation and automobile power-plants.

TaBLK I.—EXPIX)8I0N AT CONSTANT VOLXTME IN A ClOSEDChaXIBER.

In an oxamination of the times of explosion and the correspondingpressures in both tables, it will be seen that a.mixture of 1 part gas to 6parts air is the most effective and will give the higliest moan pressurein a gas-engine. There is a limit to the relative proportions of illumin-ating gas and air mixture that is explosive, somewhat variable, de-pending upon the proportion of hydrogen in the gas. With ordinarycoal-gas, 1 of gas to 15 parts of air; and on the lower end of the scale, 1volume of gas to 2 parts air, are non-explosive. With gasoline vaporthe explosive effect ceases at 1 to 1(5, and a saturated mixture of equalvolumes of vapor and air will not explode, while the most intense ex-plosive effect is from a mixture of 1 part vapor to 9 parts air. In the useof gasoline and air mixtures from a carburetor, the best effect is from 1part saturated air to 8 parts free air.

Heat and Its Work

57

Table II.— Propebtigs and Explobivg Tbmperatcre of a Mixtuke opOne Pakt op iLLUjcNATiNa Gas or 060 Thermal Units per Cubic FootWITH Various Pkoportions op Air without Mixture of Charge withTHE Productb op a PREVions Explosion. ,

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The weight, of a cnbic foot of gas and air mixture as given in Col. 2 isfound by adding the number of volumes of air multiplied by its weight,.0807, to one volume of gas of weight .035 pound per cubic foot anddividing by the total number of volumes; for example, as in the table,

.5192 6 X .0807 = = .074195 as in the first line, and so on

7

for any mixture or for other gases of different specific weight per cubicfoot. The heat units evolved by combustion of the mixture (Col. 6) areobtained by dividing the* total heat units in a cubic foot of gas by thetotal

proportion of the mixture, — = 94.28 as in the first line

7

of the table. Col. 5 is obtained by multiplying the weight of a cubic footof the mixture in Col. 2 by the specific heat

Col. 6 at a constant volume (Col. 4), = Col. 7 the total heat

Col: 5

ratio, of which Col. 8 gives the usual combustion efficiency — Col. 7 XCol. 8 gives the absolute rise in temperature of a pure mixture, as giv-en in Col. 9.

The many recorded experiments made to solve the discrepancybetween the theoretical and the actual heat development and resultingpressures in the cylinder of an explosive motor, to which much discus-sion has been given as to the possibilities of dissociation and the in-creased specific heat of the elements of combustion and non-

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combustion, as well, also, of absorption and radiation of heat, have asyet furnished no satisfactory conclusion as to what really takes place -within the cylinder walls. There seems to be very little kno^vn aboutdissociation^ and somewhat vague theories have been advanced to ex-plain the phenomenon. The fact iS, nevertheless, apparent as shown inthe production of water and other producer gases by the use of steamin contact with highly incandescent fuel. It is knowTi that a maximumexplosive mixture of pure gases, as hydrogen and oxygen or carbonicoxide and oxygon, suffers a contraction of one-third their volume bycomlnistion to their compounds, steam or carbonic acid. In the explos-ive mixtures in the cylinder of a motor, however, the combining ele-ments form so small a proportion of the contents of the cylinder thatthe shrinkage of their volume amounts to no more than 3 per cent, ofthe cylinder volume. This by no means accounts for the groat boat andpressure differences between the theoretical and actual effects.

CONVERSION OF HEAT TO POWER

The utilization of boat in any heat-engine has long been a theme of in-quiry and experiment with scientists and engineers, for tlio purpose ofobtaining the best practical conditions and construction of heat-en-gines that would represent the hi.G:host efficif^ncy or tlie nearest ap-proach to the thoorotical value of boat, as measured by empirical lawsthat have boon dorivod from experimental researches relating to itsultimate vohmio. It is well known that the

steam-engine returns only from 12 to 18 per cent, of the power dne tothe heat generated by the fuel, about 25 per cent, of the total heat be-ing lost in the chinmey, the only use of which is to create a draught forthe fire; the balance, some 60 per cent., is lost in the exhaust and byradiation. The problem of utmost utilization of force in steam hasnearly reached its limit.

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The intemal-combustion system of creating power is comparativelynew in practice, and is but just settling into definite shape by repeatedtrials and modification of details, so as to give somewhat reliable dataas to what may be expected from the rival of the steam-engine as aprime mover. For small powers, the gas, gasoline, and petroleum.oilengines are forging ahead at a rapid rate, filling the thousand wants ofmanufacture and business for a power that does not require expensivecare, that is perfectly safe at all times, that can be used in any place inthe wide world to •which its concentrated fuel can be conveyed, andthat has eliminated the constant handling of crude fuel and water.

BEQUISITES FOR BEST POWER EFFECT

The utilization of heat in a gas-engine is mainly due to the manner inwhich the products entering into combustion are distributed in rela-tion to the movement of the piston. The investigation of the foremostexponent of the theory of the explosive motor was prophetic in consid-eration of the later realization of the best conditions imder which thesemotors can be made to meet the requirements of economy and prac-ticability. As early as 1862, Beau de Rocha announced, in regard to thecoming power, that four requisites were the basis of operation for eco-nomy and best effect. 1. The greatest possible cylinder volume with theleast possible cooling surface. 2. The greatest possible rapidity of ex-pansion. Hence, high speed. 3. The greatest possible expansion. Longstroke. 4. The greatest possible pressure at the commencement of ex-pansion. High compression.

CHAPTER m

Efficiency of Internal Combustion Engines—^Various Measures of.Ef-ficiency—Temperatures and Pressures—Factors Governing Economy—Losses in Wall Cooling—Value of Indicator Cards—Compression in

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Explosive Motors—Factors Limiting Compression—Causes of HeatLosses and Inefficiency—Heat Losses to Cooling Water.

EFFICIENCY OF INTERNAL COMBUSTION ENGINES

Efficiencies are worked out through intricate formulas for a variety oftheoretical and unknown conditions of combustion in the cylinder: ra-tios of clearance and cylinder vohiine, and the uncertain condition ofthe products of combustion left from the last impulse and the wall-temperature. But they are of but little value, except as a mathematicalinquiry as to possibilities. The real commercial efficiency of a gas orgasoline-engine depends upon the volume of gas or liquid at some as-signed cost, required per actual brake horse-power per hour, in whichan indicator card should show that the mechanical action of the valvegear and ignition was as perfect as practicable, and that the ratio ofclearance, space, and cylinder volume gave a satisfactory terminalpressure and compression: i.e., the difference between the powerfigured from the indicator card and the brake power being the frictionloss of tlie engine.

In four-cycle motors of the compression type, the efficiencies aregreatly advanced by compression, producing a more complot(* infu-sion of the mixture of gas or vapor and air, ((uicker firing, and fargreater pressure than is possible with tlio two-cycle tj^ie previouslydescribed. In the practical operation of the gas-engine during the pasttwenty years, the gas-consumption efficiencies per indicated horse-power have gradually risen from 17 per cent, to a maximum of 40 percent, of the theoretical heat, and

this has been done chiefly through a decreased combustion chamberand increased compression—^the compression having gradually in-creased in practice from 30 lbs. per square inch to above 100; butthere seems to be a limit to compression, as the efficiency ratio

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decreases with greater increase in compression. It has been shownthat an ideal efficiency of 33 per cent, for 38 lbs. compression vnXl in-crease to 40 per cent, for 66 lbs., and 43 per cent, for 88 lbs. compres-sion. On the other hand, greater compression means greater explosivepressure and greater strain on the engine structure, which will prob-ably retain in future practice the compression between the limits of 40and 90 lbs. except in super-compression engines intended for highaltitude work where compression pressures as high as 125 poundshave been used.

In .experiments made by Dugald Clerk, in England, with a combustionchamber equal to 0.6 of the space swept by the piston, with a compres-sion of 38 lbs., the consumption of gas was 24 cubic feet per indicatedhorse-power per hour. With 0.4 compression space and 61 lbs. com-pression, the consumption of gas was 20 cubic feet per indicatedhorse-power per hour; and with 0.34 compression space and 87 lbs.compression, the consumption of gas fell to 14.8 cubic feet perindicated horse-power per hour—the actual efficiencies being respect-ively 17, 21, and 25 per cent. This was with a Crossley four-cycleengine.

VARIOUS MEASURES OF EFFICIENCY

The efficiencies in regard to power in a heat-engine may be divided in-to four kinds, as follows: I. The first is known as the maxirmim theor-etical efficiency of a perfect engine (represented by the lines in the in-dicator dia-

gram). It is expressed by the formula and shows

the work of a perfect cycle in an engine working between the receivedtemperature-f-absolute temperature (TJ and

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the initial atmospheric temperature-|-absolnte,temperature (To), n.The second is the actual heat effiaency, or the r^tio of the heat turnedinto work to the total heat received by the engine. It expresses theindicated horse-poiver. III. The third is the ratio between the secondor actual heat efficiency and the first or maximum theoretical effi-ciency of a perfect cycle. It represents the greatest possible utilizationof the power of heat in an internal-combustion engine. IV. The fourthis the me-

Fig. 12.—GnpUc DlAgnun SbowliiK Approxlmat* ITtlUsfttloa of FuelBurned in Intenul-Combnstlon Englno,

chanical efficiency. This is the ratio between the actual horsc-powordelivered by the engine through a dynamometer or measured by abrake (brake horse-power), and the indicated horse-power. The differ-ence between the two is the power lost by engine friction. In regard tothe general heat efficiency of the materials of power in explosive en-gines, we find tliat with good illuminating gas the practical elhciencyvaries from 25 to 40 per cent.; kerosene-motors, 20 to 30: gasoline-motors, 20 to 32; acetylene. 2i) to 3.'); alcohol, 20 to 30 per cent, oftheir heat valne. The great variation is no doubt due to imperfect mixt-nres and variable conditions of the old and new charge in the cylinder:uncertainty as to leakage and the perfec-

on of combustion. In the Diesel motors operating nnder igh pressure,up to nearly 500 pounds, an efficiency of

6 per cent, is claimed.

The graphic diagram at Fig. 12 is of special value as ; shows clearlyhow the heat produced by charge combus-on is expended in an engineof average design.

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On general principles the greater difference between 16 heat of com-bustion and the heat at exhaust is the elative measure of the heatturned into work, which epresents the degree of efficiency without lossduring spansion. The mathematical formulas appertaining to le com-putation of the element of heat and its work in n explosive engine arein a large measure dependent pon assumed values, as the conditionsof the heat of ^mbustion are made uncertain by the mixing of the fresh[large with the products of a previous combustion, and

7 absorption, radiation, and leakage. The computation f the temperat-ure from the observed pressure may be lade as before explained, butfor compression-engines lie needed starting-points for computationare very un-ertain, and can only be approximated from the exact leas-ure and value of the elements of combustion in a ylinder charge.

TEMPERATURES AND PRESSURES

Owing to the decrease from atmospheric pressure in be indrawingcharge of the cylinder, caused by valve and rictional obstruction, thecompression seldom starts above 3 lbs. absolute, especially in high-speed engines. Col. 3 a the following table represents the approximateabsolute ompression pressure for the clearance percentage and atio inCols. 1 and 2, while Col. 4 indicates the gauge pressure from the atmo-spheric line. The temperatures in Jol. 5 are due to the compression inCol. 3 from an as-umed temperature of 560'^ F. in the mixture of thefresh barge of 6 air to 1 gas A\4th the products of combustion 3ft inthe clearance chamber from the exhaust stroke of medium-speed mo-tor. This temperature is subject to

considerable variation from the difference in tlie heat-unit power ofthe gases and vapors used for explosive power, as also of the pylinder-cooling effect. In Col. 6 is given the approximate temperatures of ex-plosion for a mixture of air 6 to gas 1 of 660 heat units per cubic foot,

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for tlie relative values of the clearance ratio in CoL 2 at constantvolume.

Table III.— Gas-Engi.ve Clearance Ratio6, Approxihate CoHpaEBstox,TEMPKitATrnEs OP ExpLosios- AMI Explosive Pressures with a Mix-ture OP C!a» op 600 Heat Umtb per Cubic Foot and MncTUKE of Gm

FACTORS GOVERNING ECONOMY

In view of the experiments in this direction, it clearly shows that inpractical work, to obtain the greatest economy per effective lirakehorso-power, it is necessary: IsL To transform the heat into work withthe greatest rapidity mecliaiiically allowable. This means high piston8i)eed. 2d. To have high initial compression. 3d. To reduce the dura-tion of contact between the hot gases and the cylinder walls to thesmallest amount possible; which means short stroke and quick speed,with a spherical cylinder head. 4th. To adjust the temperature of thejacket water to

obtain the most economical ontpnt of actual power. This means water-tanks or water-coils, with air-cooling surfaces suitable and adjustableto the most economical requirement of the engine, which by late trialsrequires the jacket water to be discharged at about 200° F. 5th. To re-duce the wall surface of the clearance space or combustion chamber tothe smallest possible area, in proportion to its required volume. Thislessens the loss of the heat of combustion by exposure to a large sur-face, and allows of a higher mean wall temperature to facilitate theheat of compression.

LOSSES IN WALL COOLING

In an experimental investigation of the efficiency of a gas-engine un-der variable piston speeds made in France, it was found that the usefuleffect increases with the velocity of the piston—that is, with the rate of

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expansion of the burning gases with mixtures of uniform volumes; sothat the variations of time of complete combustion at constant pres-sure, and the variations due to speed, in a way compensate in 'their ef-ficiencies. The dilute mixture, being slow burning, will have its timeand pressure quickened by increasing the speed.

Careful trials give unmistakable evidence that the useful effect in-creases with the velocity of the piston—that is, with the rate of expan-sion of the burning gases. The time necessary for the explosion to be-come complete and to attain its maximum pressure depends not onlyon the composition of the mixture, but also upon the rate of expan-sion. This has been verified in experiments with a high-speed motor,at speeds from 500 to 2,000 revolutions per minute, or piston speedsof from 16 to 64 feet per second* The increased speed of combustiondue to increased piston speed is a matter of great importance to build-ers of gas-engines, as well as to the users, as indicating the mechanicaldirection of improvements to lessen the wearing strain due to highspeed and to lighten the vibrating parts with increased strength, in or-der that the

balancing of high-speed engines may be accomplished with the leastweight.

From many experiments made in Europe and in the United States, ithas been conclusively proved that excessive cylinder cooling by thiswater-jacket results in a marked loss of efficiency. In a series of experi-ments with a simplex engine in France, it was found that a saving of 7per cent, in gas consumption per brake horse-power was made by rais-ing the temperature of the jacket water from 141° to 165° F. A stillgreater saving was made in a trial vdth an Otto engine by raising thetemperature of the jacket water from 61° to 140° F.—^it being 9.5 percent, less gas per brake horse-power.

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It has been stated that volumes of similar cylinders increase as thecube of their diameters, while the surface of their cold walls varies asthe square of their diameters; so that for large cylinders the ratio ofsurface to volume is less than for small ones. This points to greatereconomy in the larger engines. The study of many experiments goes toprove that combustion takes place gradually in the gas-engine cylin-der, and that the rate of increase of pressure or rapidity of firing iscontrolled by dilution and compression of the mixture, as well as bythe rate of expansion or piston speed. The rate of combustion also de-pends on the size and shape of the explosion chamber, and is in-creased by the mechanical agitation of the mixture during combustion,and still more by the mode of firing.

VALUE OF INDICATOR CARDS

To the uninitiated, indicator cards are considerable of a mystery; tothose capable of reading them they form an index relative to the actionof any engine. An indicator card, such as shown at Fig. 13, is merely agraphi^^al representation of the various pressures existing in the cyl-inder for different positions of the piston. The length is to some scalethat represents the stroke of the piston. During the intake stroke, thepressure falls below the

Value of Indicator Cards

67

atmospheric line. During compression, the curve gradually becomeshigher owing to increasing pressure as the volume is reduced. After ig-nition the pressure line moves

srnx^ Press,

Aeiudl Indfcator JHafiraffifrom Otto Engint,

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^tmoHf^iA < ExhauMline

u—

i Adnn'Sifion: J

^T^U Ungth UjproporUonalJoiMMrQke qf SnoOu.-

Fig. IS, —Otta Foar-Cyde Card.

•3

I

I.

J:^— 3fin7Prei9.

H

B Atmo$ph.l<fiS,

—>l

upward, almost straight, then as the piston goes down on the explo-sion stroke, the pressure falls gradually to the point of exhaust valve,

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opening when the sudden release o't the imprisoned gas causes a re-duction in pressure to nearly atmospheric. An indicator card, or aseries of

f

Fig. 14.—^Diesel Motor Card.

them, will always show by its lines the normal or defective condition ofthe inlet valve and passages; the actual line of compression; the firingmoment; the pressure of explosion; the velocity of combustion; thenormal or defective line of expansion, as measured by the adiabaticcurve,

and the normal or defective operation of the exhaust valve, exhaustpassages, and exhaust pipe. In fact, all the cycles of an explosive motormay be made a practical study from a close investigation of the lines ofan indicator card.*

A most unique card is that of the Diesel motor (Fig. 14), which in-volves a distinct principle in the design and operation of internal-com-bustion motors, in that instead of taking a mixed charge for instantan-eous explosion, its charge primarily is of air and its compression to apress-ure at which a temperature is attained above the igniting pointof the fuel, then injecting the fuel under a still higher pressure bywhich spontaneous combustion takes place gradually wdth increasing

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volume over the compression for part of the stroke or until the fuelcharge is consumed. The motor thus operating between the pressuresof 500 and 35 lbs. per square inch, with a clearance of about 7 percent., has given an efficiency of 36 per cent, of the total heat value ofkerosene oil.

COMPRESSION IN EXPLOSIVE MOTORS

That the compression in a gas, gasoline, or oil-engine has a direct rela-tion to the power obtained, has been long known to experienced build-ers, having been'suggested by M. Beau de Rocha, in 1862, and after-ward brought into practical use in the four-cycle or Otto type about1880. The degree of compression has had a growth from zero, in theearly engines, to the highest available due to the varying ignition tem-peratures of the different gases and vapors used for explosive fuel, inorder to avoid premature explosion from the heat of compression.Much of the increased power for equal-cylinder capacity is due to com-pression of the charge from the fact that the most powerful explosionof gases, or of any form of explosive material, takes place when theparticles are in the closest contact or cohesion Anth one another, lessenergy in this form being consumed by the ingredients themselves tobring about their chemical combination, and consequently

more energy is given out in useful or available work. This is bestshown by the ignition of gunpowder, which, when ignited in the openair, bums rapidly, but without explosion, an explosion only takingplace if the powder be confined or compressed into a sma l l space.

Fig. 16.—DlAKram of Hut In tlie Qas Engine CrUnder.

In a gas or gasoline-motor with a small clearance or compressionspace—with high compression—the surface with which the burninggases come into contact is much smaller in comparison with the

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compression space in a low-compression motor. Another advantage ofa high-compression motor is that on account of the smaller clearanceof combustion space less cooling water is required than with a low-compression motor, as the temperature,

m

and consequently the pressure, falls more rapidly. The loss of heatthrough the water-jacket is thus less in the case of a high-compressionthan in that of a low-compression motor. In the non-compression typeof motor the best results were obtained with a charge of 16 to 18 partsof gas and 100 parts of air, while in the compression type the best res-ults are obtained with an explosive mixture of 7 to 10 parts of gas an-d-100 parts of air, thus showing that by the utilization of compressiona weaker charge with a greater thermal efficiency is permissible.

It has been found that the explosive pressure resulting from the igni-tion of the charge of gas or gasoline-vapor and air in the gas-enginecylinder is about 4j4 times the pressure prior to ignition. The difficultyabout getting high compression is that if the pressure is too high thecharge is likely to ignite prematurely, as compression always results inincreased temperature. The cylinder may become too hot, a deposit ofcarbon, a projecting electrode or plug body in the cylinder may be-come incandescent and ignite the charge which has been excessivelyheated by the high compression and mixture of the hot gases of theprevious explosion.

FACTORS LIMITING COMPRESSION

With gasoline-vapor and air the compression should not be raisedabove about 90 to 95 pounds to the square inch, many manufacturersnot going above 65 or 70 pounds. For natural gas the compressionpressure may easily be raised to from 85 to 100 pounds per square

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inch. For gases of low calorific value, such as blast-furnace orproducer-gas, the compression may be increased to from 140 to 190pounds. In fact the ability to raise the compression to a high point withthese gases is one of the principal reasons for their successful adoptionfor gas-engine use. In kerosene injection engines the compression of250 pounds per square inch has been used with marked economy.Many troubles in reg:ard to loss of power and increase of fuel have oc-curred and will no doubt continue,

Factors Lamiting Compression

71

owing to the wear of valves, piston, and cylinder, which produces aloss in compression and explosive pressure and a waste of fuel by leak-age. Faulty adjustment of valve movement is also a cause of loss ofpower; which may be from tardy closing of the inlet-valve or a tooearly opening of the exhaust-yalve.

The explosive pressure varies to a considerable amount in proportionto the compression pressure by the difference in fuel value and theproportions of air mixtures, so that for good illuminating gas the ex-plosive pressure may be from 2.5 to 4 times the compression pressure.For natural gas 3 to 4.5, for gasoline 3 to 5, for producer-gas 2 to 3,and for kerosene by injection 3 to 6.

The compression temperatures, although well known and easily com-puted from a known normal temperature of the explosive mixture, aresubject to the effect of the uncertain temperature of the gases of theprevious explosion remaining in the cylinder, the temperature of itsw^alls, and the relative volume of the charge, whether full or scant;which are terms too variable to make any computations reliable oravailable.

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For the theoretical compression temperatures from a known normaltemperature, we append a table of the rise in temperature for the com-pression pressures in the following table:

Table IV.— Compbession Temperatures from a Normal Temperatureof

60 Degrees Fahrenheit

100 lbs. gauge 484**

90 lbs. gauge 459**

80 lbs. gauge 433°

70 lbs. gauge 404**

60 lbs. gauge 373**

50 lbs. gauge 339**

40 lbs. gauge 301*

30 lbs. gauge 258**

CHART FOR DETERMINING COMPRESSION PRESSURES

A very useful chart (Fig. 16) for determining compression pressures ingasoline-engine cylinders for various ratios of compression space tototal cylinder volume is given by P. S. Tice, and descril)ed in theChilton Automobile Directory by the originator as follows:

It is many times desirable to have at hand a convenient means for atonce determining with accuracy what the compression pressure will be

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in a gasoline-engine cylinder, the relationship between the volume ofthe compression space and the total cylinder volume or that swept bythe piston being kno\\Ti. The curve at Fig. 16 is offered as such ameans. It is based on empirical data

gathered from upward of two dozen modern automobile engines andrepresents what may be taken to be the results as found in practice. Itis usual for the designer to find compression pressure values, knowingthe volumes from the equation

P2 = Pi

. 1

which is for adiabatie compression of air. Equation (1) is right enoughin general form but gives results which

are entirely too high, as almost all designers know from experience.The trouble lies in the interchange of heat between the compressedgases and the cylinder walls, in the diminution of the exponent (1.4 inthe above) due to the lesser ratio of specific heat of gasoline vapor andin the transfer of heat from the gases which are being compressed towhatever fuel may enter the cylinder in an unvaporized condition.Also, there is always some piston leakage, and, if the form of the equa-tion (1) is to be retained, this also tends to lower the value of the expo-nent. From experience with many engines, it appears that compres-sion reaches its highest value in the cylinder for but a short range ofmotor speeds, usually during the mid-range. Also, it appears that, atthose speeds at which compression shows its highest values, the initialpressure at the start of the compression stroke is from .5 to .9 lb.

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below atmospheric. Taking this latter loss value, which shows more of-ten than those of lesser value, the compression is seen to start from aninitial pressure of 13.9 lbs. per sq. in. absolute.

Also, experiment shows that if the exponent be given the value 1.26,instead of 1.4, the equation will embrace all heat losses in the com-pressed gas, and compensate for the changed ratio of specific heats forthe mixture and also for all piston leakage, in the average engine withrings in good condition and tight. In the light of the foregoing, and inview of results obtained from its use, the above curve is offered — val-ues of Pg being found from the equation

='^-^ a

1^6

In using this curve it must be remembered that pressures are absolute.Thus: suppose it is desired to know the volumetric relationships of thecylinder for a compression pressure of 75 lbs. gauge. Add atmosphericpressure to the desired gauge pressure 14.7 + 75 =^ 89.7 lbs. absolute.Locate this pressure on the scale of ordi-

nates and follow horizontally across to the curve and then verticallydownward to the scale of abscissas, where the ratio of the combustionchamber volume to the total cylinder volume is given, which latter isequal to the sum of the combustion chamber volume and that of thepiston sweep. In the above case it is found that the combustion spacefor a compression pressure of 75 lbs. gauge will be .225 of the total cyl-inder volume, or .225 -f- 775 = .2905 of the piston sweep volume. Con-versely, knowing the volumetric ratios, compression pressure can beread di-rectly by proceeding from the scale of abscissas vertically tothe curve and thence horizontally to the scale of ordinates.

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CAUSES OF HEAT LOSS AND INEFFICIENCY IN EXPLOSIVEMOTORS

The difference realized in the practical operation of an internal com-bustion heat engine from tHe computed effect derived from the valuesof the explosive elements is probably the most serious difficulty thatengineers have

encountered in their endeavors to arrive at a rational

•

conclusion as to where the losses were located, and the ways andmeans of design that would eliminate the causes of loss and raise theefficiency step by step to a reasonable percentage of the total efficiencyof a perfect cycle.

An authority on the relative condition of the chemical elements undercombustion in closed cylinders attributes the variation of temperatureshown in the fall of the expansion curve, and the suppression or re-tarded evolution of heat, entirely to the cooling action of the cylinderwalls, and to this nearly all the phenomena hitherto obscure in the cyl-inder of a gas-engine. Others attribute the great difference betweenthe theoretical temperature of combustion and the actual temperaturerealized in the practical operation of the gas-engine, a loss of morethan one-half of the total heat energy of the combustibles, partly to thedissociation of the eJements of combustion at extremely high temper-atures and their reassociation by expansion in the cylinder, to accountfor the supposed continued

combnstion and extra adiabatic curve of the expansion line on the in-dicator card.

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The loss of heat to the walls of the cylinder, piston, and clearancespace, as regards the proportion of wall surface to the volume, hasgradually brought this point

F^. 17.—The Thompson Indicator, an Instrument for DetannlningOom-presslons and Explosion Prossare Talnes and Recaiding Themon Oliart.

to its smallest ratio in the concave piston-head and globular cylinder-head, with the smallest possible space in the inlet and exhaust pas-sage. The wall surface of a cylindrical clearance space or combustionchamber of ono-lialf its unit diameter in length is equal to 3.1416square units, its volume but 0.3927 of a cubic unit; while the samewall

Aviation Engines

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surface in a spherical form has a volume of 0.5236 of a cubic unit. Itwill be readily seen that the volume is increased SSYs per cent, in aspherical over a cylindrical form for equal wall surfaces at the momentof explosion, when it is desirable that the greatest amount of heat isgenerated, and carrying with it the greatest possible pressure fromwhich the expansion takes place by the movement of the piston.

The spherical form cannot continue during the stroke for mechanicalreasons; therefore some proportion of piston stroke of cylinder volumemust be found to correspond vdth a spherical form of the combustionchamber to produce the least loss of heat through the walls during

Fig. 18.—Spherical Combustion Chamber.'

Fig. 19.—Enlarged Combustion Chamber.

the combustion and expansion part of the stroke. This idea is illus-trated in Figs. 18 and 19, showing how the relative volumes of cylinderstroke and combustion cham-ber may be varied to suit the require-ments due to the quality of the elements of combustion.

Although the concave piston-head shows economy in regard to the re-lation of the clearance volume to the wall area at the moment of ex-plosive combustion, it may be clearly seen that its concavity increasesits surface area and its capacity for absorbing heat, for which there isno provision for cooling the piston, save its contact with the walls ofthe cylinder and the slight air cooling of its back by its reciprocal

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motion. For this reason the concave piston-head has not been gener-ally adopted and the concave cylinder-head, as shown in Fig. 19, Avitha flat

Mercedes Aviation Engine

,.• Approxima+aly Spharical Chamber

—UeTcedes Aviation Engine CyUuder Section Sbowlng Appraxliiiat«l7Spberical Combiutton Chamljer and Concave Piston Top.

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piston-head is the latest and best practice in airplane engineconstrnction.

The practical application of the principle just outlined to one of themost efficient airplane motors ever designed, the Mercedes, is clearlyoutlined at Fig. 20.

HEAT LOSSES TO COOLING WATER

The mean temperature of the wall surface of the combustion chamberand cylinder, as indicated by the temperatures of the circulating water,has been found to be an important item in the economy of the gas-en-gine. Dugald Clerk, in England, a high authority in practical work withthe gas-engine, found that 10 per cent, of the gas for a stated amountof power was saved by using water at a temperature in which the ejec-ted water from the cylinder-jacket w^as near the boiling-point, andventures the opinion that a still higher temperature for the circulatingwater may be used as a source of economy. This could be made prac-tical in the case of aviation engines by adjusting the air-cooling surfaceof the radiator so as to maintain the inlet water at just below the boil-ing point, and by the rapid circulation induced by the pump pressure,to return the water from the cylinder-jacket a few degrees above theboiling point. The thermal displacement systems of cooling employedin automobiles are working under more favorable temperature condi-tions than those engines in which cooling is more energetic.

For a given amount of heat taken from the cylinder by tlie largestvolume of circulating water, the difference in temperature between in-let and outlet of the water-jacket should be the least possible, and thiscondition of the water circulation gives a more even temperature to allparts of the cylinder; while, on the contrary, a cold-water supply, sayat 60° F., so slow as to allow the ejected water to flow off at a temper-ature near the boiling-point, must make a great difference in

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temperature betw^een the bottom and top of the cylinder, with a lossin economy

in gas and other fuels, as well as in water, if it is obtained bymeasurement.

From the foregoing considerations of losses and inefficiencies, we findthat the practice in motor design and construction has not yet reachedthe desired perfection in its cycular operation. Step by step improve-ments have been made vd\h many changes in design though manyhave been without merit as an improvement, farther than to gratifythe longings of designers for something different from the other thing,and to establish a special construction of their own. These efforts mayin time produce a motor of normal or standard design for each kind offuel that will give the highest possible efficiency for all conditions ofservice.

CHAPTER IV

Engine Parts and Functions—Why Multiple Cylinder Engines AreBest—Describing Sequence of Operations—Simple Engines—Four andSix Cylinder Vertical Tandem Engines—Eight and Twelve Cylinder VEngines—Radial Cylinder Arrangement—Rotary Cylinder Forms.

ENGINE PARTS AND FUNCTIONS

The principal elements of a gas engine are not diffi-cult to understandand their functions are easily defined. In place of the barrel of the gunone has a smoothly machined cylinder in which a small cylindrical orbarrel-shaped element fitting the bore closely may be likened to abuUet or cannon ball. It differs in this important respect, however, aswhile the shot is discharged from the mouth of the cannon the pistonmember sliding inside of the main cylinder cannot leave it, as itsmovements back and forth from the open to the closed end and back

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again are limited by simple mechanical connection or linkage whichcomprises crank and connection rod. It is by this means that the recip-rocating movement of the piston is transformed into a rotary motionof the crank-shaft.

The fly-wheel is a heavy member attached to the crankshaft of an auto-mobile engine which has energy stored in its rim as the member re-volves, and the momentum of this revolving mass tends to equalize theintermittent pushes on the piston head produced by the explosion ofthe gas in the cylinder. In aviation engines, the weight of the propelleror that of rotating cylinders themselves performs the duty of a fly-wheel, so no separate member is needed. If some explosive is placed inthe chamber formed by the piston and closed end of the cylinder andexploded, the piston would be the only part that would yield to thepressure which would produce a downward movement. As this isforced down the crank-shaft is

turned by the connecting rod, and as this part is hinged at both ends itis free to oscillate as the crank turns, and thus the piston may slideback and forth while the crankshaft is rotating or describing a curvilin-ear path.

In addition to the simple elements described it is evident that a gasol-ine engine must have other parts. The most important of these are thevalves, of which there are generally two to each cylinder. One closesthe passage connecting to the gas supply and opens during one strokeof the piston in order to let the explosive gas into the combustionchamber. The other member, or exhaust valve, serves as a cover forthe opening through which the burned gases can leave the cylinderafter their work is done. The spark plug is a simple device which maybe compared to the fuse or percussion cap of the cannon. It permitsone to produce an electric spark in the cylinder when the piston is atthe best point to utilize the pressure which obtains when the

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compressed gas is fired. The valves are open one at a time, the inletvalve being lifted, from its seat while the cylinder is filling and the ex-haust valve is opened when the cylinder is being cleared. They are nor-mally kept seated by means of compression springs. In the simple mo-tor shown at Fig. 5, the exhaust valve is operated by means of apivoted bell crank rocked by a cam which turns at half the speed of thecrank-shaft. The inlet valve operates automatically, as will be ex-plained in proper sequence.

In order to obtain a perfectly tight combustion chamber, both intakeand exhaust valves are closed before the gas is ignited, because all ofthe pressure produced by the exploding gas is to be directed againstthe top of the movable piston. 'VMien the piston reaches the bottom ofits power stroke, the exhaust valve is lifted by means of the bell crankwhich is rocked because of the point or lift on the cam. The cam-shaftis driven by positive gearing and revolves at half the engine speed. Theexhaust valve remains open during the whole of the return stroke ofthe piston, and as this member moves toward

the closed end of the cylinder it forces ont burned gases ahead of it,through the passage controlled by the exhaust, valve. The cam-shaft isrevolved at half the engine speed because the exhaust valve is raisedfrom its seat during only one stroke out of four, or only once every tworevolutions. Obviously, if the cam was turned at the same speed as thecrank-shaft it would remain open once every revolution, whereas theburned gases are expelled from the individual cylinders only once intwo turns of the crank-shaft.

WHY MULTIPLE CYLINDER FORMS ARE BEST

Owing to the vibration which obtains from the heavy explosion in thelarge single-cylinder engines used for stationary power other formswere evolved in which the cylinder was smaUer and power obtained by

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running the engine faster, but these are suitable only for very lowpowers.

When a single-cylinder engine is employed a very heavy fly-wheel isneeded to carry the moving parts, through idle strokes necessary toobtain a power impulse. For this reason automobile and aircraft de-signers must use more than one cylinder, and the tendency is to pro-duce power by frequently occurring light impulses rather than by asmaller number of explosions having greater force. When a single-cyl-inder motor is employed the construction is heavier than is neededwith a multiple-cylinder form. Using two or more cylinders conducesto steady power generation and a lessening of vibration. Most modernmotor cars employ four-cylinder engines because a power impulsemay be secured twice every revolution of the crank-shaft, or a total offour-power strokes during two revolutions. The parts are so arrangedthat while the charge of gas in one cylinder is exploding, those whichcome next in firing order are compressing, discharging the inert gasesand drawing in a fresh charge respectively. . When the power stroke iscompleted in one cylinder, the piston in that member in

which a charge of gas has just been compressed has reached the top ofits stroke and when the gas is exploded the piston is reciprocated andkeeps the crankshaft turning. When a multiple-cylinder engine is usedther fly-wheel can be made much lighter than that of the simpler formand eliminated altogether in some designs. In fact, many modernmultiple-cylinder engines developing 300 horse-power weigh less thanthe early single- and double-cylinder forms which developed but one-tenth or one-twentieth that amount of energy.

DESCRIBING SEQUENCE OF OPERATIONS

Referring to Fig. 22, A, the sequence of operation in a single-cylindermotor can be easily imderstood. Assuming that the crank-shaft is

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turning in the direction of the arrow, it will be seen that the intakestroke comes first, then the compression, which is followed by thepower impulse, and lastly the exhaust stroke. If two cylinders are used,it is possible to balance the explosions in such a way that one will oc-cur each revolution. This is true with either one of two forms of four-cycle motors. At B, a two-cylinder vertical engine using a crank-shaftin which the crank-pins are on the same plane is shown. The two pis-tons move up and down simultaneously. Referring to the diagram de-scribing the strokes, and assuming that the outer circle represents thecycle of operations in one cylinder while the inner circle represents thesequence of events in the other cylinder, while cylinder No. 1 is takingin a fresh charge of gas, cylinder No. 2 is exploding. When cylinder No.1 is compressing, cylinder No. 2 is exhausting. During the time that thecharge in cylinder No. 1 is exploded, cylinder No. 2 is being filledA\dth fresh gas. While the exhaust gases are being discharged fromcylinder No. 1, cylinder No. 2 is compressing the gas previously taken.

The same condition obtains when the crank-pins are arranged at onehundred and eighty degrees and the cylinders are opposed, as shownat C. The reason, that tiie

Sequence of Operations

H

MJh

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ko Ci/llniir, Oppuita

2. —Dlagranu ninstratlng Sequence of Cycles in One- and Two-Oyl-ladw Inglnes Showing More Uniform Turning Effort on Oiauk-Shaftwitb wo-OjUndei Motors.

86 ^ Aviation Engines

two-cylinder opposed motor is more popular than that having two ver-tical cylinders is that it is difficult to balance the construction shown atB, so that the vibration will not be excessive. The two-cylinder op-posed motor has much less vibration than the other form, and as the

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explosions occur evenly and the motor is a simple one to construct, ithas been very popular in the past on light cars and has received lim-ited application on some early, light airplanes.

To demonstrate very clearly the advantages of multiple-cylinder en-gines the diagrams at Fig. 23 have been prepared. At A, a three-cylin-der motor, having crank-pins at one hundred and twenty degrees,which means that they are spaced at thirds of the circle, we have aform of construction that gives a more even turning than that possiblewith a two-cylinder engine. Instead of one explosion per revolution ofthe crank-shaft, one will obtain three explosions in two revolutions.The manner in which the explosion strokes occur and the manner theyoverlap strokes in the other cylinder is shown at A. Assuming that thecylinders fire in the following order, first No. 1, then No. 2, and lastNo. 3, we will see that while cylinder No. 1, represented by the outercircle, is on the power stroke, cylinder No. 3 has completed the lasttwo-thirds of its exhaust stroke and has started on its intake stroke.Cylinder No. 2, represented by the middle circle, during this sameperiod has completed its intake stroke and two-thirds of its compres-sion stroke. A study of the diagram will show that there is an appre-ciable lapse of time between each explosion.

Three-cylinder engines are not used on aircraft at the present time,though Bleriot's flight across the British Channel was made with athree-cylinder Anzani motor. It was not a conventional form, however.The three-cyl-indor engine is practically obsolete at this time for anypurpose except ''penguins" or school machhies that are incapable offlight and which are used in some French training schools for aviators.

Four- and Six-Cylinder Engines

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•Diagrams I>«moiutntlng 01«acl7 AdTantages wblcb Obtain wbwHnlUpIe-Orllnder Moton are Uwd as Power Plants.

FOUR- AND SIX-CYLINDER ENGINES

In the four-cylinder engine operation which is shown at Fig. 23, B, itwill be seen that the power strokes follow each other without loss oftime, and one cylinder begins to fire and the piston moves down just

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as soon as the member ahead of it has completed its power stroke. In afour-cylinder motor, the crank-pins are placed at one hundred andeighty degrees, or on the halves of the crank circle. The crank-pins forcylinders No. 1 and No. 4 are on the same plane, while those for cylin-ders No. 2 and No. 3 also move in unison. The diagram describing se-quence of operations in each cylinder is based on a firing order of one,two, four, three. The outer circle, as in previous instances, representsthe cycle of operations in cylinder one. The next one toward the center,cylinder No. 2, the third circle represents the sequence of events in cyl-inder No. 3, while the inner circle outlines the strokes in cylinder four.The various cylinders are w^orking as follows:

1. 2. 3. 4.

Explosion Compression Exhaust Intake

Exhaust Explosion Intake Compression

Intake Exhaust Compression Explosion

Compression Intake Explosion Exhaust

It will be obvious that regardless of the method of construction, or thenumber of cylinders employed, exactly the same number of parts mustbe used in each cylinder assembly and one can conveniently compareany multiple-cylinder power plant as a series of single-cylinder en-gines joined one behind the other and so coupled that one vnW deliverpower and produce useful energy at the crank-shaft where the otherleaves off. The same fundamental laws governing the action of a singlecylinder obtain when a number are employed, and the sequence of op-eration is the same in all members, except that the necessary functionstake place at different

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times. If, for instance, all the cylinders of a four-cylinder motor werefired at the same time, one would obtain the same effect as though aone-piston engine was used, which had a piston displacement equal tothat of the four smaller members. As is the case with a single-cylinderengine, the motor would be out of correct mechanical balance becauseall the connecting rods w^ould be placed on crank-pins that lie in thesame plane. A very large flywheel would be necessary to carry the pis-ton through the idle strokes, and large balance weights would be fittedto the crank-shaft in an effort to compensate for the weight of the fourpistons, and thus reduce vibratory stresses which obtain when partsare not in correct balance.

There w^ould be no advantage gained by using four cylinders in thismanner, and there w^ould be more loss of heat and more powder con-sumed in friction than in a one-piston motor of the same capacity.This is the reason that when four cylinders are used the arrangementof crank-pins is always as shown at Fig. 23, B—i.e., two pistons are up,while the other two are at the bottom of the stroke. With this construc-tion, we have seen that it is possible to string out the explosions so thatthere will always be one cylinder applying power to the crank-shaft.The explosions are spaced equally. The parts are in correct mechanicalbalance because two pistons are on the upstroke while the other twoare descending. Care is taken to have one set of moving membersweigh exactly the same as the other. With a four-cylinder engine onehas <;orrect balance and continuous application of energy. This in-sures a smoother running motor which has greater efficiency than thesimpler one-, two-, and three-cylinder forms previously described.Eliminating the stresses which would obtain if we had an unbalancedmechanism and irregular power application makes for longer life. Ob-viously a large number of relatively light explosions will produce lesswear and strain than would a lesser number of powerful ones. As theparts can be built lighter if the explosions are not heavy, the enginecan be oper-

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ated at liigher rotative speeds than when large and cam-bersomemembers are utilized. Four-cylinder engines intended for aviationwork have been built according to the designs showTi at Fig. 24, butthese forms are unconventional and seldom if ever used.

The six-cylinder type of motor, the action of which is shown at Fig. 23,C, is superior to the four-cylinder, inas-

Two Sets ofOppo

Fig. Zi. —Sbowlng Three Posalble Though UnconventloiulAxruigem«iiti of Foiii-CrllodeT Engines.

much as the power strokes overlap, and instead of having two explo-sions each revolution we have three explosions. The conventionalcrank-shaft arrangement in a six-cylinder engine is just the same asthough one used two three-cylinder shafts fastened together, so pis-tons 1 and 6 are on the same plane as are pistons 2 and 5. Pistons 3and 4 also travel together. AYith the cranks arranged as outlined atFig. 23, C, tlie firinjir order is one, five, three, six, two, four. Tlie

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manner in wliioli the power strokes overlap is clearly shown in the dia-gram. An interesting com-

parison is also made in the diagrams at Fig. 25 and in the upper cornerof Fig, 23, C.

A rectangle is divided into four colnmns; each of these corresponds toone hundred and eighty degrees, or half a revolution. Thus the first re-volution of the crank-shaft is represented by the first two columns,while the second revolution is represented by the last two. Taking thepor-

THE APPLICATION or MWER tN THE SIX-CVLINOER MOTOR

IMS DIAGRAH REPRESEMTS ONE "CVCLET IN WHICH THEPISTON TRAVELS 20 WCHES „QyO„ a^^i^llEPSESENTS POWER ■BCBncccurc nq POWER

iCYU

Fig. 2B. —OUgrams OatUnlng Advuitages of Unttlple Oyllnder Mo-tors, uid Wbr Tlier Dsllver Power Hon Evmlf Tlutn Single O^rUnderTypes.

tion of the diagram which shows the power impulse in a one-cylinderengine, we see that during the first revolution there has been no powerimpulse. During the first half of the second revolution, however, an ex-plosion takes place and a power impulse is obtained. The last portionof the second revolution is devoted to exhausting the burned gases, so

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that there are three idle strokes and but one power stroke. The effectwhen two cylinders are employed is shown immediately below.

Here we have one explosion during the first half of the first revolutionin one cylinder and another during the first half of the second revolu-tion in the other cylinder. With a four-cylinder engine there is an ex-plosion each half revo-^ lution, while in a six-cylinder engine there isone and one-half explosions during each half revolution. "When six

Fig. 26.—Dtagiams Showing Duration of ETanta for a Fonr-StrokeCtgI*, Six-Cylinder Engine.

cylinders are used there is no lapse of time between power impulses,as these overlap' and a continuous and smooth-turning movement isimparted to the crank shaft. The diagram shown at Fig. 2G, preparedby E. P. Pulley, can be studied to advantage in securing an idea of thecoordination of effort tliat takes place in an engine of the six-cylindertype.

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Actual Duration of Cycle Functions

ACTUAL DURATION OF DIFFEBENT STROKES

a the diagrams previously presented the writer has med, for the sakeof simplicity, that each stroke takes ; during half of one revolution ofthe crank-shaft,

7.—Diagram Showing Actual Dnratton of Different Sttokes In Degrees.

h corresponds to a crank-pin travel of one hundred eighty degrees.The actual duration of these strokes mewhat different. For example,the inlet stroke is lly a trifle more than a half revolution, and the ex-haust ways considerably more. The diagram showing the larative dur-ation of the strokes is shoiftoi at Fig. 27.

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The inlet valve opens ten degrees after the piston starts to go downand remains open thirty degrees after the piston has reached the bot-tom of its stroke. This means that the suction stroke corresponds to acrank-pin travel of two hundred degrees, while the compression strokeis measured by a movement of but one hundred and fifty degrees. It iscommon practice to open the exhaust valve before the piston reachesthe end of the power stroke so that the actual duration of the powerstroke is about one hundred and forty degrees, while the exhauststroke corresponds to a crank-pin travel of two hundred and twenty-five degrees. In this diagram, which represents proper

Fig. 23.—Another Dfagram to Facilitate Understandins S«qaeace ofFnnctions In Six-Cyllsder Eogiiie.

time for the valves to open and close, the dimensions in inches givenare measured on the fly-wheel and apply only to a certain automobilemotor. If the fly-wheel were smaller ten degrees would take up lessthan the dimensions given, while if the fly-wheel was larger a greaterspace on its circumference would represent the same crank-pin travel.Aviation engines are timed by using a timing disc attached to thecrank-shaft as they are not provided with fly-wheels. Obviously, thedistance measured in inches will depend upon the diameter of thedisc, though the number of degrees interval would not change.

EIGHT- AND TWELVE-CYLINDER V ENGIHES

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Those who have followed the development of the gasoline engine willrecall the arguments that were made when the six-cylinder motor wasintroduced at a time that the

flinder type was considered standard. The arrival eight<;ylinder hascreated similar futile discussion

practicability as this is so clearly established as to

;epted withont question. It has been a standard plant for aeroplanesfor many years, early expo-having been the Antoinette, the Woolsley,the

It, the E. N. V. in Europe and the Curtiss in the

I States.

e reason the V type shown at Fig. 29, A is favored is

le "all-in-line form" which is shown at Fig. 29, B is

—TjiMB of Elght-OyUndflr Engtnes Bbowliig Uie Adwitage of tha VMethod of Oylinder FUdng.

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actical for aircraft because of its length. Compared standard four-cyl-inder engine it is nearly twice as ind it required a much stronger andlonger crank-It will be evident that it could not be located to tage inthe airplane fuselage. These undesirable s are eliminated in the V typeeight-cylinder motor, jonsists of two blocks of four cylinders each, soar-i that one set or block is at an angle of forty-flve iS from the verticalcenter line of the motor, or at -gle of ninety degrees with the other set.This jement of cylinders produces a motor that is no

longer than a four-cylinder engine of half the power would be.

Apparently there is considerable misconception as to the advantage oftlie two extra cylinders of the eight as compared witli the six-cylinder.It should be borne in mind that the multiplication in the number ofcylinders noticed since the early days of automobile development hasnot been for solely increasing the power of the engine, but to secure amore even turning movement, greater flexibihty

Fig. 30.—CurysB Staowlng Torque of T&rlona Engine Types

Graplilcally Harked Advantage of the Elgbt-Cyllndet Type.

and to eliminate destructive vibration. The ideal internal combustionmotor is the one liaving the most uniform turning movement with tlicleast meelianical friction loss. Study of the torque outlines or plottedgraphics shoi^Ti at Figs. 25 and 30 will show how multiplication ofcylinders will iiroduce steady power delivery due to overlapping im-pulses. The most practical form would be that which more nearly con-forms to the steady running produced by a steam turbine or electricmotor. The advocates of the eight-cylinder engine bring up the item ofuniform torque

Fee Engine Advantages

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97

: one of the most important advantages of the eight-■linder design. Anumber of torque diagrams are sho^vn Fig. 30, While these appear tobe deeply technical, ey may be very easily followed wlien their purposeis iplained.- At the top is sho'WTi the torque diagram of a ngle-eylin-der motor of the four-cycle type. The high

f, 31.—Diagrama Sborlng How IncreuliiK Mniuber of 0^1nd«n Makesfor Mon Unlfoim Fowet Application.

)int in the line represents the period of greatest torque ■ power gener-ation, and it will be evident that this occurs irly in the first revolutionof the crank-shaft. Below this agram is shown a similar curve exceptthat it is pro-iced by a four-cylinder engine. Inspection will show that,e turning moment is much more uniform than in the

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single cylinder; similarly, the six-cylinder diagram is an improvementover the four, and the eight-cylinder diagram is an improvement overthe six-cylinder.

The reason that practically continuous torque is obtained in an eight-cylinder engine is that one cylinder fires every ninety degrees of crank-shaft rotation, and as each impulse lasts nearly seventy-five per cent,of the stroke, one can easily appreciate that an engine that \dll givefour explosions per revolution of the crank-shaft will run more uni-formly than one that gives but three explosions per revolution, as thesix-cylinder does, and will be twice as smooth running as a four-cylin-der, in which but two explosions occur per revolution of the crank-shaft. The comparison is so clearly shown in graphical diagrams and inFig. 31 that further description is unnecessary.

Any eight-cylinder engine may be considered a ** twin-four,'' twelve-cylinder engines may be considered **twin sixes.''

The only points in which an eight-cylinder motor differs from a four-cylinder is in the arrangement of the connecting rod, as in manydesigns it is necessary to have two rods working from the same crank-pin. This difficulty is easily overcome in some designs by staggeringthe cylinders and having the two connecting rod big ends of conven-tional form side by side on a common crank-pin. In other designs onerod is a forked form and works on the outside of a rod of the regularpattern. Still another method is to have a boss just above the mainbearing on one connecting rod to which the lower portion of the con-necting rod in the opposite cylinder is liinged. As the eight-cylinderengine may actually be made lighter than the six-cylinder of equalpower, it is possible to use smaller reciprocating parts, such as pistons,connecting rods and valve gear, and obtain higher engine speed withpractically no vibration. The firing order in nearly every case is thesame as in a four-cylinder except that tlie explosions occur alternatelv

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in each set of cylinders. The firins: order of an eight-cylinder motor isapt to be confusing to the

motoi-ist, especially if one considers that there are eight possible se-quences. The majority of engineers favor the alternate firing from sideto side. Firing orders will he considered in proper sequence.

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The demand of aircraft designers for more power has stimulated de-signers to work out twelve-cylinder motors.

Fig. :i3.—The HaU-Scott Four-Cylinder 100 Horse-Povei AviationUotor.

TIk'so are liijih-siH'cd motors incorporating all recent fea-Uiics ol' (Ic-si;rii ill securing li^lit recrjjrocating ]iarts, large valvi' o])cninfrs. cic.Tlio twclvL'-cvlindiT motor incorpor-a(('s till lu'st fi'aliins i>l' hi.^li-speed motor design and there is no need at lliis time U> diM-ussI'lii'llier the pros and cons III' tile twi-lve-ryliiider vei'sus the eiijlit orsix, because it is cnnceded liy all lliat tliere is tlie same d.'.,'ree ofsteady ]n>\ver npiilieation in llic Iwehe over the eight as there wonJdlie in (lie eight over the si\'. 'I'lie qnestion resolves

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3J.—Two Views of tlie Duesenberg Sixteen Valve Foui-Cylliider Avi-ation Motor.

itself into having a motor of liigli power tliat ■will rxm ■with minim-um vibration and that produces smooth action. This is well sliown bydiagrams at Fig. 31. It sliould be remembered that if an eight-cylinderengine vnll give four explosions per revolution of the fly-wheel, a

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twelve-cylinder type will give six explosions per revolution, and in-stead of tiie impulses coming 90 degrees crank travel apart, as in thecase of the eight-cylinder, these will come but 60

Fig. 35.—Tlie HaU-Scott Slx-C:rlltider Aviation Engine.

degrees of crank travel apart in the case of the twelve-cylinder. Forthis i-eason. the eyhiiders of a twelve are usually separated by (30 de-grees while the eiglit has the block.s spai-ed 00 degrees apart. Thecomparison can be easily made by ct.niparing the sectional views ofVee engines at Fig. o'2. AVIht-u one realizes that the actual duration ofthe power stroki- is considerably greater than 120 degrees cranktravel, it will lie apparent that the overlapping of explor^ioiis must de-liver a very unifonn application of power. Vee engines have heende\'ised

ig the cylinders spaced but 45 dof^recs apart, but the isions cannot betimed at equal intervals as when 90 ies separate the cylinder centerlines.

B.\D1AL CYLlNDKIt AllIiASGEMKNTS

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•liile the fixed cylinder forms of engines, liaving the ders in tandem inthe four- and six-cylinder models own at Figs. 33 to 35 inclusive andthe eight-cvHnder oes as outlined at Figs. 36 and .37 have been gener-ally and are most in favor at the present time, other forms otors havingunconventional cylinder ari'angements been devised, though most ofthese are practically

16.—Tbe Onrtlss Elgbt-Cyllnder, 200 Hoise-Fower Aviation Engliie.

obsolete: ^'liile many iiiftliods of decreasing weight and increasingnicciianical olTicienoy of a motor -arc know-n to designers, one of thefirst to be applied to tho construction of aeronautical power plantsw'as an endeavor to group tlie components, -wliidi in tliomsclves werenot extremely light, into a rnrni tlint woulil be considerably lighterthan I the conventional design. As an example, we may consider thosemnlti])le-cylindt'i' forms in which the cylinders are

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Fig. 37.—Tbe Sturtevant Eight-Cylinder, Hlgb SpMd Avlitlon Hotot.

disposed aronnd a short crank-case, either radiating from a commoncenter as at Fig. 38 or of tlie fan shape shown at Fiff. 3i), This makes itjiossible to nse a crank-case but sliglifly lar^'er than that needed forone or two cylinders and it also jiermits of n e[»rresj)onding decreasein length of tlie crank-shaft. The weight of tlie engine is lessened be-cause of the reduction in crank-sliaft and crank-case \vei,i,'bt ami theelimination of a number of intermediate bearinirs and their supjiort-ing webs which would be necessary witli the usual tandcnt eouslnic-tioii. AVliile there are six jiowei- iiriiMilses tn every t'.vo icvelutioiiii ofthe crank-

jbaft, in the six-cylinder engine, they are not evenly spaced IS is pos-sible with the conventional arrangement.

In the Anzani form, which is shown at Fig. 38, the crank-jase is sta-tionary and a revolving crank-shaft is employed is in conventionalconstruction. The cvUnders are five

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Fig. 38.—Anzani 40-50 Hane-Power FIve-CyUnder Air Cooled Engine.

in number and the engine develops 40 to 50 H. P. with a weight of 72kilograms or 158.4 lbs. The cylinders are of the usual air-cooled formhaving cooling flanges only part of the way down the cylinder. By us-ing five cylinders it is possible to have the power impulses come regu-larly, they coming 145° crank-shaft travel apart, the crank-shaft mak-ing two turns to every five explosions. The balance is good and poweroutput regular. The valves are

plaeed directly in tlio cylimlor head and are operated by a coiimionpushrod. Attention is directed to the novel method of installing thecarburetor which supplies the mixture to the engine base from whichinlet pipes radiate to the various cylinders. This engine is used onFrench scliool macliines.

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In the foi-m shown at Fig. 39 six cylinders are used, all being placedabove the crank-shaft center line. This

Fig. 39.—UncouTeiiUonal Six-Cylindei Aircraft Motor of HasionDulgn-

engine is also of the air-oooled form and develops 50 H. P. and -wcig-lis 10.') kilogrnniP. or 2',\\ llis. The carburetor is connected to a mani-fold casting attached to the engine base from which the inductionpipes radiate to the various cylinders. The propeller design and size re-lative to the engine is clearly shown in this view. AVliile iliglits havebeen niadf! with botli of liie engines described, this method of cnns-tiuction is not generally followed and has been ahno.st CTitiiclydis|)hii'e(l ulirnad by the revolving motors or l>y the more coiiveniionnl eiglit-cylinder V engines. Bolli of tilt! engines shown wen" di-signed about eiglit years

ago and would be entirely too small and weak for use in modern air-planes intended for active duty.

BOTARY EilGISES

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Kotarj' eiiffines such as shown at Fig. 40 are generally aspocinted withthe idea of light coustruction and it is

Tig. 40.—The Onome Fourteen-Cyllnder Bevolrlng Motor.

rather an interesting point tliiit is often overlooked in connection withthe application of this idea to flight motors, that the reason why rotaryengines are popularly supposed to he lighter than the others is becausethey form their OM'n fly-whe*;!, yet on a('i'o])lnnei*, engines are sel-dom fitted with a fly-wheel at all. As a matter of fact the

Gnome engine is not so light because it is a rotary motor, and it is arotary motor because the design that, has been adopted as that mostconducive to lightness is

. also most suited to an engine working in this way. The cylinderscould be fixed and crank-shaft revolve without increasing the w^eightto any extent. There are two prime factors governing the lightness ofan engine, one being the initial design, and the other the quality of thematerials employed. The consideration of reducing weight by cuttingaway metal is a subsidiary method that ought not to play a part instandard practice, however useful it may be in special cases. In theGnome rotary engine the lightness is entirely due to the initial designand to the materials employed in manufacture. Thus, in the first case,the engine is a radial engine, and has its seven or nine cylindersspaced equally around a crank-chamber that is no wider or ratherlonger than would be required for any one of the cylinders. This short-ening of the crank-chamber not only effects a considerable saving ofweight on its own account, but there is a corresponding saving in theshafts and other members, the dimensions of which are governed bythe size of the crank-chamber. With regard to materials, nothing butsteel is used throughout, and most of the metal is forged chrome nick-el steel. The beautifully steady running of the engine is largely due to

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the fact that there are literally no reciprocating parts in the absolutesense,

• the apparent reciprocation between the pistons and cylinders beingsolely a relative reciprocation since both travel in circular paths, thatof the pistons, however, being electric by one-half of the stroke lengthto that of the cylinder.

WTiile the Gnome engine, has many advantages, on the other handthe head resistance offered by a motor of this type is considerable;there is a large waste of lubricating oil due to the centrifugal forcewhich tends to throw the oil away from the cylinders; the gyroscopiceffect of the rotary motor is detrimental to the best working of the

aeroplane, and moreover it requires about seven per c^nt. of the totalpower developed by the motor to drive the revolving cylinders aroundthe shaft. Of necessity, the compression of this type of motor is ratherlow, and an additional disadvantage manifests itself in the fact thatthere is as yet no satisfactory way of muffling the rotary type of motor.The modern Gnome engine has been widely copied in variousEuropean countries, but its design was originated in America, theearly Adams-Farwell engine being the pioneer form. It has been madein seven- and nine-cylinder types and forms of double these numbers.The engine illustrated at Fig. 40 is a fourteen-cylinder form. Thesimple engines have an odd number of cylinders in order to secureevenly spaced explosions. In the seven-cylinder, the impulses come102.8° apart. In the nine-cylinder form, the power strokes are spaced80° apart. The fourteen-cylinder engine is virtually two seven-cylindertypes mounted together, the cranks being just the same as in a doublecylinder opposed motor, the explosions coming 51.4° apart; while inthe eighteen-cylinder model the power impulses come every 40° cylin-der travel. Other rotary motors have been devised, such as the LeEhone and the Clerget in France and several German copies of these

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various types. The mechanical features of these motors will be fullyconsidered later.

CHAPTER V

Properties of Liquid Fuels—Distillates of Crude Petroleum—Principlesof Carburetion Outlined—Air Needed to Burn Gasoline—Wliat a Car-buretor Should Do—^Liquid Fuel Storage and Supply— Vacuum FuelFeed—Early Vaporizer Forms—Development of Float Feed Carbur-etor—Maybach's Early Design—Concentric Float and JetType—Schebler Carburetor—Claudel Carburetor— Stewart MeteringPin Type—Multiple Nozzle Vaportzers—^Two-Stage Carbur-etor—Master Multiple Jet Type—Compound Nozzle Zenith Carbur-etor—Utility of Gasoline Strainers—Intake Manifold Design and Con-struction—Compensating for Various Atmospheric Conditions—HowHigh Altitude Affects Power—The Diesel System—Notes on CarburetorInstallation—Notes on Carburetor Adjustment.

There is no appliance that has more material value upon the efficiencyof the internal combustion motor than the carburetor or vaporizerwhich supplies the explosive gas to the cylinders. It is only in recentyears that engineers have realized tlie importance of using carburetorsthat are efficient and that are so strongly and simply made that therewill be little liability of derangement. As the power obtained from thegas-engine depends upon the combustion of fuel in the cylinders, it isevident that if the gas supplied does not have the proper proportionsof elements to insure rapid combustion the efficiency of the enginewillbe low. When a gas engine is used as a stationary installation it ispossible to use ordinary illnmiiiat-ing or natural gas for fuel, but whenthis prime mover is applied to automobiles or airplanes it is evidentthat considerable difficulty would be experienced in carrying enoughcompressed coal gas to supply the engine for even a very short trip.

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Fortunately, the development of the internal-combustion motor wasnot delayed by the lack of suitable fuel.

Engineers were familiar with the properties of certain

no

iqnids which gave off vapors that could be mixed with air o form anexplosive gas which burned very well in the iigine cylinders. A verysmall quantity of such liquids rould suffice for a very satisfactory peri-od of operation. ?he problem to be solved before these liquids cduld be.pplied in a practical manner was to evolve suitable apparatus for va-porizing them without waste. Among the iquids that can be combinedwith air and burned, gasoline s the most volatile and is the fuel utilizedby intemal-ombustion engines.

The widely increasing scope of usefulness of»the in-emal-combustionmotor has made it imperative that other uels be applied in some in-stances because the supply of gasoline may in time become inadequateto supply the lemand. In fact, abroad this fuel sells for fifty to two lun-dred per cent, more than it does in America because-aost of the gasol-ine used must be imported from this ountry or Russia. Because of thisforeign engineers have xperimented widely with other substances,such as alco-ol, benzol, and kerosene, but more to determine if they anbe used to advantage in motor cars than in airplane ngines.

DISTILLATES OF CRUDE PETROLEUM

Crude petroleum is found in small quantities in almost 11 parts of theworld, but a large portion of that pro-iuced commercially is derivedfrom American wells. The letroleum obtained in this country yieldsmore of the 'olatile products than those of foreign production, and forhat reason the demand for it is greater. The oil fields >f this countryare found in Pennsylvania, Indiana, and )hio, and the crude petroleum

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is usually in association rith natural gas. This mineral oil is an agentfrom which nany compounds and products are derived, and the pre-dicts will vary from heavy sludges, such as asphalt, to he lighter andmore volatile components, some of which rill evaporate very easily atordinary temperatures.

The compounds derived from crude petroleum are com-

posed principally of hydrogen and carbon and are termed *^Hydro-carbons." In the crude product one finds many impurities, such as freecarbon, sulphur, and various earthy elements. Before the oil can beutilized it must be subjected to a process of purifying which is knownas refining, and it is during this process, which is one of destructivedistillation, that the various liquids are separated. The oil wasformerly broken up into three main groups of products as follows:Highly volatile, naphtha, benzine, gasoline, eight to ten per cent. Lightoils, such as kerosene and light lubricating oils seventy to eighty percent. Heavy oils or residuum five to nine per cent. From the foregoingit will be seen that the available supply of gasoline is determinedlargely by the demand existing for the light oils forming the larger partof the products derived from crude petroleum. New processes havebeen recently discovered by which the lighter oils, such as kerosene,are reduced in proportion and that of gasoline increased, though theresulting liquid is neither the high grade, volatile gasoline known inthe early days of motoring nor the low grade kerosene.

PRINCEPLES OF CARBURETION OUTLINED

The process of carburetion is combining the volatile vapors whichevaporate from the hydrocarbon liquids with certain proportions of airto form an inflammable gas. The quantities of air needed vary with dif-ferent liquids and some mixtures burn quicker than do other combina-tions of air and vapor. Combustion is simply burning and it may be

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rapid, moderate or slow. Mixtures of gasoline and air burn quickly, infact the combustion is so rapid that it is almost instantaneous and weobtain what is commonly termed an ^^ explosion. ^^ Therefore theexplosion of gas in the automobile engine cylinder which produces thepower is. really a combination of chemical elements which produceheat and an increase in the volume of the gas because of the increasein temperature.

If the gasoline mixture is not properly proportioned

the rate of burning will vary, and if the mixture is either too rich or tooweak the power of the explosion is reduced and the amount of powerapplied to the piston is decreased proportionately. In determining theproper proportions of gasoline and air, one must take the chemicalcomposition of gasoline into account. The ordinary liquid used for fuelis said to contain about eight-four per cent, carbon and sixteen percent, hydrogen. Air is composed of oxygen and nitrogen and theformer has a great affinity, or combining power, with the two constitu-ents of hydrocarbon liquids. Therefore, what we call an explosion ismerely an indication that oxygen in the air has combined with the car-bon and hydrogen of the gasoline.

AIB NEEDED TO BURN GASOLINE

In figuring the proper volume of air to mix with a given quantity offuel, one takes into account the fact that one pound of hydrogen re-quires eight poimds of oxygen to burn it, and one pound of carbonneeds two and one-third pounds of oxygen to insure its combustion.Air is composed of one part of oxygen to three and one-half portions ofnitrogen by weight. Therefore for each pound of oxygen one needs toburn hydrogen or carbon four and one-half pounds of air must be al-lowed. To insure combustion of one pound of gasoline which is com-posed of hydrogen and carbon we must furnish about ten pounds of

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air to bum the carbon and about six pounds of air to insure combus-tion of hydrogen, the other component of gasoline. This means that toburn one pound of gasoline one must provide about sixteen pounds ofair.

While one does not usually consider air as having much weight, at atemperature of sixty-two degrees Fahrenheit about fourteen cubic feetof air will weigh a pound, and to burn a pound of gasoline one wouldrequire about two hundred cubic feet of air. This amount will providefor combustion theoretically, but it is common practice to allow twicethis amount because the element nitrogen, which is the main constitu-ent of air, is an inert gas and

posed principally of hydrogen and carbon and are termed *41ydrocar-bons." In the crude product one finds many impurities, such as freecarbon, sulphur, and various earthy elements. Before the oil can beutilized it must be subjected to a process of purifying which is knownas refining, and it is during this process, which is one of destructivedistillation, that the various liquids are separated. The oil wasformerly broken up into three main groups of products as follows:Highly volatile, naphtha, benzine, gasoline, eight to ten per cent. Lightoils, such as kerosene and light lubricating oils seventy to eighty percent. Heavy oils or residuum five to nine per cent From the foregoingit will be seen that the available supply of gasoline is determinedlargely by the demand exist-ing for the light oils forming the largerpart of the products derived from crude petroleum. New processeshave been recently discovered by which the lighter oils, such as ker-osene, are reduced in proportion and that of gasoline increased,though the resulting liquid is neither the high grade, volatile gasolineknowTi in the early days of motoring nor the low grade kerosene.

PRINCEPLES OF CARBURETION OUTLINED

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The process of carburetion is combining the volatile vapors whichevaporate from the hydrocarbon liquids with certain proportions of airto form an inflammable gas. The quantities of air needed vary withdiflFerent liquids and some mixtures burn quicker than do other com-binations of air and vapor. Combustion is simply burning and it maybe rapid, moderate or slow. Mixtures of gasoline and air burn quickly,in fact the combustion is so rapid that it is almost instantaneous andAve obtain what is commonly termed an ^'exjjlosion.^' Therefore theexplosion of gas in tlie automobile engine cylinder which produces thepower is. really a combination of chemical elonu^iits whicli produceheat and an increase in the volume of the gas because of tlie increasein temperature.

If the gasoline mixture is not properly proportioned

the rate of burning will vary, and if the mixture is either too rich or tooweak the power of the explosion is reduced and the amount of powerapplied to the piston is decreased proportionately. In determining theproper proportions of gasoline and air, one must take the chemicalcomposition of gasoline into account. The ordinary liquid used for fuelis said to contain about eight-four per cent, carbon and sixteen percent, hydrogen. Air is composed of oxygen and nitrogen and theformer has a great aflinity, or combining power, with the two constitu-ents of hydrocarbon liquids. Therefore, what we call an explosion ismerely an indication that oxygen in the air has combined with the car-bon and hydrogen of the gasoline.

AIB NEEDED TO BURN GASOLINE

In figuring the proper volume of air to mix with a given quantity offuel, one takes into account the fact that one pound of hydrogen re-quires eight poimds of oxygen to burn it, and one pound of carbonneeds two and one-third pounds of oxygen to insure its combustion.

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Air is composed of one part of oxygen to three and one-half portions ofnitrogen by weight. Therefore for each pound of oxygen one needs toburn hydrogen or carbon four and one-half pounds of air must be al-lowed. To insure combustion of one pound of gasoline which is com-posed of hydrogen and carbon we must furnish about ten pounds ofair to bum the carbon and about six pounds of air to insure combus-tion of hydrogen, the other component of gasoline. This means that toburn one pound of gasoline one must provide about sixteen pounds ofair.

While one does not usually consider air as having much weight, at atemperature of sixty-two degrees Fahrenheit about fourteen cubic feetof air will weigh a pound, and to bum a pound of gasoline one wouldrequire about two hundred cubic feet of air. This amount wall providefor combustion theoretically, but it is common practice to allow twicethis amount because the element nitrogen, which is the main constitu-ent of air, is an inert gas and

compressed and ignited in the motor cylinder. Modem carburetors arenot only called upon to supply certain quantities of gas, but these mustdeliver a mixture to the cylinders that is accurately proportioned andwhich will be of proper composition at all engine speeds.

Flexible control of the engine is sought by varying the engine speed byregulating the supply of gas to the cylinders. The power plant shoiildrun from its lowest to its highest speed without any irregularity intorque, i.e., the acceleration should be gradual rather than spasmodic.As the degree of compression will vary in value with the amount ofthrottle opening, the conditions necessary to obtain maximum powerdiffer with varying engine speeds. When the throttle is barely openedthe engine speed is low and the gas must be richer in fuel than whenthe throttle is wide open and the engine speed high.

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When an engine is turning over slowly the compression has low valueand the conditions are not so favorable to rapid combustion as whenthe compression is high. At high engine speeds the gas velocitythrough the intake piping is higher than at low speeds, and regular en-gine action is not so apt to be disturbed by condensation of liquid fuelin the manifold due to excessively rich mixture or a superabundance ofliquid in the stream of carbureted air.

UQUm FUEL STORAGE AND SUPPLY

The problem of gasoline storage and method of supplying the carbur-etor is one that is determined solely by design of the airplane. Whilethe object of designers should be to supply the fuel to the carburetorby as simple means as possible the fuel supply system of some air-planes is quite complex. The first point to consider is the location ofthe gasoline tank. This depends upon the amount of fuel needed andthe space available in the fuselage.

A very simple and compact fuel supply system is shown at Fig. 41. Inthis instance the fuel container is placed inamediately back of the en-gine cylinder. The carburetor

which is carried as indicated is joined to the tank by a short piece ofcopper or flexible rubber tubing. This is the simplest possible form offuel supply system and one used on a number of excellent airplanes.

As the sizes of engines increase and the power plant fuel consumptionaugments it is necessary to use more fuel, and to obtain a satisfactoryflying radius without frequent landings for filling the fuel tank it is ne-cessary to supply large containers.

When a very powerful power plant is fitted, as on battle planes of highcapacity, it is necessary to carry large quantities of gasoline. In orderto use a tank of sufficiently large capacity it may be necessary to carry

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it lower than the carburetor. When installed in this manner it is neces-sary to force fuel out of the tank by air pressure or to pump it with avacuum tank because the gasoline tank is lower than the carburetor itsupplies and the gaso^ line cannot flow by gravity as in the simplersystems. While the pressure and gravity feed systems are generallyused in airplanes, it may be well to describe the vacuum lift systemwhich has been widely applied to motor cars and which may havesome use in connection with airplanes as these machines aredeveloped.

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STEWART VACUUM FUEL FEED

One of the marked tendencies has been the adoption of a vacuum fuelfeed system to draw the gasoline from tanks placed lower than the car-buretor instead of using either exhaust gas or air pressure to achievethis end. The device generally fitted is the Stewart vacuum feed tankw^hich is clearly shown in section at Fig. 42. In this system the suc-tion of a motor is employed to draw gasoline from the main fuel tankto the auxiliary tank incorporated in the device and from this tank theliquid flows to the carburetor. It is claimed that all the advantages ofthe pressure system are obtained with very little more complicationthan is found on the ordinary gravity feed. The mechanism is all con-tained in the cylindrical tank shown,

Aviation Engines

which may be mounted either on the front of the dash or on the side ofthe engine as shown.

The tank is divided into two chambers, the upper one being the fillingchamber and the lower one the emptying

Fig. 42.—The Stewart Vaciiiuii Fuel Feed Tank.

chamber. The former, whicli is at the top of the device, contains thefloat valve, a.** well as the pipes running to the main fuel containerand to the intake manifold. The lower chamber is used to supply tliecarburetor with gasoline and is under atmospheric pressure at alltimes, so the flow of fuel from it is by means of gravity only. Since

•

Stewart Vacuum Feed System 119

■

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this chamber is located somewhat above the carburetor, there must al-ways be free flow of fuel. Atmospheric pressure is maintained by thepipes A and B, the latter opening into the air. In order that the fuel willbe sucked from a main tank to the upper chamber, the suction valvemust be opened and the atmospheric valve closed. Under these condi-tions the float is at the bottom and the suction at the intake manifoldproduces a vacuum in the tank which draws the gasoline from themain tank to the upper chamber. When the upper chamber is filled atthe proper height the float rises to the top, this closing the suctionvalve and opening the atmospheric valve. As the suction is now cut off,the lower chamber is filled by gravity owing to there being atmospher-ic pressure in both upper and lower chambers. A flap valve is providedbetween the two chambers to prevent the gasoline in the lower onefrom being sucked back into the upper one. The atmospheric and suc-tion valves are controlled by the levers C and D, both of which arepivoted at E, their outer ends being connected by two coU springs. It isseen that the arrangement of these two springs is such that the floatmust be held at the extremity of its movement, and that it cannot as-sume an intermediate position.

This intermittent action is required to insure that the upper part of thetank may be under atmospheric pressure part of the time for the gasol-ine to flow to the lower chamber. When the level of gasoline drops to acertain point, the float falls, thus opening the suction valve and closingthe atmospheric valve. The suction of the motor then causes a flow offuel from the main container. As soon as the level rises to the properlieight the float returns to its upper position. It takes about twoseconds for the chamber to become full enough to raise the float, asbut .05 gallon is transferred at a time. The pipe running from the bot-tom of the lower chamber to the carburetor extends up a ways, so thatthere is but little chance of dirt or water being carried to the floatchamber.

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If the engine is allowed to stand long enough so that the

tank becomes empty, it will be replenished after the motor has beencranked over four or five times with the throttle closed. The installa-tion of the Stewart Vacuum-Gravity System is very simple. The suctionpipe is tapped into the manifold at a point as near the cylinders as pos-sible, while the fuel pipe is inserted into the gasoline tank and runs tothe bottom of that member. There is a screen at the end of the fuelpipe to prevent any trouble due to deposits of sediment in the maincontainer. As the fuel is sucked from the gasoline tank a small ventmust be made in the tank filler cap so that the pressure in the maintank will always be that of the atmosphere.

EARLY VAPORIZER FORMS

The early types of carbureting devices were very crude and cumber-some, and the mixture of gasoline vapor and air was accomplished inthree ways. The air stream was passed over the surface of the liquid it-self, through loosely placed absorbent material saturated with liquid,or directly through the fuel. The first type is known as the surface car-buretor and is now practically obsolete. The second form is called the^^wick'^ carburetor because the air stream was passed over orthrough saturated wicking. The third form was known as a ^*bub-bling^* carburetor. While these primitive forms gave fairly good res-ults with the early slow-speed engines and the high grade, or veryvolatile, gasoline which was first used for fuel, they would be entirelyunsuitable for present forms of engines because they would not car-burate the lower grades of gasoline which are used to-day, and wouldnot supply the modern high-speed engines with gas of the proper con-sistency fast enough even if they did not have to use very volatile gas-oline. The form of carburetor used at the present time operates on adifferent principle. These devices are kno\\Ti as *^spraying

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carburetors.^* The fuel is reduced to a spray by the suction effect ofthe entering air stream drawing it through a fine opening.

The advantage of this construction is that a more

Early Vaporizer Fornm

121

, thorough amalgamation of the gasoline and air particles is obtained."With the earlier types previously considered the air would combinewith only the more volatile elements, leaving the heavier constituentsin the tank. As the fuel became stale it was difficult to vaporize it, andit had to

—Marine-Type Mixing Valv^ by which QmoUdo la Sprayed Into AirStream Tbiougb Small Opening In Alr-ValTe Seat.

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be drained off and fresh fuel provided before the proper mixturewould be produced. It ^^'ill be evident that when the fuel is sprayedinto the air stream, all the fuel will be used up and the heavier portionsof the gasoline will be taken into the cylinder and vaporized just aswell as the more volatile vapors.

The simplest form of spray carburetor is that shown at Fig. 43. In thisthe gasoline opening through which

the fuel is sprayed into the entering air stream is closed by the spring-controlled mushroom valve which regulates the main air opening aswell. When the engine draws in a charge of air it unseats the valve andat the same time the air flowing around it is saturated with gasolineparticles through the gasoline opening. The mixture thus formed goesto the engine through the mixture passage. Two methods of varyingthe fuel proportions are provided. One of these consists of a needlevalve to regulate tlie amount of gasoline, the otlier is a knurled screwwhich controls the amoimt of air by limiting the lift of the jump valve.

DEVELOPMENT OF FLOAT-FEED CARBURETOR

The modern form of spraying carburetor is provided with two cham-bers, one a mixing chamber through wliich the air stream passes andmixes with a gasoline spray, the other a float chamber in which a con-stant level of fuel is maintained by simple mechanism. A jet or stand-pipe is used in the mixing chamber to spray the fuel through and theobject of the float is to maintain the fuel level to such a point that itwill not overflow the jet when the motor is not drawing in a charge ofgas. With the simple forms of generator valve in which the gasolineopening is controlled by the air valve, a leak anywhere in either valveor valve seat will allow the gasoline to flow continuously whether theengine is drawing in a charge or not. The liquid fuel collects aroundthe air opening, and when the engine inspires a charge it is saturated

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with gasoline globules and is excessively rich. With a float-feed con-struction, which maintains a constant level of gasoline at the rightheight in the standpipe, liquid fuel vnll only be supplied when dra\\Tiout of the jet by the suction effect of the entering air stream.

MAYBACH^S EARLY DESIGN

The first form of spraying carburetor ever applied successfullv wasevolved l)v Mavl)ach for use on one of the

Maybach's Early Design

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V.

II

K !

it 1° II

ti S

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earliest Daimler engines. The general principles of operation of thispioneer float-feed carburetor are shown at Fig. 44, A. The mixingchamber and valve chamber were one and the standpipe or jet pro-truded into the mixing chamber. It was connected to the float com-partment by a pipe. The fuel from the tank entered the top of the floatcompartment and the opening was closed by a needle valve carried ontop of a hollow metal float. Wlien the level of gasoline in the floatchamber was lowered the float would fall and the needle valve uncoverthe opening. This would permit the gasoline from the tank to flow intothe float chamber, and as the chamber filled the float w^ould rise untilthe proper level had been reached, under which conditions the floatwould shut off the gasoline opening. On every suction stroke of the en-gine the inlet valve, which 'was an automatic tj'pe, would leave its seatand a stream of air would be dra\Mi through the air opening andaround the standpipe or jet. This would cause the gasoline to spray outof the tube and mix with the entering air stream. The form shown at Bwas a modification of Maybach's simple device and was first used onthe Phcenix-Daimler engines. Several improvements are noted in thisdevice. First, the carburetor was made one unit by casting the floatand mixing chambers together instead of making them separate andjoining them by a pipe, as shown at A. The float construction was im-proved and the gasoline shut-off valve was operated through leverageinstead of being directly fastened to the float. The spray nozzle wassurrounded by a choke tube which concentrated the air stream aroundit and made for more rapid air flow at low engine speeds. A conicalpiece was placed over the jet to break up the entering spray into a mistand insure more intimate • admixture of air and gasoline. The airopening was provided with an air cone which had a shutter controllingthe opening so that the amount of air entering could be regulated andthus vary the mixture proportions within certain limits.

CONCENTRIC FLOAT AND JET TYPE

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The form shown at B has been further improved, and the type shownat C is representative of modern single jet practice. In this the floatchamber and mixing chamber are concentric. A balanced float mech-anism which insures steadiness of feed is used, the gasoline jet orstandpipe is provided with a needle valve to vary the amount of gasol-ine supplied the mixture and two air openings are provided. The mainair port is at the bottom of the vaporizer, while an auxiliary air inlet isprovided at the side of the mixing chamber. There are two methods ofcontrolling the mixture proportions in thig form of carburetor. Onemay regulate the gasoline needle or adjust the auxiliary air valve.

SCHEBLER CARBURETOR

A Schebler carburetor, which has been used on some airplane engines,is showTi in Fig. 45. It will be noticed that a metering pin or needlevalve opens the jet when the air valve opens. The long arm of a lever-age is connected to the air valve, while the short arm is connected tothe needle, the reduction in leverage being such that the needle valveis made to travel much less than the air valve. For setting the amountof fuel passed or the size of the jet orifice when running with the airvalve closed, there is a screw which raises or lowers the fulcrum of thelever and there is also a dash control having the same effect by push-ing down, the fulcrum against a small spring. A long extension is givento the venturi tube which is very narrow around the jet orifices, whichare horizontal and shown at A in the drawing. Fuel enters the floatchamber through the union M, and the spring P holds the meteringpin upward against the restraining action of the lever. The air valvemay be set by an easily adjustable knurled screw shown in the draw-ing, and fluttering of the valve is prevented by the piston dash pot car-ried in a chamber above the valve into which the valve stem projects.The

Aviation Engines

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Claudel Carburetor

127

lary air enters beneath the jet passage and there is ■all throttle in theintake to increase the speed of air for starting purposes. The carbur-etor is adapted for use of a hot-air connection to the stove around theust pipe and it is recommended that such a fitting be ■lied. The leverwhich controls the supply of air

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.■Mixture Outlet

Fig. 46.—The Claadel Catliuietor

iigh the primary air intake is so arranged that if retl it can bo connec-ted with a linkage on the dash jntrol column by, means of a flexiblewire.

THE CLAUDEL (fIIENCII) CARBrKKTOB

!'hia carburetor is of extremely simple construction, use it has no sup-plementary or auxiliary nir valve no moving parts except the throttlecontrolling the flow. The constntrfion is already showni in Pig. 46.

The spray jet is eccentric with a surrounding sleeve or tube in whichthere are two series of small orifices, one at the top and the other nearthe bottom. The former are about level with the spray jet opening. Thesleeve surrounding the nozzle is closed at the top. The air, passing theupper holes in the sleeve, produces a vacuum in the sleeve, therebydrawing air in through the bottom holes. It is this moving interiorcolumn of air that controls the flow of gasoline from the nozzle. Owing

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to the friction of the small passages, the speed of air flow through thesleeve does not increase as fast as the speed of air flow outside thesleeve, hence there is a tendency for the mixture to remain constant.The throttle of this carburetor is of the barrel type, and the top of thespray nozzle and its surroimding sleeve are located inside the throttle.

STEWART METERING PIN CARBURETOR

The carburetor shown at Fig. 47 is a metering type in which the vacu-um at the jet is controlled by the weight of the metering valve sur-rounding the upright metering pin. The only moving part is the meter-ing valve, which rises and falls with the changes in vacuum. The airchamber surrounds the metering valve, and there is a mixing chamberabove. As the valve is drawn up the gasoline passage is enlarged on ac-count of the predetermined taper on the metering pin, and the air pas-sage also is increased proportionately, giving the correct mixture. Adashpot at the bottom of the valve checks flutter. In idling the valverests on its seat, practically closing the air and giving the necessary id-ling mixture. A passage through the valve acts as an aspirating tube.When the valve is closed altogether the primary air passes throughducts in the valve itself, giving the proper amount for idling. The oneadjustment consists in raising or lowering the tapered metering pin,increasing or decreasing the supply of gasoline. Dash control is sup-plied. This pulls down the metering pin, increasing the gasoline flow.The duplex type for eight- and twelve-cylinder motors is the same in

Multiple Nozzle Vaporizera

120

principle as model 25, but it is a double carburetor synchronized as tothrottle movements, adjustments, etc. The duplex for aeronautical mo-tors is made of cast aluminum alloy.

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MULTIPLE NOZZLE VAPORIZEBS ^

To secure properly proportioned mixtures some carburetor designershave evolved forms in which two or more nozzles are used in a com-mon mixing chamber. The usual construction is to use two, one havinga small opening and placed in a small air tube and used only for low

Fig. 17.—The Stewart Meteiing Fin Carburetor.

is held closed by a spring. The cylindrical chamber at the right of themixing chamber has an extension E of reduced diameter connecting itwith the intake manifold through a passage D. A restricted openingconnects the float chamber ^vith the cylindrical chamber so that thegasoline level is the same in both. A loosely fitting plunger P in the cyl-indrical chamber has an upward extension into the small part of thechamber. 0 is a small air opening and M is a passage from the

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cylindrical chamber to the mixing chamber. Air constantly passesthrough this when the carburetor is in operation. The carburetor isreally two in one. The primary carburetor is made up of a central jet ina venturi passage. The float chamber is eccentric. In the air passagethere is a fixed opening, and additional air is taken in by the openingthrough suction of a spring-opposed air valve. The second stage, whichcomes into play as soon as the carburetor is called upon for additionalmixture above low medium speeds, is made up of an independent airpassage containing another air valve. As the yalve is opened this jet isuncovered, and air is led past it. For easy starting an extra passageleads froA the float bowl passage to a point above the throttle. All thesuction falls upon this passage when the throttle is closed. The passagecontains a plunger and acts as a pick-up device. When the vacuum in-creases the plunger rises and shuts off the flow of gasoline from the in-take passage. As the throttle is opened the vacuum in the intake pas-sage is broken, and the plunger falls, causing gasoline to gather aboveit. This is immediately drawn through the pick-up passage and givesthe desired mixture for acceleration.

MASTER MULTIPLE-JET CARBURETOR

This carburetor, sho^^^l in detail in Figs. 49 and 50, has been verypopular in racing cars and aviation engines because of exceptionallygood pick-up qualities and its thorough atomization of fuel. Its prin-ciple of operation is the breaking up of the fuel by a series of jets,which

vary in number from fourteen to twenty-one, according to the size ofthe carburetor. These are uncovered by opening the throttle, which iscurved—a patented feature —to secure the correct progression of jets.The carbu-

8 A EStaaaar,

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Fig, 49.—Tlie Master Oarlniretor.

retor has an eccentric float chamber, from which the gasoline is led tothe jet piece from which the jets stand up in a row. The tops of thesejets are closed until the throttle is opened far enough to pass them,wliich it does progressively. The air opening is at the bottom, and thethrottle opening is such that a modified venturi is formed.

is held closed by a spring. The cylindrical chamber at the right of themixing chamber has an extension E of reduced diameter connecting itwith the intake manifold through a passage D. A restricted openingconnects the float chamber with the cylindrical chamber so that thegasoline level is the same in both. A loosely fitting plunger P in the cyl-indrical chamber has an upward extension into the small part of thechamber. 0 is a small air opening and M is a passage from the cyl-indrical chamber to the mixing chamber. Air constantly passes

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through this when the carburetor is in operation. The carburetor isreally two in one. The primary carburetor is made up of a central jet ina venturi passage. The float chamber is eccentric. In the air passagethere is a fixed opening, and additional air is taken in by the openingthrough suction of a spring-opposed air valve. The second stage, whichcomes into play as soon as the carburetor is called upon for additionalmixture above low medium speeds, is made up of an independent airpassage containing another air valve. As the yalve is opened this jet isuncovered, and air is led past it. For easy starting an extra passageleads froA the float bowl passage to a point above the throttle. All thesuction falls upon this passage when the throttle is closed. The passagecontains a plunger and acts as a pick-up device. AMien the vacuum in-creases the plunger rises and shuts off the flow of gasoline from the in-take passage. As the throttle is opened the vacuum in the intake pas-sage is broken, and the plunger falls, causing gasoline to gather aboveit. This is immediately drawn through the pick-up passage and givesthe desired mixture for acceleration.

MASTER MULTIPLE-JET CARBURETOR

This carburetor, shown in detail in Figs. 49 and 50, has been very pop-ular in racing cars and aviation engines because of exceptionally goodpick-up qualities and its thorough atomization of fuel. Its principle ofoperation is the breaking up of the fuel by a series of jets, which

vary in number from fourteen to twenty-one, according to the size ofthe carburetor. These are uncovered by opening the throttle, which iscurved—a patented feature —to secure the correct progression of jets.The earbu-

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Fig. 49.—The Huter Oarburetor,

retor has an eccentric float chamber, from which the gasoline is led tothe jet piece from which the jets stand up in a row. The tops of thesejets are closed until the throttle is opened far enough to pass them,wliich it does progressively. The air opening is at the bottom, and thethrottle opening is such that a modified venturi is formed.

Aviation Engines

The throttle is carried in a cylindrical barrel with the jets placed belowit, and the passage from the barrel to the intake is arranged so thatthere is no interruption in the flow. For easy starting a dash-controlledslmtter closes

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Fig. 50.—SecUonal View of Mutoi Oarbantor Sbowlng Farts.

off the air, throwing the suction on the jets, thus giving a rich mixture.

The only adjustment is for idling, and once that is fixed it need neverbe touched. This is in the form of a screw and regulates the position ofthe throttle when at idling position. The dasli control has high-speed,normal and ricli-starting positions. In installing the Master carburetorthe float chamber may be turned either toward the radiator or driver'sseat. If the float is turned toward the radiator, however, a forward lugplate should be ordered; otherwise it will be difficult to install the con-trol. The throttle lever must go all the way to the stop lug

or maiimtiia power will not be secured. In adjusting the idle screw it isturned in for rich and out for lean.

COMPOUND NOZZLE ZENITH CABBURETOR

The Zenith carburetor, shown at Fig. 51, has become very popular forairplane engine use because of its simplicity, as mixture compensation

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is secured by a compensating compound nozzle principle that worksvery well in practice. To illustrate this principle briefly, let us considerthe elementary type of carburetor or mixing valve, as shown in Fig. 52,A. It consists of a single jet or spraying nozzle placed in the path of theincoming air and fed from the usual float chamber. It is a natural

PRIMING HOLE If PRIMING TUBE J

CAP JET H

COMPENSATOR t

Fig. 61.—Sectional ^

Aviation Engines

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inference to suppose that as the speed of the motor in-creaseSy boththe flow of air and of gasoline will increase in the same proportion.Unhappily, such is not the case. There is a law of liquid bodies whichstates that the flow of gasoline from the jet increases under suctionfaster than the flow of air, giving a mixture which grows richer andricher—a mixture containing a much higher percentage of gasoline athigh suction than at low. The tendency is shown by the accompanyingcurve (Fig. 52, B), which gives the ratio of gasoline to air at varyingspeeds from this type of jet. The mixture is practically constant onlybetween narrow limits and at very high speed. The most commonmethod of correcting this defect is by putting various auxiliary airvalves which, adding air, tends to dilute this mixture as it gets too rich.

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It is difficult with makeshift devices to gauge this dilution accuratelyfor every motor speed.

Now, if we have a jet which grows richer as the suction increases, theopposite type of jet is one which would grow leaner under similar con-ditions. Baverey, the inventor of the Zenith, discovered the principle ofthe constant flow device which is shown in Fig. 52, C. Here a certainfixed amount of gasoline determined by the opening I is permitted toflow by gravity into the well J open to the air. The suction at jet H hasno effect upon the gravity compensator I because the suction is des-troyed by the open well J. The compensator, then, delivers a steadyrate of flow per xmit of time, and as the motor suction increases moreair is drawn up, while the amount of gasoline remains the same andthe mixture grows poorer and poorer. Fig. 52, D, shows this curve.

By combining these two types of rich and poor mixture carburetors theZenith compound nozzle was evolved. In Fig. 52, E, we have both thedirect suction or richer type leading through pipe E and nozzle G andthe ** constant flow'' device of Baverey shown at J, I, K and nozzle H%One counteracts the defects of the other, so that from the cranking ofthe motor to its highest speed there is

Aviation Engines

a constant ratio of air and gasoline to supply efficient combustion.

In addition to the compound nozzle the Zenith is equipped with astarting and idling weU, shown in the cut of Model L carburetor at Pand J. This terminates in a priming hole at the edge of the butterflyvalve, where the suction is greatest when this valve is slightly open.The gas<:rfine is draM-n up by the suction at the priming hole and,mixed iv-ith the air rushing by the butterfly, gives an ideal slow speedmixture. At higher speeds

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. Tig. 63.—The Zenith Duplex Carhnretor for Aliplans Hoton of tlw TTyp«>

with the butterfly valve opened further the priming well ceases to op-erate and the compound nozzle drains the well and compensates cor-rectly for any motor speed.

With the coming of the double motor containing eight or twelve cylin-ders arranged in two V blocks, the question of good carburetion liasbeen a problem requiring much study. The single carburetor has givenonly indifferent results due to the strong cross suction in the inletmanifold from one set of cylinders to the other. This naturally led tothe adoption of two carburetors in which each set of cylinders was in-dependently fed by a separate car-

Zenith Carburetor Installation

189

bnretor. Results from this system were very good when the two car-buretors were working exactly in unison, but as it was extremely diffi-cult to accomplish this co-operation, especially where the adjustabletype was employed,

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flrtiKe Pipe

Tig. St.—Beu View of Cnrtlss 0X2 90 Borm-Fower Airplane HotoiSliowliiK Caibnrator Location and Hot Air Iieada.

this system never gained in favor. The next logical step was the ZenithDuplex, shown at Fig. 53. This consists of two separate and distinctcarburetors joined together so that a common gasoline float chamberand air inlet could be used by both. It does away with cross suction inthe manifold because each set of cylinders has a sep-

arate intake of its own. It does away with two carburetors and makesfor simplicity. The practical application of the Zenith carburetor to theCurtiss 90 horse-power 0X2 motor used on the J.N.4 standard train-ing machine is showTi at Fig. 54, which outlines a rear view of the en-gine in question. The carburetor is carried low to permit of fuel supplyfrom a gravity tank carrieii back of the motor.

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UTILIIY OF GASOLIIfE STRAINERS

Many carburetors include a filtering screen at the point where the li-quid enters the float chamber in order to keep dirt or any other foreignmatter w^hich may be present in the fuel from entering the floatchamber. This is not general practice, however, and the majority of va-porizers do not include a filter in their construction. It is very desirablethat the dirt should be kept out of the carburetor because it may getunder the float control fuel valve and cause flooding by keeping itraised from its seat. If it finds its way into the spray nozzle it mayblock the opening so that no gasoline ^vill issue or may so constrictthe passage that only very small quantities of fuel will be supplied themixture. Whel'e the carburetor itself is not provided with a filteringscreen a simple filter is usually installed in the pipe line between thegasoline tank and the float chamber.

Some simple forms of filters and separators are shown at Fig. 55. Thatat A consists of a simple brass casting having a readily detachablegauze screen and a settling chamber of sufficient ^capacity to allowthe foreign matter to settle to the bottom, from which it is drained outby a pet cock. Any water or dirt in the gasoline will settle to the bottomof the chamber, and as all fuel delivered to the carburetor must passthrough the wire gauze screen it is not likely to contain impuritieswhen it reaches the float chamber. The heavier particles, such as scalefrom the tanlc or dirt and even water, all of which have greater weightthan the gasoline, will sink to the bottom of the

chamber, whereas light particles, such as lint, will be prevented fromflowing into the carburetor by the filtering screen.

The filtering device shown at B is a larger appliance than that shown atA, and should be more efficient as a

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Fig. 66.—T]rpw of strainers InteipoMd Between Vaporizer andOuoUne Tank to Prevent Water or Dirt Faaalng Into CarburetingDevice.

separator because the gasoline is forced to pass through three filteringscreens before it reaches the carburetor. The gasoline enters the deviceshown at C through a bent pipe which leads directly to the settlingchamber and from thence through ■ a wire gauze screen to the uppercompartment which leads to the carburetor. The device shown at D isa combination strainer, drain, and sedi-

arate intake of its own. It does away with two carburetors and makesfor simplicity. The practical application of the Zenith carburetor to theCurtiss 90 horse-power 0X2 motor used on the J.N.4 standard train-ing machine is shown at Fig. 54, which outlines a rear view of the en-gine in question. The carburetor is carried low to permit of fuel supplyfrom a gravity tank carried back of the motor.

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UTIUTY OF GASOLINE STRAINERS

Many carburetors include a filtering screen at the point where the li-quid enters the float chamber in order to keep dirt or any other foreignmatter which may be present in the fuel from entering the float cham-ber. This is not general practice, however, and the majority ofvaporizers

do not include a filter in their construction. It is verv

»

desirable that the dirt should be kept out of the carburetor because itmay get under the float control fuel valve and cause flooding by keep-ing it raised from its seat. If it finds its way into the spray nozzle it mayblock the opening so that no gasoline Anil issue or may so constrict thepassage that only very small quantities of fuel will be supplied the mix-ture. Whei'e the carburetor itself is not provided with a filtering screena simple filter is usually installed in the pipe line between the gasolinetank and the float chamber.

Some simple forms of filters and separators are shown at Fig. 55. Thatat A consists of a simple brass casting having a readily detachablegauze screen and a settling chamber of sufficient^capacity to allow theforeign matter to settle to the bottom, from which it is drained out by apet cock. Any water or dirt in the gasoline vnYl settle to the bottom ofthe chamber, and as all fuel delivered to the carburetor must passthrough the Avire gauze screen it is not likely to contain impuritieswhen it reaches the float chamber. The heavier particles, such as scalefrom the tank or dirt and even w^ater, all of which have greaterweigKt than the gasoline, will sink to the bottom of the

Utility of Gasoline Strainers

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111

chamber, whereas light particles, such as lint, will be prevented fromflowing into the carburetor by the filtering screen.

The filtering device shown at B is a larger appliance than that shown atA, and should be more efficient as a

Fig. 5S.—TypM Of Strainers IiiterpoB«d Between Vaporizer andOaaoUne Tank to Frerent Water or Dirt Passing Into OarbnretlngDevice.

separator because the gasoline is forced to pass through three filteringscreens before it reaches the carburetor. The gasoline enters the deviceshown at C through a bent pipe which leads directly to the settlingchamber and from thence through a wire gauze screen to the upper

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compartment which leads to the carburetor. The device shown at D isa combination strainer, drain, and sedi-

ment cup. The filtering screen is held in place by a spring and botli areremoved by taking ont a plug at the bottom of tlie de\ice. The shut-offvalve at the top of the device is interposed between the sediment cupand the carburetor. This separating device is incorporated with thegasoline tank and forms an integral part of the gasoline supply system.The other types shown are designed to be interposed between the gas-oline tank and the carburetor at any point in the pipe line where theymay be conveniently placed.

INTAKE MANIFOLD DESIGN AND CONSTRUCTION

On four- and six-cylinder engines and in fact on all multiple-cylinderforms, it is important that the piping Jeading from the carburetor tothe cylinders be made in such a way that the various cylinders will re-ceive their full quota of gas and that each cylinder will receive itscharge at about the same point in the cycle of operations. In order tomake the passages direct the bends should be as few as possible, andwhen curves are necessary they should be of large radius because anabrupt comer will not only impede gas flow but will tend to promotecondensation of the fuel. Every precaution should be taken with four-and six-cylinder engines to insure equitable gas distribution to thevalve chambers if regular action of the power plant is desired. If thegas pipe has many turns and angles it will be difficult to charge all cyl-inders properly. On some six-cylinder a\^ation engines, two carbur-etors are used because of trouble experienced with manifolds designedfor one carburetor. Duplex carburetors are necessary to secure thebest results from eight- and twelve-cylinder V engines.

The problem of intake piping is simplified to some extent on blockmotors where the intake passage is cored in the cylinder casting and

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Avliere but one short pipe is needed to join this passage to the carbur-etor. If the cylinders are cast in pairs a simple pipe of T or T form canbe used with success. ^Mien the engine is of a tyi>e

nsing individual cylinder castings, especially in the six-cylinder powerplants, the proper application and installation of suitable piping is adifficult problem. The reader is referred to the various engine designsoutlined to ascertain how the inlet piping has been arranged on rep-resentative aviation engines. Intake piping is constructed in two ways,the most common method being to cast the manifold of brass or alu-minum. The other method, which is more costly, is to use a built-upconstruction of copper or brass tubing with cast metal elbows and Ypieces. One of the disadvantages advanced against the cast manifold isthat blowholes may exist which produce imperfect castings and whichwill cause mixture troubles because the entering gas from the carbur-etor, which may be of proper proportions, is diluted by the excess airwhich leaks in through the porous casting. Another factor of some mo-ment is that the roughness of the walls has a certain amount of frictionwhich tends to reduce the velocity of the gases, and when projectingpieces are present, such as core wire or other points of metal, thesetend to collect the drops of liquid fuel and thus promote condensation.The advantage of the built-up construction is that the walls of thetubing are very smooth, and as the castings are small it is not difficultto clean them out thoroughly before they are incorporated in the man-ifold. The tubing and castiligs are joined together by hard soldering,brazing or autogenous welding.

COMPENSATING FOR VARYING ATMOSPHERIC CONDFIIONS

The low-grade gasoline used at the present time makes it necessary touse vaporizers that are more susceptible to atmospheric variationsthan when higher grade and more volatile liquids are vaporized. Sud-den temperature changes, sometimes being as much as forty degrees

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rise or fall in twelve hours, affect the mixture proportions to some ex-tent, and not only changes in temperature but variations in altitudealso have a bearing on'mixture proportions by aJBfecting both gasol-ine and air. As the tem-

Aviation Engines

perature falls the specific gravity of the gasoline increases and it be-comes heavier, this producing difficulty in vaporizing. The tendency ofvery cold air is to condense gasoline instead of vaporizing it and there-fore it is necessary to supply heated air to some carburetors to obtainproper mixtures during cold weather. In order that the gas mixtureswill ignite properly the fuel must be vaporized and thoroughly mixedwith the entering air either by heat or

Fig. 56. — Chart Showing Dimihation of Air Pressure as AltitudeIncreases.

high velocity of the gases. The application of air stoves to the Curtiss0X2 motor is clearly sho\\Ti at Fig. 54. It will be seen that flexiblemetal pipes are used to convey the heated air to the air intakes of theduplex mixing chamber.

HOW HIGH ALTITUDE AFFECTS POWEB

Any internal combustion engine will show less power at high altitudesthan it will deliver at sea level, and this has caused a great deal ofquestioning. * * There is a good

reason for this,** says a writer in **Motor Age,** **and it is a physicalimpossibility for the engine to do otherwise. The difference is due tothe lower atmospheric pressure the higher up we get. That is, at sealevel the atmosphere has a pressure of 14.7 pounds per square inch; at5,000 feet above sea level the pressure is approximately 12.13 pounds

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per square inch, and at 10,000 feet it is 10 pounds per square inch.From this it will be seen that the final pressure attained after the pis-ton has driven the gas into compressed condition ready for firing islower as the atmospheric pressure drops. This means that there is notso much power in the compressed charge of gas the higher up you getabove sea level.

**For example^ suppose the compression ratio to be 4j^ to 1; in otherwords, suppose the air space above the piston to have ^}i times thevolume when the piston is at the bottom of its stroke that it has whenthe piston is at the top of the stroke. That is a common compressionratio for an average motor, and is chosen because it is considered to bethe best for maximum horse-power and in order that the compressionpressure will not be so high as to cause pre-ignition. Knowing thecompression ratio, we can determine the final pressure immediatelybefore ignition by substituting in the standard formula:

y . 1.3

•■-p(?i)

in which P is the atmospheric pressure; P^ is the final

V

pressure, and — is the compression ratio, therefore P^ =

14.7 (4.5)^-'= 104 pounds per square inch, absolute.

**That is, 104 pounds per square inch is the most efficient final com-pression pressure to have for this engine at sea level, since it comesdirectly from the compression ratio.

**Now supposing we consider that the altitude is 7,000

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feet above sea level. At this height the atmospheric pressure is 11.25pounds per square inch, approximately. In this case we can again sub-stitute in the formula, usmg the new atmospheric pressure figure. Theequation becomes :

P*=11.25 (4.5)^^—79.4 pounds per square inch, absolute.

** Therefore we now have a final compression pressure of only 79.4pounds per square inch, which is considerably below the pressure wehave just found to be the most efficient for the motor. The resultingpower drop is evident.

**It should be borne in mind that these final compression pressuresare absolute pressures—that is, they include the atmospheric pressure.In the first case, to get the pressure above atmospheric you would sub-tract 14.7 and in the latter 11.25 would have to be deducted. In otherwords, where the sea level compression is 89.3 pounds per square inchabove the atmosphere, the same motor will hUve only a compressionpressure of 68.15 pounds per square inch above the atmosphere at7,000 feet elevation.

**From the above it is evident that in order to bring the final compres-sion pressure up to the efficient figure we have determined, a differentcompression ratio would have to be used. That is, the fmal volumewould have to be less, and as it is impossible to vary this to meet theconditions of altitude, the loss of power cannot be helped except by thereplacing of the standard pistons with some that are longer above thewrist-pin so as to reduce the space above the pistons when on top cen-ter. Then if the ratio is thereby raised to some such figures as 5 to 1,the engine will again have its proper final pressure, but it will still nothave as much power as it would have at sea level, since the horse-power varies directly with the atmospheric pressure, final compressionbeing kept constant. That is, at 7,000 feet the horse-power of

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an engine that had 40 horse-power at sea level would be

equal to

11.25

= 30.6 horse-power.

14.7

**If the original compression ratio of 4.5 were retained, the drop inhorse-power would be even greater than this. These computations andremarks will make it clear that the designer who contemplates build-ing an airplane for high altitude use should see to it that it is of suffi-cient power to compensate for the drop that is inevitable when it is upin the air. This is often illustrated in stationary gas-engine installa-tions. An engine that had a sea-level rating amply sufficient for thework required/might not be powerful enough when brought up severalthousand feet.** When one considers that airplanes attain heights ofover 18,000 feet, it will be evident that an ample margin of enginepower is necessary.

THE DIESEL SYSTEM

A system of fuel supply developed by the late Dr. Diesel, a Germanchemist and engineer, is attracting considerable attention at thepresent time on account of the ability of the Diesel engine to burn low-grade fuels, such as crude petroleum. In this system the engines arebuilt so that very high compressions are used, and only pure air istaken into the cylinder on the induction stroke. This is compressed toa pressure of about 500 pounds per square inch, Ind sufficient heat isproduced by this compression to explode a hydrocarbon mixture. Asthe air which is compressed to this high point cannot burn, the fuel isintroduced into the cvlinder combustion cham-ber under still higher

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compression than that of the compressed air, and as it is injected in afine stream it is immediately vaporized because of the heat. Just assoon as the compressed air becomes thoroughly saturated with the li-quid fuel, it will explode on account of tlie degree of

heat present in the combustion chamber. Such motors have been usedin marine and stationary applications, but are not practical for air-planes or motor cars because of lack of flexibility and great weight inproportion to power developed. The Diesel engine is the standardpower plant used in submarine boats and motor ships, as its efficiencyrenders it particularly well adapted for large imits.

NOTES ON CARBURETOR INSTALLATION IN AIRPLANES

A writer in **The Aeroplane,*' an English publication, discourses onsome features of carburetor installation that may be of interest to theaviation student, so portions of the dissertation are reproducedherewith.

** Users of airplanes fitted with ordinary type carburetors will do wellto note carefully the way in which these are fitted, for several costlymachines have been burnt lately through the sheer carelessness oftheir users. These particular machines were fitted with a high poweredV-type engine, made by a firm which is famous as manufacturers ofautomobiles de luxe. In these engines there are four carburetors,mounted in the V between the cylinders. When the engine is fitted as atractor, the float chambers are in front of the jet chambers. Con-sequently, when the tail of the machine is resting on the ground, thejets are lower than the level of the gasoline in the float chamber.

"Quite naturally, the gasoline runs out of the jet, if it is left turned onwhen the machine is standing in its normal position, and trickles intothe V at the top of the crank-case. Thence it runs down to the tail of

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the engine, where the magnetos are fitted, and saturates them. If leftlong enough, the gasoline manages to soak well into the fuselage be-fore evaporating. And what does evaporate makes an inflammable gasin the forward cockpit. Then some one comes along and starts up. theen§ine. The spark-gap of the magneto gives one flash, and the wholefront of the machine proceeds to give a Fourth of July performanceforthwith. Naturally, one safeguard is to turn the petrol off directly themachine lands. Another is never to turn it on till the engine is actuallybeing started up.

*'One would be asking too much of the human boy—^who is officiallyregarded as the only person fit to fly an aeroplane—if one dependedupon his memory of such a detail to save his machine, though onemight perhaps reasonably expect the older pilots to remember not toforget. Even so, other means of prevention

are preferable, for fire is quite as likely to occur from just the samecause if the engine happens to be a trifle obstinate in starting, and sogives the carburetors several minutes in which to drip —in which oper-ation they would probably be assisted by air-mechanics 'tickling' them.

**One way out of the trouble is to fit drip tins under the jet chamber tocatch the gasoline as it falls. This is all very well just to prevent firewhile the machine is being started up, but it will not save it if it is leftstanding with the tail on the ground and the petrol turned on, for thedrip tins will then fill up and run over. And if it catches then, the con-tents of the drip tins merely add fuel to the fire.

Reversing Carburetors

**Yet another way is to turn the carburetors round, so that the floatchambers are behind the jets, and so come below them when the tail ison the ground, thus cutting off the gasoline low down in the jets. There

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seems to be no particular mechanical difficulty about this, though Imust confess that I did not note very carefully whether the reversal ofthe float chambers would make them foul any other fittings on the en-gine. It has been argued, however, that doing this would starve the en-gine of gasoline when climbing at a steep angle, as the gasoline wouldthen be lowered in the jets and need more suction to get into the cylin-ders. This is rather a pretty point of amateur motor mechanics to dis-cuss, for, obviously, when the same engine is used as a 'pusher' insteadof a tractor, the jets are in front of the floats, and there seems to be nofalling off in.power.

Starvation of Mixture

"Moreover, the higher a machine goes the lower is the atmosphericpressure, and, consequently, the less is the amount of air sucked in ateach induction stroke. This means, of course, that with the gasolinesupply the mixture at high altitudes is too rich, so that, in order to getprecisely the right mixture when very high up, it is necessary to reducethe gasoline supply by screwing down the needle valve between thetank and the carburetor—at least, that has been the experience ofvarious high-flying pilots. No doubt something might be done in theway of forced air feed to compensate for reduced atmospheric pres-sure, but it remains to be proved whether the extra weight of mechan-ism involved would pay for the extra power obtained. Variable com-pression might do something, also, to even things up, but here, also,weight of mechanism has to be considered.

"In any case, at present, the higher one goes the more the

power of the engine is reduced, for less air means a less volume ofmixture per cylinder, and as the petrol feed has to be starved to suitthe smaller amount of air available, this means further loss of power. Ido not know whether anyone has evolved a carburetor which

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automatically starves the gasoline feed when high up, but it seemspossible that when an airplane is sagging about 'up against the ceil-ing'—as a French pilot described the absolute limit of climb for hisparticular machine—^it might be a good thing to have the jets in frontof the float chamber, for then a certain amount of automatic starvationwould take place.

**When a machine is right up at its limiting height, and the pilot is do-ing his best to make it go higher still, it is probably flying with its tailas low as the pilot dares to let it go, and the lateral and longitudinalcontrols are on the verge of vanishing, 80 that if the carburetor jets arebehind the float chambers there is bound to be an over-rich mixture inany case. There is even a possibility of a careless or ignorant pilot car-rying on in this tail-down position till one set of cylinders cuts out al-together, in which case the carburetor feeding that set may flood over,just as if the machine were on the ground, and the whole thing maycatch fire. Whereas, with the jets in front of the floats, though the mix-ture may starve a trifle, there is, at any rate, no danger of fire throughclimbing with the tail down.

A Diving Danger

**0n the other hand, in a 'pusher' with this type of engine, if the jetsare in their normal position—^which is in front of the floats—^there isdanger of fire in a dive. That is to say, if the pilot throttles right down,or switches oft and relies on air pressure on his propeller to start theengine again, so that the gasoline is flooding over out of the jets in-stead of being sucked into the engine, there may be flooding over themagnetos if the dive is very steep and prolonged. In any case, a longdive will mean a certain amount of flooding, and, probably, a gooddeal of choking and spitting by the engine before it gets rid of the over-rich mixture and picks up steady firing again. Which may indicate toyoung pilots that it is not good to come down too low under such

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circumstances, trusting entirely to their engines to pick up at once andget going before they hit the ground.

**0n the whole, it seems that it might be better practice to set the car-buretors thwartwise of engines, for then jets and floats would alwaysbe at approximately the same level, no matter what the longitudinalposition of the machine, and it is never long enough in one position ata big lateral angle to raise any serious carburetor troubles. Car manu-facturers who dive cheerfully into

the troubled waters of aero-engine designs are a trifle apt to forget thattheir engines are put into positions on airplanes which would be posit-ively indecent in a motor car. An angle of 1 in 10 is the exception on acar, but it is common on an airplane, and no one ever heard of a cargoing down a hill of 10 to 1—^which is not quite a vertical dive. There-fore, there is every excuse for a well-designed and properly brought-upcarburetor misbehaving itself in an aeroplane.

'*It seems, then, that it is up to the manufacturers to produce bettercarburetors—say, with the jet central with the float. But it also be-hooves the user to show ordinary common sense in handling the ma-terial at present available, and not to make a practice of burning up$25,000 worth or so of airplane just because he is too lazy to turn offhis gasoline, or to have the tail of his machine lifted up while he istinkering with his engines."

NOTES ON CARBURETOR ADJUSTMENT

The modern float feed carburetor is a delicate and nicely balanced ap-pliance that requires a certain amount of attention and care in order toobtain the best results. The adjustments can only be made by one pos-sessing an intelligent knowledge of carburetor construction and mustnever be made imless the reason for changing the old adjustment is

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understood. Before altering the adjustment of the leading forms ofcarburetors, a few hints regarding the quality to be obtained in themixture should be given some consideration, as if these are properlyunderstood this knowledge will prove of great assistance in adjustingthe vaporizer to give a good working proportion of fuel and air. Thereis some question regarding the best mixture proportions and it is es-timated that gas will be explosive in which the proportions of fuel va-por and air will vary from one part of the former to a wide range in-cluded between four and eighteen parts of the latter. A one to fourmixture is much too rich, while the one in eighteen is much too lean toprovide positive ignition.

A rich mixture should be avoided because the excessive fuel used vnRdeposit carbon and will soot the cylinder walls, combustion chamberinterior, piston top and valves and also tend to overheat the motor. Arich mixture will

also seriously interfere with flexible control of the engine, as it willchoke up on low throttle and run well on open throttle when the fullamount of gas is needed. A rich mixture may be quickly discovered byblack smoke issuing from the muffler, the exhaust gas having a verypungent odor. If the mixture contains a surplus of air there will bepopping sounds in the carburetor, which is commonly termed **blow-ing back." To adjust a carburetor is not a difficult matter when thepurpose of the various control members is understood.. The first thingto do in adjusting a carburetor is to start the motor and to retard thesparking lever so the motor will run slowly leaving the throttle abouthalf open. In order to ascertain if the mixture is too rich cut do\\7i thegasoline flow gradually by screwing down the needle valve until themotor commences to run irregularly or misfire. Close the needle valvesas far as possible without having the engine come to a stop, and afterhaving found the minimum amount of fuel gradually unscrew the ad-justing valve until you arrive at the point where the engine develops its

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highest speed. When this adjustment is secured the lock nut is screwedin place so the needle valve mil keep the adjustment. The next point tolook out for is regulation of the auxiliary air supply on those tjTpes ofcarburetors where an adjustable air valve is provided. This is done byadvancing the spark lever and opening the throttle. The air valve isfirst opened or the spring tension reduced to a point where the enginemisfires or pops back in the carburetor. When the point of maximumair supply the engine will run on is thus determined, the air valvespring may be tightened by screwing in on the regulating screw untilthe point is reached where an appreciable speeding up of the engine isnoticed. If both fuel and air valves are set right, it \\ill be possible toaccelerate the engine speed uniformly without interfering with regu-larity of engine operation by moving the throttle lever or acceleratorpedal from its closed to its wide open position, this being done withthe spark lever advanced. All types of carburetors do not have thesame

means of adjustment; in fact, some adjust only with the gasoline regu-lating needle; others must have a complete change of spray nozzles;while in others the mixture proportions may be varied only by adjust-ment of the quantity of entering air. Changing the float level is effect-ive in some carburetors, but this should never be done unless it is cer-tain that the level is not correct. Full instructions for locating carbur-etion troubles will be given in proper sequence.

It is a fact well known to experienced repairmen and motorists that at-mospheric conditions have much to do vrith carburetor action. It is of-ten observed that a motor seems to develop more power at night thanduring the day, a circumstance which is attributed to the presence ofmore moisture in the cooler night air. Likewise, taking a motor fromsea level to an altitude of 10,000 feet involves using rarefied air in theengine cylinders and atmospheric pressures ranging from 14.7 poundsat sea level to 10.1 pounds per square inch at the high altitude. All

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carburetors will require some adjustment in the course of any materialchange from one level to another. Great changes of altitude also have amarked effect on the cooling system of an airplane. Water boils at 212degrees F. only at sea level. At an altitude of 10,000 feet it will boil at atemperature nineteen degrees lower, or 193 degrees P.

In high altitudes the reduced atmospheric pressure, for 5,000 feet orhigher than sea level, results in not enough air reaching the mixture,so that either the auxiliary air opening has to be increased, or the gas-oline in the mixture cut down. If the user is to be continually at highaltitudes he should immediately purchase either a larger dome or asmaller strangling tube, mentioning the size carburetor that is atpresent in use and the type of motor that it is on, including details asto the bore and stroke. The smaller strangling tube makes an increasedsuction at the spray nozzle; the air will have to be readjusted to meet itand you can use more auxiliary

air, which is necessary. The effect on the motor without a smaUerstrangling tube is a perceptible sluggishness and failure to speed up toits normal crank-shaft revolutions, as well as failure to give power. Itmeans that about one-third of the regular speed is cut out. The re-duced atmospheric pressure reduces the power of the explosion, inthat there is not the same quantity of oxygen in the combustion cham-ber as at sea level; to increase the amount taken in, you must also in-crease the gasoline speed, which is done by an increased suctionthrough the smaller strangling aperture. Some forms of carburetorsare affected more than others by changes of altitude, which explainswhy the Zenith is so widely employed for airplane engine use. Thecompensating nozzle construction is not influenced as much bychanges of altitude as the simpler nozzle types are.

CHAPTER VI

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Early Ignition Systems—Electrical Ignition Best—Fundamentals ofMagnetism Outlined—^Forms of Magneto—Zones of Magnetic Influ-ence—How Magnets are Made—Electricity and MagnetismRelated—Basic Principles of Magneto Action—Essential Parts of Mag-neto and Functions—Transformer Coil Systems—True High TensionType—The Berling Magneto—Timing and Care—The Dixie Mag-neto—Spark Plug Design and Application—Two-Spark Ignition—Spe-cial Airplane Plug.

EARLY IGNITION SYSTEMS

One of the most important auxiliary gronps of the gasoline enginecomprising the airplane power plant and one absolutely necessary toinsure engine action is the ignition system or the method employed ofkindling the compressed gas in the cylinder to produce an explosionand useful power. The ignition system has been fully as well developedas other parts of the engine, and at the present time practically all igni-tion systems follow principles which have become standard throughwide acceptance.

During the early stages of development of the gasoline engine variousmethods of exploding the charge of combustible gas in the cylinderwere employed. On some of the earliest engines a flame burned closeto the cylinder head, and at the proper time for ignition a slide or valvemoved to provide an opening which permitted the flame to ignite thegas back of the piston. This system was practical only on the primitiveform of gas engines in which the charge was not compressed before ig-nition. Later, when it was found desirable to compress the gas a cer-tain degree before exploding it, an incandescent platinum tube in thecombustion chamber, which was kept in a heated condition by a flameburning in it, exploded the gas. The naked flame was not suitable inthis appli-

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cation because when the slide was opened to provide communicationbetween the flame and the gas the compressed charge escaped fromthe cylinder vdth enough pressure to blow out tlie flame at times andthus cause irregular ignition. WTien the flame was housed in a platin-um tube it was protected from the direct action of the gas, and as longas the tube was maintained at the proper point of incandescence regu-lar ignition was obtained.

Some engineers utilized the property of gases firing themselves if com-pressed to a sufficient degree, while others depended upon the heatstored in the cylinder-head to fire the highly compressed gas. None ofthese methods were practical in their application to motor car enginesbecause they did not permit flexible engine action which is so desir-able. At the present time, electrical ignition systems in which the com-pressed gas is exploded by the heating value of the minute electric arcor spark in the cylinder are standard, and the general practice seemsto be toward the use of mechanical producers of electricity rather thanchemical batteries.

ELECTRICAL IGNITION BEST

Two g(*iioral forms of electrical ignition systems may be used, themost popular being that in which a current of electricity uiuior hightension is made to leap a gap or air space between the points of thesparking plug screwed into tlio cylinder. The other form, which hasbeen almost eiitirclv abandoned in automobile and which was neverused witli airplane engine practice, but which is still used to some ex-tent on marine engines, is called the low-tension system because cur-rent of low voltage is used and the spark is produced by moving elec-trodes in the combustion chamber.

The essential (dements of any electrical ignition system, either higli orlow tension, are: First, a simple and practical method of current

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production; second, suitable timing apparatus to cause the spark tooccur at the right point in the cycle of engine action; third, suitablewiring

.nd other apparatus to convey the current produced by he generator tothe sparking member in the cylinder.

The various appliances necessary to secure prompt ig-ition of the com-pressed gases should be described in some ietail because of the im-portance of the ignition system, t is patent that the scope of a work ofthis character ioes not pennit one to go fully into the theory and prin-iples of operation of all appliances which may be used n connectionwith gasoline motor ignition, but at the same ime it is important thatthe elementary principles be onsidered to some extent in order thatthe reader should ave a proper understanding of the very essential ig-nition pparatus. The first point considered will be the commonaethods of generating the electricity, then the appliances 0 utilize itand produce the required spark in the cylin-er. Inasmuch as magnetoignition is universally used n connection with airplane engine ignitionit will not be lecessary to consider battery ignition systems.

FUNDAMENTALS OF MAGNETISM OUTLINED

To properly understand the phenomena and forces in-olved in thegeneration of electrical energy by mechanical leans it is necessary tobecome familiar with some of the lementary principles of magnetismand its relation to lectricity. The following matter can be read withprofit »y those who are not familiar with the subject. Most personsknow that magnetism exists in certain substances, »ut many are notable to grasp the terms used in describ-ng the operation of variouselectrical devices because of iot possessing a knowledge, of the basicfacts upon which he action of such apparatus is based.

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Magnetism is a property possessed by certain sub-tances and is mani-fested by the ability to attract and epel other materials susceptible toits effects. Wlion this phenomenon is manifested by a conductor orA\dre through rhich a current of electricity is flowing it is termed*^elec-ro-magnetisni." Magnetism and electricity are closely elated,each being capable of producing the other. Prac-

the size of the magnets used and the air gap separating the poles. If thesouth pole of one magnet is brought close to the end of the same polar-ity of the other there will be a pronounced repulsion of like force.These facts are easily proved by the simple experiment outlined at B,Fig. 57. A magnet will only attract or influence a substance having sim-ilar qualities. The like poles of magnets will repel each other becauseof the obvious impossibility of uniting two influences or forces of prac-tically equal strength but flowing in opposite directions. The unlikepoles of magnets attract each other because the force is flowing in thesame direction. The flow of magnetism is through the magnet fromsouth to north and the circuit is completed by the flow of magnetic in-fluence through the air gap or metal armature bridging it from thenorth to the south pole.

FORMS OF MAGNETS AND ZONE OF MAGNETIC INFLUENCE

DEFINED

Magnets are commonly made in two forms, either in the shape of a baror horseshoe. These two forms are made in*two types, simple or com-pound. The latter are composed of a number of magnets of the sameform united so the ends of like polarity are laced together, and such aconstruction will be more efficient and have more strength than asimple magnet of the same weight. The two common forms of simpleand compound magnets are shown at C, Fig. 57. The zone in which amagnetic influence occurs is called the magnetic field, and this force

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can be graphically shown by means of imaginary lines, which aretermed *4ines of force.'^ As will be seen from the diagram at D, Fig.57, the lines show the direction of action of the magnetic force andalso show its strength, as they are closer together and more nurtierouswhen the intensity of the magnetic field is at its maximum. A simplemethod of demonstrating the presence of the force is to lay a piece ofthin paper over the pole pieces of either a bar or horseshoe magnetand sprinkle fine iron filings

on it. The particles of metal arrange themselves in very much the man-ner shown in the illustrations and prove that the magnetic field actu-ally exists.

The form of magnet used will materially affect the size and area of themagnetic field. It will be noted that the field will be concentrated to agreater extent with the horseshoe form because of the proximity of thepoles. It should be understood that these lines have no actual exist-ence, but are imaginary and assumed to exist only to show the way themagnetic field is distributed. The magnetic influence is always greaterat the poles than at the center, and that is why a horseshoe or U-formmagnet is used in practically all magnetos or dynamos. This greater at-traction at the poles can be clearly demonstrated by sprinkling iron fil-ings on bar and U magnets, as outlined at E, Fig. 57. A large massgathers at the pole pieces, gradually tapering down toward the pointwhere the attraction is least.

From the diagrams it will be seen that the flow of magnetism is fromone pole to the other by means of curved paths between them. Thiscircuit is completed by the magnetisna flowing from one pole to theother through the magnet, and as this flow is continued as long as thebody remains magnetic it constitutes a magnetic circuit. If this flowwere temporarily interrupted by means of a conductor of electricitymoving through the field there would be a current of electricity

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induced in the conductor every time it cut the lines of force. There arethree kinds of magnetic circuits. A non-magnetic circuit is one inwhich the magnetic influence completes its circuit through some sub-stance not susceptible to the force. A closed magnetic circuit is one inwhich the influence completes its circuit through some magnetic ma-terial which bridges the gap between the poles. A compound circuit isthat in which the magnetic influence passes through magnetic sub-stances and non-magnetic substances in order to complete its circuit.

S

■•» .i::arz(//' c^itaines

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. .^ '"'M-c^**!. _z. "^^n -vars, bv contact , - '■..-'-.•-. ',-. \ ' ••• :. *r--^i5 7nbne«i ■>ii a iiiaCT.6t - "- ri .y.\ \ 'M^*:.-" virii "^HrLovp^Liiavin? a north ,-- ...-.-' •. r- \:.\ c/. : L- 7r'r^rr:es lonnd in the .---:-.--\r'\\j:v-'. T:.> ^ na^cnrrrLiizj: '^y '.t^ntact. A -.^5i - .- ... ■ "'.v.". :::■r.:iLr:-rLfirL jnpairei to it for V -r^-.',.—, • - r .:'.: : "iiir-. ui.l -t^ --niie-iiee that re-r:.> -i -i z'-r-r- -.< -->: v.io^ riLcn-rniin. Tii> propertyr',v— r- ".••■.*->-*. ■'■ ?..'■""::-: Ht* ^rt-r^ nnrji Trmg^ten and r->-'^ • - ip '-•' - > i:::ii:z:frLTtrL An^ ^arerial that

^,...,.^ .- ---jv. - --••. > c:.'v-i i< I 7y=Tr.ar:r-nr ma-rnet.

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-;--.'j '- ••:• -:• i-:.-_ .^ V.'.'. .ViLX* I Tr:?ir7>*^^ -r :*:. This

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jiih'*^ .: "' ' ;'.;••.:• i *'"::v-L t.:. --.t-TT'-iEtrre: and ur-Tif.." ".'■- ."••*' •'''. ^'yi t Tif.*L*' tiit*: :: trill not 7'*'*f.ii .'f ::;'^'"''' ^'" v/''-;. *].>''■l:t'-*ijT ^?.fi5e? t:« Sow ai''»iiii'L :*. r"^'*. ;• ■>"'. -t. l.. ':2->'-^ vLf-rf j^ermanent ma:ni*''; i.'* :'-' t- •'-•.. vj...»' j.-.: ,:•.'»!. if ^mpjcyt^ inall (•as«•^ vji*-< LvJ. :j "''7:./*''T* Tfifinj"rJr- actioii is desired.^Mui'Ti"''- u^'V. jjiarji'^r l:'* j-:vx'> Tjujdf- o: tanirsteji steel n!,f.; . :-f*.4.{N-'. wiir. :: \\l, r'T^ii. i:f maxmetism for

Tui''i i;-» ii;i;r; t.-.::.-^ It, vLjfL mnCTiotism and dec-tn':\' ;;'i ;j;i;» . J'.:ijs:Liif". [lir is a iiiedinm that of-!«•: *■"!: .i'*MM» ''•-.-•r:i' • :ijiim^sac'i' of both mag-in-i' :!:!:u*'ii''' iiii'! i-'iiw^'v- '•ij»-:-i"v. jih-liviuirli it offers more M:!::;:Tt'-i :t: :iii juiM-LL'*- (r ui*: IfitTiT. Min-erals like '?'•' ' • : ■'•• !.•• '■ *-iisl:v iiifiu-ijtv'd I'V mametism and

easily penetrated by it. When one of these is present in the magneticcircuit the magnetism will flow through the metal. Any metal is* agood conductor for the passage of the electric current, but few metalsare good conductors of magnetic energy. A body of the proper metalwill become a magnet due to induction if placed in the magnetic field,having a south pole where the lines of force enter it and a north polewhere they pass out.

We have seen that a magnet is constantly surrounded by a magneticfield and that an electrical conductor when carrying a current is alsosurrounded by a field of magnetic influence. Now if the conductor car-rying a current of electricity will induce magnetism in a bar of iron orsteel, by a reversal of this process, a magnetized iron or steel bar willproduce a current of electricity in a conductor. It is upon this principlethat the modern dynamo or magneto is constructed. If an electro-motive force is induced in a conductor by moving it across a field ofmag-netic influence, or by passing a magnetic field near a conductor,electricity is said to be generated by magneto-electric induction. All

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mechanical generators of the electric current using permanent steelmagnets to produce a field of magnetic influence are of this type.

BASIC PRINCIPLES OF MAGNETO OUTLINED

The accompanying diagram. Fig. 58, will show these principles veryclearly. As stated on an earlier page, if the lines of force in the magnet-ic field are cut by a suitable conductor an electrical impulse will beproduced in that conductor. In this simple machine the lines of forceexist between the poles of a horseshoe magnet. The conductor, whichin this case is a loop of copper wire, is mounted .upon a spindle in or-der that it may be rotated in the magnetic field to cut the lines of mag-netic influence present between the pole pieces. Both of the ends ofthis loop are connected, one with the insulated drum shown upon theshaft, the other to the shaft. Two metal brushes are employed to col-lect the current and cause it

r

tically all of the phenomena manifested by materials which possessmagnetic qualities naturally can be easily reproduced by passing a cur-rent of electricity through a body which, when not under electrical in-fluence, is not a magnetic substance. Only certain substances showmagnetic properties, these being iron, nickel, cobalt and their alloys.

The earliest known substance possessing magnetic properties was astone first found in Asia Minor. It was called the lodestone or leadingstone, because of its tendency, if arranged so it could be moved freely,of pointing one particular portion toward the north. The compass ofthe ancient Chinese mariners was a piece of this material, now knownto be iron ore, suspended by a light thread or floated on a cork in someliquid so one end would point toward the north magnetic pole of theearth. The reason that this stone was magnetic was hard to define for a

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time, until it was learned that the earth was one huge magnet and thatthe iron ore, being particularly susceptible, absorbed and retainedsome of this magnetism.

Most of us are familiar with some of the properties of the magnet be-cause of the extensive sale and use of small horseshoe magnets as toys.As they only cost a few pennies every one has o^^^led one at sometime or other and has experimented mth various materials to see ifthey would be attracted. Small pieces of iron or steel were quickly at-tracted to the magnet and adhered to the pole pieces when broughtwithin the zone of magnetic influence. It was soon learned that brass,copper, tin or zinc were not affected by the magnet. A simple experi-ment that serves to illustrate magnetic attraction of several substancesis shown at A, Fig. 57. In this, several balls are hung from a standardor support, one of these being of iron, another of steel. When a magnetis brought near either of these they will be attracted toward it, whilethe others will remain indifferent to the magnetic force. Experi-menters soon learned that of the common metals only iron or steelwere magnetic.

If the ordinary bar. or horseshoe magnet be carefully

mined, one end vnli be found to be marked N. This tcates the northpole, while the other end is not usually •ked and is the south pole. Ifthe north pole of one j^et is brought near the south pole of another, astrong ■action will exist between them, this depending upon

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177.—Some Simple Experiments to DemonstTate Various MagneticFlie-nomena and Cleaily Outline Effects of Magnetism and VariousForma of Magnets.

the size of the magnets used and the air gap separatuig the poles. If thesouth pole of one magnet is brought close to the end of the same polar-ity of the other there will be a pronounced repulsion of like force.These facts are easily proved by the simple experiment outlined at B,Fig. 57. A magnet will only attract or influence a substance having sim-ilar qualities. The like poles of magnets will repel each other becauseof the obvious impossibility of uniting two influences or forces of prac-tically equal strength but flowing in opposite directions. The unlike

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poles of magnets attract each other because the force is flowing in thesame direction. The flow of magnetism is through the magnet fromsouth to north and the circuit is completed by the flow of magnetic in-fluence through the air gap or metal armature bridging it from thenorth to the south pole.

FORMS OF MAGXETS AND ZONE OF MAGNETIC INFLUENCE

DEFINED

Magnets are commonly made in two forms, either in the shape of a baror horseshoe. These two forms are made in-two types, simple or com-pound. The latter are composed of a number of magnets of the sameform united so the ends of like polarity are laced together, and such aconstruction will be more efficient and have more strength than asimple magnet of the same weight. The two common forms of simpleand compound magnets are shown at C, Fig. 57. The zone in which amagnetic influence occurs is called the magnetic field, and this forcecan be graphically shown by means of imaginary lines, which aretermed **lines of force." As \nll be seen from the diagram at D, Fig.57, the lines show the direction of action of the magnetic force andalso show its strength, as they are closer together and more nuitierouswhen the intensity of the magnetic field is at its maximum. A simplemethod of demonstrating the presence of the force is to lay a piece ofthin paper over the pole pieces of either a bar or horseshoe magnetand sprinkle fine iron filings

Q it. The particles of metal arrange themselves in very mch the man-ner shown in the illustrations and prove lat the magnetic field actuallyexists.

The form of magnet used will materially affect the Lze and area of themagnetic field. It will be noted that le field will be concentrated to a

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greater extent with le horseshoe form because of the proximity of thepoles. t should be understood that these lines have no actual dstence,but are imaginary and assumed to exist only ) show the way the mag-netic field is distributed. The lagnetic influence is always greater at thepoles than t the center, and that is why a horseshoe or U-form lagnet isused in practically all magnetos or dynamos, his greater attraction atthe poles can be clearly dem-astrated by sprinkling iron filings on barand U mag-ets, as outlined at E, Fig. 57. A large mass gathers at le polepieces, gradually tapering down toward the point here the attraction isleast.

From the diagrams it will be seen that the flow of lagnetism is fromone pole to the other by means of irved paths between them. This cir-cuit is completed y the magnetism flowing from one pole to the otherirough the magnet, and as this flow is continued as long s the body re-mains magnetic it constitutes a magnetic ircuit. If this flow were tem-porarily interrupted by leans of a conductor of electricity movingthrough the eld there would be a current of electricity induced in leconductor every time it cut the lines of force. There re three kinds ofmagnetic circuits. A non-magnetic ircuit is one in which the magneticinfluence completes ;s circuit through some substance not susceptibleto the >ree. A closed magnetic circuit is one in which the in-aeneecompletes its circuit through some magnetic ma-jrial which bridgesthe gap between the poles. A com-ound circuit is that in which themagnetic influence asses through magnetic substances and non-magnetic sub-tances in order to complete its circuit.

HOW IRON AND STEEL BARS ARE MADE MAGNETIC

Magnetism may be produced in two ways, by contact or induction. If apiece of steel is rubbed on a magnet it will be found a magnet when re-moved, having a north and south pole and all of the properties foundin the energizing magnet. This is magnetizing by contact. A piece of

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steel will retain the magnetism imparted to it for a considerable lengthof time, and the influence that remains is known as residual magnet-ism. This property may be increased by alloying the steel with tung-sten and hardening it before it is magnetized. Any material that willretain its magnetic influence after removal from the source of magnet-ism is known as a permanent magnet If a piece of iron or steel isbrought into the magnetic field of a powerful magnet it becomes amagnet without actual contact with the energizer. This " is magnetiz-ing by magnetic induction. If a powerful electric current flows throughan insulated conductor wound around a piece of iron or steel it willmake a magnet of it. This is magnetizing by electro-magnetic induc-tion. A magnet made in this manner is termed an electro-magnet andusually the metal is of such a nature that it will not retain its magnet-ism when the current ceases to flow around it. Steel is used in all caseswhere permanent magnets are required, while soft iron is employed inall cases w^here an intermittent magnetic action is desired. Magnetofield magnets are always made of tungsten steel alloy, so treated that itwill retain its magnetism for lengthy periods.

ELECTRICITY AND MAGNETISM CLOSELY RELATED

There are many points in which magnetism and electricity are alike.For instance, air is a medium that offers considerable resistance to thepassage of both magnetic influence and electric energy, although it of-fers more resistance to the passage of the latter. Minerals like iron orsteel are very easily influenced by magnetism and

sily penetrated by it. When one of these is present the magnetic circuitthe magnetism will flow through i metal. Any metal is*a good conduct-or for the pas-?e of the electric current, but few metals are good aduct-ors of magnetic energy. A body of the proper ital will become a magnetdue to induction if placed the magnetic field, having a south polewhere the lines force enter it and a north pole where they pass out. We

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have seen that a magnet is constantly surrounded a magnetic field andthat an electrical conductor when prying a current is also surroundedby a field of mag-tic influence. Now if the conductor carrying a currentelectricity will induce magnetism in a bar of iron or jel, by a reversal ofthis process, a magnetized iron or jel bar will produce a current ofelectricity in a con-ctor. It is upon this principle that the modern dy-namo magneto is constructed. If an electro-motive force is iuced in aconductor by moving it across a field of mag-tic influence, or bypassing a magnetic field near a Qductor, electricity is said to be gener-ated by magneto-5ctric induction. All mechanical generators of theelec-c current using permanent steel magnets to produce a Id of mag-netic influence are of this type.

BASIC PRINCIPLES OF MAGNETO OUTLINED

The accompanying diagram. Fig. 58, will show these inciples veryclearly. As stated on an earlier page,

the lines of force in the magnetic field are cut by a itable conductor anelectrical impulse will be produced

that conductor. In this simple machine the lines of rce exist betweenthe poles of a horseshoe magnet. The nductor, which in this case is aloop of copper wire, mounted .upon a spindle in order that it may berotated

the magnetic field to cut the lines of magnetic influ-ce present betweenthe pole pieces. Both of the ends

this loop are connected, one with the insulated drum own upon theshaft, the other to the shaft. Two metal ushes are employed to collectthe current and cause it

Aviation Engines

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to flow through the external circuit. It can be seen that ■when theshaft is turned in the direction of the arrow the loop wll cut throughthe lines of magnetic influence and a current will be generated therein.

The pressure of the current and the amount produced vary in accord-ance to the rapidity is-ith which the lines of magnetic influence arecut. The armature of a practical magneto, therefore, differs materiallyfrom that shown in the diagram. A large mmiber of loops of wirewould be mounted upon this shaft in order that the lines of magneticinfluence would be cut a greater number of times in a given period anda core of iron used as a backing

for the wire. This would give a more rapid alternating current and ahigher electro-motive force than would bo the case with a smallernumber of loops of wire.

The illustrations at Fig. 59 show a conventional double

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Tig. 69.—Showing How StrenglJi of Magnetic Influence and of theCmrenta Induced In the Windings of Annatnie Vary witli the Bapldityof Olianges of Flow.

winding armature and field magnetic of a practical magneto in partsection and will serve to more fully emphasize the points previouslymade. If the armature or spindle were removed from between the polepieces there would 'exist a field of magnetic influence as shown at Fig.57, but the introduction of this component provides a conductor (theiron core) for the magnetic energj% regardless of its position, thoughthe facility with whicli the influence will be transmitted depends en-tirely upon the position of the core. As shown at A, the magnetic flow

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is through the main body in a straight line, while at B, w^hich positionthe armature has attained after one-eighth revolution, or 45 degreestravel in the direction of the arrow, the magnetism must pass throughin the manner indicated. At C, which position is attained every half re-volution, the magnetic energy abandons the longer path through thebody of the core for the shorter passage offer 3d by the side pieces, andthe field thrown out by the cross bar disappears. On further rotation ofthe armature, as at D, the body of the core again becomes energized asthe magnetic influence resumes its flow through it. These changes inthe strength of the magnetic field when distorted by the armature core,as well as the intensity of the energy existing in the field, affect thewindings, and the electrical energy induced therein corresponds instrength to the rapidity with w^hich these changes in magnetic flowoccur. The most pronounced changes in the strength of the field \\alloccur as the armature passes from position B to D, because the mag-netic field existing around the core will be destroyed and again re-established.

During tlie most of the armature rotation the changes in strength willbe slight and the currents induced in the wire correspondingly small;but at the instant the core becomes remagnetized, as the armatureleaves position C, the current produced ^^ill be at its maximum, and itis necessary to so time the rotation of the armature that at this instantone of the cylinders is in condition to be fired. It

is imperative that the armature be driven in such relation to the crank-shaft that each production of maximum current coincides with the ig-nition point, this condition existing twice during each revolution of thearmature, or at every 180 degrees travel. Each position shown corres-ponds to 45 degrees travel of the armature, or one-eighth of a turn,and it takes just three-eighths revolution to change the position fromA to that shown at D.

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ESSENTIAL PARTS OF A MAGNETO AND THEIR FUNCTIONS

The magnets which produce the influence that in turn* induces theelectrical energy in the winding or loops of wire on the armature, andwhich may have any even number of opposed poles, are called fieldmagnets. The loops of wire which are mounted upon a suitable drumand rotate in the field of magnetic inflence in order to cut the lines offorce is called an armature winding, while the core is the metal por-tion. The entire assembly is called the armature. The exposed ends ofthe magnets are called pole pieces and the arrangement used to collectthe current is either a commutator or a collector. The stationary pieceswhich bear against the collector or commutator and act as terminalsfor the outside circuit are called brushes. These brushes are often ofcopper, or some of its alloys, because copper has a greater electricalconductivity than any other metal.

Th^se brushes are nearly always of carbon, which is sometimes elec-troplated with copper to increase its electrical conductivity, thoughcylinders of copper vnre gauze impregnated with graphite are utilizedat times. Carbon* is used because it is not so liable to cut the metal ofthe commutator as might be the case if the contact was of the metal tometal type. The reason for this is that carbon has the peculiar propertyin that it materially assists in the lubrication of the commutator, andbeing of soft, unctuous composition, will wear and conform to any ir-regularities on the surface of the metal collector rings.

The magneto in common use consists of a number of

horseshoe magnets which are compound in form and attached tosuitable cast-iron pole pieces used to collect and concentrate the mag-netic influence of the various magnets. Between these pole pieces anarmature rotates. This is usually shaped like a shuttle, around whichare wound coils of insulated ^4re. These are composed of a large

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number of turns and the current produced depends in great measureupon the size of the wire and the number of turns per coil. An arma-ture winding of large wire will deliver a current of great amperage, butof smaU voltage. An armature wound with very fine wire will deliver acurrent of high voltage but of low amperage. In the ordinary form ofmagneto, such as used for ignition, the current is alternating in char-acter and the break in the circuit should be timed to occur when thearmature is at the point of its greatest potential or pressure. Wheresuch a generator is designed for direct current production the ends ofthe winding are attached to the segments of a commutator, but wherethe instrument is designed to deliver an alternating current one end ofthe winding is fastened to an insulator ring on one end of the armatureshaft and the other end is grounded on the frame of the machine.

The quantity of the current depends upon the strength of the magneticfield and the number of lines of magnetic influence acting through thearmature. The electro-motive force varies as to the length of the arma-ture winding and the number of revolutions at which the armature isrotated.

THE TRANSFORMER SYSTEM USES LOW VOLTAGE MAGNETO

The magneto in the various systems which employ a transformer coilis very similar to a low-tension generator in general construction, andthe current delivered at the terminals seldom exceeds 100 volts. As itrequires many times that potential or pressure to leap the gap whichexists between the points of the conventional spark plug, a separatecoil is placed in circuit to intensify the current to one of greater capa-city. The essential parts

of such a system and their relation to each other are shown in dia-grammatic form at Fig. 60 and as a complete system at Fig. 61. As istrue of other systems the magnetic influence is produced by

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permanent steel magnets clamped to the cast-iron pole pieces betweenwhich the armature rotates. At the point of greatest potential

Fig. 60.—^DUgiuu Explaining Action of Low Tanslon TruuformerOoU and Tnie Hlgb Tension Uagneto Ignition Syfltemg.

in the armature winding the current is broken by the contact breaker,which is actuated by a cam, and a current of higher value is induced inthe secondary winding of the transformer coil when the low voltagecurrent is passed through the primary winding.

It will be noted that the points of the contact breaker are together ex-cept for the brief instant when separated by the action of the point oftlie cam upon the lever. It is obvious that the armature winding isshort-circuited

Aviation Engines

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Transformer Coil-Magneto System.

ifi

npon itself except when the contact points are sex>Arati?d. "Wliile thearmature winding is thus short-circuited'ther^ will be practically nogeneration of current. When tlie points are separated there is a sudden

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flow of current through the primary winding of the transformer coil,inducing a secondary current in the other winding, which can be var-ied in strength by certain considerations in the

Fig. 61.—BorUng Two-Spuk Dtud Ignition Syatom.

preliminary design of the apparatus. This current of higher potentialor voltage is conducted directly to the plug if the device is fitted to asingle-cylinder engine, or to the distributor arm if fitted to a multiple-cylinder motor. The distributor consists of an insulator in which isplaced a number of segments, one for each cylinder to be fired, and sospaced that the number of degrees between them correspond to the ig-nition points of the motor. A two-cylinder motor would have two seg-ments, a three-cylinder, three segments, and so on within the capacityof the instrument. In the illustration a four-cylinder distributor is fit-ted, and the distributing arm is in contact

with the segment corresponding to the cylinder about U be fired.

TRUE HIGH-TENSION MAOSETOS ARE SELF-CONTAINED

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The true high-tension magneto differs from the preceding inasmuch asthe current of high voltage is produced in the armature winding direct,without the use oi the separate coil. Instead of but one coil, the arma-ture carries two, one of comparatively coarse wire, the other of manyturns of finer wire. The arrangement of these

Fig. 62.—BuUng I>01ibl«-8park Independent Bystem.

windings can be readily ascertained by reference to the diagram B, Fig.60, which shows the principle of operation very clearly. The simplicityof the ignition system is evidently by inspection of Fig. 62. One end ofthe primary winding (coarse Ti-ire) is coupled or grounded to thearmature core, and the other passes to the insulated part of the inter-rupter. "WTiile in some forms the interrupter or contact breakermechanism does not revolve, the desired motion being imparted to thecontact lever to separate the points of a revolving cam, in this the camor tripping mechanism is stationary and the contact breaker revolves.Tliis arrangement makes it possible to conduct the current f^om therevolving primary coil to the interrupter by a direct comiection, elimin ating

hie use of brushes, which would otherwise be necessary, n other formsof this appliance where the winding is tationary, the interrupter maybe operated by a revolv-ag cam, though, if desired, the used of a brushat this ►oint will permit this construction with a revolving miding.

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During the revolution of the armature the grounded 3ver makes andbreaks contact with the insulated point, hort-circuiting the primarywinding upon itself until the rmature reaches the proper position ofmaximum in-ensity of current production, at which time the circuit isroken, as in the former instance. One end of the sec-ndary winding(fine wire) is groimded on the live end of he primary, the other end be-ing attached to the revolv-Qg arm of the distributor mechanism. Solong as a closed ircuit is maintained feeble currents will pass throughthe primary winding, and so long as the contact points are ogether thiscondition will exist* When the current eaches its maximum value, be-cause of the armature be-Qg in the best position, the cam operates theinterrupter ,nd the points are separated, breaking the short circuitrhich has existed in the primary winding.

The secondary circuit has been open while the distrib-itor arm hasmoved from one contact to another and there LES been no flow of en-ergy through this winding. While he electrical pressure will rise in this,even if the dis-ributor arm contacted with one of the segments, thererould be no spark at the plug until the contact points eparated, be-cause the current in the secondary winding vovld not be of sufficientstrength. When the interrupter operates, however, the maximumprimary current will be liverted from its short circuit and can flow tothe ground >nly through the secondary winding and spark-plugcir-:uit. The high pressure now existing in the secondary nnding willbe greatly increased by the sudden flow of )rimary current, and energyof high enough potential to ;uccessfully bridge the gap at the plug isthereby pro-luced in the winding.

Aviation Engines

THE BERLnrG MAGNETO

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The Bftrling magneto is a true high tension type delivering twoiinpulst'S per revolution, but it is made in a variety of foi'ins, botlisingle and double spark. . Its principle of action does not differ in es-sentials from the liigh

Tig. 63.—Type DD Beillng High Tension Hagneto.

tension type previously deseribcd. This magneto is used on Cnrtissaviation engines and "will deliver sparks in a positive manner sufliei-ent to insure ignition of engines up to 200 horse-power and at rotativespeeds of the magneto armature up to 4,000 r. p. m. ivhich is snffi-cient to take care of an oiglit-cylinder V engine running up to 2,000

r. p. m. The magneto is driven at crank-shaft speed on four-cylinderengines, at IVa times crank-shaft speed on sLx-cylinder engines and attwice crank-shaft speed on eight-cylinder V types. The types ''D'' and^*DD" BERLING Magnetos are interchangeable with correspondingQfiagnetos of other standard makes. The dimensions of the four-, six-and eight-cylinder types ^^D" and *^DD''' are all the same.

The ideal method of driving the magneto is by mean& of flexible directconnecting coupling to a shaft intended for the purpose of driving themagneto. As the magneto must be driven at a high speed, a coupling ofsome flexibility is preferable. The employment of such a coupling willfacilitate the moimting of the magneto, because a small inaccuracy inthe lining up of the magneto with the driving shaft will be taken care ofby the flexible coupling^ whereas with a perfectly rigid coupling theline-up of the magneto must be absolutely accurate. Another advant-age of the flexible coupling is that the vibration of the motor will notbe as fully transmitted to the armature shaft on the magneto as in casea rigid coupling is used. This means prolonged life for the magneto.

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The next best method of driving the magneto is by means of a gearkeyed to the armature shaft. AVhen this method of driving is em-ployed, great care must be exercised in providing sufficient clearancebetween the gear on the magneto and the driving gear. If there shouldbe a tight spot between these two gears it will react disadvantageouslyon the magneto. The third available method is to drive the magneto bymeans of a chain. This is the least desirable of the three methods andshould be resorted to only in case of absolute necessity. It is difficult toprovide sufficient clearance when using a chain without rendering thetiming less accurate and positive.

Fig. **64, A^^ shows diagrammatically the circuit of the *'D'' typetwo-spark independent magneto and the switch used with it. In posi-tion. OFF the primary winding

of the magneto is short-circuited and in this position the switch servesas an ordinary cut-out or grounding ST^itch. In position *'l" theswitch connects the magneto in such a way that it operates as anordinary single-spark magneto. In this position one end of the

— Secondary ■• Uniiind ( Frame)

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Fig. 64. — Wiring XMagrams of BetUng Magneto Ignition SyBtemB.

secondary winding is grounded to the body of the motor. This is thestarting position. In this position of the switch the entire voltage gen-erated in the magneto is concentrated at one spark-plug instead of be-ing divided in lialf. "With the motor turning over very slowly, as is thecase in starting, the full voltage generated by the

magneto will not in all cases be sufficient to bridge simultaneously twospark gaps, but is amply sufficient to bridge one. Also, this position ofthe switch tends to retard the ignition and should be used in startingto prevent back-firing. With the switch in position **2^^ the magnetoapplies ignition to both plugs in each cylinder simultaneously. This isthe normal running position.

Fig. 64, B shows diagrammatically the circuit of the type **DD^^BERLING high-tension two-spark dual misig-neto. This type is

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recommended for certain types of heavy-duty airplane motors, whichit is impossible to turn over fast enough to give the magneto sufficientspeed to generate even a single spark of volume great enough to ignitethe gas in the cylinder. The dual feature consists of the addition to themagneto of a battery interrupter. The equipment consists of the mag-neto, coil and special high-tension switch. The coil is intended to oper-ate on six volts. Either a storage battery or dry cells may be used.

With the switch in the OFF position, the magneto is grounded, and thebattery circuit is open. With the switch in the second or battery posi-tion marked *^BAT,'^ one end of the secondary winding of the mag-neto is grounded, and the magneto operates as a single-spark magnetodelivering high-tension current to the inside distributor, and the bat-tery circuit being closed the high^ tension current from the coil is de-livered to the outside distributor. In this position the battery current issupplied to one set of spark plugs, no matter how slowly the motor isturned over, but as soon as the motor starts, the magneto supplies cur-rent as a single-spark magneto to the other set of the spark-plugs.After the engine is running, the switch should be thrown to the posi-tion marked **MAG.^^ The battery and coil are then disconnected,and the magneto furnishes ignition to both plugs in each cylinder. Thisis the normal running position. Either a non-vibrating coil type**N-1^' is

furnished or a combined vibrating and non-vibrating coil type **VN.l/'

SETTING BERUNG MAGNETO

The magneto may be set according to one of two different methods,the selection of which is, to some extent, governed by the characterist-ics of the engine, but largely due to the personal preference on the partof the user. In the first method described below, the most advantage-ous position of the piston for fully advanced ignition is determined in

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relation to the extreme advanced position of the magneto. In this case,the fully retarded ignition ^dll not be a matter of selection, but thetiming range of the magneto is wide enough to bring the fully retardedignition after top-center position of the piston. The second method forthe setting of the magneto fixes the fully retarded position of the mag-neto in relation to that position of the piston where fully retarded igni-tion is desired. In this case, the extreme advance position of the mag-neto will not always correspond with the best position of the piston forfully advanced ignition, and the amoimt of advance the magnetoshould have to meet ideal requirements in this respect must be de-termined by experiment.

First Method:

1. Designate one cylinder as cylinder No. 1.

2. Turn the crank-shaft until the piston in cylinder No. 1 is in the posi-tion where the fully advanced spark is desired to occur.

3. Eemove the cover from the distributor block and turn the armatureshaft in the direction of rotation of the magneto until the distributorfinger-brush comes into such a position that this brush makes contactwith the segment which is connected to the cable terminal marked**!.'' This is either one of the two bottom segments, depending uponthe direction of rotation.

4. Place the cam housing in extreme advance, i.e.,

tarn the cam housing until it stops, in the direction opposite to the dir-ection of rotation of the armature. With the cam housing in this posi-tion, open the cover.

5. With the armature in the approximate position as described in*^3,'^ turn the armature slightly in either direction to such a point

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that the platinum points of the magneto interrupter will just begin toopen at the end of the cam, adjacent to the fibre lever on theinterrupter.

6. With this exact position of the armature, fix the magneto to thedriving member of the engine.

Second Method:

1. Designate one cylinder as cylinder No. 1.

2. Turn the crank-shaft until the piston in cylinder No. 1 is in the posi-tion at which the fully retarded spark is desired to occur.

3. Same as No. 3 under First Method.

4. Place the cam housing in extreme retard, i.e., turn the cam housinguntil it stops, in the same direction as the direction of rotation of thearmature. With the cam housing in this position, open the cover.

5. Same as No. 5 under First Method.

6. Same as No. 6 under First Method.

WIRING THE MAGNETO

The wiring of the magneto is clearly shown by wiring diagram.

First determine the sequence of firing for the cylinders and then con-nect the cables to the spark plug in the cylinders in proper sequence,beginning with cylinder No. 1 marked on the distributor block.

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The switch used with the independent type must be mounted in such amanner that there will be a metallic connection between the frame ofthe magneto and the metal portion of the switch.

It is advisable to use a separate battery, either storage or dry cells, as asource of current for the dual equip-

ment. Connecting to the same battery that is used with the generatorand other electrical equipment may cause trouble, as a ** ground ^^in this battery causes the coil to overheat.

CARE AND MAINTENANCE

Lubrication:

Use only the very best of oil for the oil cups.

Put five drops of oil in the oil cup at the driving end of the magneto forevery fifty hours of actual running.

Put five drops of oil in the oil cup at the interrupter end of the mag-neto, located at one side of the cam housing, for every hundred hoursof actual running.

Lubricate the embossed cams in the cam housing with a thin film ofvaseline every fifty hours of actual running. Wipe off all superfluousvaseline. Never use oil in the interrupter. Do not lubricate any otherpart of the interrupter.

Adjusting the Interrupter:

With the fibre lever in the center of one of the embossed cams, as atFig. 65, the opening between the platinum contacts should be not lessthan .016'' and not more than .020". The gauge riveted to the

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adjusting wrench should barely be able to pass between the contactsw^hen fully open. The platinum contacts must be smoothed off with avery fine file. AVhen in closed position, the platinum contacts shouldmake contact with each other over their entire surfaces.

AVhcn inspecting the interrupter, make sure that the ground brush inthe back of the interrupter base is making good contact with the sur-face on which it rubs.

Cleaning the Distributor:

The distributor block cover should be removed for inspection everytwenty-five hours of actual running and the carbon deposit from thedistributor fmger-brush wiped off the distributor block by rubbingwith a rag

or piece of waste dipped in gasoline or kerosene. The high-tension ter-minal brush on the side of the magneto should also be carefully in-spected for proper tension.

LOCATING TROUBLE

Trouble in the ignition system is indicated by the motor "missing,"stopping entirely, or by inability to start.

It is safe to assume that the trouble is not in the

Fig. 66.—^The BaiUiiK Magneto Breaker Box Showing ConUct FolntsSeparatad and Intairaptoi Leror on Oam.

magneto, and the carburetor, gasoline supply and sparkplugs shouldfirst be investigated.

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If the magneto is suspected, the first thing to do is to determine if itwill deliver a spark. To determine this, disconnect one of the high-ten-sion leads from the spark-plug in one of the cylinders and place it sothat there is approximately Ka" between the terminal and the cylinderframe.

Open the pet cocks on the other cylinders to prevent the engine' fromfiring and turn over the engine until the piston is approaching the endof the compression

stroke in the cylinder from which the cable has been removed. Set themagneto in the advance position and rapidly rock the engine over thetop-center position, observing closely if a spark occurs between theend of the high-tension cable and the frame.

If the magneto is of the dual type, the trouble may be either in themagneto or in the battery or coil system, therefore disconnect the bat-tery and place the switch in the position marked **MA6.'' The mag-neto will then operate as an independent magneto and should spark inthe proper manner. After this the battery system should be investig-ated. To test the operation of the battery and coil, examine all connec-tions, making sure that they are clean and tight, and then with theswitch in the **BAT," rock the piston slowly back and fortL If a type**VN-1'' coil is used, a shower of sparks should jump between thehigh-tension cable terminal and the cylinder frame when the piston isin the correct position for firing. If no spark occurs, remove the coverfrom the coil and see that the vibrating tongue is free. If a type **N-1'*coil is used, a single spark will occur. The battery should furnish sixvolts when connected to the coil, and this should also be verified.

If the coil still refuses to give a spark and all connections are correct,the coil should be replaced and the defective coil returned to themanufacturer.

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If both magneto and coil give a spark when tested as just described,the spark-plugs should be investigated. To do this, disconnect thecables and remove the spark-plugs. Then reconnect the cables to theplugs and place them so that the frame portions of the plugs are inmetallic connection with the frame of^the motor. Then turn over themotor, thus revolving the magneto armature, and see if a spark is pro-duced at the spark gaps of the plugs.

The most common defects in spark-plugs are breaking down of the in-sulation, fouling due to carbon, or too large or small a spark gap. Toclean the plugs a stijff brush

ind gasoline should be used. The spark gap should be tbout %2" andnever less than Yet". Too small a gap nay have been caused by beads ofmetal forming due o tlie heat of the spark. Too long a gap may havebeen aused by the points burning off.

If the magneto and spark plugs are in good condition jid the enginedoes not run satisfactorily, the setting

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Ig. 66.—Tli» Dixie Hod«l 60 for Slx-Cyllnder Airplano EngineIgnlUon.

hoidd be verified according to instructions previously iven, and, if ne-cessary, readjusted.

Be careful to observe that both the type "VN-1" and ype "N-1" coils areso arranged that the spark occurs in the opening of the contacts of thetimer. As this is ust the reverse of the usual operation, it should becare-ully noted when any change in tlie setting of the timer 8 made.The timer on the dual type magneto is ad-usted so that the batteryspark occurs about 5° later

Aviation Engines

than the magneto spark. This provides an antomatie advance as soonas the switch is thrown to the magneto position "MAG." This relativetiming can be eaaly adjusted by removing the interrupter and shiftingthe cam in the direction desired.

THE DIXIE MAGNETO

The Dixie magneto, shown at Pig. 66, operates on a different principlethan the rotary armature type. It is used on the Hall-Scott and otheraviation engines. In

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Fig. 67.—iDStallBUon DimenBlonB of Dixie Model 60 Magnsto.

this magneto the rotating member consists of two pieces of magneticmaterial separated by a non-magnetic center piece. This member con-stitutes true rotating poles for the magnet and rotates in a field struc-ture, composed of two laminated field pieces, riveted between twononmagnetic rings. The bearings for the rotating poles are

ited in steel plates, which lie against the poles of the lets. "WTien themagnet poles rotate, the magnetic of force from each magnet pole arecarried directly

Rotating Magnet Po-las

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Thi rotating element of fha. Dixie magnato. IntheDlxh there are norei/ol^ing windings,thera is no moving wirt and the parts of the mag-nefo are reducad to a mi'nimur

Fig. 68.—Tbe Botating Elementa of Uie Dlxia Hftgneto.

le field pieces and through the windings, without ■sal through themass of the rotating iuember and only s. single air gap. There are nolosses by flux ■sal in the rotating part, such as take place in other

machines, and this is said to account for the high efficiency of theinstrument.

And this **Mason Principle'' involved in the operation of the Dixie issimplified by a glance at the field structure, consisting of the non-mag-netic rings, assembled to which are the field pieces between which therotating poles revolve (see Fig. 68). Rotating between the limbs of the

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magnets, these two pieces of magnetic material form true extensionsto the poles of the magnets, and are, in cojisequence, always of thesame polarity. It will be seen there is no reversal of the magnetismthrough them, and consequently no eddy current or hysteresis losseswhich are present in the usual rotor or inductor types. The simplicityfeatures of construction stand out prominently here, in that there areno revolving windings, a detail entirely differing from the orthodoxhigh-tension instrument. This simplicity becomes instantly apparentwhen it is found that the circuit breaker, instead of revolving as it doesin other types, is stationary and that the whole breaker mechanism isexposed by simply turning the cover spring aside and removing cover.This makes inspection and adjustment particularly simple, and thefact that no special tool is necessary for adjustment oi* the platinumpoints—^an ordinary small screw-driver is the whole **kit of tools*'needed in the work of disassembling or assembling—^is a feature ofsome value.

With dust- and water-protecting casing removed, and one of the mag-nets withdrawn, as in Fig. 69, the winding can be seen with its coreresting on the field pole pieces and the primary lead attached to itsside. An important feature of the high-tension winding is that theheads are of insulating material, and there is not the tendency for thehigh-tension current to jump to the side as in the ordinary armaturetype magneto. The high-tension current is carried to the distributor bymeans of an insulated block with a spindle, at one end of which is aspring brush bearing directly on the Avinding, thus shortening

the path of the high-tension current and eliminating the use of rubberspools and insulating parts. The moving parts of the magneto neednever be disturbed if the high-tension winding is to be removed.. This-winding con-

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Thewlioltbrtaktrmec/ianiim iteiposrdby iimply turning ttit covtnprinqasult and nmorinq covsr. A icrtwdeivtrkihaonly toot n*trisary to adjusttht platinumpoiolt.

Hofhing could be simpler than Dili* eun-itruclion. By loosening nutsand tuminq ilampiaside. Ifie ditiribufor block canbe rtmortd and dis-lributordiK lifted out of itt boatirig.

Tig. 69. — SnggHtloiii foi Adlnatlng uid Dlsmaatllng Dixit HaEfneto.A— Screw Driver Adjusts Contact FoIntB. B—Dlstrlbntor BlockBemOTed. 0—Taking off Magnets. D—Showing How EUU7 Condenserand High Tension Windings an Bemered.

stitutes all of the magneto windings, no external spark coil being ne-cessary. The condenser is placed directly above the winding and is eas-ily removable by taking out two screws, instead of being placed in anarmature where it is inaccessible except to an expert, and where it can-not be replaced except at the factory whence it emanated.

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CARE OF THE DIXIE MAGNETO

The bearings of the magneto are provided with oil cups and a fewdrops of light oil every 1,000 miles are sufficient. The breaker levershould be lubricated every 1,000 miles with a drop of light oil, appliedwith a toothpick. The proper distance between the platinum pointswhen separated should not exceed .020 or one-fiftieth of an inch. Agauge of the proper size is attached to the screwdriver furnished withthe magneto. The platinum contacts should be kept clean and properlyadjusted. Should the contacts become pitted, a fine file should be usedto smooth them in order to permit them to come into perfect contact.The distributor block should be removed occasionally and inspectedfor an accumulation of carbon dust. The inside of the distributor blockshould be cleaned with a cloth moistened with gasoUne and thenwiped dry with a clean cloth. When replacing the block, care must beexercised in pushing the carbon brush into the socket. Do not pull outthe carbon brushes in the distributor because you think there is notenough tension on the small brass springs. In order to obtain the mostefficient results, the normal setting of the spark-plug points should notexceed .025 of an inch, and it is advisable to have the gap just right be-fore a spark-plug is inserted.

The spark-plug electrodes may be easily set by means of the gauge at-tached to the screwdriver. The setting of the spark-plug points is animportant function which is usually overlooked, tvith the result thatthe magneto is blamed tvhen it is not at fault.

TIMING OF THE DIXIE MAGNETO

In order to obtain the utmost efficiency from the engine, the magnetomust be correctly timed to it. This operation is usually performedwhen the magneto is fitted to the engine at the factory. The correct set-ting may vary according to individuality of the engine, and some

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h

engines may require an earlier setting in order to obtain the best res-ults. However, should the occasion arise to retime the magneto, theprocedure is as follows: Rotate the crank-shaft of the engine until oneof the pistons, preferably that of cylinder No. 1, is Ke of an inch aheadof the end of the compression stroke. With the timing lever in full re-tard position, the driving shaft of the magneto should be rotated in thedirection in which it will be driven. The circuit breaker should beclosely observed and when the platinum contact points are about toseparate, the drive gear or coupling should be secured to the drive

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shaft of the magneto. Care should be taken not to alter the position ofthe magneto shaft when tightening the nut to secure the gear or coup-ling, after which the magneto should be secured to its base. Removethe distributor block and determine which terminal of the block is incontact with the carbon brush of the distributor finger and connectwith plug wdre leading to No. 1 cylinder to this terminal. Connect theremaining plug wires in turn according to the proper sequence of fir-ing of the cylinders. (See the wiring diagram for a typical six-cylinderengine at Fig. 70.) A terminal on the end of the cover spring of themagneto is provided for the purpose of connecting the wire leading toa ground switch for stopping the engine.

A special model or type of magneto is made for V engines which use acompound distributor construction instead of the simple type on themodel illustrated and a different interior arrangement permits theproduction of four sparks per revolution of the rotors. This makes itpossible to run the magneto slower than would be possible with thetwo-spark form. The application of two compound distributor magne-tos of this type to a Thomas-Morse 135 horse-power motor of theeight-cylinder V pattern is clearly shown at Fig. 71.

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SPABK-PLUQ DESIGN AHD APPLICATION

With the high-tension system of ignition the spark is produced by acurrent of high voltage jumping between two points which break the

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complete circuit, which would exist otherwise in the secondary coiland its external coimections. The spark-plug is a simple device which

Fig. 71.— How Magneto Ignition Is instaUed on Tbomas-Mon« 136 IPovn Motor.

consists of two terminal electrodes carried in a suitable shell member,wliich is screwed into the cylinder. Typical spark-plugs are shown insection at Fig. 72 and the construction can be easily understood. Thesecondary wire from the coil is attached to a terminal at the top of acentral electrode member, which is supported in a bushing of someform of insulating material. The type shown at A employs a moldedporcelain as an insulator, while that depicted at B uses a bushing ofmica. The

ineulating bushing and electrode are housed in a steel body, which isprovided with a screw thread at the bottom, by which means it isscrewed into the combustion chamber.

When porcelain is used as an insulating material it is kept from directcontact with the metal portion by some form of yielding packing, usu-ally asbestos. This is necessary becaose the steel and porcelain havedifferent coefficients of expansion and some flexibility must he

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provided at the joints to permit the materials to expand differentlywhen heated. The steel body of the plug which is screwed into the cyl-inder is in metallic contact with it and carries sparking points whichform one of the terminals of the air gap over which the spark occurs.The

current entering iat the top of the plug cannot reach the ground, whichis represented by the metal portion of the engine, until it has traversedthe full length of the central electrode and overcome the resistance ofthe gap between it and the terminal point on the shell. The porcelainbushing is firmly seated against the asbestos packing by means of abrass screw gland w^hich sets against a flange formed on the porcel-ain, and which screws into a thread at the upper portion of the plugbody.

The mica plug shown at B is somewhat simpler in construction thanthat shown at A. The mica core which keeps the central electrode sep-arated from the steel body is composed of several layers of pure sheetmica wound around the steel rod longitudinally, and hundreds ofstamped steel washers w^hich are forced over this member and com-pacted under high pressure with some form of a binding materialbetween them. Porcelain insulators are usually molded from high-grade clay and are approxi-mately of the shapes desired by the design-ers of the plug. The central electrode may be held in place by mechan-ical means such as nuts, packings, and a shoulder on the rod, as shownat A. Another method sometimes used is to cement the electrode inplace by means of some form of fire-clay cement. Whatever method offastening is used, it is imperative that the joints be absolutely tight sothat no gas can escape at the time of explosion. Porcelain is the mater-ial most widely used because it can be glazed so that it will not absorboil, and it is subjected to such high temperature in baking that it is notliable to crack when heated.

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The spark-plugs may be screwed into any convenient part of the com-bustion chamber, the general practice being to install them in the capsover the inlet valves, or in the side of the combustion chamber, so thepoints will be directly in the path of the entering fresh gases from thecarburetor.

Other insulatini^ i!iaterials sometimes used are glass,

Spark'Plug Design and Use

195

steatite (which is a form of soapstone) and lava. Mica and porcelainare the two common materials used because they give the best results.Glass is liable to crack, while lava or the soapstone insulating bushingsabsorb oil. The spark gap of the average plug is equal to about H2 ofan inch for coil ignition and Ho of an inch when used in magneto cir-cuits. A simple gauge for determining the gap setting is the thicknessof an ordinary visiting

K f'/ie' —

16 mm.

70 mm* lOmm. j

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ruM

I

f

^8-32 \y 4mm.. 7Sp.)

Across FlatSt i6.9 Threads per inch : I.Smilli meters pitch Root dia-meter $3^ inch.: 16.09 millimeters Pitch diameter 67d± inch: 17.22•*'02 millimeters Outside diameter 717Inch : IB. 2 millimeters

Fig. 73.—Standard Airplane Engine Plug Suggested 1>7 S. A. E.Standards

Committee.

card for magneto plugs, or a space equal to the thickness of a worndime for a coil plug. The insulating bushings are made in a number ofdifferent ways, and while details of construction vary, spark-plugs donot differ essentially in design. The dimensions of the standardizedplug recommended by the S. A. E. are shown at Fig. 73.

It is often desirable to have a water-tight joint between the high-ten-sion cable and the terminal screw on top of the insulating bushing ofthe spark-plug, especially in marine applications. The plug shown at C,Fig. 72,

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is provided with an insulating member or hood of porce-lain, which issecured by a clip in such a manner that it makes a water-tight connec-tion. Should the porcelain of a conventional form of plug becomecovered with water or dirty oil, the high-tension current is apt to rundown this conducting material on the porcelain and reach the groundwithout having to complete its circuit by jumping the air gap and pro-ducing a spark. It will be evident that wherever a plug is exposed to theelements, which is often the case in airplane service, that it should beprotected by an insulating hood which will keep the insulator dry andprevent short circuiting of the spark. The same end can be attained byslipping an ordinary rubber nipple over the porcelain insulator of anyconventional plug and bringing up one end over the cable.

TWO-SPARK IGNITION

On most aviation engines, especially those having large cylinders, it issometimes difficult to secure complete combustion by using a single-spark plug. If the combustion is not rapid the efficiency of the enginewill be reduced proportionately. The compressed charge in the cylin-der does not ignite all at once or instantaneously, as many assume, butit is the strata of gas nearest the plug which is ignited first. This in turnsets fire to consecutive layers of the charge until the entire mass isaflame. One may compare the combustion of gas in the gas-engine cyl-inder to the phenomenon which obtains when a heavy object is throwninto a pool of still water. First a small circle is seen at the point wherethe object has passed into the water, this circle in turn inducing othei*and larger circles until the whole surface of the pool has been agitatedfrom the one central point. The method of igniting the gas is very sim-ilar, as the spark ignites the circle of gas immediately adjacent to thesparking point, and tliis circle in turn ignites a little larger one con-centric with it. The second circle of flame

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sets fire to more of the gas, and finally the entire contents of the com-bustion chamber are burning.

While ordinarily combustion is sufficiently rapid with a single plug sothat the proper explosion is obtained at moderate engine speeds, if theengine is working fast and the cylinders are of large capacity morepower may be • obtained by setting fire to the mixture at two differentpoints instead of but one. This may be accomplished by using twosparking-plugs in the cylinder instead of one, and experiments haveshown that it is possible to gain from twenty-five to thirty per cent, inmotor power at high speed with two-spatk plugs, because the combus-tion of gas is accelerated by igniting the gas simultaneously in twoplaces. The double-plug system on airplane engines is also a safe-guard, as in event of failure of one plug in the cylinder the other wouldcontinue to fire the gas, and the engine will continue to fxmctionproperly.

In using magneto ignition some precautions are necessary relating towiring and also the character of the sparkplugs employed. The con-ductor should be of good quality, have ample insulation, and be wellprotected from accumulations of oil, which would tend to decomposerubber insulation. It is customary to protect the wiring by running itthrough the conduits of fiber or metal tubing lined with insulating ma-terial. Multiple strand cables should be used for both primary and sec-ondary wiring, and the insulation should be of rubber at least %6 inchthick.

The spark-plugs commonly used for battery and coil ignition cannotalways be employed when a magneto is fitted. The current producedby the mechanical generator has a greater amperage and more heatvalue than that obtained from transformer coils excited by battery cur-rent. The greater heat may burn or fuse the slender points used onsome battery plugs and heavier electrodes are needed to resist the

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heating effect of the more intense arc. While the current has greateramperage it is not of as high potential or voltage as that commonlyproduced by the secondary winding of an induction coil, and it

cannot overcome as much of a gap. Manufacturers of magneto plugsusually set the spark points about ^4 of an inch apart. The most effi-cient magneto plug has a plurality of points so that when the distancebetween one set becomes too great the spark will take place between

FlK. 71-—special Mica Fln£ for AvlaUoa EngliiM.

one of the other pairs of electrodes which are not separated by so greatan air space.

SPECIAI- PLUGS FOR AIRPLANE WORK

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Airplane work calls for special construction of sparkplugs, o^ving totlie high compression used in the engines and the fact that they are op-erated on open throttle practically all the time, thus causing a greatdeal of heat to

be developed. The plug shown at Fig. 74 was recently described in*'The Automobile,'' and has been devised especially for airplane en-gines and automobile racing power plants. The core C is built up ofmica washers, and has square shoulders. As mica washers of differentsizes may be used, and accurate machining, such as is necessary withconical clamping surfaces, is not required, the plug can be producedeconomically. The square shoulders of the core afford two gasket seats,and when the core is clamped in the shell by means of check nut E, it isaccurately centered and a tight joint is formed. This construction alsomakes a shorter plug than where conical fits are used, thus improvingthe heat radiation through the stem. The lower end of the shell isprovided with a baffle plate 0, which tends to keep the oil away fromthe mica. There are perforations L in this baffle plate to prevent burntgases being pocketed behind the baffle plate and pre-igniting the newcharge. This construction also brings the firing point out into the firingchamber of the engine, and has all the other advantages of a closed-end plug. The stem P is made of brass or copper, on account of theirsuperior heat * conductivity, and the electrode J is swedged into thebottom of the stem, as shown at K, in a secure manner.

The shell is finned, as shown at G, to provide greater heat radiatingsurface. There is also a fin F at the top of the stem, to increase the ra-diation of heat from the stem and electrode. The top of this finned por-tion is slightly countersunk, and the stem is riveted into same, therebyreducing the possibility of leakage past the threads on the stem. Thisfinned portion is necked at A to take a slip terminal.

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In building up the core a small section of washers, I, is built up beforethe mica insulating tube D is placed on. This construction gives a bet-ter support to section I. Baffle plate 0 is bored out to allow the elec-trode J to pass through, and the clearance between baffle plate andelectrode is made larger than the width of the gap be-

tween the firing points, so that there is no danger of the spark jumpingfrom the electrode to the baffle plate.

This plug will be furnished either with or without the finned portion,to meet individual requirements. The manufacturers lay special stressupon the simplicity of construction and upon the method of clamping,which is claimed to make the plug absolutely gas-tight.

CHAPTER Vn

Why Lubrication la Necessary—Friction Defined—Theory of Lubrica-tion—Derivation of Lubricants—Properties of Cylinder Oils— FactorsInfluencing Lubrication System Selection—Gnome Type Engines UseCastor Oil—Hall-Scott Lubrication System—Oil Suih ply by ConstantLevel Splash System—Dry Crank-Case System Best for AirplaneEngines—^Why Cooling Systems Are Necessary— Cooling SystemsGenerally Applied—Cooling by Positive Pump Circulation—Thermo-Syphon System—Direct Air-Cooling Methods —Air-Cooled EngineDesign Considerations.

WHY LUBRICATION IS NECESSARY

The importance of minimizing friction at the various bearing surfacesof machines to secure mechanical efficiency is fully recognized by allmechanics, and proper lubricity of all* parts of the mechanism is avery essential factor upon which the durability and successful opera-tion of the motor car power plant depends. All of the moving membersof the engine which are in contact with other portions, whether the

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motion is continuous or intermittent, of high or low velocity, or of rec-tilinear or continued rotary nature, should be provided with an ad-equate supply of oil. No other assemblage of mechanism is operatedunder conditions which are so much to its disadvantage as the motorcar, and the tendency is toward a simplification of oiling methods sothat the supply will be ample and automatically applied to the pointsneeding it.

In all machinery in motion the members which are in contact have atendency to stick to each other, and the very minute projections whichexist on even the smoothest of surfaces would have a tendency to clingor adhere to each other if the surfaces were not kept apart by someelastic and imctuous substance. This wall flow or spread out over thesurfaces and smooth out the inequalities exist-

ing whicli tend to produce heat and retard motion of the pieces relat-ive to each other.

A general impression which obtains is that well machined surfaces aresmooth, but while they are apparently free from roughness, and noprojections are visible to the naked eye, any smooth bearing surface,even if very carefully ground, will have a rough appearance if ex-amined with a magnifying glass. An exaggerated condition to illustratethis point is shown at Fig. 75. The amount of friction wdll vary in pro-portion to the pressure on the surfaces in contact and will augment *as the loads increase ; the rpugher surfaces will have more frictionthan smoother ones and soft bodies will produce more friction thanhard substances.

FRICTION DEFINED

Friction is always present in any mechanism as a resisting force thattends to retard motion and bring all moving parts to a state of rest.

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The absorption of power by friction may be gauged by the amount ofheat which exists at the bearing points. Friction of solids may be di-vided into two classes: sliding friction, such as exists between the pis-ton and cylinder, or the bearings of a gas-engine, and rolling friction,which is that present when the load is supported by ball or roller bear-ings, or that which exists between the tires or the driving wheels andthe road. Engineers endeavor to keep friction losses as low as possible,and much care is taken in all modern airplane engines to provide ad-equate methods of lubrication, or anti-friction bearings at all pointswhere considerable friction exists.

THEORY OF LUBRICATION

The reason a lubricant is supplied to bearing points will be easily un-derstood if one considers that these elastic substances flow betweenthe close fitting surfaces, and by filling up the minute depressions inthe surfaces and covering the high spots act as a cushion which

absorbs the heat generated and takes the wear instead of the metallicbearing snrfaee. The closer the parts fit together the more fluid thelubricant must be to pass between their surfaces, and at the same timeit must possess sufficient body so that it 'will not be entirely forced outby the pressure existing between the parts.

Oils should have good adhesive, as well as cohesive, qualities. Theformer are necessary so that the oil film

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Fig. 79.—Showing Um of Bbgnlfyliig Glass to D«moiutr»to thatAppsT«iitIy Smootli Hetal Surfaces Uay Have Hlnnte IiregnlatltieBwUcb Produce Friction.

will cling well to the surfaces -of the bearings; the latter, so the oilparticles will cling together and resist tlie tendency to separationwhich exists all the time the bearings are in operation. When used forgas-engine lubrication the oil should be capable of withstanding con-siderable heat in order that it will not be vaporized by tlie liot portionsof the cylinder. It should have sufficient cold test so that it will remainfluid and flow readily at low temperature. Lubricants should be freefrom acid, or alka-

lies, which tend to produce a chemical action with metals and result incorrosion of the parts to which they are applied. It is imperative thatthe oil be exactly the proper quality and nature for the purpose inten-ded and that it be applied in a positive manner. The requirements maybe briefly summarized as follows:

First—It must have sufficient body to prevent seizing of the parts towhich it is applied and between which it is depended upon to maintain

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an elastic film, and yet it must not have too much viscosity, in order tominimize the internal or fluid friction which exists between theparticles of the lubricant itself.

Second—The lubricant must not coagulate or gum; must not injure theparts to which it is applied, either by chemical action or by producinginjurious deposits, and it should not evaporate readily.

Third—The character of the work will demand that the oil should notvaporize when heated or thicken to such a point that it will not flowreadily when cold.

Fourth—The oil must be free from acid, alkalies, animal or vegetablefillers, or other injurious agencies.

Fifth—It must be carefully selected for the work required and shouldbe a good conductor of heat.

DERrV^ATION OF LUBRICANTS

The first oils which were used for lubricating machinery were obtainedfrom animal and vegetable sources, though at the present time mostunguents are of mineral derivation. Lubricants may exist as fluids,semifluids, or solids. The viscosity will vary from light spindle or dy-namo oils, which have but little more body than kerosene, to the heav-iest greases and tallows. The most common solid employed as a lubric-ant is graphite, sometimes termed ^^plumbago" or ^^black lead."This substance is of mineral derivation.

The disadvantage of oils of organic origin, such as those obtained fromanimal fats or vegetable substances, is that they will absorb oxygenfrom the atmosphere.

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which causes them to thicken or become rancid. Such oils have a verypoor cold test, as they solidify at comparatively high temperatures,and their flashing point is so low that they cannot be used at pointswhere much heat exists. In most animal oils various acids are presentin greater or less quantities, and for this reason they are not well adap-ted for lubricating metallic surfaces which may be raised high enoughin temperature to cause decomposition of the oils.

Lubricants derived from the crude petroleum are called * * Oleonaph-thas'' and they are a product of the process of refining petroleumthrough which gasoline and kerosene are obtained. They are of lowercost than vegetable or animal oil, and as they are of non-X)rganic ori-gin, they do not become rancid or gummy by constant exposure to theair, and they will have no corrosive action on metals because they con-tain no deleterious substances in chemical composition. By the pro-cess of fractional distillation mineral oils of all grades c^n be obtained.They have a lower cold and higher flash test and there is not the liabil-ity of spontaneous combustion that exists with animal oils.

The organic oils are derived from fatty substances, which are presentin the bodies of all animals and in some portions of plants. The generalmethod of extracting oil from, animal bodies is by a rendering process,which consists of applying sufficient heat to liquefy the oil and thenseparating it from the tissue with which it is combined by compres-sion. The only oil which is used to any extent in gas-engine lubricationthat is not of mineral derivation is castor oil. This substance has beenused on high-speed racing automobile engines and on airplane powerplants. It is obtained from the seeds of the castor plant, which containa large percentage of oil.

Among the solid substances which may be used for lubricating pur-poses may be mentioned tallow, which is obtained from the fat of

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animals, and graphite and soap-stone, which are of mineral deriva-tion. Tallow is never

•

206 Aviation Engines

used at points where it will be exposed to much heat, though it is oftenemployed as a filler for greases used in transmission gearing of autos.Graphite is sometimes mixed with oil and applied to cylinder lubrica-tion, though it is most often used in connection with greases in thelanding gear parts and for coating wires and cables of the airplane.Graphite- is not affected by heat, cold, acids, or alkalies, and has astrong attraction for metal surfaces. It mixes readily with oils andgreases and increases their efficiency in many appUcations. It is some-times used where it would not be possible to use other lubricants be-cause of extremes of temperature.

The oils used for cylinder lubrication are obtained almost exclusivelyfrom crude petroleum derived from American wells. Special care mustbe taken in the selection of crude material, as every variety will notyield oil of the proper quality to be used as a cylijider lubricant Thecrude petroleum is distilled as rapidly as possible with fire heat to va-porize off the naphthas and the burning oils. After these vapors havebeen given off superheated steam is provided to assist in distilling.When enough of the light elements have been eliminated the residue isdrawn off, passed through a strainer to free it from grit and earthymatters, and is afterwards cooled to separate the wax from it. This isthe dark cylinder oil and is the grade usually used for steam-enginecylinders.

PROPERTIES OF CYLINDER OILS

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The oil that is to be used in the gasoline enguie must be of high qual-ity, and for that reas'on the best grades are distilled in a vacuum thatthe light distillates may be separated at much lower temperatures thanordinary conditions of distilling permit. If the degree of heat is nothigh the product is not so apt to decompose and deposit carbon. If it isdesired to remove the color of the oil w^hich is caused by free carbonand other impurities it can be accomplished by filtering the oilthrough charcoal. The greater the number of times the oil is filtered,

the lighter it will become in color. The best cylinder oils have flashpoints usually in excess of 500 degrees F., and while they have a highdegree of viscosity at 100 degrees F. they become more fluid as thetemperature increases.

The lubricating oils obtained by refining crude petroleum may be di-vided into three classes:

rirst—The natural oils of great body which are prepared for use by al-lowing the crude material to settle in tanks at high temperature andfrom which the impurities are removed by natural filtration. These oilsare given the necessary body and are free from the volatile substancesthey contain by means of superheated steam which provides a sourceof heat.

Second—^Another grade of these natural oils which are filtered againat high temperatures and under pressure through beds of animal char-coal to improve their color.

Third—Pale, limpid oils, obtained by distillation and subsequentchemical treatment from the residuum produced in refining petroleumto obtain the fuel oils.

Authorities agree that any form of mixed oil in which animal and min-eral lubricants are coinbined should never be used in the Cylinder of a

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gas engine as the admixture of the lubricants does not prevent the de-composition of the organic oil into the glycerides and fatty acids pecu-liar to the fat used. In a gas-engine cylinder the flame tends to producemore or less charring. The deposits of carbon will be much greaterwith animal oils than with those derived from the petroleum base be-cause the constituents of a fat or tallow are not of the same volatilecharacter as those which comprise the hydro-carbon oils which willevaporate or volatilize before they char in most instances.

FACTORS INFLUENCING LUBRICATION SYSTEM SELECTION

The suitability of oil for the proper and efficient lubrication of all in-ternal coiAbustion engines is' determined chiefly by the followingfactors:

1. Type of cooling system (operating temperatures).

2. Type of lubricating system (method of appljring oil to the movingparts).

3. Rubbing speeds of contact surfaces.

Were the operating temperatures, bearing surface speeds and lubrica-tion systems identical, a single oil could be used in all engines withequal satisfaction. The only change then necessary in viscosity wouldbe that due. to climatic conditions. As engines are now designed, onlythree grades of oil are necessary for the lubrication of all types with theexception of Knight, air-cooled and some engines which run continu-ously at full load. In the specification of engine lubricants the featureof load carried by the engine should be carefully considered.

Full Load Engines,

1. Marine.

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2. Racing automobile.

3. Aviation.

4. Farm tractor.

5. Some stationary.

Variable Load Engines.

1. Pleasure automobile.

2. Commercial vehicle.

3. Motor cycle.

4. Some stationary.

Of the forms outlined, the only one we have any immediate concernabout is the airplane power plant. The Piatt & Washburn RefiningCompany, who have made a careful study of the lubrication problemas applied to all tjT)es of engines, have found a peculiar set of condi-tions to apply to oiling high-speed constant-duty or ^^full-load" en-gines. Modern airplane engines are designed to operate continuouslyat a fairly uniform high rotative speed and at full load over long peri-ods of time. As a sequence to this hea\'y duty the operating

temperatures are elevated. For the sake of extreme lightness in weightof all parts, very thin alloy steel aluminum or cast iron pistons are fit-ted and the temperature of the thin piston heads at the center reachesanywhere between 600° and 1,400° Fahr., as in automobile racing en-gines. Freely exposed to such intense heat hydro-carbon oils are par-tially *^cracked^' into light and heavy products or polymerized intosolid hydro-carbons. From these facts it follows that only heavy

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mineral oils of low carbon residue and of the greatest chemical purityand stability should be used to secure good lubrication. In all cases theoil should be sufficiently heavy to assure the highest horse-power andfuel and oil economy compatible with perfect lubrication, avoiding, atthe same time, carbonization and ignition failure. When aluminumpistons are used their superior heat-conducting properties aid materi-ally in reducing the rate of oil destruction.

The extraordinary evolutions described by airplanes in flight make it amatter of vital necessity to operate engines inclined at all angles to thevertical as well as in an upside-down position. To meet this situationlubricating systems -have been elaborated so as to deliver an abund-ance of oil where needed and to eliminate possible flooding of cylin-ders. This is done by applying a full force feed system, distributing oilunder considerable pressure to all working parts. Discharged throughthe bearings, the oil drains down to the suction side of a second pumplocated in the bottom of the base chamber. This pump being of greatercapacity than the first prevents the accumulation of oil in the crank-case, and forces it to a separate oil reservoir-cooler, whence it flowsback in rapid circulation to the pump feeding the bearings. With thisarrangement positive lubrication is entirely independent of engine po-sition. The lubricating system of the Thomas-Morse aviation engines,which is shown at Fig. 76, is typical of current practice.

-11II s.r St

_?S5 ^1 ft. I

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GNOME TYPE ENGINES USE CASTOR OIL

The construction and operation of rotative radial cylinder engines in-troduce additional diflSculties of lubrication to those already referredto and merit especial attention. Owing to the peculiar alimentationsystems of Gnome type engines, atomized gasoline mixed with air isdrawn through the hollow stationary crank-shaft directly into thecrank-case which it fills on the way to the cylinders. Therein lies the

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trouble. Hydrocarbon oils are soon dissolved by the gasoline andwashed off, leaving the bearing surfaces without adequate protectionand exposed to instant wear and destruction. So castor oil is resortedto as an indispensable but xmfortunate compromise. Of vegetableorigLu, it leaves a much more bulky carbon deposit in the explosionchambers than does mineral oil and its great affinity for oxygen causesthe formation of voluminous gummy deposit in the crank-case.Engines employing it need to be dismoimted and thoroughly scrapedout at frequent intervals. It is advisable to use only imblended chemic-ally pure castor oil in rotative engines, first by virtue of its insolubilityin gasoline and second because its extra heavy body can resist the hightemperature of air-cooled cylinders.

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HALL-SCOTT LUBRICATION SYSTEM

The oiling system of the Hall-Scott type A-5 125 horse-power engine isclearly shown at Fig. 77. It is completely described in the instructionbook issued by the company from which the following extracts are re-produced by permission. Crank-shaft, connecting rods and all otherparts within the crank-case and cylinders are lubricated directly or in-directly by a force-feed oiling system. The cylinder walls and wrist pinsare lubricated by oil spray thrown from the lower end of connectingrod bearings. This system is used only upon A-5 engines. Upon A-7aand A-5a engines a small tube supplies oil

from connecting rod bearing directly upon the wrist pin. The oil isdrawn from the strainer located at the lowest portion of the lowercrank-case, forced around the main intake manifold oil jacket. Fromhere it is circulated to the main distributing pipe located along the

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lower left hand side of upper crank-case. The oil is then forced directlyto the lower side of crank-shaft, through holes drilled in each mainbearing cup. Leakage from these main bearings is caught in scuppersplaced upon the cheeks of the crank-shafts furnishing oil under pres-sure to the connecting rod bearings. A-7a and A-5a engines have smalltubes leading from these bearings which convey the oil under pressureto the wrist pins. •

A bi-pass located at the front end of the distributing oil pipe can beregulated to lessen or raise the pressure. By screwing the valve in, thepressure will raise and more oil will be forced to the bearings. By un-screwing, pressure is reduced and less oil is fed. A-7a and A-5a engineshave oil relief valves located just off of the main oil pump in the lowercrank-case. This regulates the pressure at all times so that in coldweather there will be no danger of bursting oil pipes due to excessivepressure. If it is found the oil pressure is not maintained at a highenough level, inspect this valve. A stronger spring will not allow the oilto bi-pass so freely, and consequently the pressure will be raised; aweaker spring will bi-pass more oil and reduce the oil pressure materi-ally. Independent of the above-mentioned system, a small, directlydriven rotary oiler feeds oil to the base of each individual cylinder. Thesupply of oil is furnished by the main oil pump located in the lowercrank-case. A small sight-feed regulator is furnished to control thesupply of oil from this oiler. This instrument should be placed higherthan the auxiliary oil distributor itself to enable the oil to drain bygravity feed to the oiler. If there is no available place with the neces-sary height in the front seat of plane, connect it directly to the intake Lfitting on. the oiler in an upright position. It should

be regulated with full open throttle to maintain an oil level in the glass,approximately half way.

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An oil pressure gauge is provided. This should be run to the pilot's in-strument board. The gauge registers the oil pressure upon the bear-ings, also determining its cir-culation. Strict watch should be main-tained of this instrument by pilot, and if for any reason its hand shoulddrop to 0 the motor should be immediately stopped and the troublefound before restarting engine. Care should be taken that the oil doesnot work up into the gauge, as it will prevent the correct gauge regis-tering of oil pressure. The oil pressure wdll vary according to weatherconditions and viscosity of oil used. In normal weather, with the en-gine properly warmed up, the pressure will register on the oil gaugefrom 5 to 10 pounds when the engine is turning from 1,275 to 1,300 r.p. m. This does not apply to all aviation engines, however, as the prop-er pressure advised for the Curtiss 0X2 motor is from 40 to 55 poundsat the gauge.

The oil sump plug is located at the lowest point of the lower crank-case. This is a combination dirt, water and sediment trap. It is easilyremoved by imscrewing. Oil is furnished mechanically to the cam-shaft housing under pressure through a small tube leading from themain distributing pipe at the propeller end of engine directly into theend of cam-shaft housing. The opposite end of this housing is amplyrelieved to allow the oil to rapidly flow down upon cam-shaft,magneto, pinion-shaft, and crank-shaft gears, after which it returns tolower crank-case. An outside overflow pipe is also provided to carryaway the surplus oil.

BRAINING OIL FROM CRANK-CASE

The oil strainer is placed at the lowest point of the lower crank-case.This strainer should be removed after every five to eight hours • run-ning of the engine and cleaned thoroughly with gasoline. It is also ad-visable to squirt distillate up into the case through the opening

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where the strainer has been removed. Allow this distillate to drain outthoroughly before replacing the plug with strainer attached. Be suregasket is in place on plug before replacing. Pour new oil in througheither of the two breather pipes on exhaust side of motor. Be sure toreplace strainer screens if removed. If, through oversight, the enginedoes not receive sufficient lubrication and begins to heat or pound, itshould be stopped immediately. After allowing engine to cool pour atleast three gallons of oil into oil sump. Fill radiator with water afterengine has cooled. Should there be apparent damage, the engineshould be thoroughly inspected inmiediately without further running.If no obvious damage has been done, the engine should be given acareful examination at the earliest opportunity to see that the runningwithout oil ha^ not burned the bearings or caused other trouble.

Oils best adapted for Hall-Scott engines have the following properties:A flash test of not less than 400° F.; viscosity of not less than 75 to 85taken at 20° F. with Saybolt's Universal Viscosimeter.

Zeroline heavy duty oil, manufactured by the Standard Oil Companyof California; also.

Gargoyle mobile B oil, manufactured by the Vacuum Oil Company,both fulfill the above specifications. One or the other of these oils canbe obtained all over the world. .

Monogram extra heavy is also reconmiended.

OIL SUPPLY BY CONSTANT LEVEL SPLASH ^YSTEM

The splash system of lubrication that depends on the connecting rodto distribute the lubricant is one of the most successful and simplestforms for simple four- and six-cylinder vertical automobile engines,but is not as well adapted to the oiling of airplane power plants forreasons previously stated. If too much oil is supplied the surplus will

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work past the piston rings and into the combustion chamber, where itwill burn and cause carbon

deposits. Too much oil will also cause an engine to smoke and an ex-cess of lubricating oil is usually manifested by a bluish-white smoke is-suing from the exhaust.

A good method of maintaining a constant level of oil for the successfulapplication of the splash system is shown at Fig. 78. The engine basecasting includes a separate chamber which serves as an oil containerand which is below the level of oil in the crank-case. The lubricant isdrawn from the sump or oil container by means of a positive oil pumpwhich discharges directly into the engine case. The level is maintainedby an overflow pipe which allows all excess lubricant to flow back intothe oil container at the bottom of the cylinder. Before passing into thepump again the oil is strained or filtered by a screen of wire gauze andall foreign matter removed. Owing .to the rapid circulation of the oil itmay be used over and over again for quite a period of time. The oil isintroduced directly into the crank-case by a breather pipe and the levelis indicated by a rod carried by a float which rises when the containeris replenished and falls when the available supply diminishes. It willbe noted that with such system the only apparatus required besidesthe oil tank which is cast integral with the bottom of the crank-case isa suitable pump to maintain circulation of oil. This, member is alwayspositively driven, either by means of shaft and universal coupling ordirect gearing. As the sygtem is entirely automatic in action, it will fur-nish a positive supply of oil at all desired points, and it cannot betampered with by the inexpert because no adjustments are provided orneeded.

DRY CRANK-CASE SYSTEM BEST FOR AIRPLANE ENGINES

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In most airplane power plants it is considered desirable to supply theoil directly to the parts needing it by suitable leads instead of depend-ing solely upon the distributing action of scoops on the connecting rodbig ends. A system of this nature is shown at Fig. 77. The oil

Best Oiling System for Airplane

217

is carried in the crank-case, as is common practice, but the normal oillevel is below the point where it wiU be reached by the connecting rod.It is drawn from the crank-case by a plunger pump which directs it toa manifold leading directly to conductors which supply the main

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Tig. 78.— SmUouI view ot Typical Uotor Showing Parte NoadlnsLntii* cation and Method of Applying Oil bj Constant Iievel SplashSystom. Hoto alM Water Jacket and Spaces for Water Olrcolatlon.

journals. After the oil has been used on these points it drains back intothe bottom of the crank-case. An excess is provided which is suppliedto the connecting rod ends by passages drilled into the webs of thecrank-shaft and part way into the crank-pins as shown by the dottedlines. The oil which is present at the connecting rod

Fig. 79.—PresBnre Fe«d OU-Snppl^ SyBt«m of Airpluw Fmrar FUntshu Man; Oood Faatures.

crank-pins is throMTi off by centrifugal force and lubricates the cylin-der walls and other internal parts. Regulating screws are provided sothat the amount of oil supplied the different points may be regulatedat will. A relief check valve is installed to take care of excess lubricantand to allow any oil that does not pass back into the pipe line to over-flow or bi-pass into the main container.

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A simple system of this nature is shown graphically in a phantom viewof the crank-case at Fig. 79, in whidi

the oil passages afe made specially prominent. The oil is taken from areservoir at the bottom of the engine base by the usual form of gear oilpump and is supplied to a main feed manifold which extends thelength of the crank-case. Individual conductors lead to the five mainbearings, which in turn supply the crank-pins by passages drilledthrough the crank-shaft web. In this power plant the connecting rodsare hollow section bronze castings and the passage through the centerof the connecting rod serves to convey the lubricant from the crank-pins to the wrist-pins. The cylinder waUs are oiled by the spray of lub-ricant thrown off the revolving crankshaft by centrifugal force. Oil pro-jection by the dippers on the connecting rod ends from constant leveltroughs is unequal upon the cylinder walls of the two-cylinder blocksof an eight- or twelve-cylinder V engine. This gives rise, on one side ofthe engine, to imder-lubrication, and, on the other side, to over-lubric-ation, as shown at Fig. 80, A. This applies to all modifications ofsplash lubricating systems.

When a force-feed lubricating system is used, the oil, escaping past thecheeks of both ends of the crank-pin bearings, is thrown off at a tan-gent to the crank-pin circle in all directions, supplying the cylinders onboth sides with an equal quantity of oil, as at Fig. 80, B.

WHY COOLING SYSTEMS ARE NECESSARY

The reader should understand from preceding chapters that the powerof an internal-combustion motor is obtained by the rapid combustionand consequent expansion of some inflammable gas. The operation inbrief is that when air or any other gas or vapor is heated, it will expandand that if this gas is confined in a space which will not permit expan-sion, pressure will be exerted against all sides of the containing

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chamber. The more a gas is heated,- the more pressure it will exertupon the walls of the combustion chamber, it

AxHaUon Engines

Tig. 80.—Wliy Pr«Banre Feed System Is Best for Elglit-OyUiider TeaAirplane Engines

cjonfines. Pressure in a gas may be created by increasing Its temperat-ure and inversely heat may be created by pressure. When a gas is

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compressed its total volume is reduced and the temperature isaugmented.

The efficiency of any form of heat engine is determined by the powerobtained from a certain fuel consumption. A definite amount of energywill be liberated in the form of heat when a pound of any fuel isburned. The efficiency of any heat engine is proportional to the powerdeveloped from a definite quantity of fuel with the least loss of thermalunits. If the greater proportion of the heat units derived by burningthe explosive mixture could be utilized in doing useful work, the effi-ciency of the gasoline engine would be greater than that of any otherform of energizing power. There is a great loss of heat from variouscauses, among which can be cited the reduction of pressure throughcooling the motor and the loss of heat through the exhaust valveswhen the burned gases are expelled from the cylinder.

The loss through the water jacket of the average automobile powerplant is over 50 per cent, of the total fuel eflSciency, This means thatmore than half of the heat Units available for power are absorbed anddissipated by the cooling water. Another 16 per cent, is lost throughthe exhaust valve, and but 33H per cent, of the heat units do usefulwork. The great loss of heat through the cooling systems cannot beavoided, as some method must be provided to keep the temperature ofthe engine ^thin proper bounds. It is apparent that the rapid combus-tion and continued series of explosions would soon heat the metal por-tions of the engine to a red heat if some means were not taken to con-duct much of this heat away. The high temperature of the parts wouldbum the lubricating oil, even that of the best quality, and the pistonand rings would expand to such a degree, especially when deprived ofoil, that they would seize in the cylinder. This would score the walls,and the friction ^v-hich ensued would tend to bind the parts so tightly

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that the piston would stick, bearings would be bnmed out, the valveswould warp, and the engine would soon become inoperative.

The best temperature to secure efficient operation is one on whichconsiderable difference of opinion exists among engineers. The factthat the efficiency of an engine is dependent upon the ratio of heatconverted

Fig. Bl.—OpentliiK TsmpentureB of Automobile Engine Forts ITHtnl ua Guide to UnderBttmd AlipUna Power FUnt Heat.

into useful work compared to that generated by the explosion of thegas is an accepted fact. It is very important that the engine should notget too hot, and on the other hand it is equally vital that the cylindersbe not robbed of too much heat. The object of cylinder cooling is tokeep the temperature of the cylinder below the danger point, but at thesame time to have it as high as possible to secure maximum powerfrom the gas burned. The usual operating temperatures of an

antomobile engine are shown at Fig. 81, and this can be taken as anapproximation of the temperatures apt to exist in an airplane engine

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of conventional design as well when at ground level or not very high inthe air. The newer very high compression airplane engines in whichcompressions of eight or nine atmospheres are used, or about 125pounds per square inch, will run considerably hotter than the temper-atures indicated.

COOLING SYSTEMS GENERALLY APPLIED

There are two general systems of engine cooling in common use, thatin which water is heated by the absorption of heat from the engine andthen cooled by air, and the other method in which the air is directedonto the cylinder and absorbs the heat directly instead of through themedium of water. When the liquid is employed in cooling it is circu-lated through jackets which surround the cylinder casting and the wa-ter may be kept in motion by two methods. The one generally favoredis to use a positive circulating pump of some form which is driven bythe engine to keep the water in motion. The other system is to utilize anatural principle that heated water is lighter than cold liquid and thatit will tend to rise to the top of the cylinder when it becomes heated tothe proper temperature and cooled water takes its place at the bottomof the water jacket.

Air-cooling methods may be by radiation or convention. In the formercase the effective outer surface of the cylinder is increased by the addi-tion of flanges machined or cast thereon, and the air is depended on torise from the cylinder as heated and be replaced by cooler air. This, ofcourse, is found only on stationary engines. When a positive airdraught is directed against the cylinder by means of the propeller slipstream in an airplane, cooling is by convection and radiation both. So-metimes the air draught may be directed against the

cylinder walls by some form of jacket whieh confines it to the heatedportions of the cylinder.

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COOLING BY POSITIVE WATER CIKCULATION

A typical water-cooling system in which a pump is depended upon topromote circulation of the cooling liquid is shown at Figs. 82 and 83.The radiator is carried at the front end of the fuselage in most cases,and serves as a combined water tank and cooler, but in some cases it iscarried at the side of the engine, as in Fig.'

.Outlet Pipti for

Fig. B2.^Water Cooling of SalmsoD Seven-Cylindei Bodlal Alrplan«Eogliu.

84, or attached to the central portion of the aerofoil or wing structure.It is composed of an upper and lower portion joined together by aseries of pipes which may be round and provided with a series of finsto radiate the heat, or whicli may be flat in order to have the waterpass through in tliin sheets and cool it more easily. Cellular or honey-comb coolers are composed of a large number of bent tubes wliich willexpose a large area of surface to the cooling influence of the airdraught forced through tlie radiator either by tlie forward movementof the vehicle or by some tj-pe of fan. The cellular and

Cooling by Positive Circulation

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225

flat tube types have almost entirely displaced the flange tube radiatorswhich were formerly popular because they cool the water more effect-ively, and may be made lighter than the tubular radiator could be forengines of the same capacity.

The water is drawn from the lower header of the radiator by the pumpand is forced through a manifold

Fig. 83.—Hmr Wat«r OooUng STBtem of Tbomu Airplane Ensine laInstaUed In Ftualage.

to the lower portion of the water jackets of the cylinder. It becomesheated as it passes around the cylinder walls and combustion cham-bers and the hot water passes out of the top of the water jacket to theupper portion of the radiator. Here it is divided in thin streams anddirected against comparatively cool metal which abstracts the heatfrom the water. As it becomes cooler it falls to the bottom of the

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radiator because its weight increases as the temperature becomeslower. By the time it reaches

the lower tank of the radiator it has been cooled snffi-ciently so that itmay be again passed around the cylinders of the motor. The popularform of circnlatiiig pump is known as the "centrifugal type" because arotary impeller of paddle-wheel form throws water which it receives ata central point toward the outside and thus causes it to maintain a def-inite rate of circulation. The pump is always a separate appliance at-tached to the

Tig. 64.—Finned Tube BadlaUtrs at the Side of HaU-Scott Airplana IPlant Infltalled In Standard Fuselage.

engine and driven by positive gearing or direct-shaft connection. Thecentrifugal pump is not as positive as the gear form, and some manu-facturers prefer the latter because of the positive pumping features.They are very simple in form, consisting of a suitable east body inwhich a pair of spur pinions having large teeth are carried. One ofthese gears is driven by suitable means, and as it turns the other

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member they maintain a flow of water around tlie pump body. Thepump should always be installed in series with the w^ater pipe which

conveys the cool liquid from the lower compartment of the radiator tothe coolest portion of the water jacket.

WATER CIRCULATION BY NATURAL SYSTEM

• Some automobile engineers contend that the rapid water circulationobtained by using a pump may cool the cylinders too much, and thatthe temperature of the engine may be reduced so much that the effi-ciency w^ill be lessened. For this reason there is a growing tendency touse the natural method of water circidation as the cooling liquid issupplied to the cylinder jackets just below the boiling point, and thewater issues from the jacket at the top of the cylinder after it has ab-sorbed sufficient heat to raise it just about to the boiling point.

As the water becomes heated by contact with the hot cylinder andcombustion-chamber walls it rises to the top of the water jacket, flowsto the cooler, where enough of the heat is absorbed to cause it to be-come sensibly greater in weight. As the water becomes cooler, it fallsto the bottom of the radiator and it is again supplied to the water jack-et. The circidation is entirely automatic and continues as long as thereis a difference in temperature between the liquid in the water spaces ofthe engine and that in the cooler. The circulation becomes brisker asthe engine becomes hotter and thus the temperature of the cylinders iskept more nearly to a fixed point. With the thermosyphon system thecooling liquid is nearly always at its boiling point, whereas if the circu-lation is maintained by a pump the engine will become cooler at highspeed and will heat up more at low speed.

With the thermosyphon, or natural system of cooling, more watermust be carried than with the pump-maintained circulation methods.

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The water spaces around the cylinders should be larger, the inlet anddischarge water manifolds should have greater capacity, and bo freefrom sharp corners which might impede the flow. The radiator mustalso carry more water than the form used in connection with the pumpbecause of the brisker

pump circulation which maintains the engine temperature at a lowerpoint. Consideration of the above will show why the pump system isalmost universally used in connection with airplane power plantcooling.

DIRECT AIR-COOLING METHODS

•

The earliest known method of cooling the cylinder of gas-engines wasby means of a current of air passed through a jacket which confined itclose to the cylinder walls and was used by Daimler on his first gas-en-gine. The gasoline engine of that time was not as eflSdent as the laterform, and other conditions which materialued made it desirable tocool the engine by water. &V6n as gasoline engines became more andmore perfected there has always existed a prejudice against air cool-ing, though many forms of engines have been used, both in antomo-bile and aircraft applications where the air-cooling method has provento be very practical.

The simplest system of air cooling is that in which the cylinders areprovided with a series of flanges'which increase the effective radiatingsurface of the cylinder and directing an air current from a fan againstthe flanges to absorb the heat. This increase in the available radiatingsurface of an air-cooled cylinder is necessary because air does not ab-sorb heat as readily as water and therefore more surface must beprovided that the excess heat be absorbed sufficiently fast to prevent

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distortion of the cylinders. Air-cooling systems are based on a law for-mulated by Newton, which is: *'The rate for cooling for a body in auniform current of air is directly proportional to the speed of the aircurrent and the amount of radiating surface exposed to the coolingeffect."

AIR-COOLED ENGINE DESIGN CONSIDERATIONS

There are certain considerations which must be taken into account indesigning an air-cooled engine, which are. often overlooked in thoseforms cooled by water. Large

ralves must be provided to insure rapid expulsion of ;he flaming ex-haust gas and also to admit promptly the :resh cool mixture from thecarburetor. The valves of iir-cooled engines are usually placed in thecylinder-

Tie- S6.—Aiuanl TestluK Bis Flve-OyUnder Air Cooled Aviation MotorInstaUed In Blerlot UoDoplaoe. Note Exposure of Flanged Oyllndan toPropellei Slip Stream.

lead, in order to eliminate any pockets or sharp passages Fhich wouldimpede the flow of gas or retain some of he products of combustionand their heat. When high )ower is desired multiple-cylinder enginesshould be used, IS there is a certain limit to the size of a successful'

air-cooled cylinder. Much better results are secured from those havingsmall cubical contents because the heat from small quantities of gaswill be more quickly carried off than from greater amounts. All suc-cessful engines of the aviation type which have been air-cooled havebeen of the multiple-cylinder type.

An air-cooled engine must be placed in ihe fuselage, as at Fig. 85, insuch a "way that there will be a positive circulation of air aroimd it all

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the time that it is in operation. The air current may be produced by thetractor screw at the front end of the motor, or by a suction or blowerfan attached to the crank-shaft as in the Renault engine or by rotatingthe cylinders as in the Le Rhone and Gnome motors. Greater care isrequired in lubrication of the air-cooled cylinders and only the bestquality of oil should be used to insure satisfactory oiling.

The combustion chambers must be proportioned so that distributionof metal is as imiform as possible in order to prevent uneven expan-sion during increase in temperature and uneven contraction when thecylinder is cooled. It is essential that the inside walls of the combus-tion chamber be as smooth as possible because any sharp angle or pro-jection may absorb sufficient heat to remain incandescent and causetrouble by igniting the mixture before the proper time. The best gradesof cast iron or steel should be used in the cylinder and piston and themachine work must be done very accurately so the piston will operatewith minimum friction in the cylinder. The cylinder bore should notexceed 4^ or 5 inches and the compression pressure should never ex-ceed 75 pounds absolute, or about five atmospheres, or serious over-heating will result.

As an example of the care taken in disposing of the exhaust gases inorder to obtain practical air-cooling, some cylinders are provided witha series of auxiliary exhaust ports uncovered by the piston when itreaches the end of its power stroke. The auxiliary exhaust ports openjust as soon as the full force of the explosion has

been spent and a portion of the flaming gases is discharged throughthe ports in the bottom of the cylinder. Less of the exhanst gases re-mains to be discharged through the regular exhaust member in thecylinder-head and this will not heat the walls of the cylinder nearly asmuch as the larger quantity of hot gas would. That the auxiliary

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exhaust port is of considerable value is conceded by many designers offixed and fan-shaped air-cooled motors, for airplanes.

Among the advantages stated for direct air cooling, the greatest is theelimination of cooling water and its cooling auxiliaries, which is afactor of some moment, as it permits considerable reduction in horse-power-weight ratio of the engine, something very much to be desired.In the temperate zone, where the majority of airplanes are used, theweather conditions change in a very few months from the warm sum-mer to the extreme cold winter, and when water-cooled systems areemployed it is necessary to add some chemical substapce to the waterto prevent it from freezing. The substances commonly employed areglycerine, wood alcohol, or a saturated solution of calcium chloride.Alcohol has the disadvantage in that it vaporizes readily and must beoften renewed. Glycerine affects the rubber hose, while the calciumchloride solution crystallizes and deposits .salt in the radiator and wa-ter pipes.

One of the disadvantages of an air-cooling method, as stated by thosewho do not favor this system, is that engines cooled by air cannot beoperated for extended periods under constant load or at very highspeed without heating up to such a point that premature ignition ofthe charge may result. The water-cooling systems, at the other hand,maintain the temperature of the engine more nearly constant than ispossible with an air-cooled motor, and an engine cooled by water canbe operated under conditions of inferior lubrication or poor mixtureadjustment that would seriously interfere with proper and efficientcooling by air.

Air-cooled motors, as a rule, use less fuel than water-cooled engines,because the higher temperature of the cylinder does not permit of afull charge of gas being inspired on the intake stroke. As special care isneeded in operating an air-cooled engine to obtain satisfactory results

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and because of the greater diflficulty which obtains in providing prop-er lubrication and fuel mixturers which will not produce undue heat-ing, the air-cooled system has but few adherents at the present time,and practically all airplanes, with but very few exceptions, areprovided with water-cooled power plants. Those fitted with air-cooledengines are usually short-flight types where maximum lightness is de-sired in order to obtain high speed and quick climb. The water-cooledengines are best suited for airplanes intended for long flights. TheGnome, Le Ehone and Clerget engines are thoroughly practical andhave been widely used in France and England. These are rotary radialcylinder types. The Anzani is a fixed cylinder engine used on trainingmachines, while the Eenault is a V-type engine made in eight- andtwelve-cylinder V forms that has been used on reconnaissance andbombing airplanes with success. These types will be fully considered inproper sequence.

CHAPTER vrn

Methods of Cylinder Construction—Block Castings—Influence onCrank-Shaft Design—Combustion Chamber Design—Bore and StrokeRatio—Meaning of Piston Speed—Advantage of Off-Set Cylin-ders—^Valve Location of Vital Import—^Valve InstallationPractice—^Valve Design and Construction—^Valve Operation— Meth-ods of Driving Cam-Shaft—^Valve Springs—^Valve Timing-^ BlowingBack—Lead Given Exhaust Valve—Exhaust Closing, Inlet Open-ing—Closing the Inlet Valve—^Time of Ignition—^How an Engine IsTimed—Gnome "Monosoupape" Valve Timing— SpringlessValves—^Four Valves per Cylinder.

The improvements noted in the modem internal combustion motorshave been due to many conditions. The continual experimenting. byleading mechanical minds could have but one ultimate result. Theparts of the engines have been lightened and strengthened, and

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greater power has been obtained without increasing piston displace-ment. A careful study has been made of the many conditions whichmake for eflficient motor action, and that the main principles are wellrecognized by all engineers is well shown by the standardization ofdesign noted in modem power plants. There are many different meth-ods of applying the same principle, and it will be the purpose of thischapter to define the ways in which the construction may be changedand still achieve the same results. The various components may existin many different forms, and all have their advantages and disadvant-ages. That all methods are practical is best shown by the large numberof successful engines which use radically different designs.

METHODS 'OF CYLi:»rDER CONSTRUCTION

One of the most important par4:s of the gasoline engine and one thathas material bearing upon its efficiency is the cylinder unit. The cylin-ders may be cast

individually, or in pairs, and it is possible to make all cylinders a unitor block casting. Some typical methods of cylinder construction areshown in accompanying illustrations. The appearance of individualcylinder castings may be ascertained by examination of the Hall-Scottairplane engine. Air-cooled engine cylinders are always of the indi-vidual pattern.

Considered from a purely theoretical point of view, the individual cyl-inder casting has much in its favor. It is advanced that more uniformcooling is possible than where the cylinders are cast either in pairs orthree or four in one casting. More uniform cooling insures that the ex-pansion or change of form due to heating will be more equal. This isan important condition because the cylinder bore must remain trueunder all conditions of operation. If the heating effect is not uniform,which condition is liable to obtain if .metal is not evenly distributed,

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the cylinder may become distorted by heat and the bore be out oftruth. When separate cylinders are used it is possible to make a uni-form water space and have the cooling liquid evenly distributedaround the cylinder. In multiple cylinder castings this is not always therule, as in many instances, especially in four-cylinder block motorswhere compactness is the main feature, there is but little spacebetween the cylinders for the passage of \vater. Under such circum-stances the cooling effect is not even, and the stresses which obtain be-cause of unequal expansion may distort the cylinder to some extent.When steel cylinders are made from forgings, the water jackets areusually of copper or sheet steel attached to the forging by autogenouswelding; in the case of the latter and, in some cases, the former may beelectro-deposited on the cylinders.

BLOCK CASTINGS •

The advantage of casting the cylinders in blocks is that a motor may bemuch shorter than it would be if individual castings w^ere used. It isadmitted that when

Block Casting of Cylinders

285

cylinders are cast together a more compact, rigid,

stronger power plant is obtained than when cast

irately. There is a disadvantage, however, in that

ne cylinder becomes damaged it will be necessary to

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©

@^(o) (o) ^^ (5) @Mo)

@

V(^3 ^3

€3 e^

viewed from Top

^

V^^-CoN

oaoo / oo oo

ttr

• e e • « e

/

e e o o

/

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Side View

Fig. 86.—^ViewB of Foar-Oyllnder Duesenberg Airplane Engine

Cylinder Block.

ace the entire unit, which means scrapping three 1 cylinders becauseone of the four has failed. When cylinders are cast separately one needonly replace one that has become damaged. The casting of four idersin one unit is made possible By improved

foundry methods, and when proper provision is made for holding thecores when the metal is poured and the cylinder casts are good, theconstruction is one of distinct merit. It is sometimes the case that theproportion of sound castings is less when cylinders are cast in block,but if the proper precautions are observed in molding and the propermixtures of cast iron used, the ratio of defective castings is no morethan when cylinders are molded individually. As an example of thecourage of engineers in departing from old-established rules, the cyl-inder casting shown at Fig. 86 may be considered typical. This is usedon the Duesenberg four-cylinder sixteen-valve 4%"x7" engine whichhas a piston displacement of 496 cu. in. At a speed of 2,000 r.p.m.,corresponding to a piston speed of 2,325 ft. per min., the engine isguaranteed to develop 125 horse-power. The weight of the model en-gine without gear reduction is 436 lbs., but a number of refinementshave been made in the design whereby it is expected to get the weightdown to 390 lbs. The four cylinders are cast from semi-steel in a singleblock, with integral heads. The cylinder construction is the same as

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that which has always been used by Mr. Duesenberg, inlet and exhaustvalves being arranged horizontally opposite each other in the head.There are large openings in the water jacket at both sides and at theends, which are closed by means of aluminum covers, water-tightnessbeing secured by the use of gaskets. This results in a saving in weightbecause the aluminum covers can be made considerably lighter than itwould be possible to cast the jacket walls, and, besides, it permits ofobtaining a more nearly uniform thickness of cylinder wall, as thecores can be much better supported. The cooling water passes com-pletely around each cylinder, and there is a very considerable spacebetween the two central cylinders, this being made necessary in orderto get the large bearing area desirable for the central bearing.

It is common practice to cast the water jackets inte-

gral with the cylinders, if cast iron or aluminum is used, and this isalso the most economical method of applying it because it gives goodresults in practice. An important detail is that the water spaces mustbe proportioned so that they are equal around the cylinders whetherthese members are cast individually, in pairs, threes or fours. Whencylinders are cast in block form it is good practice to leave a largeopening in the jacket wall which will assist in supporting the core andmake for uniform water space. It will be noticed that the castingshown at Fig. 86 has a large opening in the side of the cylinder block.These openings are closed after the interior of the casting is thor-oughly cleaned of all sand, core wire, etc., by brass, cast iron or alu-minum plates. These also have particular value in that they may be re-moved after the motor has been in use, thus permitting one to cleanout the interior of the water jacket and dispose of the rust, sediment,and incrustation which are always present after the engine has been inactive service for a time.

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Among the advantages claimed for the practice of casting cylinders inblocks may be mentioned compactness, lightness, rigidity, simplicityof water piping, as well as permitting the use of simple forms of inletand exhaust manifolds. The light weight is not only due to the reduc-tion of the cylinder mass but because the block construction permitsone to lighten the entire motor. The fact that all cylinders are cast to-gether decreases vibration, and as the construction is very rigid, dis-alignment of working parts is practically eliminated. When inlet andexhaust manifolds are cored in the block casting, as is sometimes thecase, but one joint is needed on each of these instead of the multipli-city' of joints which obtain when the cylinders are individual castings.The water piping is also simplified. In the case of a four-cylinder''t)lock motor but two pipes are used; one for the water to enter thecylinder jacket, the other for the cooling liquid to discharge through.

Aviation Engine*

IITFLTJENCE ON CBANK-SHAFT DESIQK

The method of casting the cylinders has a material influence on thedesign of the crank-shaft as will be shown in proper sequence. "Whenfour cylinders are combined in one block it is possible to use a two-bearing crank-shaft Where cylinders are cast in pairs a three-bearingcrankshaft is commonly supplied, and when cylinders are cast

.Copper Asbestvs Gasket

''-Cylinder LipMr

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.Ahminum Cylinder W. J Pair Casting

Fig. 87.—^Twin-CyUtuUx Block of Stortevuit Alrplmne Engliie la Oattof Almnlnina, and Has Bemovable Cylinder H«ad.

as individual units it is thought necessary to supply a five-bearingcrank-shaft, though sometimes shafts having but tliree journals areused successfully. Obviously the shafts must be stronger and stiffer towithstand the stresses imposed if two supporting bearings are usedthan if a larger number are employed. In this connection it may bestated that there is less difficulty in securing alignment with a lessernumber of bearings and there is also less friction. On the otlier hand,the greater the number of points of support a crank-shaft has thelighter the webs can be made and still have requisite strength.

COMBUSTION CHAMBEK DESIGN

Another point of importance in the design of the cylinder, and onewhich has considerable influence upon the power developed, is theshape of the combustion chamber. The endeavor of designers is to ob-tain maximum power from a cylinder of certain proportions, and thegreater energy obtained without increasing piston displacement orfuel consumption the higher the efficiency of the motor. To preventtroubles due to pre-ignition it is necessary

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ng. SB.—Altuninuiii Oyllndor Vtix Casting of Tliomu 150 Hoise-PowerAirpUne Engine U of tlie L Head Type.

that the combustion chamber be made so that there will be no rough-ness, sharp corners, or edges of metal which may remain incandescentwhen heated or which will serve to collect carbon deposits by provid-ing a point of anchorage. "With the object of providing an absolutelyclean combnstion chamber some makers use a separable head unit totheir twin cylinder castings, such as shown at Fig. 87 and Fig. 88.These permit one to machine the entire interior of the cylinder andcombustion chamber. The relation of valve location and combustionchamber design will be considered in proper sequence. These cylin-ders are cast of aluminum, instead of cast iron, as

m

is customary, and are provided vnth steel or cast iron cylinder linersforced in the soft metal casting J[)ores.

BORE AND STROKE RATIO

A question that has been a vexed one and which has been the subjectof considerable controversy is the proper proportion of the bore to thestroke. The early gas engines had a certain well-defined bore to stroke

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ratio, as it was nsual at that time to make the stroke twice as long asthe bore was wide, but this cannot be done when high speed is desired.With the development of the present-day motor the stroke or pistontravel has been gradually shortened so' that the relative proportions ofbore and stroke have become nearly equal. Of late there seems to be atendency among designers to return to the proportions which formerlyobtained, and the stroke is sometimes one and a half or one and three-quarter times the bore.

Engines designed for high speed should have the stroke not milchlonger than the diameter of the bore. The disadvantage of short-strokeengines is that they will not pull well at low speeds, though they runwith great regularity and smoothness at high velocity. The long-strokeengine is much superior for slow speed work, and it will pull steadilyand with increasing power at low speed. It was formerly thought thatsuch engines should never turn more than a moderate number of re-volutions, in order not to exceed the safe piston speed of 1,000 feet perminute. This old theory or rule of practice has been discarded indesigning high efficiency automobile racing and aviation engines, andpiston speeds from 2,500 to 3,000 feet per minute are sometimesused, though the average is around 2,000 feet per minute. While bothshort- and long-stroke motors have their advantages, it would seemdesirable to average between the two. That is why a proportion of fourto five or six seems to be more general than that of four to seven oreight, which would be a long-stroke ratio. Careful analysis of a num-

ber of foreign aviation motors shows that the average stroke is abont1.2 times the bore dimensions, though some instances were notedwhere it was as high as 1.7 times the bore.

MEANING OF PISTON SPEED

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The factor which limits the stroke and makes the speed of rotation sodependent upon the travel of the piston is piston speed. Lubrication isthe main factor which determines piston speed, and the higher therate of piston travel the greater care must be taken to insure properoiling. Let us fully consider what is meant by piston speed.

Assume that a motor has a piston travel or stroke of six inches, for thesake of illustration. It would take two strokes of the piston to cover onefoot, or twelve inches, and as there are two strokes to a revolution itwill be seen that this permits of a normal speed of 1,000 revolutionsper minute for an engine with a six-inch stroke, if one does not exceed1,000 feet per minute. If the stroke was only four inches, a normalspeed of 1,500 revolutions per minute would be possible without ex-ceeding the prescribed limit. The crank-shaft of a small engine, havingthree-inch stroke, could turn at a speed of 2,000 revolutions perminute without danger of exceeding the safe speed limit. It will beseen that the longer the stroke the slower the speed of the engine, ifone desires to keep the piston speed within the bounds as recommen-ded, but modem practice allows of greatly exceeding the speedsformerly thought best.

ADVANTAGES OF OFF-SET CYLINDERS

Another point upon w^hich considerable difference of opinion existsrelates to the method of placing the cylinder upon the crank-case —i.e., whether its center line should be placed directly over the center oftlie crankshaft, or to one side of center. The motor shown at Fig. 90 isan off-set type, in that tho center line of the

cylinder is a little to one side of the center of the crankshaft. Diagramsare presented at Fig. 91 which show the advantages of off-set crank-shaft construction. The

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■Intake VaWs

Fig. 90.— Ctobs Section of Austro-D&lmler Engine, Showing OSutOrllader OonBtructlon. Note Applied Water Jacket and Fecnllu V»lTeActloa.

view at A is a section through a simple motor with the conventionalcylinder placing, tlie center line of huth crank-sliaft and cylinder coin-ciding. The view at 'B shows

the cylinder placed to one side of center so that its center line is dis-tinct from that of the crank-shaft and at some distance from it. Theamount of off-set allowed is a point of contention, the usual amount

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being from fifteen to twenty-five per cent, of the stroke. The advant-ages of the off-set are shown at Fig. 91, C. If the crank turns

in direction of the arrow there is a certain resistance to motion whichis proportional to the amount of energy exerted by the engine and theresistance offered by the load. There are two thrusts acting against thecylinder wall to be considered, that due to explosion or expansion ofthe gas, and tliat which resists the motion of the piston. These thrustsmay be represented by arrows, one which acts directly in a vertical dir-ection on the piston top, the

other along a straight line through the center of the connecting rod.Between these two thrusts one can draw a line representing a resultantforce which serves to bring the piston in forcible contact with one sideof the cylinder Avail, this being knoA\Ti as side thrust. As shown at C,the crank-shaft is at 90 degrees, or about one-half stroke, and the con-necting rod is at 20 degrees angle. The shorter connecting rod would

259/821

increase the diagonal resultant and side thrusts, while a longer onewould reduce the angle of the connecting rod and the side thrust of thepiston would be less. With the off-set construction, as slioAMi at D, itwdll be noticed that with the same connecting-rod length as shown atC and with the crankshaft at 90 degrees of the circle that theconnecting-rod angle is 14 degrees and the side thrust is reducedproportionately.

Another important advantage is that greater efficiency is obtainedfrom the explosion with an off-set crank-shaft, because the crank isalready inclined w^hen the piston is at top center, and all the energyimparted to the piston by the burning mixture can be exerted directlyinto producing a useful turning effort. When a cylinder is placed dir-ectly on a line with the crank-shaft, as shown at A, it will be evidentthat some of the force produced by the expansion of tlie gas will be ex-erted in a direct line and until the crank moves the crank throw andconnecting rod are practically a solid member. The pressure w^hichmight be employed in obtaining useful turning effort is w^asted bycausing a direct pressure upon the lower half of the main bearing andthe upper half of the crank-pin bushing.

Very good and easily understood illustrations showing advantages ofthe off-set construction are shown at E and F. This is a bicycle crank-hanger. It is advanced that the effort of the rider is not as well appliedwhen the crank is at position E as when it is at position F. Position Ecorresponds to the position of the parts when the cylinder is placeddirectly over the crank-shaft center.

Position F may be compared to the condition which is present whenthe oflf-set cylinder construction is used.

VALVE LOCATION OF VITAL IMPORT

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It has often been said that a chain is no stronger than its weakest link,and this is as true of the explosive motor as it is of any other piece ofmechanism. Many motors which appeared to be excellently designed -and which were well constructed did not prove satisfactory becausesome minor detail or part had not been properly considered by the de-signer. A factor having material bearing upon the efficiency of the in-ternal combustion motor is the location of the valves and the shape ofthe combustion chamber which is largely influenced by their placing.The fundamental consideration of valve design is that the gases be ad-mitted and discharged from the cylinder as quickly as possible in orderthat the speed of gas flow will not be impeded and produce back pres-sure. This is imperative in obtaining satisfactory operation in any formof motor. If the inlet passages are constricted the cylinder will not fillwith explosive mixture promptly, whereas if the exhaust gases are notfully expelled the parts of the inert products of combustion retaineddilute the fresh charge, making it slow burning and causing lost powerand overheating. When an engine employs water as a cooling mediumthis substance will absorb the surplus heat readily, and the effects ofoverheating are not noticed as quickly as when air-cooled cylinders areemployed. Valve sizes have a decided bearing upon the speed of mo-tors and some valve locations permit the use of larger members thando other positions.

While piston velocity is an important factor in determinations ofpower output, it must be considered from the aspect of the wear pro-duced upon the various parts of the motor. It is evident that engineswhich run very fast, especially of high power, must be under a greaterstrain than those operating at lower speeds. The valve-operatingmeelianism is especially susceptible to the in-

Axnation Engines

261/821

fluence of rapid movement, and the slower the engine the longer theparts will wear and the more reliable the valve action.

As will be seen by reference to the accompanying illustration, Fig. 92,there are many ways in which valves may be placed in the cylinder.Each method outlined possesses some point of advantage, because allof the types

Fig. 92.—Diagram Showing Forms of Cylinder Demanded by DifferentValye Placings. A—T Head Type, Valves on Opposite Sides. B— 'LHead Cylinder, Valves Side by Side. C—L Head Cylinder, One Valve inHead, other in Pocket. D—Inlet Valve Over Exhaust Member, Both inSide Pocket. E—^Valve-in-the-Head Type with Vertical Valves.

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F—^Inclined Valves Placed to Open Directly into CombustionChamber.

illustrated are used by reputable automobile manufacturers. Themethod outlined at Fig. 92, A, is widely used, and because of fts shapethe cylinder is known as the ^<T^* form. It is approved for auto-mobile use for several reasons, the most important being that largevalves can be employed and a well-balanced and symmetrical cylindercasting obtained. Two independent camshafts are needed, one operat-ing the inlet valves, the other the exhaust members. The valve-operat-ing mechanism can be very simple in form, consisting of a plunger ac-tuated by the cam which transmits the cam motion to the valve-stem,raising the valve as the cam follower rides on the point of the cam.Piping may be placed without crowding, and larger manifolds can befitted than in some other constructions. This has special value, as itpermits the use of an adequate discharge pipe on the exhaust side withits obvious advantages. This method of cylinder construction is neverfound on airplane engines because it does not permit of maximumpower output.

On the other hand, if considered from a viewpoint of actual heat eflS-ciency, it is theoretically the worst form of combustion chamber. Thisdisadvantage is probably com-pensated for by uniformity of expansionof the cylinder because of balanced design. The' ignition spark-plugmay be located directly over the inlet valve in the path of the incomingfresh gases, and both valves may be easily removed and inspected byunscrewing the valve caps without taking off the manifolds.

The valve installation shown at C is somewhat unusual, though itprovides for the use of valves of large diameter. Easy charging is in-sured because of the large inlet valve directly in the top of the cylinder.Conditions may be reversed if necessary, and the gases dischargedthrough this large valve. Both methods are used, though it would seem

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that the free exhaust provided by allowing the gases to escape directlyfrom the combustion chamber through the overhead valve to the exli-aust manifold

would make for more power. The method ontlined at Fig. 92, F and atFig. 90 is one that has been widely employed on large automobile ra-cing motors where extreme power is required as well as in enginesconstructed for aviation service. The inclination of the valves permitsthe use of large valves, and these open directly into the combustionchamber. There are no pockets to retain heat or dead gas, and free in-take and outlet of gas is obtained. This form is quite satisfactory froma theoretical point of view because of the almost ideal combustionchamber form. Some difficulty is experienced, however, in properlywater-jacketing the valve chamber which experience has shown to benecessarv if the engine is to have high power.

The motor shown at Fig. 92, B and Fig. 88 employs cylinders of the^*L'* type. Both valves are placed in a common extension from thecombustion chamber, and being located side by side both are actualfrom a common cam-shaft. The inlet and exhaust pipes may be placedon the same side of the engine and a very compact assemblage is ob-tained, though this is optional if passages are cored in the cylinderpairs to lead the gases to opposite sides. The valves may be easily re-moved if desired, and the construction is fairly good from the view-point of both foundry man and machinist. The chief disadvantage isthe limited area of the valves and the loss of heat efficiency due to thepocket. This form of combustion chamber, however, is more efficientthan the itrjyjj jj^a^j construction, though with the latter the use oflarger valves probably compensates for the greater heat loss. It hasbeen stated as an advantage of this construction that both manifoldscan be placed at the same side of the engine and a compact assemblysecured. On the other hand, the disadvantage may be cited that in or-der to put both pipes on the same side they must be of smaller size

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than can be used when the valves are oppositely placed. The *^L" formcylinder is sometimes made more efficient if but one valve is placed inthe pocket

Valve Location Practice

249

while the other is placed over it. This construction ia well shown atFig. 92, D and is found on Anzani motors. The method of valve applic-ation shown at Fig. 87 is an ingenious method of overcoming some ofthe disadvantages inherent with valve-in-the-head motors. In the firstplace it is possible to water-jacket the valves thor-

z-M^^

Adjus1ir\4 Ball End—

k&/i-« Uff»r6uid

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ng. 93.—S«cUo]Ml Vl«w of Englns Cylinder Showlug Vtl-n and CageInatalUtlon.

oughly, which is difficult to accomplish when they are momited incages. The water circulates directly around the walls of the valvechambers, which is superior to a constmetion where separate cages areused, as there are two thicknesses of metal with the latter, that of thevalve-cage proper and the wall of the cylinder. The cooling medium isin contact only with the outer wall, and as there is always a loss of heatconductivity at a joint it

is practically impossible to keep the exhaust valves and their seats at-auniform temperature. The valves may be of larger size without the useof pockets when seating directly in the head. In fact, they could beequal in

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Fig. 94.—Diagrams Sliowlng Hov Om Enten OyUndw Tbmigli Oreri-usd Valves and Otber Types. A—Tee Head Cylinder. B—L HeadCyUndsr. C—Overliead Valre.

diameter to almost half the bore of the cylinder, which provides anideal condition of charge placement and exhaust. AVhen valve grind-ing is necessary the entire head is easily removed by taking off six nutsand loosening inlet manifold connections, which operation would benecessary even if cages were employed, as in the engine sho^vTi atFig. 93.

Falve Location Practice

251

At Fig. 94, A and B, a section through a typical "L"-shaped cylinder isdepicted. It wiU be evident that where a pocket constmction is em-ployed, in addition to its facility for absorbing heat, the passage of gaswonld be impeded. For example, the inlet gas rushing in through theopen valve would impinge sharply upon the valve-cap or combustionhead directly over the valve and then must turn at a sharp angle toenter the combustion chamber

/^bc/re-rlei^er-

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Tig. M. —OonvflntloiiKl

Metbods of Opontiog Intmud

VslTML

OomboBtlOD Hot«t

and then at another sharp angle to fill the cylinders. The same condi-tions apply to the exhanst gases, though they are reversed. When thevalve-in-the-head type of cylinder is employed, as at C, the only resist-ance offered the gas is in the manifold. As far as the passage of thegases in and out of the cylinder is concerned, ideal conditions obtain.It is claimed that valve-in-the-head motors are more flexible and

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responsive than other forms, but the construction has the disadvant-age in that the valves must be opened through a rather comj)Iicatedsystem of push

rods and rocker arms instead of the simpler and direct plunger whichcan be used with either the "T" or "L" head cylinders. This is clearlyoutlined in the illustrations at Fig. 95, where A shows the valve in thehead-operating mechanism necessary if the cam-shaft is carried at thecylinder base, wliile B shows the most direct push-rod action obtainedwith *'T" or "L" head cylinder placing.

The objection can be easily met by carrying the camshaft above thecylinders and dri-jing it by means of gearing. The types of engine cyl-inders using this construction are shown at Fig. 9G, and it will bee%'ident that a positive and direct valve action is possible by followingthe construction originated by the Mercedes (German)"

Fig. 97.

CENSORED

Fig. 98.

CENSORED

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aviation engine designers and outlined at A. The other forms at B andC are very clearly adaptations of this design. The llall-Scott engine atFig. 97 is depicted in part section and no trouble will be experienced inunderstanding the bevel pinion and gear drive from the crank-

shaft to the overhead cam-shaft through a vertical counter-shaft. Avery direct valve action is used in the Duesenberg engines, one ofwhich is shown in part section at Fig. 98. The valves are parallel withthe piston top and are actuated by rocker arms, one end of which bearsagainst the valve stem, and the other rides the cam-shaft.

rig. 99.—Sactionml Views Showing Amngement of Hovel OoncentrlcValve Amuigement Devised by Fanliud for Aerial Engines.

The form shown at Fig. 9^ shows an ingenious application of thevalve-in-the-head idea which permits one to obtain large valves. It hasbeen used on some of the Panhard aviation engines and on tlieAmerican Aero-marine power plants. The inlet passage is controlledby the sliding sleeve which is hollow and slotted so as to permit the in-let gases to enter the cylinder through , the regular type poppet valve

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which seats in the exhaust sleeve. When the exhaust valve is operatedby the tappet rod and rocker arm the intake valve is also carried

down with it. The intake gas passage is closed, however, and theburned gases are discharged through the largo annular passage sur-rounding the sleeve. When the inlet valve leaves its seat in the sleevethe passage of cool gas around the sleeve keeps the temperature ofboth valves to a low point and the danger of warping is minimized. Adome-shaped combustion chamber may be used, which is an idealform in conserving heat eflSciency, and as large values may be in-stalled the flow of both fresh and exhaust gases may be obtained withminimum resistance. The intake valve is opened by a small auxiliaryrocker arm which is lifted when, the cam follow^er rides into the de-pression in the cam by the action of the strong spring around the pushrod. When the cam follower rides on the high point the exhaust sleeveis depressed from its seat against the cylinder. By using a cam havingboth positive and negative profiles, a single rod suffices for both valvesbecause of its push and pull action.

VALVE DESIGN AND CONSTRUCTION

Valve dimensions are an important detail to be considered and can bedetermined by several conditions, among which may be cited methodof installation, operating mechanism, material employed, enginespeed desired, manner of cylinder cooling and degree of lift desired. Areview of various methods of valve location has shown that when thevalves are placed directly in the head we can obtain the ideal cylinderform, though larger valves may be used if housed in a separate pocket,as afforded by the ^^T'' head construction. The method of operationhas much to do with the size of the valves. For example, if an automat-ic inlet valve is employed it is good practice to limit the lift and obtainthe required area of port opening by augmenting the diameter. Be-cause of this a valve of the automatic type is usually made twenty per

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cent, larger than one mechanically operated. AMien both are actuatedby cam mechanism, as is now common practice, they are usually madethe same

size and are interchangeable, which greatly simplifies manufacture.The relation of valve diameter to cylinder bore is one that has beendiscussed for some time by engineers. The writer's experience wouldindicate that they should be at least half the bore, if possible. While themushroom type or poppet valve has become standard and is the mostwidely used form at the present tiine, there is some difference of opin-ion among designers as to the materials employed and the angle of theseat. Most valves have a bevel seat, though some have a flat seating.The flat seat valve has the distinctive advantage of providing a clearopening vdth lesser lift, this conducing to free gas flow. It also hasvalue because it is silent in operation, but the disadvantage is presentthat best material and workmanship must be used in their construc-tion to obtain satisfactory results. As it can be made very light it is.particularly well adapted for use as an automatic inlet valve. Amongother disadvantages cited is the claim that it is more susceptible to de-rangement, owing to the particles of foreign matter getting under theseat. With a bevel seat it is argued that the foreign matter would bemore easily dislodged by the gas flow, and that the valve would closetighter because it is drawn positively against the bevel seat.

Several methods of valve construction are the vogue, the most popularform being the one-piece type; those which are composed of a-head ofone material and stem of another are seldom used in airplane enginesbecause they are not reliable. In the built-up construction the head isusually of high nickel steel or cast iron, which metals possess goodheat-resisting qualities. Heads made of these materials are not likelyto warp, scale, or pit, as is sometimes the case when ordinary grades ofmachinery steel are used. The cast-iron head construction is not popu-lar because it is often difficult to keep the head tight on the stem.

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There is a slight difference in expansion ratio between the head andthe stem, and as the stem is either screwed or riveted to the cast-ironhead

Aviation Engine$

the constant hammering of the valve against its seat may loosen thejoint. As soon as the head is loose on the stem the action of the valvebecomes erratic. The best practice is to machine the valves from tung-sten steel forgings. This material has splendid heat-resisting qualitiesand will not pit or become scored easily. Even the electrically weldedhead to stem types which are used in anto-

Fig. 100.—Showing Clearance Allowed BotwMn Tdve Btoq and ValveStem Oulde to Secure Ftm Action,

mobile engines are not looked upon with favor in the aviation engine.Valve stem guides and valve stems must be machined very accuratelyto insure correct action. The usual practice in automobile engines isshown at Fig. iOO.

V,iLVE OPEKATION

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The metliods of valve operation commonly used vary according to tlietype of cylinder construction- employed. In all cases the valves are lif-ted from their seats by cam-actuated mechanism. Various forms ofvalve-lifting cams are shown at Fig. 101. As will be seen, a cam consists

Valve'IAfting Cams

259

of a circle to which a raised, approximately triangular member hasbeen added at one point. When the cam follower rides on the circle, asshown at Fig. 102, there is no difference in height between the camcenter and its periphery and there is no movement of the plmiger. Assoon as the raised portion of the cam strikes the plmiger it will lift it,and this reciprocating movement is transmitted to the valve stem bysuitable mechanical connections.

The cam forms outlined at Fig. 101 are those commonly used. That atA is used on engines where it is

Fig. 101.—^Forms of Valye-Llfting Cams Generally Employed. A—0amProfile for Long Dwell and Quick Lift. B—^Typical Inlet Cam Usedwitb Mushroom Type FoUower. O—Average Form of Cam. Designedto Give Quick Lift and GHradnal Closing.

desired to obtain a quick lift and to keep the valve fully opened as longas possible. It is a ngisy form, however, and is not very widely

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employed. That at B is utilized more often as an inlet cam while theprofile shown at C is generally depended on to operate exhaust valves.The cam shown at B is a composite form which has some of the fea-tures of the other three types. It will give the quick opening of form A,the gradual closing of form B, and the time of maximum valve openingprovided by cam profile C.

The various types of valve plungers used are shown at Fig. 102. Thatshown at A is the simplest form, consisting of a simple cylindricalmember having a rounded end which follows the cam profile. Theseare sometimes

Aviation Engines

made of square stock or kept from rotating by meam oF a key or pin. Aline contact is possible when the plmiger is kept from turning, whereasbut a single point bearing is obtained when the plunger is cylindricaland free to revolve. The plunger shown at A will follow only Cam pro-files which have gradual lifts. The plunger shown at B is left free to re-volve in the guide bushing and is pro-

Fig. 102.—Sliowing Principal Trpea of Cam FoUoven TUch BftveBecalT«d Oflneral AppUcaUon.

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vidod with a flat mushroom head which serves as a cam follower. Thetj'pfe shown at C carries a roller at its lower end and may follow veryirregular cam profiles if abrupt lifts are desired. "UTiile forms A and Bare the simplest, that outlined at C in its various forms is more widelyused. Compound plungers are used on the Curtiss 0X2 motors, one in-side the other. The. small or inner one works on a cam of conventionaldesign, the outer plimger follows a profile having a flat spot to permitof a pull rod action instead of a push rod action. All the methods inwhich levers are used to operate valves are more or less noisy becauseclearance must be left between the valve stem and the stop of the plun-ger. The space must he taken up before the valve will leave its seat,and when

VaLve-Stem Clearances

261

e engine is operated at high speeds the forcible contact itween theplunger and valve stem produces a rattling (und until the valves be-come heated and expand and the ems lengthen out. Clearance must beleft between the live stems and actuating means. This clearance isclearly lown in Fig. 103 and should be .020" (twenty thou-ndths) whenengine is cold. The amount of clearance lowed depends entirely uponthe design of the engine

g. 103.—Diagram Showing Tnypw Clearance to Allow Between Adjust-ing Screw and Valve Stems to Hall-Scott Aviation Englnea.

id length of valve stem. On the Curtiss 0X2 engines le clearance is but.DlC (ten thousandths) because the live stems are shorter. Too littleclearance will result . loss of power or misfiring when engine is hot.Too uch clearance will not allow the valve to open its full nount andwill disturb the timing.

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METHODS OF DRIVING CAM-SHAFT

Two systems of cam-shaft operation are used. The .ost common ofthese is by means of gearing of some irm. If the cam-shaft is at rightangles to the crank-laft it may be driven by worm, spiral, or bevelgearing.

If the cam-shaft is parallel to the crank-shaft, simple spur gear orchain connection may be used to tarn it. A typical cam-shaft for aneight-cylinder V engine is sho'^u at Fig. 104. It will be seen that thesixteen cams are forged integrally with the shaft and that it is spur-gear driven. The cam-shaft drive of the Hall-Scott motor is shoira atFig. 97.

"WTiile gearing is more commonly used, considerable attention hasbeen directed of late to silent chains for cam-shaft operation. The or-dinary forms of block or roller chain have not pi'oven successful in thisappUca-

rig. 104.—Cam-Shaft of Thomas Airplane MoMi Hu Cuna ForgedInteg-raL Note Split Oam-Shaft Bearings and Metliod of OearBatantiaii.

tlon, but the silent chain, which is in reality a link belt operating overtoothed pulleys, lias demonstrated its worth. The tendency to its use ismore noted on foreign motors than those of American design. It firstcame to public notice when employed on the Daimler-Knight engine

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for driving the small auxiliary crank-shafts which reciprocated thesleeve valves. The advantages cited for the application of chains are,first, silent operation, which obtains even after the chains have wornconsiderably; second, in designing it is not necessary to figure onmaintaining certain absolute center distances between -tlic crank-shaft and cam-shaft sprockets, as would be the case if conventionalforms of gearing were used. On some forms of motor emplojing gears,three and even four

members are needed to turn the cam-shaft. With a chain drive but twosprockets are necessary, the chain forming a flexible connection whichpermits the driving and driven members to be placed at any distanceapart that the exigencies of the design demand. When chains are usedit is advised that some means for compensating chain slack beprovided, or the valve timing will lag when chains are worn. Manycombination drives may be worked out with chains that would not bepossible with other forms of gearing. Direct gear drive is favored at thepresent time by airplane engine designers because they are the mostcertain and positive means, even when a number of gears must beused as intermediate drive members. With overhead cam-shafts, bevelgears work out very well in practice, as in the Hall-Scott motors andothers of that type.

VALVE SPRINGS

Another consideration of importance is the use of proper valve-springs, and particular care should be taken with those of automaticvalves. The spring must be weak enough to allow the valve to openwhen the suction is light, and must be of suflficient. strength to close itin time at high speeds. It should be made as large as possible in dia-meter and with a large number of convolutions, in order that fatigue ofthe metal be obviated, and it is imperative that all springs be of thesame strength when •used on a multiple-cylinder engine. Practically

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all valves used to control the gas flow in airplane engines are mechan-ically opierated. On the exhaust valve the spring must be strongenough so that the valve will not be sucked in on the inlet stroke. Itshould be borne in mind that if the spring is too strong a strain will beimposed on the valve-operating mechanism, and a hammering actionproduced which may cause deformation of the valve-seat. Only pres-sure enough to insure that the operating mechanism will follow thecam is required. It is common practice to make the inlet and exhaustvalve springs of

the same tension when the valves are of the same size and both me-clianically operated. This is done merely to simplify manufacture andnot because it is necessary for

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the inlet valve-spring to be as strong as the other. Valve springs of tlieh(;lical coil tj-pc are generally used, though torsion or "scissors"springs and laminated or single-leaf springs are also utilized in specialapplications. Two

Valve Springa

265

springs are used on each valve in some valve4n-the-head types; aspring of small pitch diameter inside the regular valve-spring and con-centric with it. Its function is to

firing Stroke-All Ports Closed

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Eihoust Stroke-bchaust Ports Ope"

Fig. 106.—Diagrams SUowinE Knigbt Sleeve Valve Action.

keep the valve from falling into the cylinder in event of breakage of themain spring in some cases, and to pro^-ide a stronger return action inothers.

KNIGHT SLIDE VALVE MOTOR

The sectional view through the cylinder at Fig. 105 shows the Knightsliding sleeves and their actuating means very clearly. The diagrams atFig. 106 show graphically the sleeve movements and their relation tothe crank-shaft and piston travel. The action may be summed up asfollows: The inlet port begins to open when the lower edge of theopening of the outside sleeve which is moving down passes the top ofthe slot in the inner member also moving downwardly. The inlet portis closed when the lower edge of the slot in the inner sleeve which ismoving up passes the top edge of the port in the outer sleeve which isalso moving toward the top of the cylinder. The inlet opening extendsover two hundred degrees of crank motion. The exhaust port is im-covered slightly when the lower edge of the port in the inner sleevewhich is moving down passes the lower edge of the portion of the cyl-inder head which protrudes in the cylinder. When the top of the portin the outer sleeve traveling toward the bottom of the cylinder passesthe lower edge of the slot in the cylinder wall the exhaust passage isclosed. The exhaust opening extends over a period corresponding toabout two hundred and forty degrees of crank motion. The Knight mo-tor has not been applied to aircraft to the writer's knowledge, but aneight-cylinder Vee design that might be useful in that connection iflightened is shown at Fig. 107. The main object is to show that theKnight valve action is the only other besides the mushroom or poppet

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valve that has beefa applied successfully to high speed gasolineengines.

val\t: timing

It is in valve timing that the greatest difference of opinion prevailsamong engineers, and it is rare that one will see the same formula indifferent motors. It is true that the same timing could not be used withmotors of

different construction, as there are many factors which determine theamount of lead to be given to the valves. The most important of theseis the relative size of the valve to the cylinder bore, the speed of rota-tion it is

Fig. 107.—OroM Sectional Tlew of Knigbt Ttpo Eight Oyllnder TEngtae.

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desired to obtain, the fuel efficiency, the location of the valves, andother factors too numerous to mention.

Most of the readers should be familiar with the cycle of operation ofthe internal combustion motor of the four-stroke type, and it seemsunnecessary to go into detail except to present a review. The firststroke of the piston is one in which a charge of gas is taken into the

motor; the* second stroke, which is in reverse direction to the first, is acompression stroke, at the end of which the spark takes place, explod-ing the charge and driving the piston down on the third or expansionstroke, which is in the same direction as the intake stroke, and finally,after the piston has nearly reached the end of this stroke, anothervalve opens to allow the bnmed gases to escape, and remains open un-til the piston has reached the end of the fourth stroke and is in a posi-tion to begin the series over again. The ends of the strokes are reachedwhen the piston comes to a stop at either top or bottom of the cylinderand reverses its motion. That point is known as a center, and there aretwo for each cylinder, top and bottom centers, respectively.

All circles may be divided into 360 parts, each of which is known as adegree, and, in turn, each of these degrees may be again divided intominutes and seconds, though we need not concern ourselves with any-thing less than the degree. Each stroke of the piston represents 180degrees travel of the crank, because two strokes represent one com-plete revolution of three hundred and sixty degrees. The top and bot-tom centers are therefore separated by 180 degrees. Theoretically eachphase of a four-cycle engine begins and ends at a center, though in ac-tual practice the inertia or movement of the gases makes it necessaryto allow a lead or lag to the valve, as the case may be. If a valve opensbefore a center, the distance is called ^*lead"; if it closes after a center,this distance is kno%\Ti as ^*lag." The profile of the cams ordinarilyused to open or close the valves represents a considerable time in

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relation to the 180 degrees of the crank-shaft travel, and the area ofthe passages through which the gases are admitted or exhausted isquite small owing to the necessity of having to open or close the valvesat stated times; therefore, to open an adequately large passage for thegases it is necessary to open the valves earlier and close them laterthan at centers.

That advancing the opening of the exhaust valve was

of value was discovered on the early motors and is explained by thenecessity of releasing a large amount of gas, the volume of which hasbeen greatly raised by the heat of combustion. When the inlet valveswere mechanically operated it was found that allowing them to lag atclosing enabled the inspiration of a greater volume of gas. Disregard-ing the inertia or flow of the gases, opening the exhaust at centerwould enable one to obtain full value of the expanding gases the entirelength of the piston stroke, and it would not be necessary to keep thevalve open after the top center, as the reverse stroke would produce asuction effect which might draw some of the inert charge back into thecylinder. On the other hand, giving full consideration to the inertia ofthe gas, opening the valve before center is reached will provide forquick expulsion of the gases, which have sufficient velocity at the endof the stroke, so that if the valve is allowed to remain open a littlelonger, the amount of lag varying with the opinions of the designer,the cylinder is cleared in a more thorough manner.

BLOWING BACK

When the factor of retarded opening is considered without reckoningthe inertia of the gases, it would appear that if the valve were allowedto remain open after center had passed, say, on the closing' of the in-let, the piston, having reversed its motion, would have the effect of ex-pelling part of the fresh charge through the still open valve as it passed

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inward at its compression stroke. This effect is called blowing back,and is often noted with motors where the valve settings are not abso-lutely correct, or where the valve-springs or seats are defective andprevent proper closing.

This factor is not of as much import as might appear, as on closer con-sideration it will be seen that the movement of the piston as the crankreaches either end of the stroke is less per degree of angular move-ment than it is when the angle of the connecting rod is greater. Then,

again, a certain length of time is required for the reversal of motion ofthe piston, during which time the crank is in motion but the pistonpractically at a standstill. If the valves are allowed to remain open dur-ing this period, the passage of the gas in or out of the cylinder will beby its own momentum.

LEAD GIVEN EXHAUST VALVE

The faster a motor turns, all other things being equal, the greater theamount of lead or advance it is necessary to give the opening of the ex-haust valve. It is self-evident truth that if the speed of a motor isdoubled it travels twice as many degrees in the time necessary to lowerthe pressure. As most designers are cognizant of this fact, the valvesaire proportioned accordingly. It is well to consider in this respect thatthe cam profile has much to do with the manner in which the valve isopened; that is, the lift may be abrupt and the gas allowed to escape ina body, or the opening may be gradual, the gas issuing from the cylin-der in thin streams. An analogy may be made with the opening of anybottle which contains liquid highly carbonated. If the cork is removedsuddenly the gas escapes with a loud pop, but, oA the other hand, ifthe bottle is imcorked gradually, the gas escapes from the receptacle inthin streams around the cork, and passage of the gases to the air is

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accomplished without noise. AVliile the second plan is not harsh, it isslower than the former, as must be evident.

EXHAUST CLOSING, INLET OPENING

A point which has been much discussed by engineers is the proper re-lation of the closing of the exhaust valve and the opening of the inlet.Theoretically they should succeed each other, the exhaust closing atupper dead center and the inlet opening immediately afterward. Thereason why a certain amount of lag is given the exhaust closing inpractice is that the piston cannot drive the

gases ont of the cylinder unless they are compressed to a degree in ex-cess of that existing in the manifold or passages, and while toward theend of the stroke this pressure may be feeble, it is nevertheless indis-pensable. At the end of the piston *s stroke, as marked by the npperdead center, this compression still exists, no matter how little it maybe, so that if the exhaust valve is closed and the inlet opened immedi-ately afterward, the pressure which exists in the cylinder may retardthe entrance of the fresh gas and a certain portion of the inert gas maypenetrate into the manifold. As the piston immediately begins to as-pirate, this may not be serious, but as these gases are drawn back intothe cylinder the fresh charge will be diluted and weakened in value. Ifthe spark-plug is in a pocket, the points may be surrounded by thisweak gas, and the explosion will not be nearly as energetic a» whenthe ignition spark takes place in pure mixture.

It is a well-known fact that the exhaust valve should close after deadcenter and that a certain amount of lag should be given to opening, ofthe inlet. The lag given the closing of the exhaust valve should not beas great as that given the closing of the inlet valve. Assuming that theexcess pressure of the exhaust will equal the depression during aspira-tion, the time necessary to complete the emptying of the cylinder will

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be proportional to the volume of the gas within it. At the end of thesuction stroke the volume of gas contained in the cylinder is equal tothe cylindrical volume plus the space of the combustion chamber. Atthe end of the ^exhaust stroke the volume is but that of the deadspace, and from one-third to one-fifth its volume before, compression.While it is natural to assume that this excess of burned gas will escapefaster than the fresh gas will enter the cylinder, it will be seen that ifthe inlet valve were allowed to lag twenty degrees, the exhaust valvelag need not be more than five degrees, providing that the capacity ofthe combustion chamber was such that the gases occupied one-quarterof their former volume.

It is evident that no absolute rule can be given, as back pressure willvary with the design. of the valve passages, the manifolds, and the con-struction of the muffler. The more direct the opening, the sooner thevalve can be closed and the better the cylinder cleared. Ten degreesrepresent an appreciable angle of the crank, and the time required forthe crank to cover this angular motion is not inconsiderable and animportant quantity of the exhaust may escape, but the piston is veryclose to the dead center after the distance has been covered.

Before the inlet valve opens there should be a certain depression in thecylinder, and considerable lag nMiy be allowed before the depressionis appreciable. So far as the volume of fresh gas introduced during theadmission stroke is concerned, this is determined by the displacementof the piston between the point where the inlet valve opens and thepoint of closing, assuming that sufficient gas has been inspired so thatan equilibrium of pressure has been established between the interiorof the cylinder and the outer air. The point of inlet opening varies withdifferent motors. It would appear that a fair amount of lag would befifteen degrees past top center for the inlet opening, as a certain de-pression will exist in the cylinder, assuming that the exhaust valve hasclosed five or ten degrees after center, and at the same time the piston

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has not gone dowTi far enough on its stroke to materially decrease theamount of gas wliich will be taken into the cylinder.

CLOSING THE INLET VALVE

As in the case with the other points of opening and closing, there is awide diversity of practice as relates to closing the inlet valve. Some ofthe designers close this exactly at bottom center, but this practice can-not be commended, as there is a considerable portion of time, at leastten or fifteen degrees angular motion of the crank, before the pistonwill commence to travel to any extent on its compression stroke. Thegases rushing into the

cylinder have considerable velocity, and unless an eqni-Ubrinm is ob-tained between the pressure inside and that of the atmosphere out-side, they will continue to rush into the cylinder even after the Distonceases to exert any suction effect.

For this reason, if the valve is closed exactly on center, a full chargemay not be inspired into the cylinder, though if the time of closing isdelayed, this momentimi or inertia of the gas will be enough to insurethat a maximum charge is taken into the cylinder. The writer considersthat nothing will be gained if the valve is allowed to remain openlonger than twenty degrees, and an analysis of practice in this respectwould seem to confirm this opinion. From that point in the crankmovement the piston travel increases and the compressive effect is ap-preciable, and it would appear that a considerable proportion of thecharge might be exhausted into the manifold and carburetor if thevalve were allowed to remain open beyond a point corresponding totwenty degrees angular movement of the crank.

' TIME OF IGNmON

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In this country engineers unite Ln providing a variable time of igni-tion, though abroad some difference of opinion is noted on this point.The practice of advancing the time of ignition, when affected electric-ally, was severely condemned by early makers, these maintaining thatit was necessary because of insufficient heat and volume of the spark,and it was thought that advancing ignition w^as injurious. The engin-eers of to-day appreciate the fact that the heat of the electric spark, es-pecially when from a mechanical generator of electrical energy, is theonly means by which we can obtain practically instantaneous explo-sion, as required by the operation of motors at high speeds, and for thecombustion of large volumes of gas.

It is apparent that a motor with a fixed point of

Aviation Engines

ignition is not as desirable, in every way, as one in which the ignitioncan be advanced to best meet different requirements, and the A\Titerdoes not readily perceive any

,*S Position of Na/ Cylind'Qr Cams

when No. I Piston is on top dead center

^4

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Part A

Diagram of Gears in Hall-Sco+f Type A-5 Aviation Motor

J5

Part B

Magneto \ ^ futty >-.'. Advanc9dV

/Exhaust C/osed

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^^•-fntake Open

intake Closed'

05 Vj

'Exhaust Open

Section thru Cam Shaft

HoLfSi'ng Showing position of Cams.when Exhaust Valve is Closed

Note on Chart that Crank-Shaft is to''past top center wtien ExhaustValve is closed

Fig. 108.—Diagrams Explaining Valve and Ignition Timing of HaU-Scott

Aviation Engine.

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advantage outside of simplicity of control in establishing a fixed i)ointof ignition. In fact, there seems to be some difference of opinionamong those designers who favor

Ignition Timing

275

fixed ignition, and in one case this is located forty-three degrees aheadof center, and in another motor the point is fixed at twenty degrees, sothat it may be said that this will vary as much as one hundred per cent,in various forms. This point will vary with different methods of

Deod Center

I«r6

■ /ZO"*-"'

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Fig. 109.—Timing Diagram of Typical Six-Oyllnder Engine.

ignition, as well as the location of the spark-plug or igniter. For thesfike of 'simplicity, most airplane engines use set spark; if an advan-cing and retarding mechanism is fitted, it is only to facilitate starting,as the spark is kept advanced while in flight, and control is by throttlealone.

It is obvious by consideration of the foregoing that there can be -no ar-bitrary rules established for timing.

because of the many conditions which determine the best times foropening and closing the valves. It is customary to try various settingswhen a new motor is designed imtil the most satisfactory points aredetermined, and the setting which will be very suitable for one motoris not always right for one of different design. The timing

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Fig. lie.—Timing Diagnun of TTpical EiKbt-CyUnder V Engino.

diagram shown at Fig. 108 applies to the Hall-Scott engine, and mayhe considered typical. It should be easily followed in view of the verycomplete explanation given in preceding pages. Another six-cylinderengine diagram is shown at Fig. 109, and an eiglit-cylinder timing dia-gram is sho\ni at Fig. HO. In timing automobile engines no trouble isexperienced, because timing marks

are always indicated on the engine fly-wheel register with an indicat-ing trammel on the crank-case. To time an airplane engine accurately,as is necessary to test for a suspected cam-shaft defect, a timing disc ofaluminum is attached to the crank-shaft which has the timing marksindicated thereon. If the disc is made 10 or 12 inches in diameter, itmay be divided into degrees without difficulty.

HOW AN ENGINE IS TIMED

In timing a motor from the marks on the timing disc rim it is neces-sary to regulate the valves of but one oyUnder al a timj!^ AssuZg thatthe di«= is revolvmg in the direction of engine rotation, and that thefiring order of the cylinders is 1-3-4-2, the operation of timing wouldbe carried on as follows: The crank-shaft would be revolved until theline marked ** Exhaust opens 1 and 4'' registered with the trammel onthe motor bed. At this point the exhaust-valve of either cylinder No. 1or No. 4 should begin to open. This can be easily determined by notingwhich of these cylinders holds the compressed charge ready for igni-tion. Assuming that the spark has occurred in cylinder No. 1, thenwhen the fly-w^heel is turned from the position to that in which theline marked ** Exhaust opens 1 and 4'' coincides with the trammelpoint, the valve-plunger under the exhaust-valve of cylinder No. 1should be adjusted in such a way that there is no clearance between itand the valve stem. Further movement of the wheel in the same

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direction should produce a lift of the exhaust valve. The disc is turnedabout two hundred and twenty-five degrees, or a little less than three-quarters of a revolution; then the line marked **Exhaust closes 1 and4'' will register with the trammel point. At this period the valve-plun-ger and the valve-stem should separate and a certain amount of clear-ance obtain between them. The next cylinder to time would be No. 3.The crank-shaft is rotated until mark ^* Exhaust opens 2 and 3'^comes in line with the trammel. At this

point the exhaust valve of cylinder No. 3 should be jnst about opening.The closing is determined by rotating the shaft until the line **Exhaustcloses 2 and 3'' comes under the trammel.

This operation is carried on with all the cylinders, it being well to re-member that but one cylinder is working at a time and that a half-re-volution of the fly-wheel corresponds to a full working stroke of all thecylinders, and that while one is exhausting the others are respectivelytaking in a new charge, compressing and exploding. For instance, ifcylinder No. 1 has just completed its power-stroke, the piston in cylin-der No. 3 has reached the point where the gas may be ignited to ad-vantage. The piston of cylinder No. 4, which is next to fire, is at thebottom of its stroke and will have inspired a charge, while cylinder No.2, which is the last to fire, will have just finished expelling a charge ofburned gas, and will be starting the intfike stroke. This timing relatesto a four-cylinder engine in order to simplify the explanation. The tim-ing instructions given apply only to the conventional motor types.Eotary cylinder engines, especially the Gnome *'monosoupape," havea distinctive valve timing on account of the peculiarities of design.

GNOME * * MONOSOUPAPE" VALVE TIMING

In the present design of the Gnome motor, a cycle of operations some-what different from that employed in the ordinary four-cycle engine is

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made use of, says a writer in **The Automobile," in describing the ac-tion of this power-plant. This cycle does away with the need for theusual inlet valve and makes the engine operable with only a singlevalve, hence the name monosoupape, or ** single-valve." The cycle isas follows: A charge being compressed in the outer end of the cylinderor combustion chamber, it is ignited by a spark produced by the spark-plug located in the side of this chamber, and the burning charge ex-pands as the piston moves do\^^l in the cylinder while the latter re-volves around the crank-shaft. Wlien

the piston is.about half-way down on the power stroke, the exhaustvalve, which is located in the center of the cylinder-head, is mechanic-ally opened, and during the following upstroke of the piston the burntgases are expelled from the cylinder through the exhaust valve directlyinto the atmosphere.

Instead of closing at the end of the exhaust stroke, or a few degreesthereafter, the exhaust valve is held open for about two-thirds of thefollowing inlet stroke of the piston, with the result that fresh air isdrawn through the exhaust valve into the cylinder. When the cylinderis still 65 degrees from the end of the inlet half-revolution, the exhaustvalve closes. As no more air can get into the cylinder, and as the pistoncontinues to move inwardly, it is obvious that a partial vacuum isformed.

When the cylinder approaches within 20 degrees of the end of the inlethalf-revolution a series of small inlet ports all around the circiunfer-ence of the cylinder wall is uncovered by the top edge of the piston,whereby the combustion chamber is placed in communication withthe crank chamber. As the pressure in the crank chamber is substan-tially atmospheric and that in the combustion chamber is below atmo-spheric, there results a suction effect which causes the air from thecrank chamber to flow into the combustion chamber. The air in the

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crank chamber is heavily charged with gasoline vapor, which is due tothe fact that a spray nozzle connected with the gasoline supply tank islocated inside the chamber. The proportion of gasoline vapor in the airin the crank chamber is several times as great as in the ordinary com-bustible mixture drawn from a carburetor into the cylinder. Thisextra-rich mixture is diluted in the combustion chamber with the airwhich entered it through tlie exhaust valve during the first part of theinlet stroke, thus forming a mixture of the proper proportion for com-plete combustion.

The inlet ports in the cylinder wall remain open until

20 degrees of the compression half-revolution has been completed,and from that moment to near the end of the compression stroke thegases are compressed in the cylinder. Near the end of the stroke igni-tion takes place and this completes the cycle.

The exact timing of the different phases of the cycle is shown in thediagram at Fig. 111. It will be seen that ignition occurs substantially 20degrees ahead of the outer dead center, and expansion of the burninggases continues until 85 degrees past the outer dead center, when thepiston is a little past half-stroke. Then the exhaust-valve opens and re-mains open for somewhat more than a complete revolution of the cyl-inders, or, to be exact, for 390 degrees of cylinder travel,, until 115 de-grees past the top dead center on the second revolution. Then for 45degrees of travel the charge within the cylinder is expanded,whereupon the inlet ports are uncovered and remain open for 40 de-grees of cylinder travel, 20 degrees on each side of the inward deadcenter position.

SPRINGLESS VALVES

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Springless valves are the latest development on French racing car en-gines, and it is possible that the positively-operated types will be intro-duced on aviation engines also. Two makes of positively-actuatedvalves are shown at Fig. 6. The positive-valve motor differs from theconventional form by having no necessity for valve-springs, as a camnot only assures the opening of the valve, but also causes it to return tothe valve-seat. In this respect it is much like the sleeve-valve motor,where the uncover-ing of the ports is absolutely positive. The carsequipped with these valves were a success in long-distance auto races.Claims made for this type of valve mechanism include the possibilityof a higher number of revolutions and consequently greater enginepower. With the spring-controlled, single-cam operated valve a pointis reached where the spring is not capable of returning the valve

to its seat before the cam has again begun its opening movement. It ispossible to extend the limits considerably by using a light valve on astrong spring, but the

Fig. HI.—TlmiDg Dlkgram SbowliiE Focnllar Valve Timing of Onome"Honoaonpftpe" Botuy SIoWt.

valve stdl remains a limiting factor in the speed of the motor.

A part sectional view through a cylinder of an engine designed by G.Michaux is shown at Fig. 112, A. There are two valves per cylinder, in-clined at about ten degrees from the vertical. The valve-stems are oflarge diameter, as owing to positive control, there is no necessity oflightening this part in an unusual degree. A single over-

Aviation Engines

head cam-shaft has eight pairs of cams, which are shovn in detail at B.For each valve there is a three-armed rocker, one arm of which is con-nected to the stem of the valve and the two others are in contact

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respectively with the opening and closing cams. The connection to theend of the valve-stem is made by a short connecting link, which isscrewed on to the end of the valve-stem and

Fig. 112.—Two Methods of Operating ValTOs by FoaitiT« Own MmWlilch Closos OS Well aa Opens Them.

locked in position. This allows some adjustment to be made betweenthe valves and the actuating rocker. It ■will be evid(?nt that one camand one rocker arm produce the opening of the valve and that the cor-responding rocker ami and cam result in the closing of the valve. If theopening cam has the usual convex profile, the closing cam has a cor-respondingly concave profile. It will be noticed that a light valve-spring is shown in drawing. This is provided to give a final seating toits valve after

it has been closed by the cam. This is not absolutely necessary, as anengine has been run successfully without these springs. The wholemechanism is contained within an overhead aluminum cover.

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The positive-valve system used on the De Lage motor is shown at D. Inthis the valves are actuated as shown in sectional views D and E. Thevalve system is unique in that four valves are provided per cylinder,two for exhaust and two for intake. The valves are mounted side byside, as showoi at E, so the double actuator member may be operatedby a single set of cams. The valve-operating member consists of a yokehaving guide bars at the top and bottom. The actuating cam works in-side of this yoke. The usual form of cam acts on the lower portion ofthe yoke to open the valve, while the concave cam acts on the upperpart to close the valves. In this design provision is made for expansionof the valve-stems due to heat, and these are not positively connectedto the actuating member. As shown at E, the valves are held againstthe seat by short coil springs at the upper end of the stem. These arevery stiff and are only intended to provide for expansion. A slightspace is left between the top of the valve-stem and the portion of theoperating member that bears against them when the regular profilecam exerts its pressure on the bottom of the valve-operating mechan-ism. Another novelty in this motor design is that the cam-shafts andthe valve-operating members are carried in casing attached above themotor by housing supports in the form of small steel pillars. Theoverhead cam-shafts are operated by means of bevel gearing.

FOUR VALVES PER CYLINDER

Mention has been previously made of the sixteen-valve four-cylinderDuesenberg motor and its great power output for the piston displace-ment. This is made possible by the superior volumetric efficiency of amotor provided with four valves in each cylinder instead of

Aviation Engines

but two. This principle was thoroughly tried out in racing automobilenaotors, and is especially valuable in permitting of greater speed and

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power output from simple four- and six-cylinder engines. On eight-and twelve-cylinder types, it is doubtful if the resulting comphca-tiondue to using a very large number of valves would be worth while.When extremely large valves are used,

"'j^^Two Smalt Valvs

'One Large Valve

Fig. 113.—Diagram Comparing Two Large Valves and Four SmaUOnes ' of Practically the Same Area. Note How Easily Small Valves areInstalled to Open Directly Into the Cylinder.

as sho\\Ti in diagram at Fig. 113, it is difficult to have them open dir-ectly into the cylinder, and pockets are sometimes necessary. A largevalve would weigh more than two smaller valves having an areaslightly larger in the aggregate; it would require a stiffer valve springon accoimt of its greater weight. A certain amount of metal in thevalve-head is necessary to prevent warping; therefore, the inertiaforces will be greater in the large valve than in the two smaller valves.As a greater port

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Multiple Valve Advantages

Axnation Enginet

area is obtained by the use of two valves, the gases will be drawn intothe cylinder or expelled faster than with a lesser area. Even if the areasare practically the same as in tlie diagram at Fig. 113, the smallervalves mav

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Fig. 115.—Front View of Cnrtlss 0X3 Avlstlon Motor, Bliowtng Uncon-ventional Valve Action by Concentric Fusli Bod and Pull Inbe.

have a greater lift witliont imposing greater stresses on the valve-opor-ating mechanism and quicker gas intake and oxhaust obtained. Tliesmaller valves are not affected by boat as imieli as larger ones are. Thequicker gas movements made possible, as well as reduction of

inertia forces, permits of higher rotative speed, and, consequently,greater power output for a given piston displacement. The drawings atFig. 114 show a sixteen-valve motor of the four-cylinder type that hasbeen designed for automobUe racing purposes, and it is apparent thatvery slight modifications would make it suitable for aviation purposes.Part of the efficiency is due to the reduction of bearing friction by theuse of ball bearings, but tlie multiple-valve feature is primarily re-sponsible for the excellent performance.

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CHAPTER rX

Constructional Details of Pistons—Aluminum Cylinders and Pistons—Piston Ring Construction—Leak Proof Piston Rings—^Keeping OilOut of Combustion Chamber—Connecting Rod Forms—ConnectingRods for Vee Engines—Cam-Shaft and Crank-Shaft Designs—BallBearing Crank-Shafts—^Engine Base Construction.

CONSTRUCTIONAL DETAILS OF PISTONS

The piston is one of the most important parts of the gasoline motorinasmuch as it is the reciprocating member that receives the impact ofthe explosion and which transforms the power obtained by the com-bustion of gas to mechanical motion by means of the connecting rod towhich it is attached. The piston is one of the simplest elements of themotor, and it is one component which does not vary much in form indifferent types of motors. The piston is a cylindrical member providedwith a series of grooves in which packing rings are placed on the out-side and two bosses which serve to hold the wrist pin in its interior. Itis usually made of cast iron or aluminum, though in some motorswhere extreme lightness is desired, such as those used for aeronauticwork, it may be made of steel. The use of the more resisting materialenables the engineer to use lighter sections where it is important thatthe weight of this member be kept as low as possible consistent withstrength.

A number of piston types are shown at Fig. 116. That at A has a roundtop and is provided with four split packing rings and. two oil grooves.A piston of this type is generally employed in motors where the com-bustion clianiber is large and where it is desired to obtain a higher de-gree of compression than would be possible with a flat top piston. Thisconstruction is also stronger because of the arched piston top. Themost common form

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piston is that shown at B, and it diifers from that eviously describedonly in that it has a flat top. The ston outlined in section at C is a typeused on some

the sleeve-valve motors of the Knight pattern, and -s a concave headinstead of the convex form shown

A. The design shown at D in side and plan views is

g. 116.—Fomu of PiBtona Commonlr Emplored in QMoline Englnea.A—Dome Head Piston and Three Packing Rings. B—Flat Top FormAhnOBt Unlvenally Uaed. C—Ooncave Plstoa Utilized In Knlgbt Mo-tois and Some Having Orerbead Valvos. D— ^Two^tcIo Engine Mem-ber witb Deflector Plate Cast Intograll;. E—Differential of Two-Dia-meter Pleton Used In Some Engines Operating on Two-OydePrinciple.

e conventional form employed in two-cycle engines, ae deflector plateon the top of the cylinder is cast in-gral and is utilized to prevent theincoming fresh gases om flo'ft-ing directly over the piston top and outof the ihaust port, which is usually opposite the inlet open-g. On these

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types of two-cycle engines where a two-ameter cylinder is employed,the piston shown at E is

Aviation Engines

I

^

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//////////r//^ff£'

o

till

saga

I

be

used. This is known as a "differential piston," and has an enlarged por-tion at its lower end which fits the pumping cylinder. The usual formof deflector plate is- pro-

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OoHinctlag Sot Bearing^

Fig. IIB.—Typical Flatoa and Connecting Bod AaasmUr.

vided at the top of the piston and one may consider it as two pistons inone.

One of the important conditions in piston design is the method of se-curing the wrist pin which is used to

connect the piston to the upper end of the connectiiig rod. Variousmethods have been devised to keep the pin in place, the most commonof these being sho-wn at Fig. 117. The wrist pin should be retained bysome positive means which is not liable to become loose nnder the vi-bratory stresses which obtain at this point. If the

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rig. 119.—Parts of Sturterant Aviation Eagin«. A—O^linder HwdShowing ValvM. B—Connecting Bod. C—Piston and Bings.

■wrist pin was free to move it would work out of the bosses enough sothat the end would bear against the cylinder'wall. As it is usually madeof steel, which is a harder material than cast iron used in cylinder con-struction, the rubbing action would tend to cut a groove in the cylinderwall which would make for loss of power

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Fig. 120.—Alinnlnnm Platon and Llgbt Bnt Strong StMl OonnectlngBod uid WrlBt Fin of Tliomas Aviation Engine.

because it would permit escape of gas. The wrist pin member is asimple cylindrical element that fits the bosses closely, and it may beeither hollow or solid stock. A typical piston and connecting rod as-sembly which 'shows a piston in section also is given at Fig. 118. Thepiston of the Sturtevant aeronautical motor is shown at Fig. 119, thealuminum piston of the Thomas' airplane motor with piston rings inplace is shown at Fig. 120. A good view of the wrist pin and connectingrod are also given. The iron piston of the Gnome "Monosoupape" air-plane engine and the unconventional connecting rod assembly areclearly depicted at Fig 121.

The method of retention shown at A is the simplest and consists of aset screw having a projecting portion

passing into the wrist pin and holding it in place. The Bcrew is keptfrom taming or loosening by means of a check nut. The method out-lined at B is similar to that sho^\-n at A, except that the wrist pin issolid and the point of the set screw engages an annular groove turnedin the pin for its reception. A very positive method is showTi at C.Here the retention screws pass into the wrist pin and are then locked

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by a piece of steel wire which passes through suitable holes in theends. The method outlined at D is sometimes employed, and it varies

PiK' 121.—Cast Iron Piston of "HonoBonpape" Onome EngliieTrntollnd Oil On« of the Short Connecting Bods.

from that shown at C only in that the locking wire, which is made ofspring steel, is passed through the heads of the locking screws. Somedesigners machine a large groove around tlie piston at such a pointthat when the wrist pin is put in place a large packing ring may besprung in the groove and utilized to hold the wrist pin , in place.

The system shoiMi at F is not so widely used as the simpler methods,because it is more costly and does not offer any greater security whenthe parts are new than the simple lock sliown at A. In this a hollowTtrist pin is used, having a tapered thread cut at each end. The wristpin is slotted at three or four points, for a distance equal to the lengthof the boss, and when taper expansion plugs

re screwed in place the ends of the wrist pin are ex-anded against thebosses. This method "has the advan-ige of providing a certain degreeof adjustment if the Tist pin should loosen up after it has been in usefor ome time. The taper plugs would be screwed in deeper nd the endsof the wrist pin expanded proportionately 3 take up the loss motion.The method shown at G is n ingenious one. One of the piston bosses isprovided dth a projection which is drilled out to receive a plunger, 'he

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wrist pin is provided with a hole of sufficient size to eceive the plunger,which is kept in place by means of

spring in back of it. This makes a very positive lock nd one that can beeasily loosened when it is desired to emove the wrist pin. To unlock, apiece of fine rod is irust into the hole at the bottom of the boss whichpushes le plunger back against the spring until the wrist pin Etn bepushed out of the piston.

Some engineers think it advisable to oscillate the wrist in in the pistonbosses, instead of in the connecting rod oaall end. It is argued that thisconstruction gives more earing surface at the wrist pin and alsoprovides for lore strength because of the longer bosses that can be sed.When this system is followed the piston pin is eld in place by locking itto the connecting rod by some leans. At H the simplest method is out-lined. This con-Lsted of driving a taper pin through both rod and wristin and then preventing it from backing out by putting

split cotter through the small end of the tapered lock-ig pin. Anothermethod, which is depicted at I, consists f clamping the wrist pin bymeans of a suitable bolt ^hich brings the slit connecting rod end to-gether as hown.

ALUMINUM FOB CYLINDERS AND PISTONS

Aluminum pistons outlined at Fig. 122, have replaced ast iron mem-bers in many airplane engines, as these reigh about one-third as muchas the cast iron forms of lie same size, while the reduction in the iner-tia forces

Aviation Engines

has made it possible to increase the engine speed withont correspond-ingly stressing the connecting rods, crank-shaft and engine bearings.

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Aluminnm has not only been used for pistons, but a number of motorswill be built for the coming season that "will use aluminum cylinderblock eastings as well. Of course, the aluminum alloy is too soft to beused as a bearing for the piston, and it will not withstand the hammer-ing action of the valve. This makes the use of cast

Hourglass Piston.

Fig. 122.—Types of Almnluiun Pistons Used In AvlaUoa EukIum.

iron or steel imperative in all motors. When used in connection withan aluminum cylinder block the cast iron pieces are placed in themould so that they act as cylinder liners and valve scats, and the mol-ten metal is poured around them when the cylinder is cast. It is saidthat this construction results in an intimate bond between the castiron and the surrounding aluminum metal. Steel liners may also bepressed into the aluminum cylinders after these are bored out to re-ceive them. Aluminum has for a number of years been used in manymotor

car parts. Alloys have been developed that have greater strength thancast iron and that are not so brittle. Its use for manifolds and enginecrank and gear cases lias been general for a nmnber of years.

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At first thought it would seem as though aluminum would be entirelyunsuited for use in those portions of internal combustion engines ex-posed to the heat of the explosion, on account of the low melting pointof that metal and its disadvantageous'quality of suddenly ^^wilt-ing^'when a critical point in the temperature is reached. Those who hesit-ated to use aluminum on account of this defect lost sight of the greatheat conductivity of that metal, which is considerably more than thatof cast iron. It was found in early experiments with iduminum pistonsthat this quality of quick radiation meant that aluminum pistons re-mained considerably cooler than cast iron ones in service, which wasattested to by the reduced formation of carbon deposits thereon. Theuse of aluminum makes possible a marked reduction in power plantweight. A small four-cylinder engine which was not particularly heavyeven with cast iron cylinders was found to weigh 100 pounds lesswhen the cylinder block, pistons, and upper half of the crank-case hadbeen made of aluminum instead of cast iron. Aluminum motors are nolonger an experiment, as a considerable number of these have been inuse on cars during the past year without the owners of the cars beingapprised of the fact. Absolutely no complaint was made in any case ofthe aluminum motor and it was demonstrated, in addition to the sav-ing in weight, that the motors cost no more to assemble and cooledmuch more efficiently than the cast iron form. One of the drawbacksto the use of aluminum is its growing scarcity, which results in makingit a **near precious'* metal.

PISTON RING CONSTRUCTION

As all pistons must be free to move up and down in the cylinder withminimum friction, they must be less in

diameter than the bore of the cylinder. The amount of . freedom orclearance provided varies with the construction of the engine and thematerial the piston is made of, as well as its size, but it is nsual to

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provide from .005 to .010 of an inch to compensate for the expansionof the piston due to heat and also to leave sufficient clearance for theintroduction of lubricant between the workmg surfaces. Obviously, ifthe piston were not provided with packing rings, this amount of clear-ance would enable a portion of the gases evolved when the charge isexploded to escape by it into the engine crank-case. The packing

Fig. 123.—Types of Piston Bings and Ring Joints. A — Concentric Sing.B —Eccentrically Machined Form. O — ^Lap Joint Bing. I>—^BnttJoints Seldom Used.* E—^Diagonal Cat Member, a Popular Form*

members or piston rings, as they are caUed, are split rings of cast iron,which are sprung into suitable grooves machined on the exterior of thepiston, three or four of these being the usual number supplied. Thesehave suflS-cient elasticity so that they bear tightly against the cylinderwall and thus make a gas-tight joint. Owing to the limited amount ofsurface in contact with the cylinder wall and the elasticity of the splitrings the amount of friction resulting from the contact of properly fit-ted rings and the cylinder is not of enough moment to cause any dam-age and the piston is free to slide up and down in the cylinder bore.

These rings are made in two forms, as outlined at Fig. 123. The designshowTi at A is termed a ** concentric

ring/' because the inner circle is concentric with the outer one and thering is of nniform thickness at all points. The ring shown at B is called

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an ** eccentric ring/' and it is thicker at one part than at others. It hastheoretical advantages in that it wiU make a tighter joint than the oth-er form, as it is claimed its expansion dne to heat is more nniform. Thepiston rings must be split in order that they may be sprung in place inthe grooves, and also to insure. that they will have sufficient elasticityto take the form of the cylinder at the different points in their travel Ifthe cylinder bore varies by small amounts the rings will spring out atthe points where the bore is larger than standard, and spring in atthose portions where it is smaller than standard.

It is important that the joint should be as nearly gas-tight as possible,because if it were not a portion of the gases would escape through theslots in the piston rings. The joint shown at C is termed a *4ap joint,''because the ends of the ring are cut in such a manner that they over-lap. This is the approved joint. The butt joint shown at D is seldomused and is a very poor form, the only advantage being its cheapness.The diagonid cut shown at E is a compromise between the very goodform shown at C and the poor joint depicted at D. It is also widelyused, though most constructors prefer the lap 'joint, because it doesnot permit the leakage of gas as much as the other two types.

There seems to be some difference of opinion relative to the best pis-ton ring type—some favoring the eccentric pattern, others the concent-ric form. The concentric ring has advantages from the lubricatingengineer's point of view; as stated by the Piatt & Washburn Companyin their text-book on engine lubrication, the smaller clearance behindthe ring possible with the ring of xmiform section is advantageous.

Fig. 124, A, shows a concentric piston ring in its groove. Since the ringitself is concentric with the groove, very small clearance between theback of the ring

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and the bottom of its groove may be allowed. Small clearance leavesless space for the accumulation of oil and, carbon deposits. The gasketeffect of this ring is uniform throughout the entire length of its edges,which is its marked advantage over the eccentric ring. Thi8 type of pis-ton ring rarely burns fast in its groove. There are a large nrnnber ofdifferent concentric rings manufactured of different designs and of dif-ferent eiRciency. Figs. 124, B and 124, C show eccentric rings as-sembled in the ring groove. It will be noted that there is a large

Cylindei

Fig. 121.—Diasranis Sbowlng Advantages of Concentric FlBton Bluga.

space between the thin ends of this ring and the bottom of the groove.This empty space fills up with oil which' in the case of the upper ringfrequently is carbonized, restricting the action of the ring and nullify-ing its nse-f^^lness. The edgc^s of the tliin ends are not sufficientlywide to prevent rapid escape of gases past them. In a practical way thisleakage moans loss of compression and noticeable drop in power.'\\Tien new and properly fitted, very little difference can be notedbetween the tightness of eccentric and concentric rings. Nevertheless,after several months' use, a more rapid leakage will always occnr pastthe eccentric tlian past tiio concentric. If continuous trouble with thecarbonization of cylinders, smoking and sooting of spark-plugs is ex-perienced, it is

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I sure indication that mechanical defects exist in the en-^e, assumingof course, that a suitable oil has been ised. Such trouble can be greatlylessened, if not en-irely eliminated, by the application of concentricrings lap joint), of any good make, properly fitted into the ;rooves ofthe piston. Too much emphasis cannot be )ut upon this point. If the oilused in the engine is of he correct viscosity, and serious carbon depos-it, smoking, tc, still result, the only certain remedy then is to have hecylinders rebored and fitted with properly designed, •versized pistonsand piston rings.

LEAK-PROOF PISTON RINGS

«

In order to reduce the compression loss and leakage ►f gas by the or-dinary simple form of diagonal or lap oint one-piece piston ring anumber of compound rings lave been devised and are offered by theirmakers to ise in making replacements. The leading forms are hown atFig. 125. "That shown at A is known as the ^Statite^' and consists ofthree rings, one carried inside rhile the other two are carried on theoutside. The ring hown at B is a double ring and is known as theMcCad-len. This is composed of two thin concentric lap joint ings sodisposed relative to each other that the opening n the inner ring comesopposite to the opening in the >uter ring.

The form shown ^t C is known as the **Leektite,'' tnd is a single ringprovided with a peculiar form of lap tnd dove tail joint. The ringshown at D is known as he ^* Dunham ^^ and is of the double con-centric type being omposed of two rings with lap joints which are wel-ded ogether at a point opposite the joint so that there is no )assage bywhich the gas can escape. The Burd high ompression ring is showTi atE. The joints of these ings are sealed by means of an H-shaped coupler

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of )ronze which closes the opening. The ring ends are made v'ithtongues which ; interlock with the coupling. The

Aviation Engines

ring shown at F is called the "Evertite" and is a three-piece ring com-posed of three members as shown in the sectional view below the ring.The main part or inner ring has a circumferential channel in which thetwo outer rings lock, the resulting cross-section being rectangular justthe same as that of a regular pattern ring. All three rings are diagon-ally split and the joints are spaced equally and the distances main-tained by small pins. This

Fig. 12S.—L««k-Proof uid Otlier Componnd Flston Blngs.

results in each Joint being sealed by the solid portion of the otherrings.

The use of a number of light steel rings instead of one wide ring in thegroove is found on a number of automobile power plants, but as far asknown, this construction is not used in airplane power plants. It iscontended that where a number of light rings is employed a more

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flexible packing means is obtained and the possibility of leakage is re-duced. Rings of this design are made of square section steel wire andare given a spring temper. Owing to the limited width the diagonal

ut joint is generally employed instead of the lap joint ^hich is so popu-lar on wider rings.

KEEPING OIL OUT OF COMBUSTION CHAMBERS

An examination of the engine design that is econom-eal in oil con-sumption discloses the use of tight piston ings, large centrifugal ringson the crank-shaft where it ►asses through the case, ample coolingfins in the pistons, ents between the crank-case chamber and the valveen-losures, etc. Briefly put, cooling of the oil in this engine as beenproperly cared for and leakage reduced to a ainimum. To be specificregarding details of design: )il surplus can be kept out of the explosionchambers by Baving the lower edge of the piston skirt sharp and by heuse of a shallow groove (C), Fig. 126, just below the ower piston ring.Small holes are bored through the )iston walls at the base of thisgroove and communicate ^^ith the crank-case. The similarity of thesharp edges •f piston skirt (D) and piston ring to a carpenter ^s plane►it, makes their operation plain.

The cooling of oil in the sump (A) can be accom-)lished most effect-ively by radiating fins on its outer urface. The lower crank-case shouldbe fully exposed to he outer air. A settling basin for sediment (B)should ►e provided having a cubic content not less than one-enth ofthe total oil capacity as outlined at Fig. 126. ?he depth of this basinshould be at least 2i/^ inches, and ts walls vertical, as shown, to re-duce the mixing of sediment with the oil in circulations The inletopening to he oil pump should be near the top of the sediment basin norder to prevent the entrance into the pump with the lil of any solidmatter or water condensed from the prod-icts of combustion. This

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sediment basin should be Irained after every five to seven hours airservice of an lirplane engine. Concerning filtering screens there is ittleto be said, save that their areas should be ample md the mesh coarseenough (one-sixteenth of an inch) to

offer no serious resistance to the free flow of cold or heavy oil throughthem; otherwise the oil in the crank-case may build up above them toan undesirable level The necessary frequency of draining and flushingout the oil sump differs greatly with the age (condition) of the

Fig. 1^.—Sectional View of Engine Showing Me&na of FroTOBtlng OilIieakage B7 Piston Rings.

engine and the suitability of the oil used. In broad terms, the oil sumpof a new engine should be thoroughly drained and flushed with ker-osene at the end of the first 200

aiiles, next at the end of 500 miles and thereafter every 1,000 miles.While these instructions apply specifically to automobile motors, it isvery good practice to change the oil in airplane engines frequently. Inmany cases, the best results have been secured when the oil supply iscompletely replenished every five hours that the engine is inoperation.

CONNECTING ROD FORMS

The connecting rod is the simple member that joins the piston to thecrank-shaft and which transmits the power imparted to the piston bythe explosion so that it may be usefully applied. It transforms the re-ciprocating movement of the piston to a rotary motion at the crank-tshaft. A typical connecting rod and its wrist pin are shown at Fig. 120.It will be seen that it has two bearings, one at either end. The smallend is bored out to receive the wrist pin which joins it to the piston,while the large end has a hole of sufficient size to go on the erank-pin.

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The airplane and automobile engine connecting rod is invariably asteel forging, though in marine engines it is sometimes made a steel orhigh tensile strength bronze casting. In all cases it is desirable to havesofter metals than the crank-shaft and wrist pin at the bearing point,and for this reason the connecting rod is usually provided with bush-ings of anti-friction or white metal at the lower end, and bronze at theupper. The upper end of the connecting rod may be one piece, becausethe wrist pin can be introduced after it is in place between the bossesof the piston. The lower bearing must be made in two parts in mostcases, because the crank-shaft cannot be passed through the bearingowing to its irregular form. The rods of the Gnome engine are all onepiece types, as shown at Fig. 127, owing to the construction of the^'mother^' rod which receives the crank-pins. The complete connect-ing rod assembly is shown in Fig. 121, also at A, Fig. 127. The'^mother''

rod, with one of the other rods in place and one abont to be inserted, isshown at Fig. 127, B. The built-up crank-shaft which makes this con-struction feasible is shown at Fig. 127, B.

Some of the various designs of connecting rods that have been usedare shown at Fig. 128. That at A is a simple form often employed insingle-cylinder motors, having built-up crank-shafts; Both ends of theeonnect-

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—Connecting Kod and Crank-Shaft Oonstmction * of Gdooh "Mono-soupape" Englna.

ing rod are bushed with a one-piece bearing, as it can be assembled inplace before the crank-shaft assembly is built up. A built-up crank-shaft such as this type of connecting rod would be used with is sho^mat Fig. 106. The pattern shown at B is one that has been used to someextent on heavy work, and is known as the "marine type." It is made inthree pieces, the main portion being a steel forging having a flangedlower end to which the bronze boxes are secured by bolts. The modi-fied marine type depicted at C is the form that has received the widestapplication in automobile and aviation engine con-

Connecting Bod Forms

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m

lltl

f4

iiiii l|

lull

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!i

ml

stmction. It consists of two pieces, the main member being a steeldrop forging having the wrist-pin bearing and the upper crank-pinbearing formed integral, while the lower crank-pin bearing member isa separate forg-ing secured to the connecting rod l}y bolts. In this con-struction bushings of anti-friction metal are used at the lower end, anda bronze bushing is forced into the upper-or wrist-pin end. The rodshowTi at D has also been widely used. It is similar in construction tothe form shown at C, except that the upper end is split in order to per-mit of- a degree of adjustment of the wrist-pin bushing, and the lowerbearing cap is a hinged member which is retained by one bolt insteadof two. When it is desired to assemble it on the crank-shaft the lowercap is swung to one side and brought back into place when the con-necting rod has been properly located. Sometimes the lower bearingmember is split diagonally instead of horizontally, such a constructionbeing outlined at E.

In a number of instances, instead of plain bushed bearings anti-fric-tion forms using ball or rollers have been used at the lower end. A ball-bearing connecting rod is shown at F. The big end may be made in onepiece, because if it is possible to get the ball bearing on the crank-pinsit will be easy to put the connecting rod in place. Ball beailngs are notused very often on connecting rod big. ends because of difficulty of in-stallation, though when applied properly they give satisfactory serviceand reduce friction to a minimum. One of the advantages of the ballbearing is that it requires no adjustment, whereas the plain bushingsdepicted in the other connecting rods must be taken up from time totime to compensate for wear.

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This can be done in forms shoAvn at B, C, D, and E by bringing thelower bearing caps closer to the upper one and scraping out thebrasses to fit the shaft. A number of liners or shims of thin brass orcopper stock, varying from .002 inch to .005 inch, are sometimes in-terposed between the halves of the bearings when it is first

fitted to the crank-pin. As the brasses wear the shims may be removedand the portions of the bearings brought close enough together to takeup any lost motion that may exist, though in some motors no shimsare provided and depreciation can be remedied only by installing newbrasses and scraping to fit.

The various structural shapes in which connecting rods are formed areshown in section at G. Of these the I

Fig. 129.—Donbls Oonnecting Sod Assembly For Use On Single Orank-Fln of Vee Engine.

section is most widely used in airplane engines, because it is strongand a very easy shape to form by the drop-forging process or to ma-chine out of the solid bar when extra good steel is used. Where ex-treme lightness is desired, as in small high-speed motors used forcycle propulsion, the section sho^vTi at the extreme left is often used.If the rod is a cast member as in some marine engines, the cross, hol-low cylinder, or U sections are sometimes used. If the sections shownat the right are em-

ployed, advantage is often taken of the opportnnity for passing lubric-ant through the center of the hollow round section on vertical motorsor at the bottom of the U Bection, which would be used on a horizontalcylinder power plant

Connecting rods of Vee engines are made ia two distinct styles. Theforked or "scissors" joint rod assembly

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Tig. 130.—^Anotber Type of Double Oouuectltiig Bod tor Vm

is employed when the cylinders are placed directly opposite each oth-er. The "blade" rod, as shown at Fig. 129, fits between the lower endsof the forked rod, which oscUIate on the bearing which encircles thecrank-pin. The lower end of the "blade" rod is usually attached to thebearing brasses, the ends of the "forked" rod move on the outer sur-faces of the brasses. Another form of rod devised for use under theseconditions is shown at Fig. 130 and installed in an aviation engine atFig. 132. In this construction the shorter rod is attached to a boss onthe master rod by a short pin to form a hinge and to permit the shortrod to oscillate as the conditions die-

Connecting Rod Types

tate. This form of rod can be easily adjusted ■when the bearing depre-ciates, a procedure that is difficult with the forked type rod. The bestpractice, in the writer's opin-

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Tis- 132.—Part Sectional View of Renault Twelve-Cylinder Wktet-Oooled Engine. Showing Connecting Bod Construction and Other In-povtMrt lutemal FaTts.

ion, is to stagger the cylinders and nee side-by-side rods as is done inthe Curtiss engine. Each rod may be fitted independently of the otherand perfect compensation for wear of the big ends is i)ospible.

CAM-SHAFT AND CRANK-SHAFT DESIGN

Before going extensively into the subject of crank-aft construction itwill be well to consider cam-shaft sig^, which is properly a part of thevalve system and lich has been considered in connection M-ith theother ■ments which have to do directly with cylinder construc-m to

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some extent. Cam-shafts are usually simple mem-rs carried at the baseof the cylinder in the engine se of Vee tj-pe motors by suitable bearingsand having e cams employed to lift the valves attached at intervals.

typical cam-shaft design is shown at Fig. 133. Two iin methods of cam-shaft construction are followed—

g. 133.—Typical Oam-SIiKft, with Valve Iilftlng Caou and Gsan toOperate AnxUlary Derlcoa Foiged Integnlly.

at in which the cams are separate members, keyed and nned to theshaft, and the other where the cams are rmed integral, the latter beingthe most snitable for rplane engine requirements.

The cam-shafts shown at Figs. 133 and 134, B, are of e latter tj-pe, asthe cams are machined integrally. In lis case not only the cams butalso the gears used in -iving the auxiliary shafts are forged integral.This is more expensive construction, because of the high initial ist offorging dies as well as the greater expense of achining. It has the ad-vantage over the other form in hich the cams are keyed in place in thatit is stronger, id as the cams are a part of the shaft they can never■come loose, as might be possible where they are sepa-itely formedand assembled on a simple shaft.

Xhe importance of the crank-shaft has been previously

Aviation Engines

considered, and some of its forms have been shown in views of themotors presented in earlier portions of this work. The crank-shaft isone of the parts subjected to the greatest strain and extreme care isneeded in its con-

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Fig. 134.—Important Parts of Dueaanberg ATlation EngliM. A—TimeMala Bearing Orank-Shaft. B—Cam-Sbaft wlUi Integiia Cams. 0— ris-ton and Connecting Bod Assembly. D—Valve Bcckei Groitp. E—Piston.F—Ualn Bearing Brasses.

struction and design, because practically the entire duty of transmit-ting the power generated by the motor to the gearset devolves upon it.Crank-shafts are usually made of liigh tensile strength steel of specialcomposition. They may be made in four ways, the most common beingfrom

Crarih-Shaft Construction

815

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a drop or machine forging which is formed approximately to the shapeof the finished shaft and in rare instances (experimental motors only)they may be steel castings. Sometimes they are made from machineforgings, where considerably more machine work is necessary thanwould be the case where the shaft is formed between dies. Some en-gineers favor blocking the shaft out of a solid slab of metal and thenmachining this rough blank to form. In some radial-cylinder motors ofthe Gnome and

Fig. 135.—Showing Method of Making Crank-Shaft A—The BoughSteel Forging Before Machining. B—^The Finished Six-Throw, Seven-Bearing Orank-Shaft.

Le Bhone type the crank-shafts are built up of two pieces, held togeth-er by taper fastenings or bolts.

The form of the shaft depends on the number of cylinders and theform has material influence on the method of construction. For in-stance, a four-cylinder crank-shaft could be made by either of themethods outlined. On the other hand, a three- or six-cylinder shaft isbest made by the machine forging process, because if drop forged orcut from the blank it will have to be heated and the crank throws bentaround so that the pins will lie in three planes one hundred and twentydegrees apart, while the other types described need no further atten-tion, as the crank-pins lie in planes one hundred and eighty degreesapart. This can be better understood by referring to Fig. 135, which

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shows a six-cylinder shaft in the rough and finished stages. At A theappearance

Aviation Enginet

of the machine forging before any of the material is removed is shown,while at B the appearance of the finished crank-shaft is clearly depic-ted. The built-up crank-shaft is seldom used on multiple-cylinder mo-tors, except in

some cases where the crank-shafts revolve on ball bearings as in someautomobile racing engines.

Crank-shaft form will vary with a number of cylinders and it is pos-sible to use a number of different arrangements of crank-pins andbearings for the same number

rig. 137.—Crank-Shaft of Thoroaa-Morae Eight-Oylinder Tee Engine.

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of cylinders. The simplest form of crank-shaft is that used on simpleradial cylinder motors as it would consist of l)ut one crank-pin, twowebs, and the crank-shaft. As the number of cylinders inciease in Veemotors as a general rule more crank-pins are used. The crank-shaftthat

Crank-Shaft Construction

817

would be used on a two-cylinder opposed motor is shown at Fig. 136.This has two throws and the crank-pins are spaced 180 degrees apart.The bearings are exceptionally long. Four-cylinder crank-shafts mayhave two, three or five main bearings and three or four crank-pins. Insome forms of two-bearing crank-shafts, such as used when four-cyl-inders are cast in a block, or unit casting,

Fig. 138.—Onmk-Oase and Cnnk-SIuft OonstrnctlDn foi TwelTfr-Ojdlndn Motors. A—Dneseubei^. B—CurtUi.

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two of the pistons are attached to one common crank-pin, so that inreality the crank-shaft has but three crank-pins. A tj-pical threebearing, four-cylinder crank-shaft is shown at Fig. 134, A. The sametype can be used for an eight-cylinder Vcc engine, except for the great-er length of crank-pins to permit of side by side rods as sho\\Ti at Fig.137. Six cylinder vertical tandem and twelve-cylinder Vee enginecrank-shafts usually have four or seven main bearings depending iiponthe disposition of the crank-pins and arrangement of cylinders. At Fig.138, A,

Aviation Engines

818

the bottom view of a twelve-cylinder engine with bottom half of crankcase removed is given. This illustrates clearly the arrangement of mainbearings when the cranfc-shaft is supported on four journals. Thecrank-shaft sTiown at Fig. 138, B. is a twelve-cylinder seven-bearingtype.

In some automobile engines, extremely good results have been se-cured in obtaining steady running with mini-

.! Balance we'^hH forged / \, integrally w -'■-'

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Ftg. 139.—OooDterbalancAd Cruik-SIiafts Bednco EnEliift Vlbntionva& Fermlt of Higher BotatlTe Speeds.

miun vibration by eoiinterbalancing the crtmk-shafts as outlined atFig. 139. The shaft at A is a type suitable for a high speed four-cylindervertical or an eight-cylinder Vee type. That at B is for a six-cylindervertical or a twelve-cylinder V with scissors joint rods. Ifcounterbalancing crank-shafts lielps in an automobile engine, itshould have advantages of some moment in airplane engines, eventhough the crank-shaft weight is greater.

BALL-BEARING CRANK-SHAFTS

While crank-shafts are usually supported in plain journals there seemsto be a growing tendency of late to use anti-friction bearings of the balltype for their support. This is especially noticeable on block motorswhere but two main bearings are utilized. When ball bearings are se-lected with proper relation to the load which obtains they will givevery satisfactory service. They permit the crank-shaft to turn withminimum friction, and if properly selected will never need adjustment.The front end is supported by a bearing which is clamped in such amanner that it will take a certain amount of load in a direction parallelto the axis of the shaft, while the rear end is so supported that the

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outer race of the bearing has a certain amount of axial freedom or"float." The inner race or cone of each bearing is firmly clampedagainst shoulders on the crank-shaft. At the front end of the crank-shaft timing gear and a suitable check nut are used, while at the backend the bearing is clamped by a threaded retention member betweenthe fly-wheel and a shoulder on the crank-shaft. The fly-wheel is heldin place by a taper and key retention. The ball bearings are carried in alight housing of bronze or malleable iron, w^hich in turn are held inthe crank-case by bolts. The Kenault engine uses ball bearings at frontand rear ends of the crank-shaft, but has plain bearings aroundintermediate crank-shaft journals. The rotary engines of the Gnome,Le Ehone and Clerget forms would not be practical if ball bearingswere not used as the bearing friction and consequent depreciationwould be very high.

ENGINE-BASE CONSTRUCTION

One of the important parts of the power plant is the substantial casingor bed member, which is employed to support the cylinders and crank-shaft and which is attached directly to the fuselage engine supportingmem-

bers. This wtU vary widely in form, but as a general thing' it is an ap-proximately cylindrical member whieli may be divided either verticallyor horizontaUy in two or more parts. Airplane engine crank-cases areusually made of aluminum, a material wliich has about the samestrength as cast iron, but which only weighs a third as much. In rarecases cast iron is employed, but is not favored by most engineers be-cause of its brittle nature,

Fig. liO.—View or Thom&s 135 Horao-Power A«romotor, Model 8,Conveatlonai Method of Crank-Case Coiutructloii.

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great weight and low resistance to tensile stresses. "Where exceptionalstrength is needed alloys of bronze may be used, and in some caseswhere engines are produced in large quantities a portion of the crank-case may be a sheet steol or ahiininuni stamping.

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Crank-cases are always large enough to iiermit the crank-shaft andparts attaclicd to it to turn inside and obviously its length is determ-ined by the number of cylinders and their disposition. Tlie crank-caseof the radial cylinder or double-opposed oylindor engine would besubstantially the same in lengtli. That of a four-cylinder

Crank-Case Construction

821

will vary in length with the method of casting the cylinder. When thefour-cylinders are east in one unit and a two-bearing csank-shaft isused, the crank-case is a very

rig. 111.—views of Upper Half of Tliomaa Aeromotor Crank-CaB*.

compact and short member. ^Tion a three-bearing crankshaft is util-ized and the cylinders are cast in pairs, the engine base is longer thanit would be to support a block casting, but is shorter than one designedto sustain in-

dividual cylinder castings and a five-bearing crank-shaft It is nowcommon constmction to cast an oil container integral with the bottomof the engine base and to draw the lubricating oil from it by means of apump, as shown at Fig. 140. The arms by which the motor is supported

Fig. 142.—Metliod of Constructlns Elght-OyUnder Vae Engine,Poasllile If Alumlnnm C^lnder and Crank-OaH Caatlnss an ITMd.

in the fuselage are substantial-ribbed members cast integrally with theupper half.

The approved method of crank-ease construction favored by the ma-jority of engineers is shown at the top of Fig. 141, bottom side up. Theupper half not only forms a bed for the cylinder but is used to hpld thecrank-shaft as well. In the illustration, the three-bearing boxes formpart of the ease, while the lower brasses are in the form

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Fig. 143.—Simple vaA Oomp&ct Oiank-Oue, PoaslUe When BadlmlOyUnder Engine Design la Followed.

of separately cast caps retained by suitable bolts. In the constructionoutlined the bottom part of the case serves merely as an oil containerand a protection for the interior mechanism of the motor. The cylin-ders are held down by means of studs screwed into the crank-case top,as shown at Fig. 141, lower view. If the aluminum cylinder motor hasany future, the method of construction outlined at Fig. 142, which hasbeen used in cast iron for an automobile motor, might be used for aneight-cylinder Vee engine for airplane use. The simplicity of the crank-case needed for a revolving cylinder motor and its small weight can bewell understood by examination of the illustration at Fig. 143, whichshows the engine crank-case for the nine-cylinder "Monosoupape"Gnome engine. This consists of two accurately machined forgings heldtogether by bolts as clearly indicated.

1

• CHAPTER X

Power Plant Installation—Curtiss OX 2 Engine Mounting and Operat-ing Rules—Standard S. A. E. Engine Bed Dimensions—Hall-ScottEngine Installation and Operation—^Fuel System Rules—IgnitionSystem—Water System—Preparations to Start Engine—Mounting Ra-dial and Rotary Engines—Practical Hints to Lfocate EngineTroubles—All Engine Troubles Summarized—^Location of EngineTroubles Made Easy.

The proper installation of the airplane power plant is more importantthan is generally supposed, as while these engines are usually well bal-anced and run with little vibration, it is necessary that they be securelyanchored and that various connections to the auxiliary parts be

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carefully made in order to prevent breakage from vibration and thatattendant risk of motor stoppage while in the air. The type of motor tobe installed determines the method of installation to be followed. As ageneral rule six-cj^linder vertical engine and eight-cylinder Vee typeare mounted in substantially the same way. The radial,-fixed cylinderforms and the radial, rotary cylinder Gnome and Rhone rotary typesrequire an entirely different method of mounting. Some unconven-tional moimtings have been devised, notably that shown at Fig. 144,which is a six-cylinder German engine that is installed in just the op-posite way to that commonly followed. The inverted cylinder construc-tion is not generally followed because even with pressure feed, drycrank-case type lubricating system there is considerable danger ofover-lubrication and of oil collecting and carbonizing in the combus-tion chamber and gumming up the valve action much quicker thanwould be the case if the engine was operated in the conventional up-right position. The reason for mounting an engine in this way is to ob-tain a lower center of gravity and also to make for

Power ■Plant In8t(dlation

825

more perfect streamlining of the front end of the fuselage in somecases. It is rather doubtful if this slight advantage will compensate forthe disadvantages introduced by this unusual construction. It is notused to any extent now but is presented merely to show one of the pos-sible systems of installing an airplane engine.

In a number of airplanes of the tractor-biplane type the power plantinstallation is not very much different

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Tig. in. —UncoiiTentlonal Monntlng of (Mrmkii Inverted CylliiderUotoi.

than that which is found in automobile practice. The iUustration atFig. 145 is a very clear representation of the method of mounting theCurtiss eight-cylinder 90 H. P. or model 0X2 engine in the fuselage ofthe Curtiss JN4 tractor biplane which is so generally used in the Un-ited States as a training machine. It ^ftill be observed that the fueltank is mounted \mder a cowl directly behind the motor and that itfeeds the carburetor by means of a

flexible fuel pipe. As tlie tank is mounted higher than the carburetor, itwill feed tliat member by gravity. The radiator is mounted at the frontend of the fuselage and connected to the water piping on the motor bythe usual rubber hose connections. An oil pan is placed under the en-gine and the top is covered irith a hood just as in motor car practice.Th& panels of aluminum are attached

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Ftg. 1J5.—How Curtlsa Model OX2 Motor ia loataUed in FnaolAia ofCurtiss Tractor Biplane. Note SlmUarlty of Mounting to AutomoUlePower Plant.

to the sides of the fuselage and are supplied ■with doors ■which o])cnand provide access to the carburetor, oil-gange aii<l other parts of Hiemotor requiring inspection. The complete installation with the powerplant enclosed is given at Pig. 14(J. and in this it will be observed thattlie exhaust pipes are conneirted to discharge members llmt lend Uiegaset= aliove the top plane. In the engine sliown nt Fig. 14") tlie ex-haust flows directly into tlie air nt the i^ider; of llie iiiacliine tliroughshort pipes bolted to the exiiiuist gas outlet ports. The installation ofthe

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Aviation Engines

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radiator just back of the tractor screw insures that adequate coolingwill be obtained because of the rapid air flow due to the propeller slipstream.

IKSTAIilATION OF CUETISS 0X2 ENGINE

The following instructions are given in the Curtiss Instruction Bookfor installing the 0X2 engine and preparing it for flights, and taken inconnection with the very

Fig 117—Front Tl«w of L W F Tractor BipUne Fuselage, ShowingMethod of iDstalllug Thomas Aeromotor and Method of Disposlui; ofExhaust Oases.

clear ilhistration presented no difficulty should be experienced in un-derstanding the proper installation, and mounting of this power plant.The bearers or beds should be 2 inches wide by 3 inches deep, prefer-ably of laminated hard wood, and placed 11% inches apart. Tliey mustbe well braced. The six arms of tlie base of the motor are

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drilled for %-iiicli bolts, and none but this size should be used.

1. Anchoring the Motor. Put the bolts in from the bottom, with a largewasher under the head of each so the head cannot cut into the wood.On every bolt use a castellated nut and a cotter pin, or an ordinary nutand a lock washer, so the bolt will not work loose. Always set motor inplace and fasten before attaching any auxiliary apparatus, such as car-buretor, etc.

2. Inspecting the Ignition-Switch Wires. The wires leading from the ig-nition switch must be properly connected—one end to the motor bodyfor ground, and the other end to the post on the breaker box of themagneto.

3. Filling the Radiator. Be sure that the water from the radiator fillsthe cylinder jackets. Pockets of air may remain in the cylinder jacketseven though the radiator may appear full. Turn the motor over a fewtimes by hand after filling the radiator, and then add more water if theradiator will take it. The air pockets, if allowed to remain, may causeoverheating and develop serious trouble when the motor is running.

4. Filling the Oil Reservoir. Oil is admitted into the crank-case throughthe breather tube at the rear. It is well to strain all oil put into thecrank-case. In filling the oil reservoir be sure to turn the handle on theoil sight-gauge till it is at right angles with the gauge. The oil sight-gauge is on the side of the lower half of the crank-case. Put in about 3gallons of the best obtainable oil, Mobile B recommended. It is im-portant to remember that the very best oil is none too good.

5. Oiling Exposed Moving Parts. Oil all rocker-arm bearings beforeeach flight. A little oil should be applied where the push rods passthrough the stirrup straps.

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6. Filling the Gasoline Tanks. Be certain that all connections in thegasoline system are tight.

7. Turning on the Gasoline. Open the cock leading from the gasolinetank to the carburetor.

8. Charging the Cylinders. With the ignition switch

OFF, prime the motor by squirting a little gasoline in each exliaustport and then turn the propeller backward two revolutions. Neveropen the exhaust valve by operating the rocker-arm by hand, as thepush-rod is liable to come out of its socket in the cam follow^er andbend the rocker-arm w-hen the motor turns over.

9. Starting the Motor by Hand. Always retard the spark part way, toprevent back-firing, by pulling forward the w^ire attached to thebreaker box. Failure to so retard the spark in starting may result inserious injury to the operator. Turn on the ignition switch w-iththrottle partly open; give a quick, strong pull down and outward onthe starting crank or propeller. As soon as the motor is started advancethe spark by releasing the retard ^vire.

10. Oil Circulation. Let the motor run at low^ speed for a few minutesin order to establish oil circulation in

■

all bearings. With all parts fimctioning properly, the throttle may beopened gradually for warming up before flight.

STANDARD S.A.E. ENGINE BED DIMENSIONS

The Society of Automotive Engineers have made efforts to standardizedimensions of bed timbers for supporting powder plant in an

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aeroplane. Owing to the great difference in length no standardizationis thought possible in this regard. The dimensions recommended areas follows:

Distance between timbers 12 in. 14 in. 16 in.

Width of bed timbers 1 % in. 1 % in. 2 in.

Distance between centers of bolts. 13^ in. 15% in. 18 in.

It will be evident that if any standard of this nature w^ere adopted byengine builders that the designers of fuselage could easily arrangetheir bed timbers to conform to those dimensions, whereas it would bedifficult to have them adhere to any standard longitudinal dimensionswhich are much more easily varied in fuselages than the transverse di-mensions are. It, however, should

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be possible to standardize the longitudinal positions of the holdingdown bolts as the engine designer would still be able to allow himselfconsiderable space fore-and-aft of the bolts.

HALL-SCOTT ENGINE INSTALLATION

The very thorough manner in which installation diagrams are pre-pared by the leading engine makers leaves nothing to the imagination.

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The dimensions of the Hall-Scott four-cylinder airplane engine aregiven clearly in

Fig. 149.—Plan and Side EleTatlon of HaU-Scqtt A-7 Fonr-CrllnderAirplane Engine, wltb Initallatlon DlmenstonB.

our inch measurements with the metric equivalents at Figs. 148 and149, the former showing a vertical elevation while the latter has a planview and side elevation. The installation of this engine in airplanes isclearly shoA\Ti at Figs. 150 and 151, the former having the radiator in-stalled at the front of the motor and having all exhaust pipes joined toone common. discharge funnel.

Fig. ISO.

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CENSORED

which deflects the gas over the top plane while tiie latter has the radi-ator placed vertically above the motor at the back end and has a directexhaust gas discharge to the air.

The dimensions of the six-cylinder Hall-Scott motor which is knownas the type A-5 125* H. P. are given at Fig. 152, which is an end sec-tional elevation, and at Fig. 153, wiiich is a plan view. . The dimensionsare given both in inch sizes and the metric equivalents. Theappearance

of a Hall-Scott six-cylinder engine installed in a fuselage is given atFig. 154, whUe a diagram showing the location of the engine and thevarious pipes leading to the auxiliary groups is outlined at Fig. 155.The following instructions for installing the Hall-Scott power plant are

Fig. 151.

CENSORED

iff. 152.

CENSORED

reproduced from the instraction book issued by the maker. Operatinginstructions which are given should enable any good mechanic tomake a proper instaUation and to keep the engine in good runningcondition.

rUEL SYSTEM INSTALIATION

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Gasoline giving the best results with this equipment is as follows:Gravity 58-62 deg. Baume A. Initial boiling point—Richmond meth-od—102° Fahr. Sulphur .014.

Fig. 163.—Plan View of BaU-Scott Type A-6 126 Horae-Fowar AlzpUnaEngine, Showing InatalUtlon Dimensions.

Calorimetric bomb teat 20610 B. T. TJ. per pound. If the gasoline tankis placed in the fuselage below the level of the carburetor, a handpump must be used to maintain air pressure in gas tank to force thegasoline to the carburetor. After starting the engine the small auxiliaryair pump upon tlie engine will maintain sufficient pressure. A-7a andA-5a engines are furnished with a new type auxiliary air pump. Thisshould be frequently oiled and care taken so no grit or sand will enterwhich might lodge between the valve and its seat, which would make itfail to operate properly. An air relief valve is furnished with each en-gine. It should be screwed into tlie gas tank and properly regulated tomaintain the pressure required.

Hall-Scott Engir^ Installation

887

This is done by screwing the ratchet on top either up or down. If twotanks are used in a plane one should be installed in each tank. All airpump lines should be eare-

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Tig. 154.—Three-Quarter View of HaU-ScoU Type A-5 125 Horse-Fower Six-CyUnder Engine, with One of the Side Badiators BemOTedto Show Installatioii in Staodard Foielage.

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fully gone over quite frequently to ascertain if they are tight. Checkvalues have to be placed in these lines. In some cases the gasoline tankis placed above the engine, allowing it to drain by gravity to the car-buretor. When using this system there should be a drop of not lessthan two feet from the lowest portion of the gasoline tank to the upper

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part of the carburetor float chamber. Even this height might not besufficient to maintain the proper volume of gasoline to the carburetorat high speeds. Air pressure is advised upon all tanks to insure theproper supply of gasoline. When using gravity feed without air pres-sure be sure to vent the tank to allow circulation of air. If gravity tankis used and the engine runs satis-factorily at low speeds but cuts out athigh speeds the trouble is undoubtedly due to insufficient height of thetank above the carburetor. The tank should be raised or air pressuresystem used.

IGNITION SWITCHES

Two ** DIXIE ^^ switches are furnished with each engine. Both ofthese should be installed in the pilot's seat, one controlling the R. H.;and the other the L. H. magneto. By shorting either one or the other itcan be quickly determined if both magnetos, with their respectivespark-plugs, are working correctly. Care should be taken not to usespark-plugs having special extensions or long protruding points. Plugsgivihg best results are extremely small with short points.

WATER SYSTEMS

A temperature gauge should be installed in the water pipe, coming dir-ectly from the cylinder nearest the propeller (note illustration above).This instrument in-, stalled in the radiator cap has not alwa^fs givensatisfactory results. This is especially noticeable when the water in theradiator becomes low, not allowing it to touch the bulb on the moto-metor. For ordinary running,

it should not indicate over 150 degrees Fahr. In climbing tests,however, a temperature of 160 degrees Fahr. can be maintainedwithout any ill effects upon the engine. In case the engine becomesoverheated, the indicator will register above 180 degrees Fahr., in

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w^hich case it should be stopped immediately. Overheating is mostgenerally caused by retarded spark, excessive carbon in the cylinders,insufficient lubrication, improperly timed valves, lack of water, clog-ging of water system in any way which would obstruct the free circula-tion of the water.

Overheating will cause the engine to knock, with possible damagingresults. Suction pipes should be made out of thin tubing, and run with-in a quarter or an eighth of an inch of each other, so that when a hoseis placed over the two, it will not be possible to suck together. This isoften the case when a long rubber hose is used, which causes overheat-ing. Eadiators should be flushed out and cleaned thoroughly quite of-ten. A dirty radiator may cause overheating.

"When filling the radiator it is very important to remove the plug ontop of the water pump until water appears. This is to avoid air pocketsbeing formed in the circulating system, which might not only heat upthe engine, but cause considerable damage. All water pump hoses andconnections should be tightly taped and shellacked after the engine isproperly installed in the plane. The greatest care should be taken whenmaking engine installation not to use smaller inside diameter hoseconnection than water pump suction end casting. One inch and aquarter inside diameter should be used on A-7 and A-5 motors, whilenothing less than one inch and a half inside diameter hose or tubingon all A-7a and A-5a engines. It is further important to have light spuntubing, void of any sharp turns, leads from pump to radiator and cylin-der water outlet to radiator. In other words, the w^ater circulationthrough the engine must be as little restricted as possible. Be sure nolight hose is used, that

will often suck together when engine is started. To thoroughly drainthe water from the entire system, open the drain cock at the lowestside of the water pump.

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PREPARATIONS TO START ENGINE

Always replenish gasoline tanks through a strainer which is clean. Thisstrainer must catch all water and other impurities in the gasoline.Pour at least three gallons of fresh oil into the lower crank-case. Oil allrocker arms through oilers upon rocker arm housing caps. Be sure ra-diators are filled within one inch of the top.

After all the parts are oiled, and the tanks filled, the following must belooked after before starting: See if crank-shaft flange is tight on shaft.See if propeller bolts are tight and evenly drawn up. See if propellerbolts are wired. See if propeller is trued up to within %".

Every four days the magnetos should be oiled if the engine is in dailyuse.

Every month all cylinder hold-down nuts should be gone over to ascer-tain if they are tight. (Be sure to re-cotter nuts.)

See if magnetos are bolted on tight and wired.

See if magneto cables are in good condition.

See if rocker arm tappets have a .020" clearance from valve stem whenvalve is seated.

See if tappet clamp screws are tight and cottei'ed.

See if all gasoline, oil, water pipes and connections are in perfectcondition.

Air on gas line should be tested for leaks.

Pump at least three pounds air pressure into gasoline tank.

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After making sure that above rules have been observed, test compres-sion of cylinders by turning propeller.

''do not FORGET TO SHORT BOTH MAGNETOS^'

Be sure all compression release and priming cocks do not leak com-pression. If they do, replace same with a

i

new one immediately, as this might cause premature firing.

Open priming cocks and squirt some gasoline into each.

Close cocks.

Open compression release cocks.

Open throttle slightly.

If using Berling magnetos they should be three-quarters advanced.

If all the foregoing directions have been carefully followed, the engineis ready for starting.

In cranking engine either by starting crank, or propeller, it is essentialto throw it over compression quickly.

Immediately upon starting, close compression release cocks.

When engine is running, advance magnetos.

After it has warmed up, short one magneto and then the other,-to besure both magnetos.anij spark-plugs are firing properly. If there is a

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miss, the fouled plug must be located and cleaned. There is a possibil-ity that the jets in the carburetor are stopped up. If this is the case, donot attempt to clean same with any sharp instrument. If this is done, itmight change the opening in the jets, thus spoiling the adjustment.Jets and nozzles should be blown out with air or steam.

An open intake or exhaust valve, which might have become sluggish orstuck from carbon, might cause trouble. Be sure to remedy this at onceby using a little coal-oil or kerosene on same, working the valve byhand until it becomes free. AVe recommend using grapliite on valvestems mixed with oil to guard against sticking or undue wear.

INSTALLING KOTAKY AND KAOLVL CYLINDER ENGINES

AYhen rotary engines are installed simple steel stamping or **s])iders"ai*e attached to tlie fuselage to hold the fixed craiik-slial't. Inasmuchas the motor projects clear of the fuselage jjroper there is plenty ofroom back of

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o S

Aviation Engine*

the front spider plate to install the auxiliary parts sneh as the oilpump, air pump and ignition magneto and also the fuel and oil con-tainers. The diagram given at Fig. 156 shows how a Gnome "mono-soupape" engine is installed on the anchorage plates and it also out-lines clearly the piping necessary to convey the oil and fuel and alsothe air-piping needed to put pressure on botli fuel and oil tanks to in-sure positive supply of these liquids which

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may be carried in tanks placed lower than the motor in some installa-tions. The diagram given at Figs. 157 and 158 shows other mountingsof Gnome engines and are self-explanatory. The simple mounting pos-sible "when the Anzani ton-cylinder radial fixed type engine is usedgiven at Fig. 159. The front end of tlie fuselage is provided with a sub-stantial pressed steel plate having members projecting from it whichmay be bolted to the longerons. The bolts that hold the two halves ofthe crank-case together project through the steel plate and hold theengine seciirely to tlie front end of the fuselage.

PRACTICAL HINTS TO LOCATE ENGINE TROUBLES

One who is not thoroughly familiar with engine construction will sel-dom locate troubles by haphazard experimenting and it is only by asystematic search that the cause can be discovered and the defectseliminated. In this chapter the writer proposes to outline some of themost common power-plant troubles and to give sufficient

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Fig. 169.—How Gnome Botary Motoc May Be AUscbed to AirpUne Fu-selage HembeTS.

advice to enable those who are not thoroughly informed to locate themby a logical process of elimination. .The internal-combustion motor,which is the power plant of all gasoline automobiles as well as air-planes, is composed of a number of distinct groups, which in turn in-clude distinct components. These various appliances are so closely re-lated to each other that defective action of any one may interrupt theoperation of the entire power plant. Some of the auxiliary groups aremore necessary than others and the power plant will continue to oper-ate for a time even after the failure of some important parts of some ofthe auxiliary groups. The gasoline engine in itself is

Aviation Engines

a complete mechamsm, but it is evident that it caimot deliver anypower without some means of supplying gas to the cylinders and ignit-ing the compressed gas charge after it has been compressed in the cyl-inders. From this

^ Fixed Cylinder I Radial Engine

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Eng ne ) Support ng ' Plate

Fig. 159 —How Anzani Ten Cylinder Badlal Engine Is Installed to PlateSecurely Attached to Front End of Tractor Airplane rnselage.

it is patent that the ignition and carburetion systems are just as essen-tial parts of the power plant as the piston, connecting rod, or cylinderof the motor. The failure of either the carburetor or igniting means tofunction properly vdW be inunediately apparent by faulty action of thepower plant.

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To insure that the motor will continue to operate it is necessary tokeep it from overheating by some form of cooling system and to supplyoil to the moving parts to reduce friction. The cooling and lubricationgroups are not so important as carburetion and ignition, as the enginewould run for a limited period of time even should the cooling systemfail or the oil supply cease. It would only be a few moments, however,before the engine would overheat if the cooling system was at fault,and the parts seize if the lubricating system should fail. Any derange-ment in the carburetor or ignition mechanism would manifest itself atonce because the engine operation would be affected, but a defect inthe cooling or oiling system would not be noticed so readily.

The careful aviator will always inspect the motor mechanism beforestarting on a trip of any consequence, and if inspection is carefully car-ried* out and loose parts tightened it is seldom that irregular opera-tion will be found due to actual breakage of any of the components ofthe mechanism. Deterioration due to natural causes matures slowly,and sufficient warning is always given w^hen parts begin to wear sosatisfactory repairs may be promptly made before serious derange-ment or failure is manifested.

A TYPICAL ENGINE STOPPAGE ANALYZED

Before describing the points that may fail in the various auxiliary sys-tems it will be well to assume a typical case of engine failure and showthe process of locating the trouble in a systematic manner by indicat-ing the various steps whicli are in logical order and which could

Aviation Engines

reasonably be followed. In any case of engine failure the ignition sys-tem, motor compression, and carburetor should be tested first. If theignition system is functioning properly one should determine the

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amount of compression in all cylinders and if this is satisfactory thecarbureting group should be tested. If the ignition system is workingproperly and there is a decided resistance in the cylinders

Tig. 160.—Slda Elevation of Tbomas 135 Horso-Power AlrplanaSngiiM, Oirlng ImpoTtaot Dlmetulons.

when the propeller is turned, proving that there is good compression,one may suspect the carburetor.

If the carburetor appears to be in good condition, the trouble may becaused by the ignition being out of time, which condition is possiblewhen the magneto timing gear or coupling is attached to the armatureshaft by a taper and nut retention instead of the more positive key ortaper-pin fastening. It is possible that the inlet manifold may bebroken or perforated, that the exhaust valve is stuck on its seat be-cause of a broken or bent stem, broken or loose cam, or failure of thecam-shaft drive because the teeth are stripped from the engine shaftor cam-shaft

gears; or because the key or other fastening on either gear has failed,allowing that member to turn independently of the shaft to which it

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normally is attached. The gasoline feed pipe may -be clogged orbroken, the fuel

—Front EleTatlon of Tbomu-Mcme 135 Hontt-Fower Aetomotor,SbowlDg Main Dlmenaloni.

supply may be depleted, or the shut-off cock in the gasoline line mayhave jarred closed. The gasoline filter may be filled witli dirt or waterwhich prevents passage of the fuel.

The defects outlined above, except the failure of the

gasoline supply, are very rare, and if the container is found to containfuel and the pipe line to be clear to the carburetor, it is safe to assumethe vaporizing device* is at fault. If fuel continually runs out of themixing chamber the carburetor is said to be flooded. This conditionresults from failure of the shut-off needle to seat properly or from apunctured hollow metal float or a gasoline-soaked cork float. It is

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possible that not enough gasoline is present in the float chamber. Ifthe passage controlled by the float-needle valve is clogged or if thefloat was badly out of adjustment, this contingency would be probable.When the carburetor is examined, if the gasoline level appears to be atthe proper height, one may suspect that a particle of lint, or dust, orfine scale, or rust from the gasoline tank has clogged the bore of the jetin tlie mixing chamber.

If the ignition system and carburetor appear to be in good working or-der, and the hand crank shows that there is no compression in one ormore of the cylinders, it means some defect in the valve system. If theengine is a multiple-cylinder t}T)e and one finds poor compression inall of the cylinders it may be due to the rare defect of improper valvetiming. This may be caused by a gear having altered its position on thecam-shaft or crankshaft, because of a sheared key or pin lia\dng per-mitted the gear to turn about half of a revolution and then havingcaught and held the gear in place by a broken or jagged end so thatcam-shaft would turn, but the valves open at the wrong time. If butone of the cylinders is at fault and the rest appear to have good com-pression the trouble may be due to a defective condition either in-sideor outside of that cylinder. The external parts may be inspected easily,so the following should be looked for: a broken valve, a Avarpod valve-head, broken valve-springs, sticking or bent valve-stems, dirt undervalve-seat, leak at valve-chaniher cap or spark-plug gasket. Defectivepriming cock, cracked cylinder head (rarely occurs), leak throughcracked spark - plug insulation, valve - plunger

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stuck in the guide, lack of clearance between valve-stem end and top ofplunger caused by loose adjusting screw which has worked up andkept the valve from seating. The faulty compression may^be due todefects inside the motor. The piston-head may be cracked (rarely oc-curs), piston rings may be broken, the slots in the piston rings may be

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in line, the rings may have lost their elasticity or have becomegummed in the groves of the piston, or the piston and cylinder wallsmay be badly scored by a loose wrist pin or by defective lubrication. Ifthe motor is a type with a separate head it is possible the gasket orpacking between the cylinder and combustion chamber may leak,either admitting water to the cylinder or allowing compression toescape.

CONDITIONS THAT CAUSE FAILUKE OF IGNITION SYSTEM

If the first test of the motor had showed that the compression was as itshould be and that there were no serious mechanical defects and therewas plenty of gasoline at the carburetor, this would have' demon-strated that the ignition system was not functioning properly. If a bat-tery is employed to supply current the first step is to take the spark-plugs out of the cylinders and test the system by turning over the en-gine by hand. If there is no spark in any of the plugs, this may be con-sidered a positive indication that there is a broken main current leadfrom the battery, a defective ground connection, a loose battery ter-minal, or a broken connector. If none of these conditions are present,it is safe to say that the battery is no longer capable of delivering cur-rent. TMiile magneto ignition is generally used on airplane engines,there is apt to be some development of battery ignition, especially onengines equipped with electric self-starters which are now being ex-perimented with. The spark-plugs may be short circuited by crac]a?dinsulation or carbon and oil deposits around the electrode. The sec-ondary wires may be broken or have defective insulation whichpermits

the current to ground to some metal part of the fuselage or motor. Theelectrodes of the spark-plug may be too far apart to permit a spark toovercome the resistance of the compressed gas, even if a spark jumpsthe air space, when the plug is laid on the cylinder.

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If magnetos are fitted as is usually the case at present and a spark isobtained between the points of the plug and that device or the wireleading to it from the magneto is in proper condition, the trouble isprobably caused by the magneto being out of time. This may result ifthe driving gear is loose on the armature-shaft or crankshaft, and is arare occurrence. If no spark is produced at the plugs the secondarywire may be broken, the ground wire may make contact with somemetallic portion of the chassis before it reaches the switch, the carboncollecting brushes may be broken or not making contact, the contactpoints of the make-and-break device may be out of adjustment, thewiring may be attached to wrong terminals, the distributor filled withmetallic particles, carbon, dust or oil accumulations, the distributorcontacts may not be making proper connection because of wear andthere may be a more serious derangement, such as a burned out sec-ondary winding or a punctured condenser.

If the motor runs intermittently, i.e., starts and runs only a few revolu-tions, aside from the conditions previously outlined, defective opera-tion may be due to seizing between parts because of insufficient oil ordeficient cooling, too much oil in the crank-case which fouls the cylin-der after the crank-shaft has revolved a few turns, and derangementsin the ignitioh or carburetion systems that may be easily remedied.There are a number of defective conditions which may exist in the ig-nition group, that will result in ** skipping ^^ or irregular operationand the foUoAving points should be considered first: weak source ofcurrent due to worn out dry cells or discharged storage batteries; weakmagnets in magneto, or defective contacts at magneto; dirt in magnetodistributor or poor contact at collecting brushes. Dirty or crackedinsulator

at spark-plug will cause short circuit and can only be detected by care-ful examination. The following points should also be checked overwhen the plug is inspected: Excessive space betwen electrodes, points

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too close together, loose central electrodes, or loose point on plugbody, soot or oil particles between electrodes, or on the surface, of theinsulator, cracked insulator, oil or water on outside of insulator. Shortcircuits in the condenser or internal wiring of induction coils or mag-netos, which are fortunately not common, can seldom be remedied ex-cept at the factory where these devices were made. If an engine stopssuddenly and the defect is in the ignition system the trouble is usuallynever more serious than a broken or loose wire. This may be easily loc-ated by inspecting the wiring at the terminals. Irregular operation ormisfiring is harder to locate because the trouble can only be foundafter the many possible defective conditions have been checked over,one by one.

COMMON DEFECTS IN FUEL SYSTEMS

Defective carburetion often causes misfiring or irregular operation.Tlie common derangement of the components of the fuel system thatare common enough to warrant suspicion and the best methods fortheir location follows: First, disconnect the feed pipe from the carbur-etor and see if the gasoline flows freely from the tank. If the streamcoming out of the pipe is not the full size of the orifice it is an indica-tion that the pipe is clogged with dirt or that there is an accumulationof rust, scale, or lint in the strainer screens of the filter. It is also pos-si])le that the fuel shut-off valve may be wholly or partly closed. If thegasoline flows l)y gravity the liquid may he air l)()uiid in the tank,while if a pressure-feed system is utilized tli(^ tank may leak so that itdoes not retain pressure; the check valve retaining the pressure mayhe. ch^feetive or the pipe conveying the air or gas under i)ressure tothe tank may be clogged.

If the gasoline flows from the pipe in a steady stream :he carburetordemands examination. There may be dirt )r water in the float cham-ber, which will constrict the passage between the float chamber and

371/821

the spray nozzle, 3r a particle of foreign matter may have entered thelozzle and stopped up the fine holes therein. The float :nay bind on itsguide, the needle valve regulating the jasolLne-inlet opening in bowlmay stick to its seat. Any 3f the conditions mentioned would cut downthe gasoline supply and the engine would not receive sufficient quant-ities of gas. The air-valve spring may be weak or the stir valve broken.The gasoline-adjusting needle may be loose and jar out of adjustment,or the air-valve spring-adjusting nuts may be such a poor fit on thestem that adjustments will not be retained. These instructions applyonly to carburetors having air valves and mixture regulating meanswhich are used only in rare instances in airplane work. Air may leak inthrough the manifold, iue to a porous casting, or leaky joints in a builtup form and dilute the mixture. The air-intake dust screen may be soclogged with dirt and lint that not enough air will pass through themesh. Water or sediment in the gasoline ^ill cause misfiring becausethe fuel feed varies when the w^ater or dirt constricts the standpipebore.

It is possible that the carburetor may be out of adjustment. If clouds ofblack smoke are emitted at the exhaust pipe it is positive indicationthat too much gasoline is being supplied the mixture and the supplyshould be cut do\\Ti by screwing in the needle valve on types wherethis method of regulation is provided, and by making sure that the fuellevel is at the proper height, or that the proper nozzle is used in thoseforms where the spray nozzle has no means of adjustment. If the mix-ture contains too much air there will be a pronounced popping back inthe carburetor. This may be overcome by screwing in the air-valve ad-justment so the spring tension is increased or by slightly opening upthe gasoline-supply regulation needle. AMien a carburetor is properlyad-

372/821

justed and the mixture delivered the cylinder burns properly, the ex-haust gas will be clean and free from the objectionable odor presentwhen gasoline is burned in excess.

The character of combustion may be judged by the color of the flamewhich issues from it when the engine is running with an open throttleafter nightfall. If the flame is red, it indicates too much gasoline. If yel-lowish, it shows an excess of air, while a properly proportioned mix-ture will be evidenced by a pronounced blue flame, such as given by agas-stove burner.

The Duplex Model 0. D. Zenith carburetor used upon most of the six-and eight-cylinder airplane engines consists of a single float chamber,and a single air intake, joined to two separate and distinct spraynozzles, venturi and idling adjustments. It is to be noted that as thecarburetor barrels are arranged side by side, both valves are mountedon the same shaft, and work in unison through a single operatinglever. It is not necessary to alter their position. In order to make theengine idle well, it is essential that the ignition, especially the spark-plugs, should be in good condition. The gaskets between carburetorand manifold, and between manifold and cylinders should beabsolutely air-tight. The adjustment for low speed on the carburetor ismade by turning in or out the two knurled screws, placed one on eachside of the float chamber. After starting the engine and allowing it tobecome thoroughly warmed, one side of the carburetor should be ad-justed so that the three cylinders it affects fire properly at low speed.The other side should be adjusted in the same manner until all six cyl-inders fire perfectly at low speed. As the adjustment is changed on theknurled screw a difference in the idling of the engine should be no-ticed. If the engine begins to run evenly or speeds up it shows that themixture becomes right in its proportion.

373/821

Be sure the butterfly throttle is closed as far as possible by screwingout the stop screw which regulates the

closed position for idling. Care should be taken to have the butterflyheld firmly against this stop screw at all times while idling engine. Ifthree cylinders seem to run irregularly after changing the position ofthe butterfly, still another adjustment may have to be made with theknurled screw. Unscrewing this makes the mixture leaner. Screwing incloses off some of the air supply to the idling jet, making it richer.After one side has been made to idle satisfactorily repeat the same pro-cedure with the opposite three cylinders. In other words, each sideshould be idled independently to about the same speed. Rememberthat the main jet and compensating jet have no appreciable effect onthe idling of the engine. The idling mixture is drawn directly throughthe opening determined by the knurled screw and enters the carbur-etor barrel through the small hole at the edge of each butterfly. This iscalled the priming hole and is only effective during idling. Beyond thatpoint the suction is transferred to the main jet and compensator,which controls the power of the engine beyond the idling position ofthe throttle.

DEFECTS IN OILING SYSTEMS

While troubles existing in the ignition or carburetion groups are usu-ally denoted by imperfect operation of the motor, such as lost power,and' misfiring, derangements of the lubrication or cooling systems areusually evident by overheating, diminution in engine capacity, or noisyoperation. Overheating may be caused by poor carburetion as much asby deficient cooling or insufficient oiling. When the oiling group is notfunctioning as it should the friction between the motor parts producesheat. If the cooling system is in proper condition, as will be evidencedby the condition of the water in the radiator, and the carburetion

374/821

group appears to be in good condition, the overheating is probablycaused by some defect in the oiling system.

The conditions that most commonly result in poor

lubficati(^n are: Insufficient oil in the engine crank-case or sump,broken or clogged oil pipes, screen at filter filled with lint or dirt,broken oil pump, or defective oil-pump drive. The supply of oil may bereduced by a defective inlet or discharge-check valve at the mechanicaloiler or worn pumps. A clogged oil passage or pipe leading to an im-portant bearing point will cause trouble because the oil cannot getbetween the working surfaces. It is well to remember that much of thetrouble caused by defective oiling may be prevented by using only thebest grades of lubricant, and even if all parts of the oil system areworking properly, oils of poor quality will cause friction andoverheating.

DEFECTS IN COOLING SYSTEMS OUTLINED

Cooling systems are very simple and are not liable to give trouble as arule if the radiator is kept full of clean w^ater and the circulation isnot impeded. When overheating is due to defective cooling the mostcommon troubles are those that impede water circulation. If the radi-ator is clogged or the piping of water jackets filled with rust or sedi-ment the speed of water circulation will be slow, which will also be thecase if the water pump or its driving means fail. Any scale or sedimentin the water jackets or in the piping or radiator passages will reducethe heat conductivity of the metal exposed to the air, and the waterwill not be cooled as quickly as though the scale was not present.

The rubber hose often used in making the flexible connections deman-ded between the radiator and water manifolds of the engine may de-teriorate inside and particles of rubber hang down that will reduce the

375/821

area of the passage. Tlie grease from the grease cups mounted on thepimip-shaft bearing to lubricate that member often finds its way intothe water system and rots the inner walls of the rubber liose, this res-ulting in strips of the partly decomposed rubber lining hanging downand re-

stricting the passage. The cooling system is prone ^ to overheat afterantifreezing solutions of which calcinm chloride forms a part havebeen used. This is due to the formation of crystals of salt in the radiat-or passages or water jackets, and these crystals can only be dissolvedby suitable chemical means, or removed by scraping when the con-struction permits.

Overheating is often caused by some condition in the fuel system thatproduces too rich or too. lean mixture. Excess gasoline may be sup-plied if any of the following conditions are present: Bore of spraynozzle ol* stand-pipe too large, auxiliary air-valve spring too tight,gasoline level too high, loose regtdating valve, fuel-soaked* cork float,punctured sheet-metal float, dirt under float control shut-off valve orinsufficient air supply because of a clogged air screen. If pressure feedis utilized there may be too much pressure in the tank, or the floatcontrolled mechanism operating the shut-off in the float bowl of thecarburetor may not act quickly enough.

SOME CAUSES OF NOISY OPERATION

There are a number of power-plant derangements which give positiveindication because of noisy operation. Any knocking or rattling soundsare usually produced by w^ear in connecting rods or main bearings ofthe engine, though sometimes a sharp metallic knock, which is verymuch the same as that produced by a loose bearing, is due to carbondeposits in the cylinder heads, or premature ignition due to advancedspark-time lever. Squeaking sounds invariably indicate dry bearings,

376/821

and whenever such a sound is heard it should be immediately locatedand oil applied to the parts thus denoting their dry condition. Wliist-ling or blowing sounds ai-e produced by leaks, either in the engine it-self or in the gas manifolds. A sharp whistle denotes the escape of gasunder pressure and is usually caused by a defective packing or gasketthat seals a portion of the combustion chanil)er or that is

used for a joint as the exhaust manifold. A blowing sound indicates aleaky packing in crank-case. Grinding noises in the motor are usuallycaused by the timing gears and will obtain if these gears are dry or ifthey have become worn. Whenever a loud knocking sound is heardcareful inspection should be made to locate the cause of the trouble.Much harm may be done in a few minutes if the engine is run withloose connecting rod or bearings that would be. prevented by takingup the wear or looseness between the parts by some means ofadjustment.

BRIEF SUMMARY OF HINTS FOR STARTING ENGINE

First make sure that all cylinders have compression. »To ascertainthis, open pet cocks of all cylinders except the one to be tested, crankover motor and see that a strong opposition to cranking is met withonce in two revolutions. If motor has no pet cocks, crank and noticethat oppositions are met at equal distances, two to every revolution ofthe starting crank in a four-cylinder motor. If compression is lacking,examine the parts of the cylinder or cylinders at fault in the followingorder, trying to start the motor whenever any one fault is found andremedied. See that the valve push rods or rocker arms do not touchvalve stems for more than approximately % revolution in every 2 re-volutions, and that there is not more than .010 to .020 inch clearancebetween them depending on the make of the motor. Make sure thatthe exhaust valve seats. To determine this examine the spring and seethat it is connected to the valve stem properly. Take out valve and see

377/821

that there is no obstruction, such as carbon, on its seat. See that valveworks freely in its guide. Examine inlet valve in same manner. Listenfor hissing sound while cranking motor for leaks at other places.

Make sure that a spark occurs in each cylinder as follows: If magnetoor magneto and battery with non-vibrating coil is used: Disconnectwire from spark-plug,

•

hold end about % inch from cylinder or terminal of sparkplug. Havemotor cranked briskly and see if spark occurs. Examine adjustment ofinterrupter points. See that wires are placed correctly and not shortcircuited. Take out spark-plug and lay it on the cylinder, being carefulthat base of plug only touches the cylinder and that ignition wire isconnected. Have motor cranked briskly and see if spark occurs. Checktiming of magneto and see that all brushes are making contact.

See if there is gasoline in the carburetor. See that there is gasoline inthe tank. Examine valve at tank. Prime carburetor and see that spraynozzle passage is clear. Be sure throttle is open. Prime cylinders byputting about a teaspoonful of gasoline in through pet cock or spark-plug opening. Adjust carburetor if necessary,

LOCATION OF ENGINE TROUBLES MADE EASY

The following tabulation has been prepared and originated by thewriter to outline in a simple manner the various troubles and derange-ments that interfere with efficient internal-combustion engine action.The parts and their functions are practically the same in all gas or gas-oline engines of the four-cycle type, and the general instructions givenapply just as well to all hydro-carbon engines, even if the parts differin form materially. The essential components are clearly indicated inthe manv part sectional drawings in this book so they may be easily

378/821

recognized. The various defects that may materialize are tabulated in amaimer that makes for ready reference, and the various defective con-ditions are found opposite the part affected, and under a heading thatdenotes the main trouble to which the others are con-•tributingcauses. The various symptoms denoting the individual troubles out-lined are.given to facilitate their recognition in a positive manner.

Brief note is also made of the remedies for the restora- . tion of the de-fective part or condition. It is apparent

that a table of this character is intended merely as a guide, and it is acompilation of practically all the known troubles that may materializein gas-engine operation. While most of the defects outlined are com-mon enough to warrant suspicion, they will never exist in an engine allat the same time, and it will be necessary to make a systematic searchfor such of those as exist.

To use the list advantageously, it is necessary to know one maintrouble easily recognized. For example, if the power plant is noisy,look for the possible troubles under the head of Noisy Operation; if itlacks capacity, the derangement will undoubtedly be found imder thehead of Lost Power. It is assumed in all cas.es that the trouble exists inthe power plant or its components, and not in the auxiliary membersof the ignition, carburetion, lubrication, or cooling systems. Thenovice and student will readily recognize the parts of the average avi-ation engine by referring to the very complete and clearly lettered il-lustrations of mechanism given in many parts of this treatise.

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434/821

Igmtion System Troubles

869

Ignition System Troubles Only

Motor Will Not Start or Starts Hard

Loose Battery Terminal.

Magneto Ground Wire Shorted.

Magneto Defective (No Spark at Plugs).

Broken Spark Plug Insulation.

Carbon Deposits or Oil Between Plug Points.

Spark-Plug Points Too Near Together or Far Apart.

Wrong Cables to Plugs.

Short Circuited Secondary Cable.

Broken Secondary Cable.

Dry Battery Weak. Storage Battery Discharged. Poor Contact at Timer.Timer Points Dirty.

Battery Systems Only.

Poor Contact at Switch. Primary Wires Broken, or Short Circuited.Battery Grounded in Metal Container. Battery Connectprs Broken orLoose. Timer Points Out of Adjustment. Defects in Induction Coil.

435/821

Battery and Coil Ignition System Only.

Ignition Timing Wrong, Spark Too Late or Too Early.

Defective Platinum Points in Breaker Box (Magneto).

Points Not Separating.

Broken Contact Maker Spring.

No Contact at Secondary Collector Brush.

Platinum Contact Points Burnt or Pitted.

Contact Breaker Bell Crank Stuck.

•

Fiber Bushing in Bell Crank Swollen.

Short Circuiting Spring Always in Contact.

Dirt or Water in Magneto Casing.

Oil in Contact Breaker.

Oil Soaked Brush and Collector Ring.

Distributor Filled with Carbon Particles.

Motor Stops Without Warning

Broken Magneto Carbon Bmsh.

436/821

Broken Lead Wire.

Broken Ground Wire.

Battery Ignition Systems.

"Water on High Tension Magneto Terminal.

Main Secondary Cable Burnt Through by Hot Exhaust Pipe (Trans-former Coil, Magneto Systems).

Particle of Carbon Between Spark Plug Points.

Magneto Short Circuited by Ground Wire.

Magneto Out of Time, Due to Slipping Drive.

Water or Oil in Safety Spark Gap (Multi-cylinder Magneto).

Magneto Contact Breaker or Timer Stuck in Retard Position.

Worn Fiber Block in Magneto Contact Breaker.

Binding Fiber Bushing in Contact Breaker Bell Crank.

Spark Advance Rod or Wire Broken.

Contact Breaker Parts Stuck.

Motor Runs Irregularly or Misfires

Loose Wiring or Terminals.

Broken Spark-Plug Insulator.

437/821

Spark-Plug Points Sooted or Oily.

Wrong Spark Gap at Plug Points.

Leaking Secondary Cable.

Prematurely Grounded Primary Wire.

Batteries Running Down (Battery Ignition only).

Poor Adjustment of Contact Points at Timer.

Wire Broken Inside of Insulation.

Loose Platinum Points in Magneto.

Weak Contact Spring.

Broken Collector Brush.

Dirt in Magneto Distributor Casing or Contact Breaker.

Worn Fiber Block or Cam Plate in Magneto.

Ignition System Troubles

871

Worn Cam or Contact Roll in Timer (Battery System

only). Dirty Oil in Timer. Sticking Coil Vibrators. Coil Vibrator PointsPitted. Oil Soaked Magneto Winding. Punctured Magneto or CoilWiriding. Distributor Contact Segments Rough. Sulphated Storage

438/821

Battery Terminals. Weak Magnets in Magneto. Poor Contact at Mag-neto Contact Breaker Points.

DEFECTS IN ELECTBICAIi SYSTEM COMPONENTS

•

To further simplify the location of electrical system faults it is thoughtdesirable to outline the defects that can be present in the various partsof the individual devices comprising the ignition system. If an airplaneengine is provided with magneto ignition solely, as most engines are atthe present time, no attention need be paid to such items as storage ordry batteries, timer or induction coil. There seems to be some develop-ment in the direction of battery ignition so it has been considered de-sirable to include components of these systems as well as the almostuniversally used magneto group. Sparkplugs, wiring and switches areneeded with either system.

Axdation Engines

MAGNETO

DEFECT

Dirty oil in distributor. Metal dust in distributor. Brushes not makingcontact. Distributor segment? worn.

Collectinpr brush broken.

Distributing brush broken.

Oil soaked winding.

Magnets loose on pole pieces.

439/821

Armature rubs.

Bearings worn.

Magnets weak.

Contact breaker points pitted.

Breaker points out of adjustment

Defective winding (rare).

Punctured condenser (rare).

Driving gear loose.

Magneto armature out of time.

Magneto loose on base.

Contact breaker cam worn.

Fibre shoe or rolls worn (Bosch).

Fibre bushing binding in contact lever (Bosch).

Contact lever return spring broken.

Contact lever return spring weak.

Ground wire grounded.

Ground wire broken.

440/821

Safety spark gap dirty.

FuBed metal in spark gap.

Safety spark gap points too close.

Loose distributor terminals.

Contact breaker sticks.

TBOUBLE CAUSED

Engine misfires. Engine misfires. Current canilot pass. Enginemisfires.

Engine misfires. Engine misfires. Engine misfires. Engine misfires.Ensine misfires^ Noisy.

Weak spark. Engine misfires. Engine misfires.

No spark.

Weak or no spark.

Noise.

Spark will not fire charge.

Misfiring and noisy.

Misfiring.

Misfiring.

441/821

Misfiring.

No spark.

Misfiring.

No spark.

Engine will not stop.

No spark.

No spark.

Misfiring.

Misfiring.

No spark control.

Magneto switch &hort-circuited. No spark. Magneto switch open cir-cuit. No engine stop.

BEMEDY

Clean. Clean.

Strensrthen spring. Secure even bearing. New brush. New brush.Clean.

lighten screws. Repair bearings. Eeplace. Recharge. Clean. Reset.

Replace.

442/821

Replace.

Tighten.

Retime.

Tighten.

Replace.

Replace.

Ream alightly.

Replace.

Replace.

Insulate. Connect up. Clean. Remove. Set properly.

Tighten.

Remove and clean

bearings. Insulate. Restore contact.

STORAGE BATTERY

DEFECT

Electrolyte low.

Loose terminals. Sulphated terminals.

443/821

Battery discharged. Electrolvte weak.

Plates sulphated. Sediment or mud in bottom. Active material loose ingrids.

TROUBLE CAUSED

Weak current.

Misfiring. Misfiring.

Misfiring or no spark. Weak current.

Poor capacity. Weak current. Poor capacity.

BEMEDY

Replenish with distilled water.

Tighten.

Clean thoroughly and coat with vaseline.

New charge.

Bring to proper specific gravity.

Special slow charge.

Clean out.

New plates.

Ignition System Troubles

444/821

878

STORAGE BATTERY—Conanued

DEFECT

Moisture or acid on top of

cells. Plugged vent cap. Cracked vent cap. Cracked cell jar.

TROrnLE CAUSED

Shorts terminals.

Buckles cell jars. Acid spills out. Electrolyte runs out.

BEMEDT

Remove.

Make vent hole. New cap. New jar.

DEFECT

DRY CELL BATTERY

TROUBLE CAUSED

Broken wires. No current.

Loose terminals. Misfiring.

Weak cell (7 amperes or less). Misfiring.

445/821

Cells in contact. Short circuit.

Water in battery box.

Short circuit.

REMEDY

New wires. Tighten. New cells. Separate and insulate. Dry out.

DEFECT

Contact segments worn or

pitted. Platinum points pitted.

Dirty oil or metal dust in

interior. Worn bearing. Loose terminals. Worn revolving contactbrush. Out of time.

TIMER

TROUBLE CAUSED

Misfiring.

Misfiring.

Misfiring.

Misfiring. Misfiring. Misfiring. Irregular spark.

REMEDY

446/821

Grind down smootli.

Smooth with oil

stone. Clean out.

Replace. Tighten. Replace. Reset.

DEFECT

INDUCTION COIL

TBOUBLE CAUSED

Loose terminals. Broken connections. Vibrators out of adjustment.Vibrator points pitted. Defective condenser \ Defective winding ) Poorcontact at switch. Broken internal wiring. Poor coil unit.

Misfiring. No spark. Misfiring. Misfiring.

No spark.

Misfiring. No spark. One cylinder affected.

BEMEDY

Tighten.

Make new joints.

Readjust.

Clean.

447/821

Send to maker for

repairs. Tighten. Replace. Replace.

DEFECT

WIRING

TROUBLE CAUSED

REMEDY

Loose terminals anywhere. Misfiring. Tighten.

Broken plug wire. One cylinder will not fire. Replace.

Broken timer wire. One coil will not buzz. Replace.

Broken main battery wire. ) ^^ ,

Broken battery ground wire, j ^

Broken mapneto ground wire. Engine will not stop.

Chafed insulation anywhere. \ t^tjoC-j „

Short circuit anywhere. j " ^'

Replace. Replace. Insulate.

Carburetion System Faults Summarized

Motor Starts Hard or Will Not Start

448/821

•

No Gasoline in Tank.

No Gasoline in Carburetor Float Chamber.

Tank Shut-Oflf Closed.

Clogged Filter Screen.

Fuel Supply Pipe Clogged.

Gasoline Level Too Low.

Gasoline Level Too High (Flooding).

Bent or Stuck Float Lever.

Loose or Defective Inlet Manifold.

Not Enough Gasoline at Jet.

Cylinders Flooded with Gas.

J^uel Soaked Cork Float (Causes Flooding).

"Water in Carburetor Spray Nozzle.

Dirt in Float Chamber.

Gas Mixture Too Lean.

Carburetor Frozen (Winter Only).

449/821

Motor Stops In Flight

Gasoline Shut-Off Valve Jarred Closed.

Gasoline Supply Pipe Clogged.

No Gasoline in Tank.

Spray Nozzle Stopped Up.

Water in Spray Nozzle.

Particles of Carbon Between Spark-Plug Points.

Magneto Short Circuited by Ground in Wire.

Air Lock in Gasoline Pipe.

Broken Air Line or Leaky Tank (Pressure Feed Svstem

Only). Fuel Supply Pipe Partially Clogged. Air Vent in Tank Filler CapStopped Up (Gravity and

Vacuum Feed System). Float Needle Valve Stuck. Water or Dirt inSpray Nozzle. Mixture Adjusting Needle Jarred Loose (Rotary Motors

Only).

Motor Races, Will Not Throttle Down

Air Leak in Inlet Piping.

Air Leak Through Inlet Valve Guides.

450/821

Control Rods Broken.

Defective Induction Pipe Joints.

Leaky Carburetor Flange Packing.

Throttle Not Closing.

Poor Slow Speed Adjustment (Zenith Carburetor).

Motor Misfires

Carburetor Float Chamber Getting Dry.

Water or Dirt in Gasoline.

Poor Gasoline Adjustment (Rotary Motors).

Not Enough. Gasoline in Float Chamber.

Too Much Gasoline, Carburetor Flooding.

Incorrect Jet or Choke (Zenith Carburetor).

Broken Cylinder Head Packing Between Cylinders.

#

Noisy Operation

Popping or Blowing Back in Carburetor.

Incorrectly Timed Inlet Valves.

451/821

Inlet Valve Not Seating.

Defective Inlet Valve Spring.

Dirt Under Inlet Valve Seat.

Not Enough Gasoline (Open Needle Valve).

Muffler or Manifold Explosions.

Mixture Not Exploding Regularly.

Exhaust Valve Sticking.

Dirt Under Exhaust Valve Seat.

CHAPTER XI

Tools for Adjusting and Erecting—Forms of Wrenches—Use and Careof Files—Split Pin Removal and Installation—Complete ChiselSet—Drilling Machines—Drills, Reamers, Taps and Dies—^MeasuringTools—Micrometer Calipers and Their Use— Tyipical Tool Outfit-s-—Special Hall-Scott Tools—Overhauling Airplane Engines —^Tak-ing Engine Down—Defects in Cylinders—Carbon Deposits, Cause andPrevention—^Use of Carbon Scrapers—Burning Out Carbon with Oxy-gen—Repairing Scored Cylinders—^Valve Removal and Inspec-tion—Reseating and Truing Valves—^Valve Grinding Processes—De-preciation in Valve Operating Ssrstem— Piston Troubles—Piston RingManipulation—^Fitting Piston Rings —^Wrist-Pin Wear—Inspectionand Refitting of Engine Bearings —Scraping Brasses to Fit—^FittingConnecting Rods—^Testing for Bearing Parallelism—Cam-Shafts andTiming Gears—^Precautions in Reassembling Parts.

TOOLS FOR ADJUSTING AND ERECTING

452/821

A very complete outfit of small tools, some of which are furnished aspart of the tool equipment of various engines are sho\\Ti in group atFig. 163. This group includes all of the tools necessary to complete avery practical kit and it is not unusual for the mechanic who is con-tinually dismantling and erecting engines to possess even a larger as-sortment than indicated. The small bench vise provided is a usefulauxiliary that can be clamped to any convenient bench or table or evenfuselage longeron in an emergency and should have jaws at least threeinches wide and capable of opening four or five inches. It is especiallyuseful in that it mil save trips to the bench vises, as it has adequate ca-pacity to handle practically any of the small parts that need to beworked on when making repairs. A blow torch, tinner's snips and sol-dering copper are very useful in sheet metal work and in making anyrepairs requiring the use of solder. The torch can be used in any opera-tion requiring a source of

Adjuitabte EndWrervch

453/821

, III '^°1T°°' End Wr.ncr

Sm'all SoeketWteneh Socket

Stillson Pipe Wrench V^

Adjuiloble End, Wrtnch

Ooes Monhey Wrench A I I I ^^ tombinotionPIien' Cutting |65a^^M^£c=—

Fig. 163.—^Practical Hand Tools Useful in DlsmantllDg and BepalilngAirplane Engines.

heat. The large box wrench shown nnder the vise is used for removinglarge special nuts and sometimes has one end of the proper size to fitthe valve chamber cap. The piston ring removers are easily made fromthin strips of sheet metal securely brazed or soldered to a light wirehandle. These are used in sets of three for removing and applying pis-ton rings in a manner to be indicated. The uses of the wrenches, screwdrivers, and pliers shown are known to all and the variety outlinedshould be sufficient for all ordinary work of restoration. * The wrenchequipment is very complete, including a set of open end S-wrenches tofit all standard bolts, a spanner wrench, socket or box wrenches for

454/821

bolts that are inaccessible with the ordinary type, adjustable endwrenches, a thin monkey wrench of medium size, a bicycle wrench forhandling small nuts and bolts, a StiUson wrench for pipe and a largeadjustable monkey wrench for the stubborn fastenings of large size.

Four different types of pliers are shown, one being a parallel jaw typewith size cutting attachment, while the other illustrated near it is acombination parallel jaw type adapted for use on round work as wellas in handling flat stock. The most popular form of pliers is the com-bination pattern shown beneath the socket wrench set This is made ofsubstantial drop forgings having a hinged joint that can be set so that avery wide opening at the jaws is possible. These can be used on roundwork and for wire cutting as well as for handling flat work. Roundnose pliers are very useful also.

A very complete set of files, including square, half round, mill, flatbastard, three-cornered and rat tail are also necessary. A hacksawframe and a number of saws, some with fine teeth for tubing and oth-ers with coarser teeth for bar or solid stock will be found almost indis-pensable. A complete punch and chisel set should be provided,samples of which are shown in the group while the complete outfit isoutlined in another illustration. A number of different forms and sizesof chisels are neces-

sary, as one type is not suitable for all classes of work. The adjustable.end wrenches can be used in many places^ where a monkey wrenchcannot be fitted and where it will be difficult to use a wrench having afixed opening. The Stillson pipe wrench is useful in turning studs,round rods, and pipes that cannot be turned by any other means. Acomplete shop kit must necessarily include various sizes for Stillsonand monkey wrenches, as no one size can be expected to handle thewide range of work the engine repairman must cope with. Three sizesof each form of wrench can be used, one, a 6 inch, is as small as is

455/821

needed while a 12 inch tool will handle almost any piece of pipe or nutused in engine construction.

Three or four sizes of hammers should be provided, according to indi-vidual requirement, these being small riveting, medium and heavy-weight machinist's hammers. A very practical tool of this nature forthe repair shop can be used as a hammer, screw driver or pry iron. It isknown as the " Spartan'^ hammer and is a tool steel drop forging inone piece having the working surfaces properly hardened andtempered while the metal is distributed so as to give a good balance tothe head and a comfortable grip to the handle. The hammer headprovides a positive and comfortable T-handle when the tool is used asa screw driver or **tommy'' bar. Machinist's hammers are providedwith three types of heads, these being of various weights. The formmost commonly used is termed the **ball pein" on account of theshape of the portion used for riveting. The straight pein is just thesame as the cross pein, except that in the latter the straight portion isat right angles to the hammer handle, while in the former it is parallelto that member.

FORMS OF WRENCHES

Wrenches have been made in infinite variety and there are a score ormore patterns of different types of adjustable socket and off-setwrenches. The various wrench

Aviation Engines

types that differ from the more conventional monkey wrenches orthose of the Stillson pattern are shown at Fig. 164. The *'perfecthandle'' is a drop forged open end form provided with a woodenhandle similar to that used on a monkey wrench in order to provide abetter grip for the hand. The **Saxon'' wrench is a double alligator

456/821

form, so called because the jaws are in the form of a V-groove havingone side of the V plain, while the other is serrated in order to secure atight grip on round objects. In the form shown, two jaws of varyingsizes

MILLER

Fig. 164.—^Wrenches are Offered in Many Forms.

are provided, one for large work, the other to handle the smaller rods.One of the novel features in connection with this wrench is the provi-sion of a triple die block in the centre of the handle which is providedwith three most commonly used of the standard threads including%6-uich-18, %-inch-16, and i/^-irich-13. This is useful in cleaning upburred threads on bolts before they are replaced, as burring is un-avoidable if it has been necessary to drive them out with a hammer.The ^^Lakeside'* wrench has an adjustable pawl engaging with one ofa series of notches by which the opening may be held in any desiredposition.

Ever since the socket wrench was invented it has been

a popular form because it can be used in many places where the ordin-ary open end or monkey wrench cannot be applied owing to lack of

457/821

room for the head of the wrench. A typical set which has been made tofit in a very small space is shown at D. It consists of a handle, which isnickel-plated and highly polished, a long extension bar, a universaljoint and a number of case hardened cold drawn steel sockets to fit allcommonly used standard nuts and bolt heads. Two screw-driver bits,one small and the other large to fit the handle, and a long socket to fitsparkplugs are also included in this outfit. The universal joint permitsone to remove nuts in a position that would be inaccessible to any oth-er form of wrench, as it enables the socket to be turned even if thehandle is at one side of an intervening obstruction.

The * * Pick-up'' wrench, shown at E, is used for sparkplugs and theupper end of the socket is provided with a series of grooves into whicha suitable blade carried by the handle can be dropped. The handle ispivoted to the top of the socket in such a way that the blades may bepicked up out of the grooves by lifting on the end of the handle anddropped in again when the handle is swung around to the properpoint* to get another hold on the socket. The **Miller*' wrench shownat F, is a combination socket and open end type, made especially foruse with spark-plugs. Both the open end and the socket are conveni-ent. The **Handy'* set shown at G, consists of a number of thinstamped wrenches of steel held together in a group by a simple clampfitting, which enables either end of any one of the four doublewrenches to be brought into play according to the size of the nut to beturned. The **Cronk'' wrench shown at H, is a simple stamping havingan alligator opening at one end and a stepped opening capable ofhandling four different sizes of standard nuts or bolt heads at the oth-er. Such wrenches are very cheap and are worth many times theirsmall cost, especially for fitting nuts where there is not sufficient roomto admit the more conventional pattern. The

**Starretf wrench set, which is shown at I, consists rf a ratchet handletogether with an extension bar and universal joint, a spark-plug

458/821

socket, a drilling attachment which takes standard square shank drillsfrom i/^-inch to i^-inch in diameter, a double ended screw-driver bitand several adjustments to go with the drilling attachment Twenty-eight assorted cold drawn steel sockets similar in design to thoseshown at D, to fit all standard sizes of square and hexagonal headednuts are also included. The reversible ratchet handle, which may beslipped over the extension bar or the tmiversal joint and which is alsoadapted to take the squared end of any one of the sockets is exception-ally useful in permitting, as it does, the instant release of pressurewhen it is desired to swing the handle back to get another hold on thenut. The socket wrench sets are usually supplied in hard wood cases orin leather bags so that they may be kept together and protected againstloss or damage. With a properly se lected socket Wrench set, either ofthe ratchet handle or T-handle form, any nut on the engine may bereached and end wrenches will not be necessary.

«

USE A'ND CARE OF FILES

Mention has been previously made of the importance of providing acomplete set of files and suitable handles. These should be in variousgrades or degrees of fineness and three of each kind should beprovided. In the flat and half round files three grades are necessary,one with coarse tooth for roughing, and others with medium and finetooth for the finishing cuts. The round or rat tail file is nocossary in fil-ing out small holes, the half round for finishing the interior of largeones. Half round-files are also well adapted for finishing surfaces ofpeculiar contour, such as tho inside of bearing boxes, connectine: rodand main bearing caps, etc. Square files are useful in finishing koy-ways or cleaning out burred splines, while the triangular section orthree-cornered file is of value in

459/821

Use and Care of Files

888

aning out burred threads and sharp comers. Flat files 3 used on allplane surfaces.

The file brush shown at Fig. 165, A, consists of a large mber of mrebristles attached to a substantial wood

Wt^S^tsries

/Ivfoie

2?

^/l£

460/821

Fig. 165.—^niustratlng Use and Care of Files.

3k having a handle of convenient form so that the sties may bedraA\Ti through the interstices between \ teeth of tlie file to removedirt and grease. If the

teeth are filled with pieces of soft metal, such as solder or babbitt, itmay be necessary to remove this accunmla-tion with a piece of sheetmetal as indicated at Fig. 165, B. The method of holding a file forworking on plain surfaces when it is fitted with the regular form ofwooden handle is shown at C, while two types of handles enabling themechanic to use the flat file on plain surface^ of such size that thehandle type indicated at C, could not be used on account of interferingwith the surface finished are shown at D. The method of using a filewhen surfaces are finished by draw filing is shown at E. This differsfrom the usual method of filing and is only used when surfaces are tobe polished and very little metal removed.

SPLIT PIN BEMOVAL AND INSEBTION

One of the most widely used of the locking means to prevent nuts orbolts from becoming loose is the simple split pin, sometimes called a**cotter pin/* These can be handled very easily if the special pliersshown at Fig. 166, A, are used. They have a curved jaw that permits ofgrasping the pin firmly and inserting it in the hole ready to receive it.

461/821

It is not easy to insert these split pins by other means because the endsare usually spread out and it is hard to enter the pin in the hole. Withthe cotter pin pliers the ends may be brought close together and as theplier jaws are small the pin may be easily pushed in place. Another useof this plier, also indicated, is to bend over the ends of the split pin inorder to prevent it from falling out. To remove these pins a simplecurved lever, as shown at Fig. 166, B, is used. This has one end taper-ing to a point and is intended to be inserted in the eye of the cotter pin,the purchase offered by the handle permitting of ready removal of thepin after the ends have been closed by the cotter pin pliers.

Miscellaneous Small Tools

COMPLETE CHISEL SET

A complete chisel set suitable for repair shop use is o shown at Fig.166. The type at C is known as a ape" chisel and has a narrow cuttingpoint and is in-ided to chip kejTvays, remove metal out of corners and■ all other work where the broad cutting edge chisel,

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twn at D, cannot be used. The form with the wide ting edge is used inchipping, cutting sheet metal, etc. E, a round nose chisel used in mak-ing oil ways is out->d, while a similar tool having a pointed cuttingedge I often used for the same purpose is shown at F. The tre punchdepicted at G, is very useful for marking ts either for identification orfor. drilling. In addition

to the chisels shown, a number of solid punches or drifts resemblingvery much that shown at E, except that the point is blunt should beprovided to drive out taper pins, bolts, rivets, and other fastenings ofthis nature. These should be provided in the common sizes. A com-plete set of real value would start at %-inch and increase by incre-ments of H2-inch up to i^-inch. A simple spring winder is shown atFig. 166, H, this making it possible for the repairman to wind coilsprings, either on the lathe or in the vise. It will handle a number ofdifferent sizes of wire aad can be set to space the coils as desired.

«

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DRIIiLING MACHINES

Drilling machines may be of two kinds, hand or power operated. Fordrilling small holes in metal it is necessary to run the drill fast, there-fore the drill chuck is usuaUy driven by gearing in order to producehigh driU speed without turning the handle too fast. A ^mall handdrill is shown at Fig. 167, A. As will be observed, the chuck spindle isdriven by a small bevel pinion, which in turn, is operated by a largebevel gear turned by a crank. The gear ratio is such that one turn of thehandle will turn the chuck five or six revolutions. A drill of this designis not suited for drills any larger than one-quarter inch. For use withdrills ranging from one-eighth to three-eighths, or even half-inch thehand drill presses shown at C and D are used. These haVe a pad at theupper end by which pressure may be exerted with the chest in order tofeed the drill into the work, and for this reason they are termed^^breast drills.'' The form at C has compound gearing, the drill chuckbeing driven by the usual form of bevel pinion in mesh with a largerbevel gear at one end of a countershaft. A small helical spur pinion atthe other end of this countershaft receives its motion from a largergear turned by the hand crank. This arrangement of gearing permits ofhigh spindle speed without the use of large gears, as would be neces-

Drilling Machines

887

ry if but two were used. The form at D gives two aeds, one for use withsmall drills is obtained by en-ging the lower bevel pinion with thechuck spindle and

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Fig. 167,—FormB of Hand Operated Drming Macblnea.

iving it by the large ring gear. The slow speed is ob-ned by shifting theclutch so that the top bevel pinion ives the drill chuck. As tliis mesheswith a gear but ghtly larger in diameter, a slow speed of the drill lick ispossible. Breast drills are provided with a

handle screwed* into the side of the frame, these are used to steadythe drill press. For drilling extremely large holes which are beyond thecapacity of the usual form of drill press the ratchet form shown at B,may be used or the bit brace outlined at E. The drills used with eitherof these have square shanks, whereas those used in the drill presseshave round shanks. The bit brace is also used widely in wood work andthe form shown is provided with a ratchet by which the bit chuck may

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be turned through only a portion of a revolution in either direction ifdesired.

DBILLS, BEAMEBS, TAPS AND DIES

In addition to the larger machine tools and the simple hand tools pre-viously described, an essential item of equipment of any engine orplane repair shop, even in cases where the ordinary machine tools arenot provided, is a complete outfit of drills, reamers, and threadingtools. Drills are of two general classes, the flat and the twist drills. Theflat drill has an angle between cutting edges of about 110 degrees andis usually made from special steel commercially knowm as drill rod.

A flat drill cannot be fed into the work very fast because it removesmetal by a scraping, rather than a cutting process. The twist drill in itssimplest form is cylindrical throughout the entire length and has spiralflutes which are ground off at the end to form the cutting lip andwhich also serve to carry the metal chips out of the holes. The simplestform of twist drill used is shown at Fig. 168, C, and is known as a**chuck'' driU, because it must be placed in a suitable chuck to turn it.A twist drill removes metal by cutting and it is not necessary to use aheavy feed as the drill will tend to feed itself into the work.

Larger drills than %-inch are usually made with a tapered shank asshown at Fig. 168, B. At the end of the taper a tongue is formed whichengages with a suitable opening in the collet, as the piece used tosupport

the drill is called. The object of this tongue is to relieve the taperedportion of the drill from the stress of driving by frictional contactalone, as this would not turn the drill positively and the resulting slip-page would wear the socket, this depreciation changing the taper and

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making it unfit for other drills. The tongue is usually proportioned soit is adequate to drive the drill under any con-

/? C

Fig. 168.—Fonns of DiiUs Used in Hand and Power Drilling Machlnos.

dition. A small keyway is provided in the collet into which a taperingkey of flat stock may be driven against the end of the tongue to drivethe drill from the spindle. A standard taper for drill shanks generallyaccepted by the machine trade is knouTi as the Morse and is a taper offive-eighths of an inch to the foot. The Brown and Sharp form taperssix-tenths of an inch to the foot. Care must be taken, therefore, whenpurchasing drills and collets,

to make sure that the tapers coincide, as no attempt should be made toran a Morse taper in a Brown and Sharp collet, or vice versa.

Sometimes cylindrical drills have straight flutes, as outlined at Fig.168, A. Such drills are used with soft metals and are of value when thedrill is to pass entirely through the work. The trouble with a drill withspiral flutes is that it will tend to draw itself through as the cutting lips

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break through. This catching of the drill may break it or move thework from its position. With a straight flute drill the cutting action ispractically the same as with the flat drill shown at Fig. 168, E and F.

If a drill is employed in boring holes through close-grained, toughmetals, as wrought or malleable iron and steel, the operation will befacilitated by lubricating the drill with plenty of lard oil or a solution ofsoda and water. Either of these materials will effectually remove theheat caused by the friction of the metal removed against the lips of thedrill, and the danger of heating the drill to a temperature that willsoften it by drawing the temper is minimized. In drilling large or deepholes it is good practice to apply the lubricating medium directly at thedrill point. Special drills of the form shown at Fig. 62, D, having a spir-al oil tube running in a suitably formed channel, provides communica-tion between the point of the drill and a suitable receiving hole on adrilled shank. The oil is supplied by a pump and its pressure not onlypromotes positive circulation and removal of heat, but also assists inkeeping the hole free of chips. In drilling steel or wrought iron, lard,oil applied to the point of the drill wiU facilitate the drilling, but thismaterial should never be used with either brass or cast iron.

The sizes to be provided depend upon the nature of the work and theamount of money that can be invested in drills. It is common practiceto provide a set of drills, such as shown at Fig. 169, which are carriedin a suitable metal stand, these being known as number drills on ac-

count of conforming to the wire gauge standards. Ninn-ber drills donot usually nin higher than 54e inch in diameter. Beyond this pointdrills are usually sold by the diameter. A set of chuck drills, rangingfrom % to % inch, advancing by ^2 inch, and a set of Morse tapershank drills ranging from % to I14 inches, by increments of Ma inch,■will be all that is needed for the most pretentious repair shop, as it is

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cheaper to bore holes larger than 134 inches with a boring tool than itis to carry a

Tig. 169.—^Uaofol B«t of NumtMc DrUla, Bbowlng aUnd for KeepliiKThan In an Ordarly Uumei.

number of large drills in stock that would be used very seldom, per-haps not enough to justify their cost.

In grinding drills, care must be taken to have the lips of the samelength, so that they will form the same angle with the axis. If one lip islonger than the other, as shown in the fiat drill at Fig. 168, E, the holewill be larger than the drill size, and all the work of cutting ■ftiU comeupon the longest lip. The drill ends should be symmetrical, as shownat Fig. 168, F.

It is considered very difficult to drill a hole to an exact diameter, butfor the most work a variation of a few thousandths of an incli is of nogreat moment. \Miere accuracy is necessary, holes must be reamedout to the required size. In reaming, a hole is drilled about ^2 inch

Aviation Engines

smaller than is required, and is enlarged with a cutting tool known asthe reamer. Reamers are usually of the fluted form sho^Ti at Fig. 170,A. Tools of this nature are not designed to remove considerableamounts of metal, but are intended to augment the diameter of thedrill hole by only a small fraction of an inch. Reamers

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Fig. 170.—^niustrating Standard Forms of Hand and MacMneReamers.

are tapered slightly at the point in order that they will enter the holeeasily, but the greater portion of the fluted part is straight, all cuttingedges being parallel. Hand reamers are made in either the straight ortaper forms, that at A, Fig. 170, being straight, while B has taperingflutes. They are intended to bo turned by a wrench similar to that em-ployed in turning a tap, as sliowTi at Fig.

172, C. The reamer shown at Fig. 170, C, is a hand reamer. The form atD has spiral flutes similar to a twist drjU, and as it is provided with ataper shank it is intended to be turned by power through the mediumof a suitable collet.

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As the solid reamers must become reduced in size w^hen sharpened,various forms of inserted blade reamers have been designed. One ofthese is shown at E, and as the cutting surfaces become reduced in dia-meter it is possible to replace the worn blades with others of propersize. Expanding reamers are of the form shown at F. These have a boltpassing through that fits into a tapering hole in the interior of the splitreamer portion of the tool. If the hole is to be enlarged a few thou-sandths of an inch, it is possible to draw up on the nut just above thesquared end of the shank, and by drawing the tapering wedge fartherinto the reamer body, the cutting portion will be expanded and will cuta larger hole.

Reamers must be very carefully sharpened or there Avill be a tendencytoward chattering with a consequent production of a rough surface.Thei'e are several methods of preventing this chattering, one being toseparate the cutting edges by. irregular spaces, while the most com-mon method, and that to be preferred on machine reamers, is to usespiral flutes, as shown at Fig. 170, D. Special taper reamers are madeto conform to the various taper pin sizes which are sometimes used inholding parts together in an engine. A taper of Me inch per foot is in-tdided for holes where a pin, once driven in, is to remain in place."When it is desired that the pin be driven out, the taper is made steep-er, generally 14 inch per foot, which is the standard taper used ontaper pins.

"When threads are to be cut in a small hole, it will be apparent that itw^ill be difficult to perform this operation economically on a lathe,therefore when internal threading is called for, a simple device knownas a **tap" is used. There are many styles of taps, all conforming todifferent standards. Some are for metric or foreign

threads, some conform to the American standards, while others arensed for pipe and tubing. Hand taps are tlie form most used in repair

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shops, these being outlined at Fig. 171, A and B. They are usually soldin sets of threp, known respectively as taper, plug, and bottoming. Tlietaper tap is the one first put into the liole, and is then followed by theplug tap which cuts the threads deeper.

Fig. 171.—Tools for Thread Cutting.

If it is imperative that the thread should be full size clear to tlie hottomof the hole, tlio third tap of the set, which is straight-sided, is used. Itwould be difficult to .itart a bottoming tap into a hohi becau.se itwould be larger in dianu't<'r at its point than the hole. The taper tap,as shown at A, Fig. 171, has a portfou of the cutting lands ground awayat the point in order that it will enter tiie hole. The manipulation of atap is not hard, as it does not need to be forced into tlie work, as thethread

will draw it into the hole as the tap is turned. The tapering of a tap isdone so that no one thread is called upon to remove all of the metal, asfor about half way up the length of the tap each succeeding thread iscut a little larger by the cutting edge until the full thread enters the

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hole. Care must be taken to always enter a tap straight in order to havethe thread at correct angles to the surface.

In cutting external threads on small rods or on small pieces, such asbolts and studs, it is not always economical to do this work in thelathe, especially in repair work. Dies are used to cut threads on piecesthat are to be placed in tapped holes that have been threaded by thecorresponding size of tap. Dies for small work are often made solid, asshown at Fig. 171, C, but solid dies are usually limited to sizes below i^inch. Sometimes the solid die is cylindrical in shape, with a slotthrough one side which enables on6 to obtain a slight degree of adjust-ment by squeezing the slotted portion tog'ether. Large dies, or thesizes over i/^ inch, are usually made in two pieces in order that thehalves may be closed up or brought nearer together. The advantage ofthis form of die is that either of the two pieces may be easilysharpened, and as it may be adjusted very easily the thread may be cutby easy stages. For example, the die.may be adjusted to cut large,which will produce a shallow thread that will act as an accurate guidewhen the die is closed up and a deeper thread cut.

A common form of die holder for an adjustable die is shown at Fig.172, A. As will be apparent, it consists of a central body portion havingguide members to keep the die pieces from falling out and levers ateach end in order to permit the operator to exert sufficient force to re-move tlie metal. Tlie method of adjusting the depth of thread with aclamp screw when a two-piece die is employed is also clearly outlined.The diestock shoA\Ti at B is used for the smaller dies of the one-piecepattern, having a slot in order that they may be closed up slightly

Aviation Engines

by the clamp screw. The reverse side of the diestock shown at B is out-lined below it, and the guide pieces, which may be easily moved in or

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out, according to the size of the piece to be threaded by means of ec-centrically disposed semi-circular slots in the adjustment plate, are

1

Tt/o/^/fC^ P/s

/fi>LO£K

'M^^5c/^£kf

Fig. 172.—Showing Holder Designs for One- and Two-Piece ThreadCutting

Dies.

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shown. These movable guide members have small pins let into theirsurface which engage the slots, and they may be moved in or out, asdesired, according to the position of the adjusting plate. The use of theguide pieces makes for accurate positioning or centering of the rod tobe threaded. Dies are usuallv sold in sets, and are com-monly fur-nished as a i)ortion of a complete outfit such as

Measuring Tools

897

outlined at Fig. 173. That shown has two sizes of die-stock, a tapwrench, eight assorted dies, eight assorted taps, and a small screwdriver for adjusting the die. An automobile repair shop should heprovided with three different sets of taps and dies, as three differentstandards for the bolts and nuts are used in fastening automobile com-ponents. These are tiie American, metric

Fig. 173.—UBefnl Outfit of Taps and DIM for the Engliie Bepafr Shop.

(used on foreign engines), and the S. A. E. standard tlireads. A set ofpipe dies and taps will also be found useful.

MEASURING TOOLS

The tool outfit of the machinist or the mechanic who aspires to do ma-chine work must include a number of measuring tools which are not

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needed by the floor man or one who merely assembles and takes apartthe finished pieces. Tlie machinist who must convert raw material intofinished products requires a number of measuring tools, some ofwhich are used for taking only approximate measurements, such ascalipers and scales, while others are intended to take very accuratemeasurements, such as the Vernier and the micrometer. A number ofcommon forms of calipers are shown at Fig. 174. These are known asinside or outside calipers, depending upon the measurements they areintended to take. That at A

is an inside caliper, consisting of two legs, A and D, and a gaugingpiece, B, which can be locked to leg A, or released from that memberby tlie screw, C. The object of this construction is to permit of meas-urements being taken at the bottom of a two diameter liole, where thepoint to be measured is of larger diameter than the portion of the holethrough which the calipers entered. It ■will be apparent that the legs Aand D must be brouglit close together to pass tlirough the smallerholes. This

Fig. 174.—Common Foims of Itulde and Outside 0«lip«is.

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may be done without losing the setting, as the guide bar B will remainin one position as determined by the size of tlie hole to be measured,while the leg A may be swung in to clear the obstruction as the calipersare lifted out. When it is desired to ascertain the measurpincnts the legA is pushed back into place into the slotted portion of tlie guide B, andlocked by the cJanip screw C. A tool of tliis form is known as an in-ternal transfer caliper.

The form of caliper sliown at B is an" outside caliper. Those at C and Dare special forms for inside and out-

side work, the former being used, if desired, as a divider, while the lat-ter may be employed for measuring the walls of tubing. The calipers atE are simple forms, having a friction joint to distinguish them fromthe spring calipers shown at B, C and D. In order to permit of readyadjustment of a spring caliper, a split nut as shown at G is sometimesused. A solid nut caliper can only be adjusted by screwing the nut in orout on the screw, which may be a tedious process if the caliper is to beset from one extreme to the other several times in succession. With aslip nut as shown at Gt it is possible to slip it from one end of thethread to the other without turning it, and of locking it in place at anydesired point by simply allowing the caliper leg to come in contactwith it. The method of adjusting a spring caliper is shown at Fig. 174,H.

Among the most common of the machinist's tools are thqse used forlinear measurements. The usual forms are shown in group. Fig. 175.The most common tool, which is widely known, is the carpenter'sfolding two-foot rule or the yardstick. While these are very convenientfor taking measurements where great accuracy is not required, themachinist must work much more accurately than the carpenter, andthe standard steel scale which is showTi at D, is a popular tool for themachinist. The steel scale is in reality a graduated straight edge and

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forms an important part of various measuring tools. Thpse are madeof high grade steel and vary from 1 to 48 inches in length. They arecarefully hardened in order to preserve the graduations, and all sur-faces and edges are accurately ground to insure absolute parallelism.The graduations on the high grade scales are produced with a specialdevice known as a dividing engine, but on cheaper scales, etching suf-fices to provide a fairly accurate graduation. The steel scales may bevery thin and flexible, or may be about an eighth of an inch thick onthe twelve-inch size, which is that commonly used with combinationsquares, protractors and other tools of that

Aviation Engines

nature. The repairman's scale should be graduated both with the Eng-lish system, in which the inches are divided into eighths, sixteenths,thirty-secondths and sixty-

[M^

,i,.i-Li...i.,.i![.H,i.,i !i,..i.j.ui,,.,.i,.i.a.,,

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Fig. 176.—^Measuring Appliances for the MacUnlst and Floor Man.

fourths, and also in the metric system, divided into millimeters andcentimeters. Some machinists use scales graduated in tenths, twenti-eths, iiftieths and hundredths.

This is not as good a system of graduation as the more conventionalone first described.

Some steel scales are provided with a slot or groove cut the entirelength on one side and about the center of the scales. This permits theattachment of various fittings such as the protractor head, which en-ables the machinist to measure angles, or in addition the heads con-vert the scale into a square or a tool permitting the accurate bisectingof pieces of circular section. Two scales are sometimes joined togetherto form a right angle, such as shown at Fig. 175, C. This is known as asquare and is very valuable in ascertaining the truth of vertical piecesthat are supposed to form a right angle with a base piece.

The Vernier is a device for reading finer divisions on a scale than thoseinto which the scale is divided. Sixty-fourths of an inch are about thefinest division that can be rej^d accurately with the naked eye. Whenfine work is necessary a Vernier is employed. This consists essentiallyof two rules so graduated that the true scale has each inch divided intoten equal parts, the upper or Vernier portion has ten divisions occupy-ing the same space as nine of the divisions of the true scale. It is evid-ent, therefore, that one of the divisions of the Vernier is equal to nine-tenths of one of those on the true scale. If the Vernier scale is moved tothe right so that the graduations marked ^'1'' shall coincide, it willhave moved one-tenth of a division on the scale or one-hundredth ofan inch. AVhen the graduations numbered 5 coincide the Vernier willhave moved five-hundredths of an inch; when the lines marked 0 and10 coincide, the Vernier will have moved nine-hundredths of an inch,

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and when 10 on the Vernier comes opposite 10 on the scales, the upperrule will have moved ten-hundredth s of an inch, or the whole of onedivision on the scale. By this means the scale, though it may be gradu-ated only to tenths of an inch, may be accurately set at points with po-sitions expressed in hundredths of an inch. When graduated to read inthousandths, the true scale is divided into fifty parts and

tlie Vernier into twenty parts. Each division of the Vernier is tliereforeequal to nineteen-twentieths of one of the true scale. If the Vernier bemoved so the lines of the first division coincide, it "will have movedone-twentieth of one-fiftieth, or .001 inch. The Vernier principle canbe readily grasped by stud>'ing the section of tlie Vernier scale andtrue scale shoMTi at Fig. 176, A.

The caliper scale which is shoMTi at Fig. 175, A, permits of taking tlieover-all dimension of any parts that

Fig. 176.—At Left, Special Foim of Vender Caliper foi UeaanrlnK 0*aaTeetli; at Bight, Ulcrometer for Accurate Internal Ueasurements.

will go between the jaws. Tliis scale can be adjusted very accurately bymeans of a fine thread screw attached to a movable jaw and the divi-sions may he divided by eye into two parts if one sixty-fourth is thesmallest of the divisions. A line is indicated on tlie movahle jaw' and

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coincides with the graduations on the scale. As "ttill be apparent, it'tlie linc^ does not coincide exactly with one of the graduations it willbe at some point between the lines and the true measurement may beapproximated without troubles

A group of various other measuring tools of value to the macliinist issliown at Fig. 177. Tlie small scale at .\ is termed a "center gauge." be-cause it can be used to test

Meaauring Tools

408

the truth of the taper of eitlier a male or female lathe coiiter. The twosmaller nicks, or v's, indicate the shape of a standard thread, and maybe used as a guide for grinding the point of a thread-cutting tool. Tliecross level whieli is shown at B is of marked utility in erecting, as itwill indicate absolutely if the piece it is used to test

Fig. 177.—^MeasuTlng Appliances of Value In Airplane Bepalr Work.

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is levpl. It will indicate if the piece is level along its width as well as itslength.

A very simple attacliment for use witli a scale that enables tlie machin-ist to scribe lines along the length of a cylindrical piece is sliown at Fig.177, C. These are merely small wedge-shaped clamps -having an angu-lar face to rest upon the bars. The tlircad pitch gauge which is shownat Fig. 177, D, is an excellent pocket tool for the mechanic, as it is oftennecessary to determine without loss of time the pitch of the tiirend ona bolt or in a nut. This consists of a number of leaves ha\'ing serra-tions on cue edge corresponding to the standard thread it is to be

used in measuring. The tool shown gives all pitches up to 48 threadsper inch. The leaves may be folded in out of the way when not in use,and their shape admits of their being used in any position without theremainder of the set interfering with the one in use. The fine pitchgauges have slim, tapering leaves of the correct shape to be used infinding the pitch of small nuts. As the tool is round when the leavesare folded back out of the w^ay, it is an excellent pocket tool, as thereare no sharp comers to wear out the pocket. Practical application of aVernier having measuring heads of special form for measuring gearteeth is shown at Fig. 176, A. As the action of this tool has been previ-ously explained, it will not be necessary to describe it further.

MICROMETER CALIPERS AND THEIR USE

Where great accuracy is necessary in taking measurements the micro-meter caliper, which in the simple form will measure easily .001 inch(one-thousandth part of an inch) and when fitted with a Vernier thatwill measure .0001 inch (one ten-thousandth part of an inch), is used.The micrometer may be of the caliper form for measuring outside dia-meters or it may be of the form shoA\Ti at Fig. 176, B, for measuringinternal diameters. The operation of both forms is identical except

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that the internal micrometer is placed inside of the bore to be meas-ured while the external form is used just the same as a caliper. Theform outlined will measure from one and one-half to six and a halfinches as extension points are provided to increase the range of the in-strument. The screw has a movement of one-half inch and a hardenedanvil is placed in the end of the thimble in order to prevent unduewear at that point. The extension points or rods are accurately made instandard lengths and are screwed into the body of the iiistnmient in-stead of being pushed in, this insuring firmness and accuracy. Twoforms of micrometers for external measurements are showTi at Fig.178. The

Micrometers and Their Use

405

top one is graduated to read in thousandths of an inch, while the lowerone is graduated to indicate hundredths of a millimeter. The mechan-ical principle involved in the construction of a micrometer is that of ascrew free to

to Th(Ht90tM$94t

fin fnchi

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o S 10

liiiiliiiilii

liiiiiiniiii

15 10

O 5 lO B* ^

tli i i l f iii li iC •

UUUIIIU|#^

40

^\

$0 49

Scoi4 on Oorrei

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Fig. 178.—Standard Forms of Bficrometer Caliper for ExternalMeasurements.

move in a fixed nut. An opening to receive the work to be measured isprovided by the backward movement of the thimble which turns thescrew and the size of the opening is indicated by the graduations onthe barrel.

The article to be measured is placed between the anvil and spindle, theframe being held stationary while the thimble is revolved by thethumb and finger. The pitch of the screw thread on the concealed partof the spindle is 40 to an inch. One complete revolution of the spindle,therefore, moves it longitudinally one-fortieth, or twenty-five thou-sandths of an inch. As will be evident from the development of thescale on the barrel of the inch micrometer, the sleeve is marked vdilaforty lines to the inch, each of these lines indicating twenty-five thou-sandths. The thimble has a beveled edge which is graduated intotwenty-five parts. When the instrument is closed the graduation onthe beveled edge of the thimble marked 0 should correspond to the 0line on the barrel. If the micrometer is rotated one full turn the open-ing between the spindle and anvil will be .025 inch. If the thimble isturned only one graduation, or one twenty-fifth of a revolution, theopening between the spindle and anvil wiU be increased only by .001inch (one-thousandth of an inch).

As many of the dimensions of the airplane parts, especially of those offoreign manufacture or such parts as ball and roller bearings, arebased on the metric system, the competent repairman should possessboth inch and metric micrometers in order to avoid continual refer-ence to a table of metric equivalents. With a metric micrometer thereare fifty graduations on the barrel, these representing .01 of a milli-meter, or approximately .004 inch. One full turn of the barrel meansan increase of half a millimeter, or .50 mm. (fifty one-hundredths). As

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it takes two turns to augment the space between the anvil and the stemby increments of one millimeter, it will be evident that it would not bedifficult to divide the spaces on the metric micrometer thimble inhalves by.the eye, and thus the average workman can measure to.0002 inch plus or minus w^ithout difficulty. As set in the illustration,the metric micrometers show a space of 13.5 mm., or about one milli-meter more than half an inch. The

inch micrometer shown is set to five-tentjis or five hundred one-thon-sandths or one-half inch. A little study of the foregoing matter willmake it easy to understand the action of eitlier the inch or metricmicrometer.

Both of the micrometers shoAXTi have a small knurled knob at theend of the barrel. This controls the ratchet stop, which is a device thatpermits a ratchet to slip by a pawl when more than a certain amount ofpressure is applied, thereby preventing the measuring spindle fromturning further and perhaps springing the instrument. A simple rulethat can be easily memorized for reading the inch micrometer is tomultiply the number of vertical divisions on the sleeve by 25 and addto that the number of. divisions on the bevel of the thimble readingfrom the zero to the line which coincides vnth the horizontal line onthe sleeve. For example: if there are ten divisions visible on the sleeve,multiply this number by 25, then add the number of divisions shownon the bevel of the thimble, which is 10. The micrometer is thereforeopened 10x25 equals 250 plus 10 equals 260 thousandths.

Micrometers are made in many sizes, ranging from those having amaximum opening of one inch to special large forms that will measureforty or more inches. While it is not to be expected that the repairmanwill have use for the big sizes, if a caliper having a maximum openingof six inches is provided with a mmiber of extension rods enabling oneto measure smaller objects, practically all of the measuring needed in

486/821

repairing engine parts can be made accurately. Two or three smallermicrometers having a maximum range of two or three" inches will alsobe found valuable, as most of the measurements will be made withthese tools which will be much easier to handle than the larger sizes.

T^T>ICAI. TOOL OT'TFITS

The equipment of tools necessary for repairing airplane engines de-pends entirely upon the type of the power

plant and while the conunon hand tools can be used on all forms, thework is always facilitated by having special tools adapted for reachingthe nuts and screws that would be hard to reach otherwise. Specialspanners and socket wrenches are very desirable. Then again, thenature of the work to be performed must be taken into consideration.Kebuilding or overhauling an engine calls for considerably more toolsthan are furnished for making field repairs or minor adjustments. Acomplete set of tools supplied to men working on Curtiss OX-2 en-gines and JN-4 training biplanes is shown at Fig. 179. The tools, areplaced in a special box provided with a hinged cover and are arrangedin the systematic manner outlined. The various tools and suppliesshown are: A, hacksaw blades; B, special socket wrenches for enginebolts and nuts; C, ball pein hammers, four sizes; D, five assorted sizesof screw drivers ranging from very long for heavy work to short andsmall for fine work; E, seven pairs of pliers including combination inthree sizes, two pairs of cutting pliers and one round nose; F, two splitpin extractors and spreaders; G, wrench set including three adjustablemonkey wrenches, one Stilson or pipe wrench, five sizes adjustableend wrenches and ten double end S wrenches; H, set of files, includingflat, three cornered and half round; I, file brush; J, chisel and drift pin;K, three small punches or drifts; L, hacksaw frame; M, soldering cop-per; N, special spanners for propeller re-taining nuts; 0, special span-ners; P, socket wrenches, 'long handle; Q, long handle, stiff bristle

487/821

brushes for cleaning motor; E, gasoline blow torch; S, hand drill; T,spools of safety wire; U, flash lamp; V, special puller and castlewrenches; W, oil can; X, large adjustable monkey wrench; Y, washerand gasket cutter; Z, ball of heavy twine. In addition to the tools, vari-ous supplies, such as soldering acid, solder, shellac, valve grindingcompound, bolts and nuts, split pins, washers, wood screws, etc., areprovided.

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AxAation Engines

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The special tools and fixtures recommended by the Hall-Scott Com-pany for work on their engines are clearly shown at Fig. 180. All tools

504/821

are numbered and their uses may be clearly understood by referenceto the illustration and explanatory list given on pages 410 and 411.

OVERHAULING AmPLANE ENGINES

After an airplane engine has been in use for a period ranging from 60to 80 hours, depending upon the type, it is necessary to give it a thor-ough overhauling before it is returned to service. To do this properly,the engine is removed from the fuselage and placed on a special sup-porting stand, such as shown at Fig. 181, so it can be placed in any pos-ition and completely dismantled. With a stand of this kind it is as easyto work on the bottom of the engine as on the top and every part canbe instantly reached. The crank-case shoA^Ti in place in illustration isin a very convenient position for scraping in the crank-shaft bearings.

In order to look over the parts of an engine and to restore the worn ordefective components it is necessary to take the engine entirely apart,as it is only when the power plant is thoroughly dismantled that theparts can be inspected or measured to determine defects or w-ear. Ifone is not familiar mth the engine to be inspected, even though thework is done by a repairman of experience, it will be found of value totake certain precautions when dismantling the engine in order to in-sure that all parts vdM be replaced in the same position they occupiedbefore removal. There are a number of ways of identifying the parts,one of the simplest and surest being to mark them with steel numbersor letters or with a series of center punch marks in order to retain theproper relation when reassembling. This is of special importance inconnection with dismantling multiple cylinder engines as it is vitalthat pistons, piston rings, connecting rods, valves, and other cylinderparts be always replaced in

505/821

Aviation Knyiiu-i

the same cylinder from wliicli tliey wore romovod. lii-oanse it isnnt'ommon to finil eijiial dopreciatinn in nil fvlindcrs. SonicI'cpairnn'n use small slii])pin,fc iix'^^ !■' idcnlily tlic pi<>t-rs. Tliis

506/821

can Ih- crilicisi-d ln-caiis,' t!i-tap:s niav bcconK^ detai-iicd and lostand tlir idt-ntitv \ii

rii'. 181.—Spptial Stand to Make Motor Overhauling Work Easier.

.<li..|, «li,.n. ulli.r ,.iu!,i,.s „r til,. NUM.- umkc. iir,- l...iii.' «,irii,.l .,11.111,. i.,.|,iii|.|,i;in slniiiM hp |,|.„vi,l,.,l will, a lari;,. ,.|i,.>t I'llhil »illi al,..k ami li,,, in wliii-li all „r 111,- Slilall.r parl^, sii,.|i as r,„U. I„,ll,- nii.liiiil.«, valv,...,, u.,.ars, valv,-.-liriim-s. ,-aiii-sliallr. ,1,-.. iiia.v l„...^I,,n.,l la iir,.v,.nl tli,' IK).<sii,ility ,,r (.(.iirii..,!,,:, Willi similariii,;iiilK'i.s of otlier

engines. All parts should be thoroughly cleaned with gasoline or in thepotash kettle as removed, and wiped clean and dry. This is necessaryto show wear which will be evidenced by easily identified indicationsin cases where the machine has been used for a time, but in others, thedeterioration can only be detected by delicate measuring instruments.

In taking down a motor the smaller parts and fittings such as spark-plugs, manifolds and wiring should be removed first. Then the moreimportant members such as cylinders may be removed from thecrank-case to give access to the interior and make possible the exam-ination of the pistons, rings and connecting rods. After the cylindersare removed the next operation is to disconnect the connecting rodsfrom the crank-shaft and to remove them and the pistons, attached asa unit. Then the crank-case is dismembered, in most cases by remov-ing the bottom half or oil sump, thus exposing the main bearings andcrankshaft. The first operation is the removal of the inlet and exhaustmanifolds. In some cases the manifolds are cored integral with the cyl-inder head casting and it is merely necessary to remove a short pipeleading from the carburetor to one inlet opening and the exhaust pipefrom the outlet opening common to all cylinders. In order to removethe carburetor it is necessary to shut off the gasoline supply at the tank

507/821

and to remove the pipe coupling at the float chamber. It is also neces-sary to disconnect the throttle operating rod. After the cylinders areremoved and before taking the crank-case apart it is well to removethe water pump and magneto. The wiring on most engines of moderndevelopment is carried in conduits and usually releasing two or threeminor fastenings will permit one to take off the plug wiring as a unit.The wire should be disconnected from both spark-plugs and magnetodistributor before its removal. When the cylinders are removed, thepistons, piston rings, and connecting rods are clearly exposed andtheir condition may be readily noticed.

Before disturbing the arrangement of the timing gears, it is importantthat these be marked so that they will be replaced in exactly the samerelation as intended by the engine designer. If the gears are properlymarked the valve timing and magneto setting will be imdisturbedwhen the parts are replaced after overhauling. With the cylinders off,it is possible to ascertain if there is any undue wear present in the con-necting rod bearings at either the wrist pin or crank-pin ends and alsoto form some idea of the amount of carbon deposits on the piston topand back of the piston rings. Any wear of the timing gears can also bedetermined. The removal of the bottom plate of the engine enables therepairman to see if the main bearings are worn unduly. Often bearingsmay be taken up sufficiently to eliminate all looseness. In other casesthey may be worn enough so that careful refitting will be necessary.Where the crank-case is divided horizontally into two portions, the up-per one serving as an engine base to which the cylinders and in fact allimportant working parts are attached, the lower portion performs thefunctions of an oil container and cover for the internal mechanism.This is the construction generally followed.

DEFECTS IN CYLINDERS

508/821

After the cylinders have been removed and stripped of all fittings, theyshould be thoroughly cleaned and then carefully examined for defects.The interior or bore should be looked at with a view of finding scoremarks, grooves, cuts or scratches in the interior, because there aremany faults that may be ascribed to depreciation at this point. The cyl-inder bore may be worn out of round, which can only be determinedby measuring with an internal caliper or dial indicator even if the cyl-inder bore shows no sign of wear. The flange at the bottom of the cyl-inder by which it is held to the engine base may be cracked. The waterjacket Avail may have opened up due

to freezing of the jacket water at some time or other or it may be filledwith scale and sediment due to the use of impure cooling water. Thevalve seat may be scored or pitted, while the threads holding the valvechamber cap may be worn so that the cap will not be a tight fit. Thedetachable head construction makes it possible to remove that mem-ber and obtain ready access to the piston tops for scraping out carbonwithout taking the main cylinder portion from the crank-case. Whenthe valves need grinding the head may be removed and carried to thebench where the work may be performed with absolute assurance thatnone of the valve grinding compound will penetrate into the interior ofthe cylinder as is sometimes unavoidable with the I-head cylinder. Ifthe cylinder should be scored, the water jacket and combustion headmay be saved and a new cylinder casting purchased at considerablyless cost than that of the complete unit cylinder.

The detachable head construction has only recently been applied onairplane engines, though it was one of the earliest forms of automobileengine construction. In the early days it was difficult to procure gas-kets or packings that would be both gas and water tight. The sheet as-bestos commonly used was too soft and blew out readily. Besides anew gasket had to be made every time the cylinder head was removed.Woven wire and asbestos packings impregnated with rubber, red lead,

509/821

graphite and other filling materials were more satisfactory than thesoft sheet asbestos, but were prone to burn out if the water supply be-came low. Materials such as sheet copper or brass proved to be toohard to form a sufficiently yielding packing medium that would allowfor the inevitable slight inaccuracies in machining the cylinder headand cylinder. The invention of the copper-asbestos gasket, which iscomposed of two sheets of very thin, soft copper bound together by athin edging of the same material and having a piece of sheet asbestosinterposed solved this problem. Copper-asbestos packings form an ef-fective seal against leakage of water and a positive reten-

tion means for keeping the explosion pressure in the cylinder. Thegreat advantage of the detachable head is that it permits of very easyinspection of the piston tops and combustion chamber and ready re-moval of carbon deposits.

CARBON DEPOSITS, THEIR CAUSE AND PREVENTION

Most authorities agree that carbon is the result of imperfect combus-tion of the fuel and air mixture as well as the use of lubricating oils ofimproper flash point Lubricating oils that work by the piston ringsmay become decomposed by the great heat in the combustion cham-ber, but at the same time one cannot blame the lubricating oil for allof'the carbon deposits. There is little reason to suspect that pure petro-leum oil of proper body will deposit excessive amounts of carbon,though if the oil is mixed with castor oil, which is of vegetable origin,there would be much carbon left in the interior of the combustionchamber. Fuel mixtures that are too rich in gasoline also producethese undesirable accumulations.

A very interesting chemical analysis of a sample of carbon scrapedfrom the interior of a motor vehicle engine shows that ordinarily the

510/821

lubricant is not as much to blame as is commonly supposed. The ana-lysis was as follows:

Oil 14.3%

other combustible matter 17.9

Sand, clay, etc 24.8

Iron oxide 24.5

•

Carbonate of lime 8.9

Other constituents 9.6

It is extremely probable that the above could be divided into two gen-eral classes, these being approximately 32.2% oil and combustiblematter and a much larger proportion, or 67.8% of earthy matter. Thepresence of such a large percentage of earthy matter is undoubtedlydue to the impurities in the air, such as road dust which

•

has been sucked in through the carburetor. The fact that over 17% ofthe matter which is combustible was not of an oily nature lends strongsupport to this view. There w^ould not be the amount of earthy mater-ial present in the carbon deposits of an airplane engine as above statedbecause the air is almost free from dust at the high altitudes planes areusually flown. One could expect to find more combustible and lessearthy matter and the carbon w^ould be softer and more easily re-moved. It is very good practice to provide a screen on the air intake toreduce the amounts of dust sucked in with the air as well as observing

511/821

the proper precautions relative to supplying the proper quantities ofair to the mixtui*e and of not using any more oil than is needed to in-sure proper lubrication of the internal mechanism.

USE OF CARBON SCRAPERS

It is. not unusual for one to hear an aviator complain that the enginehe operates is not as responsive as it was when new after he has run itbut relatively few hours. There does not seem to be anything actuallywrong with the engine, yet it does not respond readily to the throttleand is apt to overheat. While these symptoms denote a rundown con-dition of the mechanism, the trouble is often due to nothing more seri-ous than accumulations of carbon. The remedy is the removal of thismatter out of place. The surest way of cleaning the inside of the motorthoroughly is to remove the cylinders, if these members are cast integ-rally with the head or of removing the head member if'that is a separ-ate casting, to expose all parts.

In certain forms of cylinders, especially those of the L form, it is pos-sible to introduce simple scrapers down through the valve chambercap holes and through the spark-plug hole if this component is placedin the cylinder in some position that communicates directly to the in-terior of the cylinder or to the piston top. No claim can be made fororiginality or novelty of this process as

is has been used for many years on large stationary engines. The firststep is to dismantle the inlet and exhaust piping and remove the valvecaps and valves, although if the deposit is not extremely hard orpresent in large quantities one can often manipulate the scrapers inthe valve cap openings without removing either the piping or thevalves. Commencing with the first cylinder, the crank-shaft is turnedtill the piston is at the top of its stroke, then the scraper may be inser-ted, and the operation of removing the carbon started by drawing the

512/821

tool toward the opening. As this is similar to a small hoe, the cuttingedge will loosen some of the carbon and will draw it toward the open-ing. A swab is made of a piece of cloth or waste fastened at the end of awire and well soaked in kerosene to clean out the cylinder.

When available, an electric motor with a length of flexible shaft and asmall circular cleaning brush having wire bristles can be used in theinterior of the engine. The electric motor need not be over one-eighthhorsepower running 1,200 to 1,600 E. P. M., and the wire brush must,of course, be of such size that it can be easily inserted through thevalve chamber cap. The flexible shaft permits one to reach nearly allparts of the cylinder interior without difficulty and the spreading outand flattening of the brush insures that considerable surface will becovered by that member.

BURNING OUT CARBON WITH OXYGEN

A process of recent development that gives very good results in remov-ing carbon without disassembling the motor depends on the process ofburning out that material by supplying oxygen to support the combus-tion and to make it energetic. A number of concerns are already offer-ing apparatus to accomplish this work, and in fact any shop using anautogenous welding outfit may use the oxygen tank and reducing valvein connection with a simple special torch for burning the carbon. Be-

Carbon Memovfd

421

suits have demonstrated that there is little danger of damaging themotor parts, and that the cost of oxygen and labor is much lower tlianthe old method of removing the cylinders and scraping the carbon out,as well as being very much quicker than the alternative process of us-ing carbon solvent. The only drawback to this system is that there is no

513/821

absolute insurance that every particle of carbon will be removed, assmall protruding particles may be left at' points that the flame doesnot reach and

Fig. 182.—Showliig Wbera Carbon DepMlta Collect In Engine Combn-ation Cbamlier, and How to Born Tbem Ont wlUi tbe Aid of Oxygen.A— Special Torch. B—Torcb Coupled to Oxygen Tank. O—Torcb inUse.

cause pre-ignition and consequent poimding, even after the oxygentreatment. It is generally known that carbon ■will burn in the pres-ence of oxygen, which supports combustion of all materials, and thisprocess takes advantage of this fact and causes tlie gas to be injectedinto the combustion chamber over a flame obtained by a match or waxtaper.

It is suggested by those favoring this process that the night before theoxygen is to be used the engine be given a conventional kerosene treat-ment. A half tumbler ' full of this liquid or of denatured alcohol is to hepoured

into each cylinder and permitted to remain there over night. As a pre-caution against fire, the gasoline is shut off from the carburetor beforethe torch is inserted in the cylinder and the motor started so that thegasoline iii the pipe and carburetor float chamber will be consumed.

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Work is done on one cylinder at a time. A note of caution was recentlysounded by a prominent spark-plug manufacturer recommending thatthe igniter member be removed from the cylinder in order not to in-jure it by the heat developed. The outfits on the market consist of aspecial torch having a trigger controlled valve and a length of flexibletubing such as shown at Fig. 182, A, and a regulating valve and oxygentank as shown at B. The gauge should be made to register about twelvepounds pressure.

The method of operation is very simple and is outlined at C. The burn-er tube is placed in the cylinder and the trigger valve is opened and theoxygen permitted to circulate in the combustion chamber. A lightedmatch or wax taper is dropped in the chamber and the injector tube ismoved around as much as possible so as to cover a large area. The car-bon takes fire and burns briskly in the presence of the oxygen. Thecombustion of the carbon is accompanied by sparks and sometimes byflame if the deposit is of an oily nature. Once the carbon begins toburn the combustion continues without interruption as long as theoxygen flows into the cylinder. Full instructions accompany each outfitand the amount of pressure for which the regulator should be set de-pends upon the design of the torch and the amount of oxygen con-tained in the storage tank.

REPAIRIKG SCORED CYLINDERS

If the engine has been run at any time without adequate lubrication,one or more of the cylinders may be found to have vertical scratchesrunning up and down the cylinder walls. The depth of these will varyaccord-

ing to the amonnt of time the cylinder was without lubrication, and ifthe grooves are very deep the only remedy is to purchase a new mem-ber. Of course, if sufficient stock is available in the cylinder walls, the

515/821

cylinders may be rebored and new pistons which are oversize, Le., lar-ger than standard, may be fitted. Where the scratches are not deepthey may be ground out with a high speed emery wheel or lapped out ifthat type of machine is not available. Wrist pins have been known tocome loose, especially when these are retained by set screws that arenot properly locked, and as wrist-pins are usually of hard-ened steel itwill be evident that tie sharp edge of that member can act as a cattingtool and make a pronounced groove in the cylinder. Cylinder grindingis a job that requires skilled mechanics, but may be accomplished onany lathe fitted with an internal grinding attachment. While auto-mobile engine cylinders usually have sufficient wall thickness to standreboring, those of airplane engines seldom have sufficient metal topermit of enlarging' the bore very much by a boring tool. A few thou-sandths of an inch may be ground out without danger, however. Anairplane engine cylinder with deep grooves must be scrapped as a gen-eral rule.

Where the grooves in the cylinder are not deep or where it has warpedenough so the rings do not bear equally at all parts of the cylinderbore, it is possible to obtain a fairly accurate degree of finish by a lap-ping process in which an old piston is coated with a mixture of fineemery and oil and is reciprocated up and down in the cylinder as wellas turned at the same time. This may be easily done by using a dummyconnecting rod having-only a wrist pin end boss, and of such size atthe other end so that it can be held in the chuck of a drill press. Thecylinder casting is firmly clamped on the drill press table by suitableclamping blocks, and a wooden block is placed in the combustionchamber to provide a stop for the piston at its lower extreme position.The back gears are put in and the drill chuck is revolved slowly. All the

while that the piston is turning the drill chuck should be raised up anddown by the hand feed lever, as the best results are obtained when the

516/821

lapping member is given a combination of rotary and reciprocatingmotion.

VALVE REMOVAL AND INSPECTION

One of the most important parts of the gasoline engine and one thatrequires frequent inspection and refitting to keep in condition, is themushroom or poppet valve that controls the inlet and exhaust gasflow. In overhauling it is essential that these valves be removed fromtheir seatings and examined carefully for various defects which will beenumerated at proper time. The problem that concerns us now is thebest method of removing the valve. These are h-eld against the seatingin the cylinder by a coil spring which exerts its pressure on the cylin-der casting at the upper end and against a suitable collar held by a keyat the lower end' of the valve stem. In order to remove the valve it isnecessary to first compress the spring by raising the collar and pullingthe retaining key out of the valve stem. Many forms of valve spring lift-ers have been designed to permit ready removal of the valves.

When the cylinder is of the valve in-the-head form, the method ofvalve removal will depend entirely upon the system of cylinder con-struction followed. In the Sturtevant cylinder design it is possible toremove the head from the cylinder castings and the valve springs maybe easily compressed by any suitable means when the cylinder head isplaced on the work bench where it can be easily worked on. The usualmethod is to place the head on a soft cloth with the valves bearingagainsl; the bench. The valve springs may then be easily pushed dowTiwith a simple forked lever and the valve stem key removed to releasethe valve spring collar. In the Curtiss OX-2 (see Fig. 1821^) and Hall-Scott engines it is not possible to remove the valves without taking thecylinder

Valve Removal and Inspection

517/821

425

r the crank-case, because the valve seats are machined rectly in thecylinder head and the valve domes are cast tegrally with the cylinder.This means that if the valves •ed grinding the cylinder must be re-moved from the Lgine base to provide access to the valve heads whiche inside of that member, and which cannot be reached

t. 182yi.—Put Sectional Vi«w, Showing Valve Anangement In Cylinderof OurtUs OZ-2 Aviation Engine.

om the outside as is true of the L-cylLnder construction. I the CurtissVX engines, the valves are carried in de--chable cages which may beremoved when the valves *ed attention.

RESEATING AND TRUING VALVES

Much has been said relative to valve grinding, and ■spite the mass ofinformation given in the trade prints

it is rather amusing to watch the average repairman or the engine nserwho prides himself on maintaining his own motor performing this es-sential operation. The common mistakes are attempting to seat abadly grooved or pitted valve head on an equally bad seat, which is analmost hopeless job, and of using coarse emery and bearing down withall one's weight on the grinding tool with the hope of quickly wearingaway the rough surfaces. The use of improper abrasive material is afertile cause of failure to obtain a satisfactory seating. Valve grinding isnot a difficult operation if certain precautions are taken before under-taking the work. The most important of these is to ascertain if thevalve head or seat is badly scored or pitted. If such is found to be thecase no ordinary amount of grinding will serve to restore the surfaces.In this event the best thing to do is to remove the valve from its seatingand to smooth down both the valve head and the seat in the cylinder

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before attempt is made to fit them together by grinding. Another im-portant precaution is to make sure that the valve stem is straight, andthat the head is not warped out of shape.

A number of simple tools is available at the present time for reseatingvalves, these being outlined at Fig. 183. That shown at A is a simplefixture for facing off the valve head. The stem is supported by suitablebearings carried by the body or shank of the tool, and the head isturned against an angularly disposed cutter which is set for the propervalve seat angle. The valve head is turned by a screw-driver, theamount of stock removed from the head depending upon the locationof the adjusting screw. Care must be taken not to remove too muchmetal, only enough being taken off to remove the most of the rough-ness. Valves are made in two stalndard tapers, the angle being either45 or 60 degrees. It is imperative that the cutter blade be set correctlyin order that the bevel is not changed. A set of valve truing and valve-seat reaming cutters is shown at Fig. 183, B. This is adaptable to vari-ous size valve heads, as the cutter

Valve Restoration

le D may be moved to correspond to the size of the re head being truedup. These cutter blades are made*

^pr

C^/rrcK

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Fig. 1B3.—Tools for Raatorlng Talvfl H«ad and Seats.

tool steel and have a bevel at each end, one at 45 de-;es, the other at60 degrees. The valve seat reamer twn at G will take any one of theheads sho'\\ii at F.

428 . Aviation Engines

It will also take any one of the guide bars shown at R The function ofthe guide bars is to fit the valve stem bearing in order to locate thereamer accurately and to insure that the valve seat is machined con-centrically vith its normal center. Another form of valve seat reamerand a special wrench used to turn it is shown at C. Tlie valve head

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truer shown at Fig. 183, D, is intended to be placed in a vise and is ad-aptable to a variety of valve head sizes. The smaller valves merely fitdeeper in the conical depression. The cutter blade is adjustable andthe valve stem is supported by a simple self-centering bearing. In op-eration it is intended that the valve stem, which protrudes through thelower portion of the guide bearing, shall be turned by a drill press orbit stock while the valve head is set against the cutter by pressure of apad carried at the end of a feed screw which is supported by a hingedbridge member. This can be* swung out of place as indicated to permitplacing the valve head against the cutter or removing it.

As the sizes of valve heads and stems vary considerably a **Universal''valve head truing tool must have some simple means of centering thevalve stem in order to insure concentric machining of the valve head. ^valve head truer which employs an ingenious method of guiding thevalve stem is shown at Fig. 183, E. The device consists of a body por-tion, B, provided wHith an external thread at the top on which the cut-ter head. A, is screwed. A number of steel balls, C, are carried in thegrooves which may be altered in size by the adjustment nut, F, whichscrews in the bottom of the body portion, B. As the nut F is screwed inagainst the spacer member E, the V-grooves are reduced in size andthe steel balls, C, are pressed out in contact Avith the valve stem. Asthe circle or annulus is filled with balls in both upper and lower por-tions the stem may be readily turned because it is virtually supportedby ball bearing guides. "WTien a larger valve stem is to be supported,the adjusting nut F, is screwed out which increases the size of thegrooves

and permits the balls, C, to spread out and allow the larger stem to beinserted.

VALVE GRINDIKG PROCESSES

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Mention has been previously made of the importance of truing bothvalve head and seat before attempt is made to refit the parts by grind-ing. After smoothing the valve seat the next step is to find some way ofturning the valve. Valve heads are usually provided with a screw-driver slot passing through the boss at the top of the valve or with twodrilled holes to take a forked grinding tool. A combination grindingtool • has been devised which may be used when either the two drilledholes or the slotted head form of valve is to be rotated. This consists ofa special form of screw driver having an enlarged boss just above theblade, this boss serving to support a U-shape piece which can be se-curely held in operative position by the clamp screw or which can beturned out of the way if the screw driver blade is to be used.

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As it is desirable to turn the valve through a portion of a revolutionand back again rather than turning it always in the same direction, anumber of special tools has been designed to make this oscillating mo-tion possible without trouble. A simple valve grinding tool is shown atFig. 184,. C. This consists of a screw-driver blade mounted in a handlein such a way that the end may turn freely in the handle. A pinion issecurely fastened to the screw-driver blade shank, and is adapted to fita race provided with a wood handle and guided by a bent bearingmember securely fastened to the screw-driver handle. As the rack ispushed back and forth the pinion must be turned first in one directionand 'then in the other.

A valve grinding tool patterned largely after a breast drill is shown atFig. 184, D. This is worked in such a manner that a continuous rota-tion of the operating crank will result in an oscillating movement ofthe chuck carrying the screw-driver blade. The bevel pinions which are

AxHation Engines

used to turn the chuck are normally free unless clotched | to the chuckstem by the sliding sleeve which mast turn I with the chuck stem andwhich carries clutching members j

Fig. 184.—Tools and ProcesBM UtUised In Valve Orlndlng.

at each end to engage similar members on the bevel pinions and lockthese to the chuck stem, one at a time. The bevel gear carries a cam-piece which moves the clutch

sleeve back and forth as it revolves. This means that the pinion givingforward motion of the chuck is clutched to the chuck spindle for a por-tion of a revolution of. the gear and clutch sleeve is moved back by thecam and clutched to the pinion giving a reverse motion of the chuckduring the remainder of the main drive gear revolution.

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It sometimes happens that the adjusting screw on the valve lift plun-ger or the valve lift plunger itself when L head cylinders are used doesnot permit the valve head to rest against the seat. It will be apparentthat unless a definite space exists between the end of the valve stemand the valve lift plunger that grinding will be of little

*

avail because the valve head will not bear properly against the abrasivematerial smeared on the valve seat. The usual methods of valve grind-ing are clearly outlined at Fig. 184. The view at the left shows themethod of turning the valve by an ordinary screw driver and alsoshows a valve head at A, having both the drilled holes and the screw-driver slot for turning the member and two special forms of fork-endvalve grinding tcois. In the sectional view shown at the right, the use ofthe light spring between the valve head and the bottom of the valvechamber to lift the valve head from the seat whenever pressure on thegrinding tool is released is clearly indicated. It will be noted also that aball of waste or cloth is interposed in the passage between the valvechamber and the cylinder interior to prevent the abrasive materialfrom passing into the cylinder from the valve chamber. When a bit-stock is used, instead of being given a true rotary motion the chuck ismerely oscillated through the greater part of the circle and back again.It is necessary to lift the valve from its seat frequently as the grindingoperation continues; this is to provide an even distribution of the ab-rasive material placed between the valve head and its seat. Only suffi-cient pressure is given to the bitstock to overcome the uplift of thespring and to insure that the valve will be held against the seat. Where

the spring, is not used it is possible to raise the valve from time to timewith the hand which is placed under the valve stem to raise it as thegrinding is carried on. It is not always possible to lift the valve in thismanner when the cylinders are in place on the engine base owing to

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the space between the valve lift plunger and the end of the valve stem.In this event the use of the spring as shoA\Ti in sectional view will bedesirable.

The abrasive generally used is a paste made of medimn or fine emeryand lard oil or kerosene. This is used until the surfaces are comparat-ively smooth, aft«r which the final polish or finish is given with a pasteof flour emery, grindstone dust, crocus, or ground glass and oil. An er-roneous impression prevails in some quarters that the valve head sur-face and the seating must have a niirror-like polish. While this is notnecessary it is essential that the seat in the cylinder and the bevel sur-face of the head be smooth and free from pits or scratches at the com-pletion of the operation. All traces of the emery and oil should be thor-oughly washed out of the valve chamber with gasoline before the valvemechanism is assembled and in fact it is advisable to remove the oldgrinding compound at regular intervals, wash the seat thoroughly andsupply fresh material as the process is in progress.

The truth of seatings may be tested by taking some Prussian blue pig-ment and spreading a thin film of it over the valve seat. The valve isdropped in place and is given about one-eighth turn vdth a little pres-sure on the tool. If the seating is good both valve head and seat will becovered uniformly with color. If high spots exist, the heavy deposit ofcolor will show these while the low spots will be made evident becauseof the lack of pigment. The grinding process should be continued untilthe test shows an even bearing of the valve head at all points of the cyl-inder seating. AMien the valves are held in cages it is possible to catchthe cage in a vise and to turn the valve in any of the ways indicated. Itis much

easier to clean off the emery and oil and there is absolutely no dangerof getting the abrasive material in the cylinder if the construction issuch that the valve cage or cylinder head member carrying the valve

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can be removed from the cylinder. When valves are held in cages, thetightness of the seat may be tested by partially filling the cage wdthgasoline and noticing how much liquid oozes out around the valvehead. The degree of moisture present indicates the efficacy of thegrinding process.

The valves of Curtiss OX-2 cylinders are easily ground in by using asimple fixture or tool and working from the top of the cylinder insteadof from the inside. A tube having a bore just large enough to go overthe valve stem is provided with a wooden handle or taped at one endand a hole of the same size as that drilled through the valve stem is putin at the other. To use, the open end of the tube is pushed over thevalve stem and a split pin pushed through the tube and stem. Thevalve may be easily manipulated and ground in place by oscillating inthe customary manner.

DEPRECIATION IN VALVE OPERATING SYSTEMS

There are a number of points to be watched in the valve operating sys-tem because valve timing may be seri-ously interfered with if there ismuch lost motion at the various bearing points in the valve lift mech-anism. The two conventional methods of opening valves are shown atFig. 185. That at A is the type employed when the valve cages aremounted directly in the head, while the form at B is the system usedwhen the valves are located in a pocket or extension of the cylindercasting as is the case if an L, or T-head cylinder is used. It will be evid-ent that there are several points where depreciation may take place.The simplest form is that shown at B, and even on this there are fivepoints where lost motion may be noted. The periphery of the valveopening cam or roller may be worn, though this is not likely unless theroller or cam has

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been inadvertently left soft. The pin which acts as a bearing for theroller may become worn, this occurriiig quite often. Looseness maymaterialize between the bearing surfaces of the valve lift plunger andthe plunger

Fig. 186.—Outlining Polnta In VaIto Operating Mechanlani Wliai«Dtpn-claUon Ig Apt to Exist.

^ide casting, and there may also be excessive clearance between thetop of tlio plunger and the valve stem.

On the form shown at A, there are several parts added to those indic-ated at B. A walking beam or rocker lever is necessary to transform theupward motion of the tappet rod to a downward motion of the valvestem. The pin

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on which this member fulcrmns may wear as will also.the other pinacting as a hinge or bearing for the yoke end of the tappet rod. It willbe apparent that if slight play existed at each of the points mentionedit might result in a serious diminution of valve opening. Suppose, forexample, that there were .005-inch lost motion at each of three bear-ing points, the total lost motion would be .015-inch or sufficient toproduce noisy action of the valve mechanism. "When valve plungers ofthe adjustable form, such as shown at B, are used, the hardened bolthead in contact with the end of the valve stem may become hollowedout on account of the hammering action at that * point. It is imperat-ive that the top of this member be ground off true and the clearancebetween the valve stem and plunger properly adjusted. If the plungeris a non-adjustable type it will be necessary to lengthen the valve stemby some means in order to reduce the excessive clearance. The onlyremedy for wear at the various hinges and bearing pins is to bore theholes out slightly larger and to fit new hardened steel pins of largerdiameter. Depreciation between the valve plunger guide and the valveplunger is usually remedied by fitting new plunger guides in place ofthe worn ones. If there is sufficient stock in the plunger guide castingas is sometimes the case when these members are not separable fromthe cylinder casting, the guide may be bored out and bushed with alight bronze bushing.

A common cause of irregular engine operation is due to a stickingvalve. This may be owing to a bent valve stem, a weak or broken valvespring or an accumulation of burnt or gummed oil between the valvestem and the valve stem guide. In .order to prevent this the valve stemmust be smoothed with fine emery cloth and no burrs or shoulders al-lowed to remain on it, and the stem must also be straight and at rightangles to the valve head. If the spring is weak it may be strengthenedin some cases by stretching it out after annealing so that a larger spacewill exist between the coils and re-hardening. Obviously

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if a spring is broken the only remedy is replacement of the defectivemember.

Mention has been made of wear in the valve stem guide and its influ-ence on engine action. When these members are an integral part of thecylinder the only method of compensating for this wear is to drill theguide out and fit a bushing, which may be made of steel tube.

In some engines, especially those of recent development, the valvestem guide is driven or screwed into the cylinder casting and is a sep-arate member which niay be removed when worn and replaced with anew one. When the guides become enlarged to such a point that con-siderable play exists between them and the valve stems, they may beeasily knocked out or unscrewed.

PISTON TROUBLES

If an engine has been entirely dismantled it is very easy to examine thepistons for deterioration. While it is important that the piston be agood fit in the cylinder it is mainly upon the piston rings that compres-sion depends. The piston should fit the cylinder with but little loose-ness, the usual practice being to have the piston about .001-inch smal-ler than the bore for each inch of piston diameter at the point wherethe least heat is present or at the bottom of the piston. It is necessaryto allow more than this at the top of the piston owing to its expansiondue to the direct heat of the explosion. The clearance is usually gradu-ated and a piston that would be .005-inch smaller than the cylinderbore at the bottom would be about .0065-inch at the middle and.0075-inch at the top. If much more play than this is evidenced thepiston will ''slap" in the cylinder and the piston will be worn at theends more than in the center. Alumimlm or alloy pistons require moreclearance than cast iron ones do, usually 1.50 times as much. Pistons

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sometimes warp out of shape and are not truly cylindrical. This resultsin the high spots rubbing on the cylinder while the low

Piston and Ring Troubles 487

^- spots will be blackened where a certain amount of gas has leakedby.

Mention has been previously made of the necessity of reboring or reg-rinding a cylinder that has become scored or scratched and which al-lows the gas to leak by tho piston rings. "WTien the cylinder is groundout, it is necessary to use a larger piston to conform to the enlargedcylinder bore. Most manufacturers are prepared to furnish over-sizepistons, there being four standard* oversize dimensions adopted bythe S. A. E. for rebored cylinders. These are .010-inch, .020-inch,.030-inch, and .040-inch larger than the original bore.

The piston rings should be taken out of the piston grooves and all car-bon deposits removed from the inside of the ring and the bottom ofthe groove. It is important to take this deposit out because it preventsthe rings from performing their proper functions by reducing the ringelasticity, and if the deposit is allowed to accumulate it may eventuallyresult in sticking and binding of the ring, this producing excessive fric-tion or loss of compression. When the rings are removed they shouldbe tested to see if they retain their elasticity and it is also well to seethat the small pins in some pistons which keep the rings from turningaround so the joints will not come in line are still in place. If no pinsare fouivi there is no cause for alarm because these dowels are not al-ways used. When fitted, they are utilized with rings having a butt jointor diagonal cut as the superior gas retaining qualities of the lap or stepjoint render the pins unnecessary.

531/821

If gas has been blow^ing by the ring or if these members have notbeen fitting the cylinder properly the points where the gas passed milbe evidenced by burnt, brown or roughened portions of the polishedsurface of the pistons and rings. The point where this discolorationwill be noticed more often is at the thin end of an eccentric ring, thediscoloration being present for about i/^-inch or %-inch each side oftlie slot. It may be possible that

the rings were not true when first put in. This made it possible for thegas to leak by in small amomits initially which increased due to con-tinued pressure until quite a large area for gas escape had beencreated.

PISTON RING MANIPULATION

- Eemoving piston rings without breaking them is a difficult operationif the proper means are not taken, but is a comparatively simple onewhen the trick is known. The tools required are very simple, beingthree strips of thin steel about one-quarter inch wide and four or fiveinches long and a pair of spreading tongs made up of one-quarter inchdiameter keystock tied in the center vdth a copper wire to form ahinge. The construction is such that when the hand is closed and thehandles brought together the other end of the expander spreads out,an action just opposite to that of the conventional pliers. The methodof using the tongs and the metal strips is clearly indicated at Fig. 186.At A the ring expander is shown spreading the ends of the rings suffi-ciently to insert the pieces of sheet metal between one of the rings andthe piston. Grasp the ring as shown at B, pressing with the thumbs onthe top of the piston and the ring will slide off easily, the thih metalstrips acting as guide members to prevent the ring from catching inthe other piston grooves. Usually no difficulty is experienced in re-moving the top or bottom rings, as these members may be easily ex-panded and worked off directly without the use of a metal strip. When

532/821

removing the intermediate rings, however, the metal strips will befound very useful. These are usually made by the repairman by grind-ing the teeth from old hacksaw blades and rounding the edges andcorners in order to reduce the liability of cutting the fingers. By the useof the three metal strips a ring is removed mthout breaking or distort-ing it and practically no time is consumed in the operation.

FITTING PISTON RINGS

Before installing new rings, they should be carefully fitted to thegrooves to which they are applied. The tools required are a large pieceof fine emery cloth, a thin, flat file, a small vise with copper or leadenjaw clips, and a smooth hard surface such as that afforded by the topof a surface plate or a well planed piece of hard wood. After makingsure that all deposits of burnt oil and carbon have been removed fromthe piston grooves, three rings are selected, one for each groove. Thering is turned all around its circumference into the groove it is to fit,which can be done without springing it over the piston as the outsideedge of the ring may be used to test the width of the groove just as wellas the inside edge. The ring should be a fair fit and while free to movecircumferentially there should be no appreciable up and dow:n mo-tion. If the ring is a tight fit it should be laid edge down upon the pieceof emery cloth which is placed on the surface plate and carefullyrubbed down until it fits the groove it is to occupy. It is advisable to fiteach piston ring individually and to mark them in some way to insurethat they wiU be placed in the groove to which they are fitted.

The repairman next turns his attention to fitting the ring in the cylin-der itself. The ring should be pushed into the cylinder at least twoinches up from the bottom and endeavor should be made to have thelower edge of the ring parallel with the bottom of the cylinder. If thering is not of correct diameter, buf is slightly larger than the cylinderbore, this condition will be evident by the angular slots of the rings

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being out of line or by difficulty in inserting the ring if it is a lap jointform. If such is the case the ring is removed from the cylinder andplaced in the vise between soft metal jaw clips. Sufficient metal is re-moved vdih a fine file from the edges of the ring at the slot until theedges come into line and a slight space exists between them when thering is placed into the cylinder. It is important that this space be leftbetween the

ends, for if this is not done when the ring becomes hesW the expan-sion of inctal may cause the ends to abut ui the ring to jam in thecylinder.

It is necessary to use more than ordinary caution Id replacing the ringson the piston l)ecause they are usnillj

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Tig. 186.—Uethodof Removing Piston Binge, and Simple Olamp t tateInsertion of Rings In Cylinder.

made of cast iron, a metal tliat is very fragile and liable to break ltc-cau.se of its hrittlcncss. Special care should be taken in rephicing newrings as these members are

:rinore apt to break than old ones. This is probably accounted for bythe heating action on used rings which tends to anneal the metal aswell as making it less springy. The bottom ring should be placed in po-sition first which - is easily accomplished by springing the ring openenough to pass on the piston and then sliding it into place in the -lower groove which on some types of engines is below the wrist pin,whereas in others all grooves are above that member. The other mem-bers are put in by a reversal of the process outlined at Fig. 186, A andB. It is not always ' necessary to use the guiding strips of metal whenreplacing rings as it is often possible, by putting the rings on the pistona little askew and maneuvering .them to pass the grooves withoutspringing the ring into them. The top ring should be the last oneplaced in position.

Before placing pistons in the cylinder one should make sure that theslots in the piston rings are spaced equidistant on the piston, and ifpins are used to keep the ring from turning one should be careful tomake sure that these pins fit into their holes in the ring and that theyare not Tinder the ring at any point. Practically all cylinders arechamfered at the lower end to make insertion of piston rings easier.The operation of putting on a cylinder casting over a piston really re-quires two pairs of hands, one to manipulate the cylinder, the otherperson to close the rings as they enter the cylinder. This may be donevery easily by a simple clamp member made of sheet brass or iron andused to close the ring as indicated at Fig. 186, C. It is apparent that theclamp must be* adjusted to each individual ring and that the .split

535/821

portion of the clamp must coincide with the split portion of the ring.The cylinder should be well oiled before any attempt is made to installthe pistons. The engine should be run with more than the ordinaryamount of lubricant for "Several hours after new piston rings havebeen inserted. On first starting the engine, one may be disappointed inthat the compression is even less than that obtained wdth the oldrings. This condition will soon be remedied as the rings become

polished and adapt themselves to the contour of the cylinder..

WRIST PIN WEAR

While wrist pins are usually made of very tough steel, case hardenedwith the object of wearing out an easily renewable bronze bushing inthe upper end of the connecting rod rather than the wrist pin it some-times happens that these members will be worn so that even the re-placement of a new bushing in the connecting rod will not reduce thelost motion and attendant noise due to a loose wrist pin. The onlyRemedy is to fit new wrist pins to the piston.. Where the connectingrod is clamped to the wrist pin and that member oscillates in the pis-ton bosses the wear will usually be indicated on bronze bushingswhich are pressed into the piston bosses. These are easily renewed andafter running a reamer through them of the proper size no difficultyshould be experienced in replacing either the old or a new wrist pindepending upon the condition of that member. If no bushings areprovided, as in alloy pistons, the bosses can sometimes be bored outand thin bushings inserted, though this is not always possible. The al-ternative is to ream out the bosses and upper end of rod a trifle largerafter holes are trued up and fit oversize wrist pins.

INSPECTIOX AND REFITTING OF ENGINE BEARINGS

536/821

While the engine is dismantled one has an excellent opportunity to ex-amine the various bearing points in the engine crank-case to ascertainif any looseness exists due to depreciation of the bearing surfaces. Aswill be evident, both main crank-shaft bearings and the lower end ofthe connecting rods may be easily examined for deterioration. Withthe rods in place, it is not difficult to feel the amount of lost motion bygrasping the connecting rod firmly with the hand and moving it upand down. After the connecting rods have been removed and the

•

propeller hub taken off the crank-shaft to permit of ready handling,any looseness in the main bearing may be detected by lifting np oneither the front or rear end of the crank-shaft and observing if there isany lost motion between the shaft journal and the main bearing caps.It is not necessary to take an engine entirely apart to (examine themain bearings, as in most forms these may be readily reached by re-moving the sump. The symptoms of worn main bearings are not hardto identify. If an engine knocks regardless of speed or spark-lever posi-tion, and the trouble is not due to carbon deposits in the. combustionchamber, one may reasonably surmise that the main bearings have be-come loose or that lost motion may exist at the connecting rod bigends, and possibly at the wrist pins. The main journals of any wellresigned engine are usually proportioned with ample surface and willnot wear unduly unless lubrication has been neglected. The connectingrod bearings wear quicker than the main bearings owing to being sub-jected to a greater imit stress, and it may be necessary to take these up.

ADJUSTING MAIN BEARINGS

When the bearings are not worn enough to require refitting the lostmotion can often be eliminated by removing one or more of the thinshims or liners ordinarUy used to separate the bearing caps from the

537/821

seat. These are shown at Fig. 187, A. Care must be taken that an evennumber of shims of the same thickness are removed from each side ofthe journal. If there is considerable lost motion after one or two shimshave been removed, it will be advisable to take out more shims and toscrape the bearing to a fit before the bearing cap is tightened up. Itmay be necessary to clean up the crank-shaft journals as these may bescored due to not having received clean oil or having had bearingsseize upon them. It is not diflScult to true up the crank-pins or mainjournals if the score marks are not deep. A fine file and

^ RS ndng

Bear ng * rf"*" *^ A'w/

^^i^^uff ^

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Fig. 187.—Tools and Processes Used In Befitting Eugia* BeaifnSB.

emery cloth may be used, or a lapping tool such as depicted at Fig. 187,B. The latter is preferable because the file and emery cloth will only

539/821

tend to smooth the surface while the lap will have the effect of restor-ing the crank to proper contour.

A lapping tool may be easily made, as shown at B, tJie blocks being oflead or hard wood. As the width of these are about half that of thecrank-pin the tool may be worked from side to side as it is rotated. Anabrasive paste composed of fine emery powder and oil is placedbetween the blocks, and the blocks are firmly clamped to the crank-pin. As the lead blocks bed down, the wing nut should be tightened toinsure that the abrasive will be held with some degree of pressureagainst the shaft. A liberal supply of new abrading material is placedbetween the lapping blocks and crank-shaft from time to time and theold mixture cleaned off with gasoline. It is necessary to maintain a sideto side movement of the lapping tool in order to have the process af-fect the whole width of the crank-pin equally. The lapping is continueduntil a smooth surface is obtained. If a crank-pin is worn out of true toany extent the only method of restoring it is to have it ground down toproper circular form by a competent mechanic having the necessarymachine tools to carry on the work accurately. A crank-pin truing toolthat may be worked by hand is shown at Fig. 187, K.

After the crank-shaft is trued the next operation is to fit it to the mainbearings or rather to scrape these members to fit the shaft journal. Inorder to bring the brasses doser together, it may be necessary to re-move a little metal from the edges of the caps to compensate for thelost motion. A very simple way of doing this is shown at Fig. 187, D. Apiece'of medium emery cloth is rested on the surface plate and the boxor brass is pushed back and forth over that member by hand, theamount of pressure and rapidity of movement being determined bythe amount of metal it is necessary to remove. This is better than fil-ing, because the edges will be flat and there will be

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no tendency for the bearing caps to rock when placed against the bear-ing seat. It is important to take enough off the edges of the boxes to in-sure that they will grip the crank tightly. The outer diameter must bechecked with a pair of calipers during this operation to make sure thatthe surfaces remain parallel. Otherwise, the bearing brasses will onlygrip at one end and with such insufficient support they will quicklywork loose, both in the bearing seat and bearing cap.

SCRAPING BRASSES TO FIT

To insure that the bearing brasses will be a good fit on the trued-upcrank-pins or crank-shaft journals, they must be scraped to fit thevarious crank-shaft jonmals. The process of scraping, while a tediousone, is not difficult, requiring only patience and some degree of care todo a good job. The surface of the crank-pin is smeared with Prussianblue pigment which is spread. evenly over the entire surface. The bear-ings are then clamped together in the usual manner with the properbolts, and the crank-shaft revolved several times to indicate the highspots on the bearing cap. At the start of the process of scraping in, thebearing may seat only at a few points as shown at Fig. 187, G. Contin-ued scraping will bring the bearing surface as indicated at H, which isa considerable improvement, while the process may be consideredcomplete when the brass indicates a bearing all over as at I. The highspots are indicated by blue, as where the shaft does not bear on thebearing there is no color: The high spots are removed by means of ascraping tool of the form shown at Fig. 187, F, which is easily madefrom a worn-out file. These are forged to shape and ground hollow asindicated in the section, and are kept properly sharpened by frequentrubbing on an ordinary oil stone. To scrape properly, the edge of thescraper must be very keen. The straight and curved half-roundscrapers, shown at M and N, are used for bearings. The

541/821

three-cornered scraper, outlined at 0, is also used on curved surfaces,and is of value in rounding off the sharp corners. The straight orcurved half-round type works weU on soft-bearing metals, such asbabbitt, or white brass, but on yeUow brass or bronze it cuts veryslowly, and as soon as the edge becomes dull considerable pressure isneeded to remove any metal, this calling for frequent sharpening.

When correcting errors on flat or curved surfaces by hand-scraping, itis desirable, of course, to obtain an evenly spotted bearing with as littlescraping as possible. When the part to be scraped is first applied to thesurface-plate, or to a journal in the case of a bearing, three or four**high^' spots may be indicated by the marking materiaL The time re-quired to reduce these high spots and obtain a bearing that is distrib-uted over the entire surface depends largely upon the way the scrapingis started; If the first bearing marks indicate a decided rise in the sur-face, much time can be saved by scraping larger areas than are coveredby the bearing marks; this is especially true of large shaft ai;id enginebearings, etc. An experienced workman wiU not only remove theheavy marks, but also reduce a larger area; then, when the bearing istested again, the marks will generally be distributed somewhat. If theheavy marks which usually appear at first are simply removed by lightscraping, these **point bearings'' are gradually enlarged, but a muchlonger time will be required to distribute them.

The number of times the bearing must be applied to the journal fortesting is important, especially when the box or bearing is large andnot easily handled. The time required to distribute the bearing marksevenly depends largely upon one's judgment in **reading" thesemarks. In the early stages of the scraping operation, the marks shouldbe used partly as a guide for showing the high areas, and instead ofmerely scraping the marked spot the surface surrounding it shouldalso be reduced, unless it is evident that the unevenness is local. Theidea should

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be to obtain first a few large but generally distributed marks; then anevenly and finely spotted surface can be produced quite easily.

In • fitting brasses when these are of the removable type, two methodsmay be used. The upper half of the engine base may be inverted on asuitable bench or stand and the boxes fitted by placing the crank-sha5ft in position, clamping down one bearing cap at a time and fittingeach bearing in succession until they bed equally. From that time onthe bearings should be fitted at the same time so the shaft will be par-allel vdth. the bottom of the cylinders. Considerable time and handlingof the heavy crankshaft may be saved if a preliminary fitting of thebearing brasses is made by clamping them together with a carpenter'swood clamp as shown at Fig. 187, J, and leaving the crank-shaft at-tached to the bench as shown at C. The brasses are revolved aroundthe crank-shaft journal and are scraped to fit w^herever high spots areindicated until they begin to seat fairly. When the brasses assume afinished appearance the final scraping should be carried on with alll3earings in place and revolving the crankshaft to determine the areaof the seating. When the brasses are properly fitted they will not onlyshow a full bearing .surface, but the shaft will not turn unduly hard ifrevolved with a moderate amount of leverage.

Bearings of white metal or babbitt can be fitted tighter than those ofbronze, and care must be observed in supplying lubricant as consider-ably more than the usual amount is needed until the bearings are runin by several hours of test block work. Before the scraping process isstarted it is well to chisel an oil groove in the bearing as showTi at Fig.187, L. Grooves are very helpful in insuring uniform distribution of oilover the entire width of bearing and at the same time act as reservoirsto retain a supply of oil. The tool used is a round-nosed chisel, the ef-fort being made to cut the grooves of uniform depth and havingsmooth sides. Care should be taken not to cut the grooves too deeply,as this will seriously

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reduce the strength of the bearing bushing. The shape of the grooveordinarily provided is clearly shown at Fig. 187, G, and it will be ob-served that the grooves do not extend clear to the edge of the bearing,"but stop about a quarter of an inch from that point. The hole throughwhich the oil is supplied to the bearing is usually drilled in such a waythat it will conununicate with the groove,

The tool shown at Fig, 187, K, is of recent development, and is knownas a * *'crank-shaft equalizer.'* This is a hand-operated turning tool,carrying cutters which are intended to smooth down scored crank-pinswithout using a lathe. The feed may be adjusted by suitable screws andthe device may be fitted to crank-pins and shaft-journals of differentdiameters by other adjusting screws. This device is not hard to oper-ate, being merely clamped around the crank-shaft in the same manneras the lapping tool previously described, and after it has been properlyadjusted it is turned around by the levers provided for the purpose, thecontinuous rotary motion removing the metal just as a lathe toolwould.

FITTING CONNECTING BODS

In the marine type rod, which is the form generally used in airplaneengines, one or two bolts are employed at each side and the cap mustbe removed entirely before the bearing can be taken off of the crank-pin. The tightness of the brasses around the crank-pin can never bedetermined ^solely by the adjustftient of the bolts, as while it is im-portant that these- should be drawn up as tightly as possible, the bear-ing should fit the shaft without undue binding, even if the brassesmust be scraped to insure a proper fit. As is true of the main bearings,the marine form of connecting rod in some engines has a number ofliners or shims interposed between the top and lower portions of therod end, and these may be reduced in number when necessary to bring

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the brasses closer together. The general tendency in airplane enginesis to

Aviation Engines

eliminate shims in either the main or connecting rod bearings, andwhen wear is noticed the boxes or liners are removed and new onessupplied. The brasses are held in the connecting rod and cap by brassrivets and are generally attached in the main bearing by small brassmachine screws. The form of box generally favored is a brass sandcasting rich in copper to secure good heat conductivity which forms abacking for a thin layer of white brass, babbitt or similar anti-frictionmetal.

In fitting new brasses there are two conditions to be avoided, these be-ing outlined at Fig. 18S, B and C. In

Tig, 188.—Showing Points

OlwerTe Wlten Fitting Connecting Bod

the case sho^v-n at C the light edges of the bushings are ■ in contact,but the connecting rod and its cap do not meet. When the retainingnuts are tightened the entire strain is taken on the comparatively small

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area of the edges of the bushings which are not strong enough to with-stand the strains existing and which flatten out quickly, permitting thebearing to run loose. In the example outlined at B tlip edges of thebrasses do not touch ■when the connecting rod rap is drawn in place.This is not good practice, because the brasses soon become loose intheir retaining member. In the case outlined it is neces-

!2

Testing Sprung Cam-shaft 451

sary to file off the faces of the rod and cap tintil these meet, and to in-sure contact of the edges of the brasses "• as well. In event of thebrasses coming together before ^' the cap and rod make contact, asshown at C, the bearing '■ halves should be reduced at the edges untilboth the caps ' and brasses meet against each other or the surfaces ofthe liners as shown at A.

SPRUJNG CAM-SHAFT

If the cam-shaft is sprung or twisted it will alter the valve timing tosuch an extent that the smoothness of operation of the engine will bematerially affected. If this condition is suspected the cam-shaft may beswung on lathe centers and turned to see if it nms out and caS bestraightened in any of the usual form of shaft-straight-e»ing machines.The shaft may be twisted without being spr^g. This can only be de-teLined by supporting Z end of the shaft in an index head and the oth-er end on a milling machine center. The cams are then checked to seethat they are separated by the proper degree of angularity. This pro-cess is one that requires a thorough knowledge of the valve timing ofthe engine in question, and is best done at the factory where the en-gine was made. The timing gears should also be examined to see if theteeth are worn enough so that considerable back lash or lost motion

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exists between them. This is especially important where worm or spir-al gears are used. A worn timing gear not only produces noise, but itwill cause the time of opening and closing of the engine valves to varymaterially.

PRECAUTIONS IK REASSEMBLING PARTS

When all of the essential components of a power plant have been care-fully looked over and cleaned and all defects eliminated, either by ad-justment or replacement of worn portions, the motor should be reas-sembled, taking

* *

care to have the parts occupy just the same relative positions they didbefore the motor was dismantled. As each part is added to the as-semblage care should be taken to insure adequate lubrication of allnew points of bearing by squirting liberal quantities of cylinder oilupon them with a hand oil can or syringe provided for the purpose. Inadjusting the crank-shaft bearings, tighten them one at a time and re-volve the shafts each time one of the bearing caps is set up to insurethat the newly adjusted bearing does not have undue friction. All re-taining keys and pins must be positively placed and it is good practiceto cover such a part with lubricant before replacing it because it willnot only drive in easier, but the part may be removed more easily if ne-cessary at some future time. If not oiled, rust collects around it.

"When a piece is held by more than one bolt or screw, especially if.it isa casting of brittle material such as cast iron or aluminum, the fasten-ing bolts should be tightened uniformly. If one bolt is tightened morethan the rest it is liable to spring the casting enough to break it Springwashers, oheck nuts, split pins or other locking means should always

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be provided, especially on parts which are in motion or subjected toheavy loads.

Before placing the cylinder over the piston it is imperative that theslots in the piston rings are spaced equidistant and that the piston iscopiously oiled before the cylinder is slipped over it. When reas-sembling the inlet and exhaust manifolds it is well to use only perfectpackings or gaskets and to avoid the use of those that seem to havehardened up or flattened out too much in service. If it is necessary touse new gaskets it is imperative to employ these at all joints on a man-ifold, because if old and new gaskets are used together the new onesare apt to keep the manifold from bedding properly upon the usedones. It is well to coat the threads of all bolts and screws subjected toheat, such as cylinder head and exliaust manifold retaining bolts, witha mixture of graphite and oil. Those that enter the water jacket should

be covered with white or red lead or pipe thread compound. Gasketswill hold better if coated with shellac before the manifold or otherparts are placed over them, The shellac fills any irregularities in thejoint and assists materially in preventing leakage after the joint ismade up and the coating has a chance to set.

Before assembling on the shaft, it is necessary to fit the bearings byscraping, the same instructions given for restoring the contour of themain bearings applying just as well in this case. It is apparent that ifthe crank-pins are not round no amount of scraping will insure a truebearing. A point to observe is to make sure that the heads of the boltsare imbedded solidly in their proper position, and that they are notraised by any burrs or particles of dirt under the head which will flat-ten out after thB engine has been run for a time and allow the bolts toslack off. Similarly, care should be taken that there is no foreign mat-ter under the brasses and the box in which they seat. To guard againstthis the bolts should be struck with a hammer several times after they

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are tightened up, and the connecting rod can be hit sharply severaltimes under the cap with a wooden mallet or lead hammer. It is im-portant to pin the brasses in place to prevent movement, as lubricationmay be interfered with if the bushing turns round and breaks the cor-rect register between the oil hole in the cap and brasses.

Care should be taken in screwing on the retaining nuts to insure thatthey will remain in place and not slack off. Spring washers should notbe used on either connecting rod ends or main bearing nuts, becausethese sometimes snap in two pieces and leave the nut slack. The bestmethod of locking is to use well-fitting split pins and castellated nuts.

TESTING BEARING PARALLELISM

It is not possible to give other than general directions regarding theproper degree of tightening for a connecting rod bearing, but as aguide to correct adjustment

it may be said that if the connecting rod cap is tightened sufficiently sothe connecting rod will just about fall over from a vertical position dueto the piston weight when the bolts are fully tightened up, the adjust-ment will be nearly correct. As previously stated, babbitt or white met-al bearings can be set up more tightly than bronze, as the metal issofter and any high spots will soon be leveled down with the running*of the engine. It is important that care be taken to preserve parallelismof the wrist-pins and crank-shafts while scraping in bearings. This canbe determined in two ways. That shown at Fig. 189, A,'is used whenthe parts are not in the engine assembly and when the connecting rodbearing is l^eing fitted to a mandrel or arbor the same size as thecrank-pin. The arbor, which is finished very smooth and of uniformdiameter, is placed in two V blocks, which in turn are supported by alevel surface plate. An adjustable height gauge may be tried, first atone side of the wrist-prQ which is placed at the upper end of the

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connecting rod, then at the other, and any variation wiD be easily de-termined by the degree of tilting of the rod. This test may be madewith the wrist-pin alone, or if the piston is in place, a straight edge orspirit level may be employed. The spirit level will readily show any in-clination while the straight edge is used in connection with the heightgauge as indicated. Of course, the surface plate must be absolutelylevel when tests are made. When the connecting rods are being fittedwith the crank-shaft in place in crank-case, and that member securedin the frame, a steel square may be used as it is reasonable to assumethat the wrist-pin, and consequently the piston it carries, should ob-serve a true relation with the top of the engine base. If the piston sideis at right angles with the top of the engine base- it is reasonable to as-sume that the wrist-pin and crank-pin are parallel If the piston is can-ted to one side or the other, it will indicate that the brasses have beenscraped tapering, which would mean considerable heating and unduefric-

■n if the piston is installed in the cylinder on account the pressureagainst one portion of the cylinder wall, the degree of canting is nottoo great, the connecting

is may be spmng very slightly to straighten np the

VM*-

Mandrel-_ 'Block

■ Straight £dge

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, Connecting Rod

^f^fe^Att r^ffi^

Surface Plate--

Front Bearing ''^^"^'"' ^"^^'"^ '"^End Bearing

C lS9.^U«tliodB of Testing to Inanre PanUellmi of Beulngs AftoiFitting.

tton, but this is a makeshift that is not advised. The ight gauge methodshown above may be used instead the steel square, if desired, becausethe top of the ink-case is planed or milled true and should be parallelth the center line of the crank-shaft.

CAM-SHAFTS AND TIMING GEABS

Knocking sounds are also evident if the cam-shaft is loose in its bear-ings, and also if the canas or timing gears are loose on the shaft. Thecam-shaft is usually supported by solid bearings of the removablebushing type, having no compensation for depreciation. If these bear-ings wear the only remedy is replacement with new ones. In the oldermakes of cars it was general practice to machine the cams separatelyand to secure these to the cam-shaft by means of taper pins or keys.These members sometimes loosened and caused noise. In the event of

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the cams being loose, care should be taken to use new keys or taperpins, as the case may be. If the fastening used was a pin, the holethrough the cam-shaft will invariably be slightly oval from wear. In or-der to insure a tight job, the holes in cam and shaft must be reamedwith the next larger size of standard taper reamer and a larger pindriven in. Another point to watch is the method of retaining the cam-shaft gear in place. On some engines the gear is fastened to a flange onthe cam-shaft by retaining screws. These are not apt to become loose,but where reliance is placed on a key the cam-shaft gear may often beloose on its supporting member. The only remedy is to enlarge the keyslot in both gear and shaft and to fit a larger retaining key.

CHAPTER Xn

Aviation Engine Types —^Division in Classes—^AnzaniEngines—Canton and Unn6 Engine—Construction of GnomeEngines—"Monosou-pape" Gnome—German "Gnome" Type—^LeRhone Engine— Renault Air-Cooled Engine—Simplex Model "A"Hispana-Suiza —Curtiss Aviation Motors—^Thomas-Morse Model 88Engine— Duesenberg Engine—Aeromarine Six-Cylinder—WisconsinAviation Engines—^Hall-Scott Engines—^Mercedes Motor—BenzMotor —^Austro-Daimler—Sunbeam-Coatalen.

AVIATION ENGINE TYPES

Inasmuch as numerous forms of airplane engines have been devised, itwould require a volume of considerable size to describe even the mostimportant developments of recent years. As considerable explanatorymatter has been given in preceding chapters and the principles in-volved in internal combustion engine operation consid-ered in detail,a relatively brief review of the features of some of the most successfulairplane motors should suffice to give the reader a complete enoughunderstanding of the art so all types of engines can be readily

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recognized and the advantages and disadvantages of each type under-stood, as well as defining the constructional features enough so themethods of locating and repairing the common engine and auxiliarysystem troubles will be fully grasped.

Aviation engines can be divided into three main classes. One of theearliest attempts to devise distinctive power plant designs for aircraftinvolved the construction of engines utilizing a radial arrangement ofthe cylinders or a star-wise disposition. Among the engines of thisclass mav be mentioned the Anzani, R. E. P. and the Salmson or Can-ton and Unne forms. The two former are air-cooled, the latter desin:nis water-cooled. Engines

of this type have been built in cylinder numbers ranging from three totwenty. While the simple forms vrere popular in the early days of avi-ation engine development, they have been succeeded by the more con-ventional arrangements which now form the largest class. The reasonfor the adoption of a star-wise arrangement of cylinders has been pre-viously considered. Smoothness of running can only be obtained byusing a considerable number of cylinders. The fundamental reason forthe adoption of the star-wise disposition is that a better distribution ofstress is obtained by having all of the pistons acting on the samecrank-pin so that the crank-throw and pin are continuously undermaximum stress. Some difficulty has been experienced in lubricatingthe low^er cylinders in some forms of six cylinder, rotary crank, radialengines but these have been largely overcome so they are not as seri-ous in practice as a theoretical consideration would indicate.

Another class of engines developed to meet aviation requirements is acomplete departure from the preceding class, though when the en-gines are at rest, it is difficult to differentiate between them. This classincludes engines having a star-wise disposition of the cylinders but thecvlinders themselves and the crank-case rotate and the crank-shaft

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remains stationary. The important rotary engines are the Gnome, theLe Rhone and the Clerget. By far the most important classification isthat including engines which retain the approved design of the types ofpower plants that have been so widely utilized in automobiles andwhich have but slight modifications to increase reliability and mech-anical strength and produce a reduction in weight. This class includesthe vertical engines such as the Duesenberg and Hall-Scott four-cylin-der; the Wisconsin, Aeromarine, Mercedes, Benz, and Ilall-Scott six-cylinder vertical engines and the numerous eight- and twelve-cylinderVee designs such as the Ciirtiss, Renault, Thomas-Morse, Sturtevant,Sunbeam, and others.

ANZANI ENGINES

The attention of the mechanical world was first di*-rected to the greatpossibilities of mechanical flight when Bleriot crossed the EnglishChannel in Jnly, 1909, in a monoplane of his own design and con-struction, having the power furnished by a small three-cylinder air-cooled engine rated at about 24 horse-power and having cylinders 4.13inches bore and 5.12 inches stroke, stated to develop the power atabout 1600 R.P.M. and weighing 145 pounds. The arrangement of thisearly Anzani engine is shown at Fig. 190, and it will be apparent thatin the main, the lines worked out in motorcycle practice were followedto a large extent. The crank-case was of the usual vertically dividedpattern, the cylinders and heads being cast in one piece and held to thecrank-case by stud bolts passing through substantial flanges at the cyl-inder base. In order to utilize but a single crank-pin for the three cylin-ders it was necessary to use two forked rods and one rod of the con-ventional type. The arrangement shown at Fig. 190, called for the useof counterbalanced flywheels which were built up in connection withshafts and a crank-pin to form what corresponds to the usual crank-shaft assembly.

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The inlet valves were of the automatic type so that a very simple valvemechanism consisting only of the exhaust valve push rods wasprovided. One of the difficulties of this arrangement bf cylinders wasthat the impulses are not evenly spaced. For instance, in the formsw^here the cylinders were placed 60 degrees apart the space betweenthe firing of the first cylinder and that next in order was 120 degreescrank-shaft rotation, after which there was an interval of 300 degreesbefore the last cylinder to fire delivered its power stroke. In order toincrease the power given by the simple three-cylinder air-cooled en-gine a six-cylinder water-cooled type, as shown at Figs. 191 and 192,was devised. This was practically the same in action as the three-cylin-der except

Aviation Engines

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Fig. 190ft.—Dlnstrfttioiu Depleting Wrong and Bight Methods of"Swinging tbe Stlclc" to Start Airplane Engine. At Top, Poor Positionto a«t Full Throw and Qet Out of the Way. Below, Correct Foeltlon toG«t Qnlck Torn Over of Crank-Shaft and Spring Away from Fropoller.

Aviation Engine*

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ttiat a doubhf throw crank-shaft was Bsed and while the explosionswere not evenly spacfid th« nmnber of explosions obtained resulted infairly uniform application of power.

The latest design of three-cylinder Anzani engine, which is used tosome extent for school machines, is showii at Fig. 193. In this, thethree-cylinders are s\Tn-

Flg. 191.—The Anzani Stx-Cyllnder Water-Cooled AvlatlOD Snglne.

metrically arranged about the crank-case or 120 degrees apart. Tliebalance is greatly improved by this arrangement and the powerstrokes occur at eqnal intervals of 240 degrees of eraiik-shaft rotation.This method of construction is kno^^■n as the Y design. By groupingtwo of these engines together, as outlined at Fig. 194, which gives aninternal view, and at Fig. 195, which shows the sectional view, and us-ing the ordinary form of double throw crank-shaft with crank-pinsseparated by 180 degrees, a eix-cylinder radial engine is producedwhich runs

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very qiiietly and furnishes a steady output of power. The peculiarity ofthe construction of this eng^ine is in the method of grouping the con-necting rod about the common crank-pin without using forked rods orthe **Mother rod" system employed in the Gnome engines. In the An-zani the method followed is to provide each

Fig. 192.—Sectional VIew.of Ancaul Slx-Oyllnder Watw-CoolftdAvUUtm

connecting rod big end with a shoe which consists of a portion of ahollow cylinder held agaiost the crank-pin by split clamping rings. Thedimensions of these shoes are so proportioned that the two adjacentconnecting rods of a group of three will not come into contact evenwhen the connecting rods are at the minimum relative angle. Thethree shoes of each group rest upon a bronze sleeve which is in halvesand which surrounds the crank-pin

Aviation Engines

and rotates relatively to it once in each crank-shaft rero-lution. Thecollars, which are of tough bronze, resist ik inertia forces while the dir-ect pressure of the explosioni is transmitted directly to the crank-pinbushing by the shoes at the big end of the connecting rod. The same

Fig. 193.—Tbiee-CyUnder Anzani Ali-Oooled T-Fonn Engine.

method of construction, modified to some extent, is used in theLeRhone rotary cylinder engine.

Both cylinders and pistons of the Anzani engines are of cast iron, thecylinders being provided with a liberal pumber of cooling flanges"which are cast integrally. A series of auxiliary exhaust ports is drillednear the base

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Anzani Engine Construction

465

of each cylinder so that a portion of the exhaust gases ^- will flow outof the cylinder when the piston reaches the " end of its power stroke.This reduces the temperature

of the gases passing around the exhaust valves and pre-

Fig. IM.—Aiuuil Fixed Oruik Cane Engine of Uie Blz-OyUnder FormUtilizes Air Cooling Successfully,

vents warping of these members. Another distinctive feature of thisengine design is the method of attaching the Zenith carburetor to anannular chamber surrounding the rear portion of the crank-ease fromwhich the intake pipes leading to the intake valves radiate. Themagneto

Aviation Engines

is the usual six-cylinder form having the armature geared to revolve atone and one-half times crank-shaft speed.

The Anzani aviation engines are also made in teii-and twenty-cylinderforms as shown at Fig. 196. It ■will

exhaast ^ve Rocker.

, Exhaust ^JvePushffod

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'Primary Mr In fake

'flir do'ed Cylinder

Fig. 195.—SectiODtJ View SIiowliiK Internal Parte of Slx-OylinderAmul Engine, witli Starwlse Disposition of OyUnders.

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Aviation Engines

be appar-^nt that in tlie ten-cylinder form explosions will occur every72 degrees of crank-shaft rotation, while in tlic twenty-cylinder, 200liorse-power engine at any in-

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rig. 197.—Application of R. E. P. rivs-CyUnder Fan-Sbape Alr-CooledMotor to Early Monoplane.

slant five i»f till' <-yliridcr.s are always working and ex-l)l().«i()ns an'occurriii,!,^ every 'M't .dt'f^rees of erank-shal't rotiilion. Oti tlietwenty-eyltiidcr I'li.iriiif. twu carlmretors

are used and two magnetos, which are driven at tw^o and one-halftimes crank-shaft speed. The general cylinder and valve constructionis practically the sarnie, as in the simpler engines.

CANTON AND UNNE ENGINE

This engine, which has been devised specially for aviation service, isgenerally knowTi as the /^Salmson'* and is manufactured in bothFrance and Great Britain. It is a nine-cylinder water-cooled radial en-gine, the nine-cylinders being symmetrically disposed around thecrankshaft while the nine connecting rods all operate on a commancrank-pin in somewhat the same manner as the rods in the Gnomemotor. The crank-shaft of the Salm-son engine is not a fixed one andinasmuch as the cylinders do not rotate about the crank-shaft it is ne-cessary for that member to revolve as in the conventional engine. Thestout hollow steel crank-shaft is in two pieces and has a single throw.The crank-shaft is built up somewhat the same as that of the Gnomeengine. Ball bearings are used throughout this engine as will be evid-ent by inspecting the sectional view given at Fig. 199. The nine steelconnecting rods are machined all over and are fitted at each end withbronze bushings, the distance between the bearing centers being about3.2& times crank length. The method of connecting up the rods to thecrank-pin is one of the characteristic features of this design. No**mother'' rod as supplied in the Gnome engine is used in this typeinasmuch as the steel cage or connecting rod carrier is fitted with sym-metrically disposed big end retaining pins. Inasmuch as the carrier is

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mounted on ball bearings some means must be provided of regulatingthe motion of the carrier as if no means were provided the resultingmotion of the pistons would be irregular.

The method by A^hich the piston strokes are made to occur at preciseintervals involves a somewhat lengthy and detailed technical explana-tion. It is sufficient to say

Aviation Engines

that an cpicyclie train of gears, one of which is rigidly attached to thecrank-case so it cannot rotate is used, while other gears make a con-nection between the fixed gear and with another gear which is exactlythe same

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Fig. 198.—The Cantou and Unne Nine-Cylinder Watei-Cooled Badlal

Engine.

size as the fixed gear attached to the crank-case and which is toniie<liiitef!;rally "with the connt'ctiiig rod carrier. The action uf the gcariu.tjis such that the cage carrying the big end retaining pins does not rotateindependently o(

Canton and UnnS Engine

471

le crank-shaft, though, of course, the crank-shaft or ither crank-pinbearings mtist turn inside of the big :id carrier cage.

Cylinders of this engine are of nickel steel machined II over and carrywater-jackets of spun copper which re attached to the cylinders bybrazing. The water

., ^

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Fig. 199.—Bectlonal View Showing Oonstniction of Canton and VaaiWater-Oooled Radial Cylinder Engine.

adtets are corrugated to permit the cylinder to expand reely. The igni-tion is similar to that of the tixed crank otating cylinder engine. An or-dinary magneto of the ivo Spark typo driven at 1% times crank-shaftspeed is officient to ignite tlie seven-cylinder form, while in the

nine-cylinder engines the ignition magneto is of the ' ^^shield^^ typegiving four' sparks per revolution. The magneto is driven at 1% timescrank-shaft speed. Nickel steel valves are used and are carried in cast-ings or cages which screw into bosses in the cylinder head. Each , valveis cam operated through a tappet, push rod and rocker arm, sevencams being used on a seven-cylinder engine and nine cams on thenine-cylinder. One cam serves to open both valves as in its rotation itlifts the tappets in succession and so operates the exhaust and inletvalves respectively. This method of operation in- | volves the sameperiod of intake and exhaust. In normal engine practice the inlet valve

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opens 12 degrees late and closes 20 degrees late. Th6 exhaust opens 45degrees early and closes 6 degrees late. This means about 188 degreesin the case of inlet valve and 231 degrees crank-shaft travel for exhaustvalves. In the Salmson engine, the exhaust closes and the inlet opensat the outer dead center and the exhaust opens and the inlet closes atabout the inner dead center. This engine is also made in a fourteen-cylinder 200 B. H. P. design which is composed of two groups ofseven-cylinders, and it has been made in an eighteen-cylinder designof 600 horse-power. The nine-cylinder 130 horse-power has a cylinderbore of 4.73 inches and a stroke of 5.52 inches. Its normal speed of ro-tation is 1250 E. P. M. Owing to the radial arrangement of the cylin-ders, the weight is but 4l^ pounds per B. H. P.

CONSTRUCTION OF EARLY GNOME MOTOR

It cannot be denied that for a time one of the most widely used of aero-plane motors was the seven-cylinder revolving air-cooled Gnome,made in France. For a total weight of 167 pounds this motor developed45 to 47 horsepower at 1,000 revolutions, being equal to 3.35 poundsper horse-power, and lias proved its reliability by securing many long-distance and endurance records. The same

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engineers have produced a nine-cylinder and by combining two singleengines a fourteen-cyUiider revolving Gnome, having a nominal ratingof 100 horse-power, with which world's speed records w^ere broken.A still more powerful engine has been made with eighteen-cylinders.The nine-cylinder * * monosoupape'' delivers 100 horse-powder at

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1200 R. P. M., the engine of double that number of cylinders is ratedat about 180 horse-power.

Except in the number of cylinders and a few mechanical details thefourteen-cylinder motor is identical with the seven-cylinder one; fullythree-quarters of the parts used by the assemblers would do just*asw^ell for one motor as for the other. Owing to the greater power de-mands of the modern airplane the smaller sizes of Gnome engines arenot used as much as they were except for school machines. There isvery little in this motor that is common to the standard type of verticalmotorcar engine. The cylinders are mounted radially round a circularcrank-case; the crank-shaft is fixed, and the entire mass of cylindersand crank-case revolves around it as outlined at Fig. 200. The explos-ive mixture and the lubricating oil are admitted through the fixedhollow crank-shaft, passed into the explosion chamber through anautomatic intake valve in the piston head in the early pattern, and thespent gases exhausted through a mechanically operated valve in thecylinder head. The course of the gases is practically a radial one. A pe-culiarity of the construction of the motor is that nickel steel is usedthroughout. Aluminum is employed for the two oil pump housings; thesingle compression ring known as the '^obdurator^' for each piston ismade of brass; there are three or four brass bushes; gun metal is em-ployed for certain pins—the rest is machined out of chrome nickelsteel. The crank-case is practically a steel hoop, the depth dependingon w^hether it has to receive seven- or four teen-cylinder s; it has sev-en or fourteen holes bored as illustrated on its circumference. AVhenfourteen or eighteen cylinders are used the holes are

3d in two distinct planes, and offset in relation one to other.

The cylinders of the small engine which have a bore W\o inches and astroke of 4Ko inches, are machined of the solid bar of steel until thethickness of the walls nly 1.5 millimeters—.05905 inch, or practically

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Mg inch. ;h one has twenty-two fins which gradually taper down :heregion of greatest pressure is departed from. In ition to carrying awayheat, the fins assist in strength-ig the walls of the cylinder. The barrelof the cylin-is slipped into the hole bored for it on the circum-mce of.the crank-case and secured by a locking member he nature of a stoutcompression ring, sprung onto a ove on the base of the cylinder withinthe crank cham-. On each lateral face of the crank chamber are sevenis, drilled right through the chamber parallel with the tik-shaft. . Eachone of these holes receives a stout dng-pin of such a diameter that itpresses against split rings of two adjacent cylinders; in addition li cyl-inder is fitted with a key-way. This construction lot always followed,some of the early Gnome engines ig the same system of cylinder reten-tion as used on latest **monosoupape^' pattern.

The exhaust valve is mounted in the cylinder head, . 201, its seatingbeing screwed in by means of a cial box spanner. On the fourteen-cyl-inder model the ire is operated directly by an overhead rocker arm li agun metal rocker at its extremity coming in con-; with the extremity ofthe valve stem. As in standard :or car practice, the valve is opened un-der the lift of vertical push rod, actuated by the cam. The distinc-\ fea-ture is the use of a four-blade leaf spring with ■orked end encirclingthe valve stems and pressing inst a collar on its extremity. On theseven-cylinder iel the movement is reversed, the valve being openedthe downward pull of the push rod, this lifting the er extremity of themain rocker arm, which tips a >ndary and smaller rocker arm in directcontact with

AiAation Engines

the extremity of the valve stem. The springs are same in each ease. Thetwo types are compared al and B, Fig. 202.

_.--yalve Depresiing Exhaust Valve Spring, \^>X~'*^~r-^ Rocker

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rig. 201.—Sectlooal Viev of Early Type Onome CyUuder uid P< Show-ing Constnictlon and Application of Inlet and Ezlianst Valvei

The pistons, like the cylinders, are machined out the solid bar of nickelsteel, and have a portion of tl wall cut away, so that the two adjacentones will come together at the extremity of their stroke. The 1

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of the' piston is slightly reduced in diameter and is provided with agroove into which is fitted a very light L-section brass split ring; backof this ring and carried within the groove is sprung a light steel com-pression ring, serving to keep the brass ring in expansion. As alreadymentioned, the intake valves are automatic, and are mounted in the

572/821

head of the piston as outlined at Fig. 202, C. The valve seating is inhalves, the lower portion being made to receive the wrist-pin and con-necting rod, and the upper portion, carrying the valve, being screwedinto it. The spring is composed of four flat blades, with the hollowedstem of the automatic valve passing through their center and their twoextremities attached to small levers calculated to give balance againstcentrifugal force. The springs are naturally within the piston, and arelubricated by splash from the crank chamber. They are of a delicateconstruction, for it is necessary that they shall be accurately balancedso as to have no tendency to fly open under the action of centrifugalforce. The intake valve is withdrawn by the use of special tools throughthe cylinder head, the exhaust valve being first dismounted. Thefourteen-cylinder motor shown at Fig. 203, has a two-throw crank-shaft with the throws placed at 180 degrees, each one receiving sevenconnecting rods. The parts are the same as for the seven-cylinder mo-tor, the larger one consisting of two groups placed side by side. Foreach group of seven-cylinders there is one main connecting rod, to-gether with six auxiliary rods. The main cgnnecting rod, which, likethe others, is of H section, has machined with it two L-section ringsbored with six holes —51^ degrees apart to take the six other connect-ing rods. The cage of the main connecting rod carries two ball races,one on either side, fitting onto the crank-pin and receiving the thrustof the seven connecting rods. The auxiliary connecting rods are se-cured in position in each case by a hollow steel pin passing throughthe two rings. It is evident that there is a slightly greater angu-laritvfor the six shorter rods, known as auxiliary con-

Gnome En^i-ne Details

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necting rods, than for the longer main rods; this does not appear tohave any influence on the running of the motor.

Coming to the manner in which the earliest design exhaust valves areoperated on the old style motor, this at first sight appears to be one ofthe most complicated parts of the motor, probably because it is one inwhich standard practice is most widely departed from. Within the cyl-indrical casing bolted to the rear face of the crank-case are seven, thinflat-faced steel rings, forming female cams. Across a diameter of each

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ring is a pair of projecting rods fitting in brass guides and having theirextremities terminating in a knuckle eye receiving the adjustable pushrods operating the overhead rocker arms of the exhaust valve. Theguides are not all in the same plane, the difference being equal to thethickness of the steel rings, the total thickness being practically 2inches. Within the female cams is a group of seven male cams of thesame total thickness as the former and rotating within them. As theboss of the male cam comes into contact with the flattened portion ofthe ring forming the female cam, the arm is pushed outward and theexhaust valve opened through the medium of the push-rod and over-head rocker. This construction was afterwards changed to seven malecams and simple valve operating plunger and roller cam followers asshown at Fig. 204.

On the face of the crank-case of the fourteen-cylinder motor oppositeto the valve mechanism is a bolted-on end plate, carrying a pinion fordriving the two magnetos and the two oil pumps, and having bolted toit the distributor for the high-tension current. Each group of seven-cylinders has its own magneto and lubricating pump. The two magne-tos and the two pumps are mounted on the fixed platform carrying thestationary crank-shaft, being driven by the pinion on the revolvingcrank chamber. The magnetos are geared up in the proportion of 4 to7. Mounted on the end plate back of the driving pinion are the twohigh-tension distributor plates, each one with seven brass segments letinto it and connection

Gnome Engine Details

481

made to the plugs by means of plain brass wire. The wire passesthrough a hole in the plug and is then wrapped round itself, giving aloose connection.

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Fig- 201.— 0am and 0«m-G«ar Cue of tlis GnoiuB Seven-OyUnderBeTOlrlng Engine.

Aviation Engines

A good many people doubtless wonder why rotary engines are usuallyprovided with an odd number of cylinders in preference to an evennumber. It is a matter of even torque, as can easily be miderstood fromthe accompanying diagram. Fig. 205, A, represents a six-cylinderrotary engine, the radial lines indicating the cylinders. It is possible to

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fire the charges in two ways, firstly, in rotation, 1, 2, 3, 4, 5, 6, thushaving six impulses in one revolution and none in the next; or altern-ately, 1, 3, 5, 2, 4, 6, in which case the engine will have turned through

Pig. 205.—DiagiEuns Sbowlng Wli; An Odd Number of Orllnden ii Btrifor Botary Cylinder Motors.

an equal number of degree's between impulses 1 and 3, and 3 and 5,but a greater number between 5 and 2, even again between 2 and 4, 4and 6, and a less nxmiber between 6 and 1, as will be clearly seen onreference to the diagram. Turning to Fig. 205, B, which represents aseven-cylinder engine. If the cylinders fire alternately it is obvious thatthe engine turns through an eqnal number of degrees between eachimpulse, thus, 1, 3, 5, 7. 2, 4, 6, 1, 3, etc. Thus supposing the engine tobe revolving, the explosion takes place as each alternate cylinderpasses, for instance, the point 1 on the diagram, and the ignition is ac-tually operated in this way by a single contact.

Gnome Engine Details

488

The crank-shaft of the Gnome, as already explained, is -fixed and hol-low. For the seven- and nine-cylinder motors it has a single throw, andfor the fourteen- and eighteen-cylinder models has two throws at 180degrees. It is of the built-up type, this being necessary on accouiit

.Crank-Shaft End

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ng. 206.—simple

CarbnTetor Used On Earl^ Qnome Engines Attacked to Fixed Orank-SIiaft End.

of the distinctive mounting of the connecting rods. The carburetorshown at Fig. 206 is mounted at one end of the stationary crank-shaft,and the mixture is drawn in through a valve in the piston as alreadyexplained. There is neither float chamber nor jet. In many of the testsmade at the factory it is said the motor will rim with the extremity ofthe gasoline pipe pushed into the hollow

Aviation Engines

crank-shaft, speed being regulated entirely by increaeiiig or decreasingthe flow through the shut^off valve in the base of the tank. Even underthese conditions the motor has been throttled down to run at 350 re-volutions without misfiring. Its normal speed is 1,000 to 1,200

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revolutions a minute. Castor oil is used for lubricating the engine, theoil being injected into the hoUow crank-shaft

Pump Dr lie Saar

Fig. 207.—S«ctlonftl Vt«wB Of Uie Gnome Oil Pomp.

through slight-feed fittings by a mechanically operated pump which isclearly shown in sectional diagrams at Fig. 207.

The Gnome is a considerable consumer of lubricant, the makers' es-timate being 7 pints an hour for the 100 horse-power motor; but inpractice this is largely exceeded. The gasoline consumption is given as300 to 350 grammes per horse-power. The total weight of the four-teen-cylinder motor is 220 pounds without fuel or labri-

Gnome Engine Details

485

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eating oil. Its full power is developed at 1,200 revolutions, and at thisspeed about 9 horse-power is lost in overcoming air resistance to cyl-inder rotation.

While the Gnome engine has many advantages, on the other hand, thehead resistance offered by a motor of this

Current Supply Brush,

_5it

."'Secondary Wire io Plug

^-Ignition Current Supply Wire

^"Magneto Collector Ring

580/821

j w j f ^ Spark Plug

Breaker Points^

Condenser

'Double wound Armature

Magnet"'

,'Pole Pieces,

Fig. 208.—Simplified Diagram Showing Gnome Motor MagnetoIgnition

System.

type is considerable; there is a large waste of lubricating oil due to thecentrifugal force which tends to throw the oil away from the cylinders;the gyroscopic effect of the rotary motor is detrimental to the bestworking of the aeroplane, and moreover it requires about seven percent, of the total power developed by the motor to drive the revolvingcylinders around the shaft. Of necessity, the

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compression of this type of motor is rather low, and an additional dis-advantage manifests itself in the fact that there is as yet no satisfactoryway of muffling the rotary type of motor.

GNOME ''mONOSOUPAPe'' TYPE

The latest type of Gnome engine is known as the **monosoupape"type because but one valve is used in the cylinder head, the inlet valvein the piston being dispensed with on account of the trouble caused bythat | member on earlier engines. The construction of this latest typefollows the lines established in the earlier designs to some extent andit differs only in the method of charging. The very rich mixture of gasand air is forced into the crank-case through the jet inside the crank-shaft, and enters the cylinder when the piston is at its lowest position,through the half-roimd openings in the guiding flange and the smallholes or ports machined in the cylinder and clearly shown at Fig. 210.The returning piston covers the port, and the gas is compressed andfired in the usual way. The exhaust is through a large single valve inthe cylinder head, which gives rise to the name **monosoupape/^ orsingle-valve motor, and this valve also remains open a i>ortion of theintake stroke to admit air into the cylinder and dilute the rich gasforced in from the crank-case interior. Aviators who have used theearly form of Gnome say that the inlet valve in the piston type wasprone to catch on fire if any valve defect materialized, but the^^monoson-pape" pattern is said to be nearly free of this danger. Thebore of the 100 horse-power nine-cylinder engine is 110 nmi., the pis-ton stroke 150 mm. Extremely careful machine work and fitting is ne-cessary. In many parts, tolerances of less than .0004" (four ten thou-sandths of an inch) are all that are allowed. This is about one-sixth thethickness of the average human hair, and in other parts the size mustbe absolutely standard, no appreciable variation being allowable. Themanufacture

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of this engine establishes new mechanical standards of engine produc-tion in this country. Much machine work is needed in producing thefinished components from the bar and forging.

The cylinders, for example, are machined from 6 inch solid steel bars,which are sawed into blanks 11 inches

Fig. 209.—Tlw O. V. Onomo "HoDOBOupap«" Nine-Oylluder BotaryEngine Mounted on Testing Stand.

in length and weighing about 97 pounds. The first operation is to drilla 2^6 inch hole through the center of the block. A heavy-duty drillingmachine performs this

Aviation Engines

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work, then the block goes to the lathe for further operations. Fig. 211shows six stages of the progress of a cylinder, a few of the intermediatesteps being omitted.

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Fig. 211.—How a Qnome OyUnder la Reduced from Solid Chunk ofBMel Weighing 97 Pounds to Finished Cylindei Weighing 51/3Founds.

These give, however, a good idea of the work done. The turning of thegills, or cooUng flanges, is a difficult proposition, owing to the depthof the cut and the thin metal that forms the gills. This operation re-quires the utmost care of tools and the use of a good lubricant toprevent

the metal from tearing as the tools approach their full depth. Thesegills are only 0.6 mm., or 0.0237 in., thick at the top, tapering to athickness of 1.4 mm. (0.0553 in.) at the base, and are 16 nun. (0.632

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in.) deep. When the machine work is completed the cylinder weighsbut 5^^ pounds.

GNOME FUEL SYSTEM, IGNITION AND LUBEICATION

The following description of the fuel supply, ignition and oiling of the**monosoupape,'' or single valve Gnome, is taken from **The Auto-mobile.'^

Gasoline is fed to the engine by means of air pressure at 5 pounds persq. in., which is produced by the air pump on the engine clearly shownat Fig. 210. A pressure gauge convenient to the operator indicates fMspressure, and a valve enables the operator to control it. No carburetoris used. The gasoline flows from the tank through a shut-off valve nearthe operator and through a tube leading through the hollow crank-shaft to a spray nozzle located in the crank-case. There is no throttlevalve, and as each cylinder always receives the same amount of air aslong as the atmospheric pressure is the same, the output cannot bevaried by reducing the fuel supply, except within narrow limits. A fuelcapacity of 65 gallons is provided. The fuel consumption is at the rateof 12 U. S. gallons per hour.

The high-tension magnetos, with double cam or two break per revolu-tion interrupter, is located on the thrust plate in an inverted position,and is driven at such a speed as to produce nine sparks for every tworevolutions; that is, at 214 times engine speed. A Splitdorf magneto isfitted. There- is no distributor on the magneto. The high-tension col-lector brush of the magneto is connected to a distributor brush holdercarried in the bearer plate of the engine. The brush in this brush hold-er is pressed against a distributor ring of insulating material molded inposition in the web of a gear wheel

Gnome Monosoupape Engine

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491

-keyed to the thmst plate, which gear serves also for starting the en-gine by hand. Molded in this ring of insulating material are nine brasscontact sectors,' connecting with contact screws at the back side of thegear, from which bare wires connect to the spark-plugs. The distribut-or revolves at engine speed, instead of at half engine speed as on or-dinary engines, and the distributor brush is brought into electricalconnection with each

Fig. 212.—^Tlw OnoiiM Engine Oun-Oear Oaw, a Fine Example of Ac-cniate MacUne Work.

spark-plug every time the piston in the cylinder in which this spark-plug is located approaches the outer dead center. However, on the ex-haust stroke no spark is being generated in the magneto, hence none isproduced at the spark-plug.

Ordinarily the engine is started by turning on the propeller, but foremergency purposes as in seaplanes or for a qiiick "get away" if land-ing inadvertently in enemy territory, a hand starting crank is provided.

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This is supported in bearings secured to the pressed sted carriers ofthe engine and is provided with a universal .

joint liC'Uvci'ii tlio two supports so as to prevent binding of the crankin tlie bearings <lne to poRsil>le distortion of the supports. The pearon this starting erank and tlic one on tlie thrust plate with which itmeslies are cut

Fig. 213.—G. V. anome "Monoaonpape," with Cam-CaH« Covei Se-moved to Sbow Cams and Valve-Opera ting Pluneeis witli Boiler CamFoUowers.

witli lielical tei'lh of sueli liand tliat tlic starting pinion is tliro\ni outnt! iiiesli as soon as the engine picks up its cycle. A coili-d springsurnuinds ])art of the sliaft of the starting r-iaiik and holds it out of

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gear wlioii not in ii«'. J.nbriraling (lil is (■aiTir<l in a tank ol' '17) gal-hm capacity, and il' lliis tank lias to be placed in a low position

t is connected with the air-pressure line, so that the luction of the oilpump is not depended upon to get the dl to the pump. From the bot-tom of the oil tank a pipe eads to the pump inlet. There are two outletsfrom the )ump, each entering the hollow crank-shaft, and there is Lbranch from each outlet pipe to a circulation indicator onvenient tothe operator. One of the oil leads feeds 0 the housing in the thrustplate containing the two rear ►all bearings, and the other lead feedsthrough the crank-)in to the cams, as already explained.

Owing to the effect of centrifugal force and the fact hat the oil is notused over again, the oil consumption >f a revolving cylinder engine isconsiderably higher than hat of a stationary cylinder engine. Fuel con-sumption s also somewhat higher, and for this reason the revolv-tigcylinder engine is not so weU suited for types of air-)lanes designedfor long trips, as the increased weight .f' suppUes required for suchtrips, as compared with tationary cylinder type motors, more than off-sets the igh weight efficiency of the engine itself. But for short rips,and especially where high speed is required, as in ingle ^ated scoutand battle planes or **avious de basse,'* as the French say, the re-volving cylinder engine tas the advantage. The oil consumption of theGnome ngine is as high as 2.4 gallon per hour. Castor oil is ' ised forlubrication because it is not cut by the gasoline list present in the en-gine interior as an oil of mineral ierivation would be.

GERMAN ''gnome'' TYPE ENGINE

A German adaptation of the Gnome design is shown i Fig. 214. This isknown as the Bayerischen Motoren resellshaft engine and the typeshown is an early design ated at 50 horse-power. The bore is 110 mm.,the stroke s 120 mm., and it is designed to run at a speed of 1,200 I. P.

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M. It is somewhat similar in design to the early jnome *^valve-in-pis-ton" design except that two valves

Aviation. Engine*

are carried in the piston top instead of one. The valve operating ar-rangement is different also, as a single four point cam is used to oper-ate the seven exhaust valves. It is driven by epicyclic gearing, the cambeing driven by an internal gear machined integrally with it, the cam

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being turned at % times the engine speed. Another feature is the meth-od of holding the cylinders on the crank-case. The cylinder is providedwith a flange that registers with a corresponding member of the samediameter on the crank-case. A U section, split clamping ring is boltedin place as shown, this holding both flanges firmly together and keep-ing the cylinder firmly seated against the crank-case flange. The*^monosoupape^' type has also been copied and has received someapplication in Germany, but the most successful German airplanes arepowered with six-cylinder vertical engines" ^uch as the Benz andMercedes.

THE LE RHONE MOTOR

The Le Rhone motor is a radial revolving cylinder engine that hasmany of the principles which are incorporated in the Gnome but whichare considered to be an improvement by many foreign aviators. In-stead of having but one valve in the cylinder head, as the latest type**monosoupape'^ Gnome has, the Le Rhone has two valves, one forintake and one for exhaust in each cylinder. By an ingenious rockerarm and tappet rod arrangement it is possible to operate both valveswith a single push rod. Inlet pipes communicatie with the crank-caseat one end and direct the fresh gas to the inlet valve cage at the other.Another peculiarity in the design is the method of holding the cylin-ders in place. Instead of having a vertically divided crank-case as theGnome engine has and clamping both valves of the case around thecylinders, the crank-case of the Le Rhone engine is in the form of a cyl-inder having nine bosses provided with threaded openings into whichthe cylinders are screwed.

A thread is provided at the basn of each cylinder and wlien till' cylin-dei- lias been screwed down the proper amount it is prevented fromfurther rotation about its awn axis bv a substantial lock nut whichscrews down

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Fig. 215.—Nine-Cylinder Bevolvliig Le Bbone Tjdo Aviation Engine.

against tlic tiireailed boss on the crank-ease. Tlie px-ternalai)p('annK'C' of the T.e Ulione ty|)e motor is clearly shown at Fi<r.2ir>, whih- the genera! fcalures of eon-structinn are eliarly outlined inthe sectional views givi'ii at Figs, i>J(» and 217.

'I

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The two main peealiarities of this motor are the method of valve actu-ation by two large cams and the distinctive crank-shaft and connectingrod big end construction. The connecting rods are provided with**feet" or shoes on the end which fit into grooves lined with bearingmetal which are machined into erank discs

Fig. 217.—Side Sectional Vleir of Lo BIioiM AvUtloa Snglne.

revolving on ball bearings and which are held together so that the con-necting rod big ends are sandwiched between them by clampingscrews. This construction is a modification of that used on the Anzanisis-cylinder radial engine. There are three grooves machined in eacherank disc and three connecting rod big ends run in each pair ofgrooves. The details of this construction can be readily ascertained byreference to explanatory diagrams at Figs. 218 and 219, A. Three of therods which woA

in the groove nearest the crank-pm are provided with short shoes asshown at Fig. 219, B. The short shoes are nsed on the rods employed incylinders number 1, 4, and 7. The set of connecting rods that work inthe central grooves are provided with medium-length shoes

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Valve L fiRads

Fig. 818»-Tl«w Bhnring Ls Bhono Valva Action uid Oonnectlng SodBig End ATTang«iiieiit.

and actnate the pistons in cylinders numbers 3, 6, and 9. The threerods that work in the outside grooves have still longer shoee and areemployed in cylinders numbers 2, 5, and 8. The peculiar profile of theinlet and exhaust cam plates are shown at C, Fig. 219, while the con-struction of the wrist-pin, wrist-pin bushing and piston are clearly out-lined at the sectional view at E. The method

dOO

Aviation Enginet

of valve actuation is clearly outlined at Pig. 220, -which shows an endsection through the cam ease and also a partial side elevation showing

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one of the valve operating levers which is fulcnimed at a central pointand which

Fig. 219.—Dlagcains Showing Impoitant Components of Le RhoneMotor.

has a roller at one end bearing on one cam "while the roller or cam fol-lower at the other end bears on the other cam. Tlie valve rocker armactuating rod is, of course, operated by this simple lever and is at-tached to it in such a way that it can be pulled dovm to depress the in-let valve and pushed up to open the exhaust valve.

Le Rhone Engine Deimh

501

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A carburetor of peculiar construction is employed in the Le Rhone en-gine, this being a very simple type as outlined at Fig. 221. It is attachedto the threaded end of the hollow crank-shaft .by a right and leftcoupling.

Hockvr Shaft Actuafor..

—Row tbo Cams of tbe tn Bhoa« Motor Oan Operate Two Valves witha Single Push Bod.

Aviation Engines

596/821

The fuel is pumped to the spray nozzle, the opening in which is con-trolled by a fuel regulating needle having a long taper which is liftedout of the Jet opening when the air-regulating slide is moved. Theamount of fuel supplied the carburetor is controlled by a specialneedle valve fitting which combines a filter screen and which is shownat B. In regulating the speed of the Le Rhone

Regulafing Slide-

englne, there are two possible means of controlling the mixture, oneby altering the position of the air-regulating slide, which also worksthe metering needle in the jet, and the other by controlling the amountof fuel supplied to the spray nozzle through the special fitting providedfor that purpose.

In considering the action of this engine one can refer to Fig. 222. Thecrank 0. M. is fixed, while the cylinders can turn about the crank-shaftcenter O and the piston

Le Rhone Engine Action

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508

turns around the crank-pin M, because of the eccentricity of the cen-ters of rotation the piston will reciprocate in the cylinders. This dis-tance is at its maximum when the cylinder is above 0 and at a minim-um when it is above M, and the difference between these two positionsis equal to the stroke, which is twice the distance of the crank-throw 0,M. The explosion pressure resolves itself into the force F exerted alongthe line of the connecting rod A, M, and also into a force N,.whichtends to make

X

/

I

Crank Pin —• Center

Crank Shaft' Center

\

*

\

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Firing Order h^-S-7-9-2-4'6-

Fig. 222.—Diagrams Showing Le Bhone Motor Action and FiringOrder.

the cylinders rotate around point 0 in the direction of the arrow. Anodd number of cylinders acting on one crank-pin is desirable to secureequally spaced explosions, as the basic action is the same as theGnome engine.

The magneto is driven by a gear having 36 teeth attached to crank-case which meshes with 16-tooth pinion on armature. The magnetoturns at 2.25 times crank-case speed. Two cams, one for inlet, one for

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exhaust, are mounted on a carrjdng member and act on nine rockerarms which are capable of giving a push-and-pull

Aviation Engineg

motion to the valve-actuating rocker-operating rods. A gear driven bythe crank-case meshes M'ith a larger member having internal teethcarried by the cam carrier. Each cam has iive profiles and is moimtedin staggered

Fig. 223.—Diagram Showing PoaltlonH of Platon In lie Bhone EoUryCylinder Motor.

relation to the other. These give the nine fulcnuned levers the propermotion to open tlie inlet and exhanst valves at the proper time. Thecams are driven at *''/w or %v of the motor speed. The cylinder dinieii-sions and timing' follows; the weight can be approximated by figuring3 pounds per horse-power.

Renault Air-Cooled Vee Engine

505

80 H. P 105 M/M bore 4.20' bore.

140 M/M stroke 5.60* stroke.

110 H. P .112 M/M bore 4.48' bore.

170 M/M stroke 6.80'' stroke.

imine:—Intake valve openincr, lag: 18°^

Intake valve closincr, lag 35°

600/821

Exhaust valve opening, lead 55° }-110 H. P.

Exhaust valve closing, lag 5°

Ignition time advance 26°

18°^ 35° 45° 5° 26°^

^80 H. P.

THE BENAULT AIK-COOLED VEE ENGINE

Air-cooled stationary engines are rarely used in air-lanes, but theEenault Freres of France have for several ears manufactured a com-plete series of such engines of he general design shoWn at Fig. 225,ranging from a

r'^"^v

Opening of Inlet Valve A

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Inlet Valve Closing B ^

Iqnition Point

c

Firing Order l-3-5-7-d-2-4b'd

•->

Opening of Exhaust D

L"xhauL»f V»I\.o Clooinq

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Ig. 224.—Diagrams Showing Valve Timing of Le Rhone AviationEngine.

low-powered one developed eight or nine years ago and rated at 40and 50 horse-power, to later eight-cylinder

B/ovirer Casing-

"Su^nortlng Tubes

Tig. 225.—^Diagrams Showing How OyUndei Oo<ding !■ Effvctad InRenault Vee EnglneE.

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models rated at 70 horse-power and a twelve-cylinder, or twin six,rated at 90 horse-power. The cylinders are of cast iron and are fur-nished with nmnerous cooling ribs

Renault Air-Cooled Fee Engine

507

wMch are cast integrally. The cylinder heads are separate castings andare attached to the cylinder as in early motorcycle engine practice, andserve to hold the cylinder in place on the aluminum alloy crank-caseby a cruciform yoke and four long hold-down bolts (Fig, 226). The

TUC- 22$^-Eiid Sectloiul Vl«w of Beusnlt Alz-Oooled ArlkUonBnglue.

pistons are of cast steel and utilize piston rings of cast iron. The valvesare situated on the inner side of the cylinder head, the arrangement

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being unconventional in that the exhaust valves are placed above theinlet. The inlet valves seat in an extension of the combustion head andare actuated by direct push rod and cam in the usual manner while anoverhead gear in which rockers are oper-

- 1

•T

1 >

•^

■'. '

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Aviation Engine*

which, of conrso, lowers the mean effective pressure and makes tlie (-nginc less efficient than water-cooled forms wilt-re it is possible to usecompression pressure of 100

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7a'

of Renault TwelveXylinder Engitw Orank-Oua, Showing MagnetoSloimting.

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or more pounds per square inch. The 70 horse-power engine* has cyl-inders with a bore of 3.78 inches and a stroke of 5.52 inches. Its weightis given as 396 pounds, w^hen in running order, which figures 5.7pounds per horse-power. The same cylinder size is used on the twelve-cylinder 100 horse-power and the stroke is the same. This engine inrunning order w^eighs 638 pounds, which figures approximately 6.4pounds per B. H. P.

SIMPLEX MODEL ''a'' HISPANO-SUIZA

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The Model A is of the water-cooled four-cycle Vee type, wdth eight cyl-inders, 4.7245 inch bore by 5.1182 inch stroke, piston displacement718 cubic inches. At sea-level it develops 150 horse-powder at 1,450 E.P. M. It can be run successfully at much higher speeds, depending onpropeller design and gearing, developing proportionately increasedpower. The weight, including carburetor, two magnetos, propeller hub,starting magneto and crank, but without radiator, w^ater or oil or ex-haust pipes, is 445 pounds. Average fuel consumption is ..5 pound perhorse-powder hour and the oil consumption at 1,450 R. P. M. is threequarts per hour. The external appearance is showTi at Fig. 230.

Four cylinders are contained in each block, w^hich is of built-up con-struction; the w^ater jackets and valve ports are cast aluminum andthe individual cylinders heat-treated steel forcings tlireaded into thebored holes of the aluminum castings. Each block after assembly isgiven a number of protective coats of enamel, both inside and out,baked on. Coats on the inside are applied under pressure. The pistonsare aluminum castings, ribbed. Connecting rods are tubular, of theforked type. One rod bears directly on the crank-pin; the other rod hasa bearing on the outside of the one first mentioned.

The crank-shaft is of the five-bearing type, very short, stiff in design,bored for lightness and for the oiliiifi: system. The crank-sliaft exten-sion is tapered for the

French standard propeller hub, which is keyed and locked to the shaft.Tliis makes possible instant change of propellers. The ease is in twohalves divided on the center line of the crank-shaft, the bearings beingfitted between the upper and lower sections. The lower half is deep,providing a large oil reservoir and stiffening the engine. The upper halfis simple and provides magneto supports on extension ledges of thetwo main faces. The valves are of large diameter with hollow stems.

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working in cast iron bushings. They are directly operated by a singlehollow cam-shaft located over the valves. The cam-shafts are drivenfrom the crank-shaft by vertical shafts and bevel gears. The cam-shafts, cams and heads of the valve stems are all enclosed in oil-tightremovable housings of cast aluminum.

Oiling is by a positive pressure system. The oil is taken through a filterand steel tubes cast in the case to main bearings, through crank-shaftto crank-pins. The fourth main bearing is also provided Avith an oillead from the system and through tubes running up the end of eachcylinder block, oil is provided for .the cam-

shafts, cams and bearings. The surplus oil escapes through the end ofthe cam-shaft where the driving gears are mounted, and with the oilthat has gathered in the top casing, descends through the drive shaftand gears to the sump.

Ignition is by two eight-cylinder magnetos firing two spark-plugs percylinder. The magnetos are driven from each of the two vertical shaftsby small bevel pinions meshing in bevel gears. The carburetor ismounted between the two cylinder blocks and feeds the two blocksthrough aluminum manifolds which are partly water-jacketed. The en-gine can be equipped with a geared hand crank-starting device.

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STURTEVANT MODEL 5a 140 HORSE-POWER ENGINE

These motors are of the eight-cylinder ** V type, four-stroke cycle,water-cooled, having a bore of 4 inches and a stroke of 5^ inches,equivalent to 102 mm. x 140 mm. The normal operating speed of thecrank-shaft is 2,000 R. P. M. The propeller shaft is driven through re-ducing gears which can be furnished in different gear ratios. Thestandard ratio is 5.3, allowing a propeller speed of 1,200 R. P. M.

The construction of the motor is such as to permit of the application ofa direct drive. The change from the direct drive to gear drive, or viceversa, can be accomplished in approximately one hour.

The cylinders are cast in pairs from an aluminum alloy and areprovided with steel sleeves, carefully fitted into each cylinder. A per-fect contact is secured between cylinder and sleeve; at the same time asleeve can be replaced without injury to the cylinder proper. No diffi-culties due to expansion occur on account of the rapid transmission ofheat and the fact that the sleeve is always at higher temperature thanthe cylinder. A moulded copper asbestos gasket is placed between thecylinder and the head, permitting: the cooling water to circulate

freely and at the same time insuring a tight joint. The cylinder headsare cast in pairs from an aluminum alloy and contain ample water pas-sages for circulation of cooling water over the entire head. Trouble dueto hot valves is thereby eliminated, a most important consideration inthe operation of an aeroplane motor. The water jacket of the head cor-responds to the water jacket of the cylinders and large openings inboth allow the unobstructed circulation of the cooling water. The cyl-inder heads and cylinders are both held to the base by six long bolts.The valves are located in the cylinder heads and are mechanically op-erated. The valves and valve springs are especially accessible and ofsuch size as to permit high volumetric efficiency. The valves are

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constructed of hardened tungsten steel, the heads and stems beingmade from one piece. The valve rocker arms located on the top of thecylinder are provided with adjusting screws. A check nut enables theadjusting screw to be securely locked in position, once the correctclearance has been determined. The rocker arm bearings are ad-equately lubricated by a compression grease cup. Cam-rollers are in-terposed between the cams and the push rods in order to reduce theside thrust on the push rods.

A system of double springs is employed which greatly reduces thestress on each spring and insures utmost reUabiUty. A spring of ex-tremely large diameter returns the valve; a second spring located atthe cylinder base handles the push rod linkage. These springs, whichoperate under low stress, are made from the best of steel and are givena special double heat treatment. The pistons are made from a specialaluminum alloy; are deeply ribbed in the head for cooling and strengthand provided with two piston rings. These pistons are exceedinglylight weight in order to minimize vibration and prevent wear on thebearings. The piston pin is made of chrome nickel steel, bored hollowand hardened. It is allowed to turn, both in piston and connecting rod.The

piston rings are of special design, developed after j^ears of experi-menting in aeronautical engines.

The connecting rods are of ^^H'^ section, machijied all over from for-gings of a special air-hardening chrome nickel steel which, after beingheat treated has a tensile strength of 280,000 pounds per square inch.They are consequently very strong and yet unusually light, and beingmachined all over are of absolutely uniform section, which gives asnearly perfect balance as can be obtained. The big ends are lined withwhite metal and the small ends arQ bushed with phosphor bronze. Theconnecting rods are all alike and take their bearings side by side on the

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crank-pin, the cylinders being offset to permit of this arrangement.The crank-shaft is machined from the highest grade chrome nickelsteel, heat treated in order to obtain the best properties of this materi-al. It is 21/4 inches in diameter (57 mm.) and bored hollowthroughout, insuring maximum strength mth minimum weight. It iscarried in three large, bronze-backed white metal bearings. A newmethod of producing these bearings insures a perfect bond betweenthe* two metals and eliminates breakage.

The base is cast from an aluminum alloy. Great strength and rigidity iscombined with light weight. The sides extend considerably below thecenter line of the crank-shaft, providing an extremely deep section. Atall highly stressed points, deep ribs are provided to distribute the loadevenly and eliminate bending. The lower half of the base is of cast alu-minum alloy of extreme lightness. This collects the lubricating oil andacts as a small reservoir for same. An oil-filtering screen of large areacovers the entire surface^ of the sump. The propeller shaft is carriedon two large annular ball bearings driven from the crank-shaft byhardened chrome nickel steel spur gears. These gears are containedwithin an oil-tight casing integral with the base on the opposite endfrom the timing gears. A ball-thrust bearing is provided on the pro-peller shaft to take the thrust of

a propeller or tractor, as the case may be. In case of the direct drive astub shaft is fastened direct to the crankshaft and is fitted with adouble thrust bearing.

The cam-shaft is contained within the upper half of the base betweenthe two groups of cylinders, and is supported in six bronze bearings. Itis bored hollow throughout and the cams are formed integral A\dththe shaft and ground to the proper shape and finish. An important de-velopment in the shape of cams has resulted in a maintained increaseof power at high speeds. -The gears operating the cam-shaft, magneto,

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oil and water pumps are contained within an oil-tight casing and oper-ate in a bath of oil.

Lubrication is of the complete forced circulating system, the oil beingsupplied to every bearing under high pressure by a rotary pump oflarge capacity. This is operated by gears from the crank-shaft. The oilpassages from the pump to the main bearings are cast integral withthe base, the hollow crank-shaft forming a passage through thecoiuiecting rod bearings and the hollow camshaft distributing the oilto the cam-shaft bearings. The entire surface of the lower half of thebase is covered with a fine mesh screen through which the oil passesbefore reaching the pump. Approximately one gallon of oil is con-tained within the baSe and this is continually circulated through anexternal tank by a secondary pump operated by an eccentric on thecam-shaft. This also draws fresh oil from the external tank which canbe made of any desired capacity.

SPECIFICATIONS—MODEL 5a TYPE 8

»

Horse-power rating, 140 at 2,000 R. P. M.

Bore, 4 inches = 102 mm.

Stroke, 5^ inches = 140 mm.

Number of cylinders, 8.

Arrangement of cylinders, **V.^^

Cooling, water. Circulation by centrifugal pump.

Cycle, four stroke.

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Ignition (double), 2 Bosch or Splitdorf magnetos.

Carburetor, Zenith duplex. Water jacket manifold. I

Oiling system, complete forced. Circulating gear pump. |

Normal crank-shaft speed, 2,000 E. P. M.

Propeller shaft, % crank-shaft speed at normal, 1,200

E. P. M. Stated power at 30'' barometer, 140 B. H. P. Stated weightwdth all accessories but without water,

gasoline or oil, 514 pounds = 234 kilos. Weight per B. H. P., 3.7pounds = 1.68 kilos. Stated w^eight wdth all accessories witli water,550 pounds

. = 250 kilos. Weight per B. H. P. with water, 3.95 pounds = 1.79

kilos.

THE CURTISS AVIATION MOTORS

The Curtiss OX motor has eight cylinders, 4-inch bore, 5-inch stroke,delivers 90 horse-power at 1,400 turns, and the weight turns out at4.17 pounds per horse-power. This motor has cast iron cylinders withmonel metal jackets, overhead inclined valves operated by means oftwo rocker arms, push-and-puU rods from the central cam-shaft loc-ated in the crank-case. The cam and push rod design is extremely in-genious and the whole valve construction turns out very light. Thismotor is an evolution from the early Curtiss type motor >vhich wasused by Glenn Curtiss when he won the Gordon Bennett Cup atRheims. A slightly larger edition of this type motor is the OXX 5, assho\NTi at Figs. 231 and 232, w^hich has cylinders 4l^ inches by 5

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inches, delivers 100 horse-power at 1,400 turns and has the same fueland oil consumption as the OX type motor, namely, .60 pound of fuelper brake horse-power hour and .03 pound of lubricating oil per brakehorse-power hour.

The Curtiss Company have developed in the last two years a larger-sized motor now known as the V-2, which was originally rated at 160horse-powder and which

Curtiss Axnation Motors

519

has since been refined and improved so that the motor gives 220horse-power at 1,400 turns, with a fuel consumption of ^%oo of apound per brake horse-power hour and an oil consumption of .02 of apound per brake horse-power hour. This larger motor has a weight of3.45 pounds per horse-power and is now said to be giving

Magn^tr-,

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Fig. 231.—The OurtUs OXSS AvUtlon Engine 1b an Blglit-OyUndeTType Irfirgely UMd on Training Hacbiues.

very satisfactory service. The V-2 motor has drawn steel cylinders,with a bore of 5 inches and a stroke of 7 inches, with a steel water jack-et top and a monel metal cylindrical jacket, both of which are brazedon to the cylinder barrel itself. Both these motors use side by side con-necting rods and fully forced lubrication. The cam-shafts act as a gal-lery from which the oil is distributed to the cam-shaft bearings, themain crank-shaft

Aviation Engines

bearirigs, and the gearing. Here again we find extremely short rods,■which, as before mentioned, enables the height and the consequentweight of construction to be very much reduced. For ordinary flying ataltitudes of 5,000

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rig. 232.—Top and Bottom Views of the CurtiBs 0ZX6 100 Horoo-Powt ATlatlon Engine.

to 6,000 feet, tlie motors are sent out with an aluminura liner, boltedbetween the cylinder and the crank-case in order to give a eonipres-sioii ratio which does not result in pre-ignitioii at a low altitude. Forhigh flying, however, these aluminum liners are taken out and thecom-

)ression volume is decreased to about 18.6 per cent, of he totalvolume.

The Curtiss Aeroplane Company announces that it has ecently built,and is offering, a twelve-cylinder 5''x7" Qotor, which was designed foraeronautical uses primar-ly. This engine is rated at 250 horse-power,but it is laimed to develop 300 at 1,400 E. P. M. Weights—Motor, ,125

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pounds; radiator, 120 pounds; cooling water, 100 rounds; propeller,95 pounds.

Gasoline Consumption per Horse-power Hourj %o rounds.

Oil Consumption per Hour at Maximum Speed—2 »ints.

Installation Dimensions—Overall length, 84% inches; •verall width,34% inches; overall depth, 40 inches; sddth at bed, 30^/^ inches;height from bed, 21l^ inches; • !epth from bed, 18% inches.

THOMAS-MORSE MODEL. 88 ENGINE

The Thomas-Morse Aircraft Corporation of Ithaca, r. Y., has produceda new engine. Model 88, bearing a. lose resemblance to the earHermodel. The main features f that model have been retained; in fact,many parts re interchangeable in the two engines. Supported by tiegreat development in the wide use of aluminum, the %omas engineershave adopted this material for cylinder onstruction, which adoptionforms the main departure rom previous accepted design.

The marked tendency to-day toward a higher speed f rotation has beenconclusively justified, in the opinion f the Thomas engineers, by thecontinued reliable per-ormance of engines with crank-shafts operatingat speeds tear 2,000 revolutions per minute, driving the propellerhrough suitable gearing at the most efficient speed, ligh speed de-mands that the closest attention be paid 0 the design of reciprocatingand rotating parts and heir adjacent units. Steel of the highestobtainable

tensile strength must be used for connecting rods and piston pins, thatthey may be light and yet retain a sufficient factor of safety. Pistondesign is like\^ise j subjected to the same strict scrutiny. At the

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present j day, aluminum alloy pistons operate so satisfactorily thatthey may be said to have come to stay.

The statement often made in the past, that the gearing down of an en-gine costs more in the weight of reduction gears and propeller shaftthan is warranted by the increase in horse-power, is seldom heard to-day.

The mean effective pressure remaining the same, the * brake horse-power of any engine increases as the speed. That is, an engine deliver-ing 100 brake horse-power at 1,500 revolutions per minute will show133 brake horse-powder at 2,000 revolutions per minute, an increaseof 33 .brake horse-power. To utilize this increase in horsepower, amatter of some fifteen pounds must be spent in gearing and anotherfifteen perhaps on larger valves, bearings, etc. Two per cent, may beassumed lost in the gears. In other words, the increase in horse-powerdue to increasing the speed has been attained at the expense of aboutone pound per brake horse-power.

The advantages of the eight-cylinder engine over the six and twelve,briefly stated, are: lower w^eight per horsepower, shorter length, sim-pler and stiffer crank-shaft, cam-shaft and crank-case, and simplerand more direct manifold arrangement. As to torque, the eight is su-perior to the six, and yet in practice not enough inferior to the twelveto warrant the addition of four more cylinders. It must, however, berecognized that the eight is subject to the action of inlierent unbal-anced inertia couples, which set up horizontal vibrations, impossibleof total elimination. These vibrations are functions of the reciprocatingweights, Avhich, as already mentioned, are cut doA\Ti to the minim-um. Vibrations due to the elasticity of crank-case, crank-shaft, etc.,can be and are reduced in the Thomas engine to minor quantities byample webbing of the crank-case and judi-

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cious nse of metal elsewhere. All things considered, there is actually solittle difference to be discerned between the balance of a properlydesigned eight-cylinder engine and that of a six or twelve as to make adiscussion of the pros and cons more one of theory than of practice,

The main criticisms of the L head cylinder engine are that it is less effi-cient and heavier. This is granted, as it relates to cylinders alone. .More thorough investigation, however, based on the maindesideratum, weight-power ratio, leads us to other conclusions, partic-ularly with reference to high speed engines. The valve gear must notbe forgotten. A cylinder cannot be taken completely away from itscomponent parts and judged, as to its weight value, by itself alone. Apart away from the whole becomes an item unimportant in comparis-on with the whole. The valve gear of a high speed engine is a too oftenoverlooked feature. The stamp of approval has been made by highspeed automobile practice upon the overhead cam-shaft drive, withvalves in the cylinder head operated direct from the cam-shaft or bymeans of valve lifters or short rockers.

The overhead cam-shaft mechanism applied to an eight-cylinder en-gine calls for two separate cam-shafts carried above and supported bythe cylinders in an oil-tight housing, and driven by a series of spurgears or bevels from the crank-shaft. It is patent that this valve gearingis heavy and complicated in comparison with the simple moving valveunits of the L head engine, w^hich are operated from one single cam-shaft, housed rigidly in the crank-case. The inherently lower volumet-ric efficiency of the L head engine is largely overcome by the use of aproperly designed head, large valves and ample gas passages. Again,the customary use of a dual ignition system gives to tlie L head a relat-ively better opportunity for the advantageous placing of spark-plugs,in order that better flame propagation and complete combustion maybe secured.

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The Thomas llodel 88 engine is 4%-mch bore and 514-inch stroke. Thecylinders and cylinder heads are of aluniinum, and as steel liners areused in the cylinders

Ftg. 233.—End View of Thorn as-Morse 150 Horse-Power AlomlDumOylindei Arlatlon Motor Having Detachable Cylinder Heads.

the pistons are also made of aluminum. This engine is actually lighterthan the earlier model of less power. It weighs hut 525 pounds, withself-starter. The general

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features of design can be readily ascertained by study of the illustra-tions: Fig. 233, which shows an end view; Fig. 234, which is a sideview, and Fig. 235, which out-

flf. S31.—side VlBw of Tliomas-Moim High Speed 160 HoTBe-PoweiAvlftUon Motor with Oeand Down Propeller DtItb.

lines the reduction gear-case and the propeller shaft snpportmgbearings.

SIXTEEKT-VALVE DTJESETTBEEG ENGINE

This engine is a four-cylinder, 4%"x7", 125 horsepower at 2,100 H. P.M. of the crank-shaft and 1,210 B. P. M. of the propeller. Motors aresold on above rating; actual power tests prove this motor capable ofdeveloping 140 horse-power at 2,100 R. P. M. of the motor. The exactweight with magneto, carburetor, gear reduction and propeller hub, asillustrated, 509 pounds; without gear reduction, 436 pounds. This mo-tor has been produced as a power plant weighing 3.5 pounds perhorse-power, yet nothing has been sacrificed in rigidity and strength.At its normal speed it develops 1 horse-

Aviation Engines

power for every 3.5 cubic inches piston displacement Cylinders aresemi-steel, with aluminum plates enclosing water jackets. Pistons spe-cially ribbed and made of Magnalite aluminum compound. Pistonrings are special Duesenberg design, being three-piece rings. Valvesare

Fig. 235.—Tlie Bedactioii GeaT-Case of Ttkomas-Morse 150 Horse-Po-vei Aviation Motor, Showing BaU Bearing and Propeller Drive ShaftGear.

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tungsten stct-l. V'-/U" inlets and 2" exhausts, two of each to each tyl-indor. Arranged horizontally in the liead, allowing vory thoroughwator-jaeketing. Inlet valves in cagps. p^xlmust valves, seating dir-ectly in the cylinder head, are r(Miioval)le through the inlet valveholes. Valve stems hihriratod by splash in the valve action covers.Valve rocker arms forged with cap screw and nut at

upper end to adjust clearance. Entirely enclosed by aluminum hous-ing, as is entire valve mechanism. Connecting rods are tubular,chrome nickel steel, light and strong. Crank-shaft is one-piece forging,hollow bored, 2i/^-inch diameter at main bearings. Connecting rodbearings, 214-inch diameter, 3 inches long. Front main bearing, 3i/^inches long; intermediate main bearing, 314 inches long; rear mainbearing, 4 inches long. Crank-case of aluminum, barrel type, oil panon bottom removable. Hand hole plates on both sides. Stronglywebbed. The oiling system of this sixteen-valve Duesenberg motor isone of its vital features. An oil pump located in the base and sub-merged in oil forces oil through cored passages to the three main bear-ings, then through tubes under each connecting rod into which the roddips. The oil is thrown off from these and lubricates every part of themotor. This constitutes the main oiling system; it is supplemented by asplash system, there being a trough under each connecting rod intowhich the rod slips. The oil is returned to the main supply sump bygravity, Avhere it is strained and re-used. Either system is in itself suf-ficient to operate the motor. A pressure gauge is mounted for observa-tion on a convenient part of the system. A pressure of approximately25 pounds is maintained by the pressure system, which insures effi-cient lubrication at all speeds of the motor. The troughs under the con-necting rods are so constructed that no matter what the angle of flightmay be, oil is retained in each individual trough so that each connect-ing rod can dip up its supply of oil at each revolution.

AEROMARINE SIX-CYLINDER VERTICAL MOTOR

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These motors are four-stroke cycle, six-cylinder vertical type, with cyl-inder 4*>i6'' bore by 5%'' stroke. The general appearance of this motoris sho^vn in illustration at Fig. 236. This engine is rated at 85-90horsepower. All reciprocating and revolving parts of this

Aviation Engines

motor are made of the highest grades of steel obtainable as are thestuds, nuts and bolts. The upper and lower parts of crank-case aremade of composition aluminmn casting. Lower crank-case is made ofhigh grade aluminum composition casting and is bolted directly to theupper half. The oil reservoir in this lower half casting provides suffi-cient oil capacity for five hours' continuoos running at full power. In-creased capacity can be pro-

Fig. 236.—Tbe Stx-CyUndei AeTomariDS Engine.

vided if needed to meet greater endurance requirements. Oil is forcedunder pressure to all bearings by means of high-pressured duplex-geared pumps. One side of this pump delivers oil under pressure to allthe hearings, while the other side draws the oil from the splash caseand delivers it to the main sump. The oil reservoir is entirely separate

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from the crank-case chamber. Under ' no circumstances will oil floodthe cylinder, and the oilinir system is not affected in any way by anyangle of flight or position of motor. An oil pressure gauge is placed oninstrument board of machine, which gives at all times

the pressure in oil system, arid a sight glass at lower half of case indic-ates the amount of oil contained. The oil pump is external on magnetoend of motor, and is very accessible. An external oil strainer isprovided, which is removable in a few minutes' time without the lossof any oil. All oil from reservoir to the motor passes through thisstrainer.. Pressure gauge feed is also attached and can be piped to anypart of machine desired.

The cylinders are made of high-grade castings and are machined andground accurately to size. Cylinders are bolted to crank-case withchrome nickel steel studs and nuts which securely lock cylinder to up-per half of crank-case. The main retaining cylinder studs go throughcrank-case and support crank-shaft bearings so that crank-shaft andcylinders are tied together as one unit. Water jackets are of copper,Ke" thick, electrically deposited. This makes a non-corrosive metal.Cooling is furnished by a centrifugal pump, which delivers 25 gallonsper minute 1,400 E. P. M. Pistons are made cast iron, accurately ma-chined and ground to exact dimensions, which are carefully balanced.Piston rings are semi-steel rings of Aeromarine special design.

Connecting rods are of chrome nickel steel, H-section. Crank-shaft ismade of chrome nickel steel, machined all over, and cut from solid bil-let, and is accurately balanced through the medium of balance weightsbeing forged integral with crank. It is drilled for lightness and pluggedfor force feed lubrication. There are seven main bearings to crank-shaft. All bearings are of high-grade babbitt, die cast, and are inter-changeable and easily replaced. The main bearings of the crank-shaftare provided with a single groove to take oil under pressure from

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pressure tube which is cast integral with case. Connecting rod bearingsare of the same type. The gudgeon pin is hardened, ground and se-cured in connecting rod, and is allowed to work in piston. Cam-shaft isof steel, with cams forged integral, drilled for lightness and forced-feedlubrication, and is case-hardened.

Aviatlun Engiws

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—Tlie Wis'onsiii Aviation Engine, at Top, as Viewed from CarliumtorSide. Bnlow, the Enhauat Side.

Wiscoimn Aviation Engine

581

The bearings of cam-shaft are of bronze. Magneto, two high-tensionBosch D. U. 6. The intake manifold for qarburetors are almninimicastmgs and are so desifjned that each carburetor feeds three cylin-ders, thereby insuring easy flow of vapor at all speeds. "Weight, 420pounds.

WISCONSIN AVIATION ENGINES

The new six-cylinder Wisconsin aviation engines, one of which isshown at Fig. 237, are of the vertical type,

Tig. 238.—Dimansloned End Elevatioa of Wisconsin Six Uotor.

with cylinders in^pairs and valves in the head. Dimensioned drawingsof tlie six-cylinder vertical type are given at Figs. 238 and 239. TJic cji-indcrs are made of aluminum alloy castings, are bored and macliinodand then fitted with hardened steel sleeves about Yia incli in thickness.After those sleeves have been shrunk into the cylinders, they are fin-ished by grinding in place. Gray iron valve seats are cast into the cylin-ders. Tlie valve seats and cylinders, as well as the valve jiorts, are

entirely surrounded by water jackets. The valves set in the heads at anangle of 25° from the vertical, arc made of tungsten steel and are'provided with double springs, the outer or main spring and the inneror auxiliary spring, which is used as a precautionary measure to pre-vent a valve falling into the cylinder in remote case of a main spring

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breaking. The cam-shaft is made of one solid forging, case-hardened.It is carried in an

Fig. 230.—Dlmenaloiud Side ElavaUon of Wisconsin Six Motor.

aluminum housing bolted to the top of the cylinders. This housing issplit horizontally, the upper half carrying the chrome vanadium steelrocker levers. The lower half has an oil return trough cast integral,- in-to wliich the excess oil overflows and then drains back to the crank-case. Small inspection plates are fitted over the cams and inner ends ofthe cam rocker levers. The cam-shaft runs in bronze l)earings and thedrive is through vertical shaft and bevel gears.

The erank-case is made of aluminum, the upper half

carrying the bearings for the crank-shaft. The lower half carries the oilsump in which all of the oil except that circulating through the systemat the time is carried. The crank-shaft is made of chrome vanadiumsteel of an elastic limit of 115,000 pounds. The crank-pins and ends ofthe shaft are drilled for lightness and the cheeks are also drilled for oilcirculation. The crank-shaft runs in bronze-backed, Fahrig metal-linedbearings, four in nimiber. A double thrust bearing is also provided, so

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that the motor may be used either in a tractor or pusher type of ma-chine. Outside of the thrust bearing an annular ball bearing is used totake the radial load of the propeller. The propeller is mounted on ataper. At the opposite end of the shaft a bevel gear is fitted whichdrives the cam-shaft, through a vertical shaft, and also drives the wa-ter and oil pumps and magnetos. All gears are made of chrome vana-dium steel, heat-treated.

The connecting rods are tubular and machined from chrome vana-dium steel forgings. Oil tubes are fitted to the rods which carry the oilup to the wrist-pins and pistons. The rods complete with bushingsweigh 5^ pounds each. The pistons are made of aluminum alloy andare very light and strong, weighing only 2 pounds 2 ounces each. Twoleak-proof rings are fitted to each piston. The wrist-pins are hollow, ofhardened steel, and are free to turn either in the piston or the rod. Abronze bushing is fitted in the upper end of the rod, but no bushing isfitted in the pistons, the hardened steel w^ist-pins making an excel-lent bearing in the aluminum alloy.

The water circulation is by centrifugal pump, which is mounted at thelower end of the vertical shaft. The water is pumped through brasspipes to the lower end of the cylinder water jackets and leaves the up-per end of the jackets just above the exhaust valves. The lubricatingsystem is one of the main features of the engines,, being designed towork with tlie motor at any angle. The oil is carried in the sump, fromwhore it is taken

by the oil circulating pump through a strainer and forced through aheader, extending the full length of the crank-case, and distributed tothe main bearings. From tlii> main bearings it is forced through thehollow crankshaft to the connecting rod big ends and then throngh

Wisconsin Aviation Engine

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585

tubes on the rods to wrist-pins and pistons. Another lead takes oilfrom the main header to the cam-shaft bearings. The oil forced out ofthe ends of the camshaft bearings fills pockets under the cams and inthe cam rocker levers. The excess flows back through pipes andthrough the train of gears to the crank-case. A strainer is fitted at eachend of the crank-case, through which the oil is drawn by separatepumps and returned to the sump. Either one of these pumps is largeenough

Fig. 241.—Timing Diagram, Wisconsin Aviation Engine.

to take care of all of the return oil, so that the operation is perfectwhether the motor is inclined up or down. No splash is used in thecrank-case, the system being a full force feed. An oil level indicator isprovided, showing the amount of oil in the sump at all times. The oilpressure in these motors is carried at ten pounds, a relief valve beingfitted to hold the pressure constant.

Ignition is by two Bosch magnetos, each on a separate set of plugsfired simultaneously on opposite sides of the cylinders. Should onemagneto fail, the other would still run the engine at only a slight lossin power. The Zenith double carburetor is used, three cylinders beingsupplied by each carburetor. This insures a higher volumetri" effi-ciency, which means more power, as there is no ovc-

lapping of inlet valves whatever by this arrangement All parts of thesemotors are very accessible. The water and oil pumps, carburetors,magnetos, oil strainer or other parts can be removed without disturb-ing other parts. The lower crank-case can be removed for inspection oradjustment of bearings, as the crank-shaft and bearing caps are

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carried by the upper half. The motor supporting lugs are also part ofthe upper crank-case.

The six-cylinder motor, without carburetors or magnetos, weighs 547pounds. With carburetor and magnetos, the weight is 600 pounds.The weight of cooling water in the motor is 38 pounds. The siunp wdllcarry 4 gallons of oil, or about 28 pounds. A radiator can be furnishedsuitable for the motor, weighing 50 pounds. This radiator will hold 3gallons of water or about 25 pounds. The motor vdM drive a two-blade, 8 feet diameter by 6.25 feet pitch Paragon propeller 1400 re-volutions per minute, developing 148 horse-power. The weight of thispropeller is 42 pounds. This makes a total weight of motor, completewith propeller, radiator filled with water, but without lubricating oil,755 pounds, or about 5.1 pounds per horse-power for complete powerplant. The fuel consumption is .5 pound per horse-power per hour.The lubricating oil consumption is .0175 pound per horse-power perhour, or a total of 2.6 pounds per hour at 1400 revolutions per minute.This would make the weight of fuel and oil, per hour's run at fullpower at 1400 revolutions per minute, 76.6 pounds.

PRINCIPAL. DIMENSIONS

Following are the principal dimensions of the six-cylinder motor:

Bore 5 inches.

Stroke 6^/^ inches.

Crank-shaft diameter throughout 2 inches.

Length of crank-pin and main bearings 3^/2 inches.

Diameter of valves 3 inches (2% inches clear).

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Lift of valves ^ inch.

Volume of compression space 22 per cent, of total.

Diameter of wrist-pins 1%6 inches.

Firing order 1-4-2-6-3-5.

The horse-power developed at 1200 revolutions per minute is 130, at1300 revolutions per minute 140, at 1400 revolutions per minute 148.1400 is the maximum speed at which it is recommended to run thesemotors.

»

TWELVE-CYUNDER ENGINE

A twelve-cylinder V-type engine illustrated, is also being built by thiscompany, similar in dimensions of cylinders to the six. The principaldifferences being in the drive to cam-shaft, which is through spurgears instead of bevel. A hinged type of connecting rod is used whichdoes not increase the length of the motor and, at the same time, thisconstruction provides for ample bearings. A double centrifugal waterpump is provided for this motor, so as to distribute the water uni-formly to both sets of cylinders. Four magnetos are used, two for eachset of six cylinders. The magnetos are very accessibly located on abracket on the spur gear cover. The carburetors are located on the out-side of the motors, w^here they are very accessible, while the exhaustis in the center of the valley. The crank-shaft on the twelve is 2y2inches in diameter and the shaft is bored to reduce weight. Dimen-sioned drawings of the twelve-cylinder engine are given at Figs. 242and 243 and should prove useful for purposes of comparison with oth-er motors.

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HALL-SCOTT AVIATION ENGINES

The following specifications of the Hall-Scott **Big Four^' engines ap-ply just as well to the six-cylinder vertical types which are practicallythe same in construe-tion except for the structural changes necessaryto accommodate the two extra cylinders. Cylindisrs are cast

separately from a special mixture of semi-steel, having cylinder headwith valve seats integral. Special attention has been given to the designof the water jacket aroimd the valves and head, there being two inchesof water

space above same. The cylinder is amiealed, rough ' machined, thenthe inner cylinder wall and valve seats ground to mirror finish. This

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adds to the durability of the cylinder, and diminishes a great deal ofthe excess friction;

Hall-Scott Engines

589

Great care is taken in the casting and machining of these cylinders, tohave the bore and walls concentric ■with each other. Small ribs arecast between onter and inner walls to assist cooling as well as to trans-fer stresses direct from the explosion to hold-down bolts which mnfrom steel main bearing caps to top of cylinders. The cylinders are ma-chined upon the sides so that when assembled on the crank-case withgrooved hold-down

Fig. 213.—Dimensioned Side Elevation of Wisconsin TwelTe-CrlindetAirplane Motor.

waahers tightened, they form a solid block, greatly assisting the rigid-ity of crank-case.

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The connecting rods are very light, being of the I beam type, milledfrom a solid Chrome nickel die forging. The caps are held on by two1/2"-20 thread Chrome nickel through bolts. The rods are firstroughed out, then annealed. Holes are drilled, after which the rods arehardened and holes ground parallel with each other. The piston end isfitted with a gun metal bushing, while the crank-pin end carries twobronze serrated shells, which are tinned and babbitted hot, beingbroached to harden the babbitt. Between the cap and rod proper areplaced

laminated shims for adjustment. Crank-cases are cast of the best alu-minum alloy, hand scraped and sand blasted inside and out. The loweroil case can be removed without breaking any connections, so that theconnecting rods and other working parts can readily be inspected. Anextremely large strainer and dirt trap is located in the center and low-est point of the case, which is easily removed from the outside withoutdisturbing the oil pump or any working parts. A Zenith carburetor isprovided. Automatic valves and springs are absent, making the adjust-ment simple and efficient. This carburetor is not affected by altitude toany appreciable extent. A Hall-Scott device, covered by U. S. PatentNo. 1,078,919, allows the oil to be taken direct from the crank-caseand run around the carburetor manifold, which assists carburetion aswell as reduces crank-case heat. Two waterproof four-cylinder Split-dorf ^^Dixie'' magnetos are provided. Both magneto interruptors areconnected to a rock shaft integral with the motor, making outside con-nections unnecessary. It is worthy of note that with this independentdouble magneto system, one complete magneto can become inoperat-ive, and still the motor will run and continue to give good power.

The pistons as provided in the A-7 engines are cast from a mixture ofsteel and gray iron. These are extremely light, yet provided with sixdeep ribs imder the arch head, greatly aiding the cooling of the pistonas well as strengthening it. The piston pin bosses are located very low

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in order to keep the heat from the piston head away from the upperend of the connecting rod, as well as to arrange them at the pointwhere the piston fits the cylinder best. Three i/4" rings are carried.The pistons as provided in the A-7a engines are cast from aluminumalloy. Four 14" rings are carried. In both piston types a large diameter,heat treated. Chrome nickel steel wrist-pin is provided, assembled insuch a way as to assist the circular rib between the wrist-pin bosses tokeep the piston from being distorted from the explosions.

The oiling system is Known as the high pressure type, oil being forcedto the under side of the main bearings with from 5 to 30 points pres-sure. This system is not affected by extreme angles obtained in flying,or whether the motor is used for push or pull machines. A large gearpmnp is located in the lowest point of the oil sump, and being sub-merged at all times wdth oil, does away with troublesome stuffingboxes and check valves. The oil is first drawn from the strainer in oilsmnp to the long jacket around the intake manifold, then forced to themain distributor pipe in crank-case, which leads to all main bearings.A bi-pass, located at one end of the distributor pipe, can be regulatedto provide any pressure required, the surplus oil being returned to thecase. A special feature of this system is the dirt, water and sedimenttrap, located at the bottom of the oil sump. This can be removedwithout disturbing or dismantling the oil pump or any oil pipes. Asmall oil pressure gauge is provided, which can be run to the aviator^s instrument board. This registers the 'oU pressure, and also deter-mines its circulation.

The cooling of this motor is accomplished by the oil as well as the wa-ter, this being covered by patent No. 1,078,919. This is accomplishedby circulating the oil around a long intake manifold jacket; the carbur-etion of gasoline cools this regardless of weather conditions. Crank-case heat is therefore kept at a minimum. The uniform temperature ofthe cylinders is maintained by the use of ingenious internal outlet

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pipes, running through the head of. each of the six-cylinders, rubberhose connections being used so that any one of the cylinders may beremoved without disturbing the others.. Slots are cut in these pipes sothat cooler water is drawn directly around the exhaust valves. Extralarge water jackets are provided upon the cylinders, two inches of wa-ter space is left above the valves and cylinder head. The water is circu-lated by a large centrifugal pump insuring ample circulation at allspeeds.

//

tl

542 Aviation Engines

The crank-shaft is of the five bearing type, being machined from a spe-cial lieat treated drop forging of the highest grade nickel steel. The for-ging is first drilled, then ronghed out. After this the shaft isstraightened, turned do\\Ti to a grinding size, then ground accuratelyto size. The bearing surfaces are of extremely large size, over-size, con-sidering general practice in the building of high speed engines of simil-ar bore and stroke. The crank-shaft bearings are 2" in diameter byl^^ie long, excepting the rear main bearing, which is 4% long, andfront main bearing, which is 2%6" long. Steel oil scuppers are pinnedand sweated onto the webs of the shaft, which allows of properly oilingthe connecting rod bearings. Two thrust bearings are installed on thepropeller end of the shaft, one for pull and the other for push. The pro-peller is driven by the crank-shaft flange, which is securely held inplace upon the shaft by six keys. These drive an outside propeller -flange, the propeller being clamped between them by six throughbolts. The flange is fitted to a long'taper on crank-shaft. This enablesthe propeller to be removed without disturbing the bolts. Timing gearsand starting ratchets are bolted to a flange turned integral with shaft.

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The cam-shaft is of the one piece type, air pump eccentric, and gearflange being integral. It is made from a low carbon specially heattreated nickel forging, is first roughed out and drilled entire length;the cams are then formed, after which it is case hardened and groundto size. The cam-shaft bearings are extra long, made from Parson'sWliite Brass. A small clutch is milled in gear end of shaft to drive re-volution indicator. The cam-shaft is enclosed in an aluminum housingbolted directly on top of all six cylinders, being driven by a verticalshaft in connection with bevel gears. This shaft, in conjunction withrocker arms, rollers and other working parts, are oiled by forcing theoil into end of shaft, using same as a distributor, allo\^dng the surplussupply to flow back into the crank-case through hollow vertical

tube. This supply oils the magneto and pump gears. Extremely largeTimgsten valves, being one-half the cylinder diameter, are seated inthe cylinder heads. Large diameter oil tempered springs held in toolsteel cups, locked with a key, are provided. The ports are very largeand short, being designed to allow the gases to enter and exhaust withthe least possible resistance. These valves are operated by overheadone piece cam-shaft in connection with short Chrome nickel rockerarms. These arms have hardened tool steel rollers on cam end withhardened tool steel adjusting screws opposite. This construction al-lows accurate valve timing at all speeds with least possible weight.

CENSORED

GERMAN AIRPLANE MOTORS

In a paper on ** Aviation Motors, ^^ presented by E. H. Sherbondybefore the Cleveland section of the S. A. E. in June, 1917, the Mercedesand Benz airplane motor is discussed in some detail and portions ofthe description follow.

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MERCEDES MOTOR

The 150 horse-power six-cylinder Mercedes motor is 140 millimetersbore and 160 millimeters stroke. The Mercedes company started withsmaller-sized cylinders, namely 100 millimeters bore and 140 milli-meters stroke, six-cylinders. The principal features of the design areforged steel cylinders with forged steel elbows for gas passages,pressed steel water jackets, which when welded

CENSORED

Argu9 Engine Construction

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together forms the cylinder assembly, the use of inclined overheadvalves operated by means of an overhead camshaft through rockerarms which multiply with the motion of the cam. By the use of steelcylinders, not only is the weight greatly reduced, but certain freedomfrom distortion through unequal sections, leaks and cracks are entirelyavoided. . The construction is necessarily very expensive.- It is cer-tainly a sound job. In the details of this construction there are a num-ber of important things, such as finished gas passages, water-cooledvalve guides and a very small mass of metal, which is water-cooled,surrounding the spark-plug. Of course, it is necessary to use very highcompression in aviation motors in order to secure high power and eco-nomy and owing to the fact that aviation motors are worked at nearlytheir maximum, the heat flow through the cylinder, piston, and valvesis many times higher than that encountered in automobile motors. Ithas been found necessary to develop special types of pistons to carrythe heat from the center of the head in order to prevent pre-ignition.In the Mercedes motor the pistons have a drop forged steel headwhich includes the piston boss and this head is screwed into a castiron skirt which has been machined inside to secure uniform wallthickness.

The carburetor used on this 150 horse-power Mercedes motor is pre-cisely of the same type used on the Twin Six motor. It has two venturithroats, in the center of which is placed the gasoline spray nozzle ofconventional type, fixed size orifices, immediately above which are

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placed two panel type throttles with side outlets. An idling or primarynozzle is arranged to discharge above the top of the venturi throat. Thecarburetor body is of cast aluminum and is w^ater jacketed. It isbolted directly to air j)assage passing through the top and bottom halfof tlie crank-case which passes down through the oil reservoir. Tlie airbefore reaching the carburetor proper to some extent has cooled theoil in the crank chamber and has itself been heated to assist

Mercedes Engine Details

549

in the vaporization. The inlet pipes themselves are copper. All the pas-sages between the venturi throat and the inlet valve have been care-fully finished and polished. The only abnormal thing in the design ofthis motor is the short connecting rod which is considerably less thantwice the stroke and would be considered very bad practice in motorcar engines. A short connecting rod, however,

Fig. Z46.—Put BacUonal Vlnr of 90 Hoiae-Paw«r Usrcedaa EnglnstWUch ti Trplcftl of tbe DMlgn of Larger Sins.

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possesses two very real virtues in that it cuts down height of the motorand the piston passes over the bottom dead center much more slowlythan with a long rod.

Other features of the design are a very stiff crank-case, both halves ofwhich are bolted together by means of long through bolts, the crank-shaft main bearings are seated in the lower half of the case instead ofin the usual caps and no provision is made for taking up the mainbearings. The Mercedes company uses a plunger

type of pump having mechanically operated piston valves and it isdriven by means of worm gearing.

The overhead cam-shaft construction is extremely light. The cam-shaftis mounted in a nearly cylindrical cast bronze* case and is driven bymeans of bevel gears from the crank-shaft. The vertical bevel gearshaft through which the drive is taken from the crank-shaft to thecam-shaft operates at one and one-half times the crank-shaft speedsand the reduction to the half-time cam-shaft is secured through a pairof bevels. On this vertical shaft there is mounted the water pump and abevel gear for driving two magnetos. The water pump mounted on thisshaft tends to steady the drive and avoid vibration in the gearing.

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The cylinder sizes of six-cylinder aviation motors which have beenbuilt by Mercedes are

The largest of these motors has recently had its horsepower increasedto 176 at 1450 E. P. M. This general design of motor has been thefoundation for a great many other aviation motor designs, some ofwhich have proved very successful but none of which is equal to theoriginal. Among the motors which follow more or less closely thescheme of design and arrangement are the Hall-Scott, the Wisconsinmotor, the Renault water-cooled, the Packard, the Christofferson andthe Rolls-Royce. Each of these motors show considerable variation indetail. The Rolls-Royce and Renault are the only ones who have usedthe steel cylinder with the steel jacket. The Wisconsin motor uses analuminum cylinder with a hardened steel liner and cast-iron valveseats. The Christofferson has somewhat similar design to the Wiscon-sin with the exception that the valve seats are threaded into the alumi-

num jacket and the cylinder head has a blank end which is secured tothe aluminum casting by means of the valve seat pieces. The Rolls-Royce motors show small differences in details of design in cylinderhead and cam-shaft housing from the Mercedes on which it has takenout patents, not only abroad but in this country,

THE BENZ MOTOR

In the Kaiser prize contest for aviation motors a four-cylinder Benzmotor of 130 by 180 mm. won first prize, developing 103 B. H. P. at.1290 R. P. M. The fuel con-sumption was 210 grams per horse-powerhour. Total weight of the motor was 153 kilograms. The oil consump-tion was .02 of a kilogram per horse-power hour. This motor was af-terward expanded into a six-cylinder design and three different sizeswere built.

The accompanying table gives some of the details of weight, horse-power, etc.

Motor tjrpe B FD FF

Rated horse-power 85 100 150

Horse-power at 1250 r.p.m 88 108 150

Horse-power at 1350 r.p.m 95 115 160

Bore in mUlimeters 106 116 130

Stroke in millimeters 150 160 180

Offset of the cylinders in millimeters 18 20 20

Rate of gasoline consumption in grams 240 230 225

Oil consumption in grams per b.h.p. hour. ... 10 10 10

Oil capacity in kilograms 36 4 4^

Water capacity in litres 5% 7% 9%

The weight with water and oil but with two

magnetos, fuel feeder and air pump in

kilograms 170 200 245

The weight of motors. Including the water

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pump, two magnetos, double ignition, etc.. 160 190 230 The weight ofthe exhaust pipe, complete in

kilograms 4 4.8 5 ^

The weight of the propeller hub in kilograms. 3 ^ 4 4

The Ben^ cylinder is a simple, straightforward design and a very reli-able construction and not particularly' difficult to manufacture. Thecylinder is cast of iron without

a water jacket but including 45 degrees angle elbows to the valve ports.The cylinders are machined wherever possible and at other pointshave been hand filed and scraped, after which a jacket, which ispressed in two halves, is gas welded by means of short pipes welded onto the jacket.' The bottom and the top of the cylinders become watergalleries, and by this means separate water pipes with their attendantweight and complication are eliminated. Enbber rings held in alumin-um clamps serve to connect the cylinders together. The whole con-struction turns out very neat and light. The cylinder walls are 4 mm. or%6'' thick and the combustion chamber is of cylindrical pancake fornaand is 140 mm. or 5.60 inch in diameter. The valve seats are 68 nam.in diameter and the valve port is 62 mm. in diameter.

The passage joining the port is 57 mm. in diameter. In order to insertthe valves into the cylinder the valve stem is made with two diametersand the valve has to be cocked to insert it in the guide, which has abronze bushing at its upper end to compensate for the smaller valvestem diameter. The valve stem is 14 mm. or %6" in diameter and is re-duced at its upper portion to 9^ mm. The valves are operated througha push rod. and rocker arm construction, which is %6" and exceed-ingly light. Rocker arm supports are steel studs with enlarged heads totake a double row ball bearing. A roller is mounted at one end of the

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rocker arm to impinge on the end of the valve stem, and the rockerarm has an adjustable globe stud at the other end. The push rods arelight steel tubes with a wall thickness of 0.75 mm. and have ahardened steel cup at their upper end to engage the rocker arm globestud and a hardened steel globe at their lower end to socket in theroller plunger.

The Benz cam-shaft has a diameter of 26 nun. and is bored straightthrough 18 mm. and there is a spiral gear made integrally with theshaft in about the tjenter of its length for driving the oil pump gear.The cam faces are 10 mm. wide. There is also, in addition to the intake

and exhaust cams, a set of half compression cams. The shaft is movedlongitudinally in its bearings by means of an eccentric to put thesecams into action. At the fore end of the shaft is a driving gear flangewhich is very small in diameter and very thin. The flange is 68 mm. indiameter and 4 mm. thick and is tapped to take 6 mm. bolts. The totallength of cam-shaft is 1038 mm., and it becomes a regular gun boringjob to driU a hole of this length.

The cam-shaft gear is 140 mm. or 5^^ inches outside diameter. It hasfifty-four teeth and the gear face is 15 mm. or ^%2''. The flange andweb have an average liiick-ness of 4 mm. or %2'^ and the web isdrilled full of holes interposed between the spur gear mounted on thecamshaft and the cam-shaft gear. There is a gear which serves to drivethe magnetos and tachometer, also the air pump. The shaft is made in-tegrally with this gear and has an eccentric portion against which theair pump roll plunger impinges.

The seven-bearing crank-shaft is finished all over in a beautiful man-ner, and the shaft out of the particular motor we have shows no signsof wear whatever. The crank-pins are 55 mm. in diameter and 69 mm.long. Through both the crank-pin and main bearings there is drilled a

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28 mm. hole, and the crank cheeks are plugged with solder. The crankcheeks are also built to convey the lubricant to the crank-pins. At thefore end of the crank cheek there is pressed on a spur driving gear.There is screwed on to the front end of the shaft a piece which forms abevel water pump driving gear and the starting dog. At the rear end ofthe shaft very close to the propeller hub mounting there is a doublethrust bearing to take the propeller thrust.

Long, shouldered studs are screwed into the top half of the crank-caseportion of the case and pass clean through the bottom half of the case.The case is very stiff and well ribbed. The three center bearing dia-phragms have double walls. The center one serves as a

duct through which water pipe passes, and those on either side of thecenter form the carburetor intake air passages and are enlarged in sec-tion at one side to take the carburetor barrel throttle.

The pistons are of cast iron and carry three concentric rings 1/4 i^chwide on their upper end, which are pinned at the joint. The top of thepiston forms the frustum of the cone and the pistons are 110 mm. inlength. The lower portion of the skirt is machined inside and has a wallthickness of 1 mm. Eiveted to the piston head is a conical diaphragmwhich contacts with the piston pin when in place and serves to carrythe heat off the center of the piston.

The oil pump assembly comprises a pair of plunger pumps which drawoil from a separate outside pump, and constructed integrally with it isa gear pump which delivers the oil under about 60 pound pressurethrough a set of copper pipes.in the base to the main bearings. Theplunger oil pump shows great refinement of detail. A worm wheel andtwo eccentrics are machined up out of one piece and serve to operatethe plungers.

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Some interesting details of the 160 horse-power Benz motor, which isshown at Fig. 246, are reproduced from the ** Aerial Age Weekly, ^^and show how carefully the design has been considered.

Maximum horse-power, 167.5 B. H. P.

Speed at maximimi horse-power, 1,500 E. P. M.

Piston speed at maximum horse-power, 1,770 ft. per minute.

Normal horse-power, 160 B. H. P.

Speed at normal horse-power, 1,400 E. P. M.

Piston speed at normal horse-power, 1,656 ft. per minute.

Brake mean pressure at maximum horse-power, 101.2 pound persquare inch.

Brake mean pressure at normal horse-power, 103.4 pound per squareinch.

The Benz Motor

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Specific power cubic inch swept volume per B. H. P., 5.46 cubic inch;160 B. H. P.

Weight of piston, complete with gudgeon pin, rings, etc.,. 5.0 pound.

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Weight of connecting rod, complete with bearings, 4.99 pound; 1.8pound reciprocating.

Weight of reciprocating parts per cylinder, 6.8 pound.

Weight of reciprocating parts per square inch of piston area, 0.33pound.

Outside diameter of inlet valve, 68 nun.; 2.68 inches.

Diameter of inlet valve port (rf), 61.5 mm.; 2.42 inches.

Maximum lift of inlet valve (fe), 11 mm., 0.443 inch.

Area of inlet valve opening (wrffe), 21.25 square cm.; 3.29 squareinches.

Inlet valve opens, degrees on crank, top dead center.

Inlet valve closes, degrees on crank, 60° late; 35 mm. late.

Outside diameter of exhaust valve, 68 mm., 2.68 inches.

Diameter of exhaust valve port (rf), 61.5 nun.; 2!42 inches.

Maximum lift or exhaust valve (h) 11 nun.; 0.433 inch.

Area of exhaust valve opening (wrf/i), 21.25 square cm.; 3.29 squareinches.

Exhaust valve opens, degrees on crank, 60° early; 35 mm. early.

Exhaust valve closes, degrees on crank, 16^^° late; 5 mm. late.

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Length of connecting rod between centers, 314 mm.; 12.36 inches.

Ratio connecting rod to crank throw, 3.49:1.

Diamoter of crank-sliaft, 56 mm. outside, 2.165 inches; 28 mm. inside,1.103 inches.

Diameter of crank-pin, 55 mm. outside, 2.165 inches; 28 mm. inside,1.102 inches.

Diamoter of gudgeon pin, 30 mm. outside, 1.181 inches; 19 mm. in-side, 0.708 inch.

Diameter of cam-shaft, 26 mm. outside, 1.023 inches; 18 mm. inside,0.708 inch.

Number of crank-shaft bearings, 7.

Projected area of crank-pin bearings, 36.85 square cm.; 5.72 squareinches.

Projected area of gudgeon pin bearings, 22.20 square cm.; 3.44 squareinches.

Filing sequence, 1, 5, 3, 6, 2, 4.

Type of magnetos, ZH6 Bosch.

Direction of rotation of magneto from driving end, one clock, one anti-clock.

Magneto timing, full advance, 30° early (16 nam. early).

Type of carburetors (2) Benz design.

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Fuel consumption per hour, normal horse-power, 0.57 pint.

Normal speed of propeller, engine speed, 1,400 E. P. M.

AUSTRO-DAIMLER ENGINE

One of the first very successful European flying engines which was de-veloped in Europe is the Austro-Daimler, which is shown in end sec-tion in a preceding chapter. The first of these motors had four-cylin-ders, 120 by 140 millimeters, bore and stroke, with cast iron cylinders,overhead valves operated by means of a single rocker arm, controlledby two cams and the valves were closed by a single leaf spring whichoscillates with the rocker arm. The cylinders are cast singly and haveeither copper or steel jackets applied to them. The four-cylinder designwas afterwards expanded to the six-cylinder design and still later a six-cylinder motor of 130 by 175 millimeters was developed. This motoruses an offset crank-shaft, as does the Benz motor, and the effect ofoffset has been discussed earlier on in this treatise. The Benz motoralso uses an offset cam-shaft which improves the valve operation andchanges the valve lift diagram. The lubrication also is different thanany other aviation motor, since

individual high pressure metering pumps are used to deliver fresh oilonly to the bearings and cylinders, as was the custom in automobilepractice some ten years ago.

SUNBEAM AVIATION ENGINES

These very successful engines have been developed by Louis Coatalen.At the opening of the war the largest sized Coatalen motor was 225horse-power and was of the Lrhead type having a single cam-shaft foroperating valves and was an evolution from the twelve-cylinder racingcar which the Sunbeam Company had previously built. Since 1914 theSunbeam Company have produced engines of six-, eight-, twelve- and

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eighteen-cylinders from 150 to 500 horse-power with both iron andalmninum cylinders. For the last two years all the motors have hadoverhead cam-shafts with a separate shaft for operating the intake andexhaust valves. Cam-shafts are connected through to the crank-shaftby means of a train of spur gears, all of which are mounted on twodouble row ball bearings. In the twin six, 350 horse-power engine, op-erating at 2100 R. P. M., requires about 4 horse-power to operate thecam-shafts. This motor gives 362 horsepower at 2100 revolutions andhas a fuel cousmnption of '^Koo of a pint per brake horse-power hour.The cylinders are 110 by 160 millimeters. The same design has beenexpanded into an eighteen-cylinder which gives 525 horsepower at2100 turns. There has also been developed a very successful eight-cyl-inder motor rated at 2220 horsepower which has a bore and stroke of120 by 130 millimeters, weight 450 pounds. This motor is an alumin-um block construction with steel sleeves inserted. Three valves are op-erated, one for the inlet and two for the exhaust. One cam-shaft oper-ates the three valves.

The modern Sunbeam engines operate with a mean effective pressureof 135 pounds with a compression ratio of 6 to 1 sea level. The con-necting rods are of the articulated t\T)e as in the Renault motor andare very short

Sunbeam Aviation Engines

559

The ■weight of these motors turns out at 2,6 pounds per brake horse-power, and they are able to go through a 100 hour test without anytrouble of any kind. The lubricating system comprises a dry base andoil pump for

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Tig. 217,—At Top, tbB Simb«im Orerliflad VUve 170 Hone-Powai BlXrGTliiUm Engine. Beloir, Sldo View of Simbeiiii 360 Hone-PoverTwelTO-C:^lnder V«e Engine.

drawing the oil off from the base, whence it is delivered to the filterand cooling system. It then is pumped by a separate high pressuregear pump through the entire motor. In these larger European motors,castor-oil is

Aviation Engines

IJjgJJ

.In

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Sunbeam Aviation Engines

561

used largely for lubrication. It is said that without the use of castor-oilit is impossible to hold full power for five hours. Coatalen favors alu-minum cylinders rather than cast iron. The series of views in Figs. 247to 250 inclusive, illustrates the vertical, narrow type of engine; the V-form; and the broad arrow type wherein three

Fig. 2d9.—Simbeua EiglitMn-Cylliider Motor, Vlewod from Pump andMagneto End.

rows, each of six-cylinders, are set on a common crank-case. In thiswater-cooled series the gasoline and oil consumption are notably low,as is the weight per horsepower.

In the eighteen-cylinder overhead valve Sunbeam-Coatalen aircraftengine of 475 brake horse-power, there are no fewer than half a dozen

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magnetos. Each magneto is inclosed. Two sparks are furnished to eachcylinder

Aviation Engines

from' independent magnetos. On this engine there are also no fewerthan six carburetors. Shortness of crankshaft, and therefore of enginelength, and absence of vibration are achieved by the linking of theconnecting-rods. Those concerned with three-cylinders in the broadarrow formation work on one crank-pin, the outer rods being linked tothe central master one. In consequence

Ftg. 250.—PiopeUer End of Sonbeam Elghtasu-Oyllitdei f75 BTTPAvlaUon Engine.

of this arrangement, the piston travel in the case of the central row ofcylinders is 160 mm., while the stroke of the pistons of the cylindersset on either side is in each ease 168 mm. Inasmuch as each set of six-

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cylinders is completely balanced in itself, this difference in stroke doesnot affect the balance of tlie engine as a whole. The

inplicate ignition scheme also applies to the twelve-ylinder 350 brakehorse-power Sunbeam-Coatalen over-lead valve aircraft engine type. Itis distinguishable, Qcidentally, by the passage formed through thecenter of ach induction pipe for the sparking plug in the center ylinderof each block of three. In this, as in the eighteen-ylinder and the six-cylinder types, there are two cam-hafts for each set of cylinders. Thesecam-shafts are abricated by low pressure and are operated through arain of inclosed spur wheels at the magneto end of the [lachine. Thesix-cylinder, 170 brake horse-power vertical ype employs the samegeneral principles, including the etail that each carburetor serves gasto a group of three-ylinders only. It will be observed that this enginepre-ents notably little head resistance, being suitable for lulti-enginedaircraft.

nroiCATING METERS FOR AUXILIARY SYSTEMS

The proper functioning of the power plant and the arious groups com-prising it may be readily ascertained t any time by the pilot becausevarious indicating meters nd pressure gauges are provided which arelocated on a ash or cowl board in front of the aviator, as shown at 'ig.251. The speed indicator corresponds to the speedom-ter of an auto-mobile and gives an indication of the speed le airplane is making,which taken in conjunction with the lock will make it possible to de-termine the distance cov-red at a flight. The altimeter, which is an an-eroid arometer, outlines with fair accuracy the height above le groundat which a plane is flying. These instruments re furnished to enable theaviator to navigate the air-lane when in the air, and if the machine isto be used ^r cross-country flying, they may be supplemented by aDmpass and a drift set. It will be evident that these re purely navigat-ing instruments and only indicate the lotor condition in an indirect

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manner. The best way of eeping track of the motor action is to watchthe tachom-

Aviation Engines

3ter or revolution conntep which is driven from the 3ngine by a flex-ible shaft. This indicates directly the Qumber of revolutions the engineis making per minute and, of course, any slowing up of the engine innormal lights indicates that something is not functioning as it should.

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The tachometer operates on the same principle as the speed indicatingdevice or speedometer used in automobiles except that the dial is cal-ibrated to show revolutions per minute instead of miles per hour. Atthe extreme right of the dash at Fig. 251 the spark advance and throttlecontrol levers are placed. These, of course, regulate the motor speedjust as they do in an automobile. S'ext to the engine speed regulatinglevers is placed a push button cut-out switch to cut out the ignitionand stop the motor. Three pressure gauges are placed in a ine. The oneat the extreme right indicates the pressure )f air oh the fuel when apressure feed system is used, rhe middle one shows oil pressure, whilethat nearest :he center of the dash board is employed to show the airpressure available in the air starting system. It will be evident that thecharacter of the indicating instruments idU vary with the design of theairplane. If it was pro-dded with an electrical starter instead of an airsystem electrical indicating instruments would have to be pro-idded.

COMPRESSED AIR-STARTING SYSTEMS

Two forms of air-starting systems are in general use, )ne in which thecrank-shaft is turned by means of an lir motor, the other class wherecompressed air is ad-nitted to the cylinders proper and the motorturned over because of the air pressure acting on the engine pistons. A.system known as the ^ ^ Never-Miss" utilizes a small iouble-cylinderair pump is driven from the engine by neans of suitable gearing andsupplies air to a substan-:ial container located at some convenientpoint in the fuselage. The air is piped from the container to adash-3ontrol valve and from tliis member to a peculiar form

of air motor mounted near the crank-shaft. The air motor consists of apiston to which a rack is fastened which engages a gear monnted onthe crank shaft provided with some form of ratchet clutch to permit itto revolve only in one direction, land then only when the gear is turn-ing faster than the engine crank-shaft.

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The method of operation is extremely simple, the dash-control valveadmitting air from the supply tank to the top of the pump cylinder.When in the i>osition shown in cut the air pressure wiU force the pis-ton and rack down and set the engine in motion. A variety of air mo-tors are used and in some the pump and motor may be the samedevice, means being provided to change the pump to an air motorwhen the engine is to be tamed over.

The * * Christensen ^ ^ air starting system is shown at Figs. 252 and253. An air pump is driven by the engine, and this supplies air to anair reservoir or container attached to the fuselage. This container com-municates with the top of an air distributor when a suitable controlvalve is open. An air pressure gauge is provided to enable one to ascer-tain the air pressure available. The top of each cylinder is providedwith a check valve, through which air can flow only in one direction,i.e., from the tank to the interior of the cylinder. Under explosive pres-sure these check valves close. The function of the distributor is practic-ally the same as that of an ignition timer, its purpose being to distrib-ute the air to the cylinders of the engine only in the proper firing or-der. All the while that the engine is running and the car is in motionthe air pump is functioning, unless thrown out of action by an easilymanipulated automatic control. When it is desired to start the engine astarting valve is opened which permits the air to flow to the top of thedistributor, and tlion tlirough a pipe to the check valve on top of thecylinder about to explode. As the air is going through under consider-able pi»essure it will move the piston do\vTi just las the explosionwould, and start the engine rotating. The inside of the distrilnitor ro-tates and directs a charge

of air to the cylinder next to fire. In this way the engine is given a num-ber of revolutions, and finally a charge of gas wUl be ignited and theengine start off on its cycle of operation. To make starting positive andeasier some

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psaammm

Fig. 262.—Puts of Chrlsteusen Air Starting System Sbown at A, andApplication of Piping and Check Valves to Cylinders of Tbomas-HoneAeromotor OntUued at B.

gasoline is injected in with the air so an inflammable mixture ispresent in the cylinders instead of air only. This ignites easily and theengine starts off sooner than would otherwise be the case. The airpressure required varies from 125 to 250 pounds per square inch, de-pending upon the size and type of the engine to be set in motion.

Aviation Engines

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ELECTRIC STARTING SYSTEMS

Starters utilizing electric motors to turn over the engine have been re-cently developed, and when properly made and maintained in an effi-cient condition they answer all the requirements of an ideal startingdevice. The capacity is very high, as the motor may draw current froma storage battery and keep the engine turning over for considerable

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time on a charge. The objection against their use is that it requiresconsiderable complicated and costly apparatus which is difficult to un-derstand and which requires the services of an expert electrician to re-pair shoidd it get out of order, though if battery ignition is used thegenerator takes the place of the usual ignition magneto.

In the Delco system the electric current is generated by a combinedmotor-generator permanently geared to the engine. When the motor isrunning it turns the armature and the motor generator is acting as adynamo, only supplying current to a storage battery. On account of thevarying speeds of the generator, which are due to the fluctuation in en-gine speed, some form of automatic switch which will disconnect thegenerator from the battery at such times that the motor speed is notsufficiently high to generate a current stronger than that delivered bythe battery is needed. These automatic switches are the only delicatepart of the entire apparatus, and while they require very delicate ad-justment they seem to perform very satisfactorily in practice.

When, it is desired to start the engine an electrical connection is estab-lished between the storage battery and the motor-generator unit, andthis acts as a motor and turns the engine over by suitable gearingwhich engages the gear teeth cut into a special gear or disc attached tothe engine crank-shaft. When the motor-generator furnishes currentfor ignition as w^ell as for starting the motor, the fact that the currentcan be used for this work as well as starting justifies to a certain extentthe rather

complicated mechanism which forms a complete starting and ignitionsystem, and which may also be used for lighting if necessary in nightflying.

An electric generator and motor do not complete a self-starting sys-tem, because some reservoir or container for electric current must be

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provided. The current from the generator is usually stored in a storagebattery fron^ which it can be made to return to the motor or to thesame armature that produced it. The fundamental units of a self-start-ing system, therefore, are a generator to produce the electricity, a ^storage battery to serve as a reservoir, and ah electric motor to rotatethe motor crankshaft. Generators are usually driven by enclosed gear-ing, though silent chains are used where the center distance betweenthe motor shaft and generator shaft is too great for the gears. An elec-tric starter may be directly connected to the gasoline engine, as is thecase where the combined motor-generator replaces the fly-wheel in anautomobile engine. The motor may also drive the engine by means of asilent chain or by direct gear reduction.

Every electric starter must use a switch of some kind for starting pur-poses and most systems include an output regulator and a reversecurrent cut-out. The output regulator is a simple device that regulatesthe strength of the generator current that is supplied the storage bat-tery. A reverse current cut-out is a form of check valve that preventsthe storage battery from discharging through the generator. Briefmention is made of electric starting because such systems will un-doubtedly be incorporated in some future airplane designs. Battery ig-nition is already being experimented with.

BATTERY IGNITION SYSTEM PARTS

A battery ignition system in its simplest form consists of a current pro-ducer, usually a set of dry cells or a storage battery, an induction coilto transform the low tension current to one ha\nng sufficient strengthto jump

the air gap at the spark-ping, an igniter member placed in the combn-stion chamber and a timer or mechanical switch operated by the en-gine so that the circuit will be closed only when it is desired to have a

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spark take place in the cylinders. Battery ignition systems may be oftwo forms, those in which the battery current is stepped up or intensi-fied to enable it to jump an air gap between the points of the sparkplug, these being called **high tension^' systems and the low tensionform (never used on airplane motors) in which the battery current isnot intensified to a great degree and a spark produced in the cylinderby the action of a mechanical circuit breaker in the combustion cham-ber. The low tension system is the simplest electrically but the morecomplex mechanically. The high tension system has the fewest movingparts but numerous electrical devices. At the present time all airplaneengines use high tension ignition systems, the magneto being the mostpopular at the present time. The current distribution and timingdevices used with modern battery systems are practically the same assimilar parts of a magneto.

A

PAGE

Action of Four-cycle Engine 38

Action of Le Bhone Botary Engine 503

Action of Two-cycle Engine 41

Action of Vacuum Feed System 119

Actual Duration of Different Functions 93

Actual Heat Efficiency 62

Adiabatic Diagram 51

Adiabatic Law 50

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Adjustment of Bearings 449

Adjustment of Carburetors 151

Aerial Motors, Must be Light • 20

Aerial Motors, Operating Conditions of 19

Aerial Motors, Bequirements of •... 19

Aeromarine Six-cylinder Engine f... 527

Aeronautics, Division in Branches 18

Aerostatics 18

Air-cooled Engine Design 229

Air-cooling Advantages 231

Air-cooling, Direct Method 228

Air-cooling Disadvantages 231

Air-cooling Systems 223

Aircraft, Heavier Than Air 17

Aircraft, Lighter Than Air 18

Aircraft Types, Brief Consideration of 17

Air Needed to Burn Gasoline 113

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Airplane Engine, Power Needed 21

Airplane Engines, Overhauling 412

Airplane Engine, How to Time 269

Airplane Engine Lubrication 209

Airplane, How Supported 21

Airplane Motors, German 543

Airplane Motor Types 20

Airplane Motors, Weight of 21

Airplane Power Plant Installation 324

Airplane Types 18

Airplanes, Horse-power Used in 26

Air Pressure Diminution, With Altitude 144

Altitude, How it Affects Mixture 153

Aluminum, Use in Pistons 297

American Aviation Engines, Statisties $46

Anzani Badial Engine Installation M

Anzani Six-cylinder Star Engine 465

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Anzani Six-cylinder Water-cooled Engine 459

Anzani Ten- and Twenty-cylinder Engines 468

Anzani Three-cylinder Engine 459

Anzani Three-cylinder Y Type 462

Argus Engine Construction 545

Armature Windings 168

Atmospheric Conditions, Compensating For 143

Austro-Daimler Engine 557

Aviatics ■ ••••>••••••••••••• 18

Aviation Engine, Aeromarine 527

Aviation Engine, Anzani Six-cylinder Star 465

Aviation Engine, Canton and, Unn6 469

Aviation Engine Cooling .". 219

Aviation Engine, Curtiss 519

Aviation Engine Cylinders 233

Aviation Engine, Early Gnome 472

Aviation Engine, German Gnome Type 4K

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Aviation Engine, Gnome Monosoupape 486

Aviatioq Engine, How To Dismantle 415

Aviation Engine, How to Start 460

Aviation Engine, Le Bhone Botary 485

Aviation Engine Oiling 218

Aviation Engine Parts, Functions of 88

Aviation Engine, Renault Air-cooled 507

Aviation Engine, Stand for Supporting 414

Aviation Eugine, Sturtevant 515

Aviation Engine, Thomas-Morse 521

Aviation Engine Types 457

Aviation Engine, Wisconsin 531

Aviation Eugines, Anzani Six-cylinder Water-cooled 459

Aviation Eogines, Anzani Ten- and Twenty-cylinder 468

Aviation Engines, Anzani Three-cylinder 459

Aviation Engines, Anzani Y Type 462

Aviation Engines, Argus 545

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Aviation Engines, Austro-Daimler 657

Aviation Engines, Benz 551

Aviation Engines, Four- and Six-cylinder 88

Aviation Engines, German 543

Aviation Engines, Hall-Scott 539

Aviation Engines, Hispana-Suiza 512

Aviation Eugines, Mercedes 543

Aviation Engines, Overhauling 412

Aviation Engines, Principal Parts of 80

Aviation Engines, Starting Systems For 567

Aviation Engines, Sunbeam 558

B

PAGB

.need Crank-shafts 318

-bearing Crank-shafts , 319

ery Ignition Systems 571

3rey Compound Nozzle 137

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ings, Adjustment of 449

ing Alignment 453

ing Brasses, Fitting 450

ing Parallelism, Testing 453

ing Scrapers and Their Use 446

s Aviation Engines 551

: Engine Statistics 551

ing Magneto 174

ing Magneto, Adjustment of 180

ing Magneto Care 180

ing Magneto Circuits '. 176

ing Magneto, Setting 178

k Castings .• 234

ring Back 269

J, Screwing Down 452

and Stroke Batio r. 240

es Law 49

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ton Engine 48

ker Box, Adjustment of 180

8t and Hand Drills 387

ing Out Carbon Deposits 421

ings, Camshaft^ Wear in 456

O

»er8, Inside and Outside 898

Followers, Types of 260

I for Valve Actuation 259

shaft Bushings 456

shaft Design 313

shaft Drive Methods 261

shaft Testing 451

shafts and Timing Gears 456

on and Unn6 Engine 469

on. Burning out with Oxygen 421

on Deposits, Cause of 418

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on Bemoval 419

on Scrapers, How Used 420

aretion I^rinciples 112

aretion System Troubles 355

aretor, Claudel 127

aretor. Compound Nozzle Zenith 135

Carburetor, Concentric Float and Jet Type 125

Carburetor, Duplex Zenith 138

Carburetor, Duplex Zenith, Trouble in 357

Carburetor Installation, In Airplanes '. 14S

Carburetor, Le Rhone 501

Carburetor, Master Multiple Jet 133

Carburetor, Schebler 125

Carburetor Troubles, How to Locate 354

Carburetor, Two Stage 131

Carburetor, What it Should Do 114

Carburetors, Float Feed * 122

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Carburetors, Multiple Nozzle 130

Carburetors, Notes on Adjustment 151

Carburetors, Beversing Position of 149

Carburetors, Spraying 120

Care of Dixie Magneto 188

^listor Oil, for Cylinder Lubrication 205

Olfflor Oil, Why Used In Gnome Engines 211

Ctater Gauge 403

ChiselB, Forms of 384

Chriatansen Air Starting System 567

Circuilyi, Magnetic 161

ClassiAfeation of Engines 458

Claudel Carburetor 127

Cleaning Distributor 180

Clearances Between Valve Stem and Actuators 261

Combustion Chamber Design 239

Combustion Chambers, Spherical 76

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Common Tools, Outfit of ... .* 378

Comparing Two-cycle and Four-cycle Types 44

Compound Cam Followers 260

Compound Piston Rings 301

Compressed Air Starting System 565

Compression, Factors Limiting 69

Compression, in Explosive Motors, Value of 68

Compression Pressures, Chart for 72

Compression Temperature 71

Computations for Horse-power Needed 25

Computations for Temperature 52

Concentric Piston Ring 299

Concentric Valves 255

Connecting Rod Alignment, Testing 454

Connecting Rod, Conventional 308

Connecting Rod Forms 305

Connecting Rod, Gnome Engine 305

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Connecting Rods, Fitting 4-*^

Connecting Rods for Vce Engines 310

Connecting Rods, Le Rhone 498

ConneetiDg Bods, Master 310

Constant Level Splash System 215

Construction of Dixie Magneto 186

ConstTUctioD of Pistons 288

Conversion of Heat to Power 58

CooliDg by Air 223

CooliDg by Positive Water Circnlation 224

Cooling, Heat Loss in 6S

Cooling System Defects 358

Cooling SyBtema Used '. 223

Cooling Systems, Why Needed 219

Cotter Pin Pliers 384

Cntnlc-case, Conventional 320

Crank-case Forms 320

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Cmnk-caso, Gnome 323

Crank shaft, Built Up 315

■ Crank-shaft Construction -' 315

Crank-shaft Design 315

Crankshaft Equalizer *48

Crank-shsft Form 815

Crank shaft, Gnome Engine 483

Crank shafts, Balanced 318

Crank shiifta. Ball Bearing 319

Cross Level 413

Crude Petroleum, Distillates of HI

Curtiss Aviation Engines 519

Cnrtiss Engine Installation 328

OuTtisB Engine Repairing Tools 408

Cutting Oil Grooves «8

Cylinder Blocks, Aclvnntagcs of 237

Cylinder Block, Dueaenberg 235

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(^linder CaslingB, Individual 234

Cylinder Coostruction 233

Cylinder Faults nud Correction 418

Cylinder Form nn.i Crnnk-sliaft Design 238

Cylinder Head Packings 417

Cylinder Head, Bemovable 239

■ Cylinder, I Head Form 248

Cylinder, L Head Form 248

Cylinder Oils 206

Cylinder Placing 20

Cylin4er Placing in V Motor 99

Cylinder Betention, Gnome *75

Cylinder, T Head Form 248

Cylinders, Cast in Blocks 23S

Cylinders, Odd Number in Rotary Engines 482

(flinders, Eepairing Scored 423

Cylinders, Valve Location in 245

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Defects in Cylinders 417

Defects in Dry Battery 373

Defects in Fuel System 354

Defects in Induction Coil 373

Defects in Magneto 372

Defects in Storage Battery 372

Defects in Timer 373

Defects in Wiring and Remedies 373

Die Holder 394

Dies for Thread Cutting 395

Diesel Motor Cards 67

Diesel System 144

Direct Air Cooling • 228

Dirigible Balloons 18

Dismantling Airplane Engine 415

Distillates of Crude Petroleum Ill

Division of Circle in Degrees 268

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Dixie Ignition Magneto 184

Dixie Magneto, Care of / 188

Draining Oil From Crank-case 214

Drilling Machines 386

Drills, Types and Use 388

Driving Cam-shaft, Methods of 262

Dry Cell Battery, Defects in 373

Duesenberg Sixteen Valve Engine 525

Duesenberg Valve Action 255

Duplex Zenith Carburetor 138

E

Early Gnome Motor, Construction of 472

Early Ignition Systems 155

Early Types of Gas Engine 28

Early Vaporizer Forms 120

Eccentric Piston Ring 299

Economy, Factors Governing 64

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Efficiency, Actual Heat 62

Efficiency, Maximum Theoretical 61

Efficiency, Mechanical 62

Efficiency of Internal Combustion Engine 60

Efficiency, Various Measures of 61

Eight-cylinder Engine 95

Eight-cylinder Timing Diagram 276

Electricity and Magnetism, Relation of 162

Electrical Ignition Best 156

Electric Starting Systems 569

Engine, Advantages of V Type 95

PAGI

Engine Base Gonstraction 319

Engine Bearings, Adjusting 443

Engine Bearings, Befitting 442

Engine Bed Timbers, Standard 330

Engine, Four-cycle, Action of 38

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Engine, Four-cycle, Piston Movements in 40

Engine Functions, Duration of 93

Engine Ignition, Locating Troubles 353

Engine Installation, Gnome 344

Engine Installation, Anzani Badial 344

Engine Installation, Hall-Scott 332

Engine Installation, Botary 342

Engine Operation, Sequence of 84

Engine Parts and Functions 80

Engine Starts Hard, Ignition Troubles Causing 369

Engine Stoppage, Causes of 347

Engine Temperatures 221

Engine Trouble Charts H69

Engine Troubles, Cooling 358

Engine Troubles, Hints For Locating 345

Engine Troubles, Ignition 353

Engine Troubles, Noisy Operation 359

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Engine Troubles, Oiling 357

Engine Troubles Summarized 350

Engine, Two-cycle, Action of 41

Engines, Classification of 458

Engines, Cylinder Arrangement 31-32

Engines, Eight-cylinder V 95

En^nes, Four-cylinder Forms ^ 88

Engines, Oraphic Comparison of 33-34-35

Engines, Internal Combustion, Types of 30

Engines, Multiple Cylinder, Power Delivery in 91

Engines, Multiple Cylinder, Why Best 83

Engines, Botary Cylinder 107

Engines, Six-cylinder Forms 88

Engines, Twelve-cylinder 96

Equalizer, Crank-shaft 449

Exhaust Closing 270

Exhaust Valve Design, Early Gnome 475

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Exhaust Valve Opening 270

Explosive Gases, Mixtures of 56

Explosive Motors, Inefficiency in 74

Explosive Motors, Why Best 27

F

Factors Governing Economy 64

Eactors Limiting Compression 70

Faults in Ignition 352

MCE ^

Figuring Horse-power Needed 21

Files, Use and Care of 383

First Law of Gases 49

Fitting Bearings By Scraping 447

Fitting Brasses 450

Fitting Connecting Rods 449

Fitting Main Bearings : 448

Fitting Piston Rings 439

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Float Feed Carburetor Development 124

Float Feed Carburetors 122

Force Feed Oiling System 218

Forked Connecting Bods 310

Four-cycle Engine, Action of 38

Four-cycle Engine, Why Best 45

Fourteen-cylinder Engine 474

Four Valves Per Cylinder 284

Friction, Definition of 302

Fuel Feed By Gravity 116

Fuel Feed by Vacuum Tank i 117

Fuel Storage and Supply 116

Fuel Strainers, Types of Ul

Fuel Strainers, Utility of 140

Fuel System Faults 354

Fuel System Installation, Hall-Scott 336

Fuel System, Gnome 490

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Fuel Utilization Chart ^ 62

G

Gas Engine, Beau de Bocha 'a Principles 59

Gas Engine Development 28

Gas Engine, Early Forms of 48

Gas Engine, Inventors of 29

Gas Engine, Theory of 47

Gases, Compression of 49

Gases, First Law of 49

Gases, Second Law of 50

Gaskets, How to Use 452

Gasoline, Air Needed to Burn 113

Gas Engines, Parts of 80

Gas Vacuum Engine, Brown's 28

German Airplane Motors 543

German Gnome Type Engine 495

Gnome Aviation Engine, Early Form 472

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Gnome Crank-shaft 483

Gnome Cylinder, Machining 489

Gnome Cylinder Retention 475

Gnome Engine, Fuel^ Lubrication and Ignition 490

PAOB

Gnome Engine, German Type 495

Gnome Engine Installation 344

Gnome Firing Order 482

Gnome Fourteen-Cylinder Engine 474

Gnome Fourteen-cylinder Engine Details 480

Gnome Monosoupape, How to Time 278

Gnome Monosonpape Type Engine 486

Graphic C!omparison of Engine Types 33-34-35

Graphic Comparison, Two- and Four-cycle 46

Gravity Feed System 116

Grinding Valves 429

Hall-Scott Aviation Engines 539

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Hall-Scott Engine Installation 332

Hall-Scott Engine, Preparations For Starting 341

Hall-Scott Engine- Tools 410

Hall-Scott Lubrication System 211

Hall-Scott Statistic Sheet 644

Heat and Its Work 54

Heat in Gas Engine Cylinder ...-. 69

Heat Given to Cooling Water 78

Heat Loss, Causes of «* 74

Heat Loss in Airplane* Engine 221

Heat Loss in Wall Cooling 65

High Altitude, How it Affects Power 144

High Tension Magneto 172

Hints For Locating Engine Troubles 345

Hints for Starting Engine 361

Hispana-Suiza Model A Engine 512

Horse-power Needed in Airplane 21

698/821

Horse-power Needed, How Figured 22

How An Engine is Timed 277

Tgnition, Electric 156

Ignition, Elements of 157

Ignition of Gnome Engine 490

Ignition System, Battery 571

Ignition Systems, Early 155

Ignition System Faults 352

Ignition, Time of 273

Ignition, Two Spark 196

I Head Cylinders 248

Improvements in Gas Engines 29

Indicating Meters, Engine Speed 563

«

Indicating Meters, Oil and Air Pressure 563

Indicator Cards, How To Bead 66

Indicator Cards, Value of ; 66

699/821

Individual Cylinder Castings ... •• 234

Induction Coil, Defects in ' 373

Inefficiency, Causes of 74

Inlet Valve Closing 272

Inlet Valve Opening 270

Installation, Airplane Engine 324

Installation, Curtiss OX 2 Engine 328

Installation, HalJ-Scott Engine ' 332

Installation of Rotary Engines 342

Intake Manifold Construction 143

Intake Manifold Design 142

Internal Combustion Engine, Efficiency of 60, 62

Internal Combustion Engines, Main Types of .-. 30

Inverted Engine Placing 325

Isothermal Diagram 51

Isothermal Law 48

K

700/821

«

Keeping Oil Out of Combustion Chamber 303

Knight Sleeve Valves 266

L

Lag and Lead, Explunation of 268

Lapping Crank-pins 445

Lead Given Exhaust Valve 270

Leak Proof Piston Rings 301

Lenoir Engine Action 4S

Le Rhone Cams and Valve Actuation 500

Le Rhone Carburetor 501

Le Rhone Connecting Rod Assembly, Distinctive 493

Le Rhone Engine Action 503

Le Rhone Rotary Engine 495

L Head Cylinders 248

Liquid Fuels, Properties of 110

Locating Carburetor Troubles 354

701/821

Locating Engine Troubles 350

Locating Ignition Troubles 353

Locating Oiling Troubles 357

Location of ^Magneto Trouble ISl

Losses in Wall Cooling 65

Lost Power and Overheating, Summary of Troubles Causing 363

Lubricants, Derivation of 204

Iiubricants, Requirements of 204

PACK

Lubricating System Classification 208

Lubricating Systems, Selection of 208

Lubrication By Constant Level Splash System 215

Lubrication By Dry Crank-case Method 218

Lubrication By Force Feed Best 218

Lubrication of Magneto 180

Lubrication System, Gnome 490

Lubrication System, Hall-Scott 211

702/821

Lubrication System, Thomas-Morse 210

Lubrication, Theory of 202

Lubrication, Why Necessary 201

M

Magnetic Circuits 161

Magnetic Influence Defined 15S

Magnetic Lines of Force 161

Magnetic Substances 158

Magnetism, Flow Through Armature 166

Magnetism, Fundamentals of 157

Magnetism, Relation to Electricity 162

Magneto, Action of High Tension 17S

Magneto Armature Windings ', 168

Magneto, Basic Principles of 16S

Magneto*, Berling 174

Magneto, Defects in 372

Magneto Distributor, Cleaning 180

703/821

Magneto Ignition Systems 169 *

Magneto Ignition Wiring 179

Magneto Interrupter, Adjustment of 180

Magneto, Low Voltage 168

Magneto, Lubrication of 180

Magneto Maintenance 180

Magneto, Method of Driving 175

Magneto Parts* and Functions 167"

Magneto, The Dixie 184

Magneto Timing 179

Magneto, Timing Dixie 188

Magneto, Transformer System 171

Magneto Trouble, Location of 181

Magneto, True High Tension 172

Magneto, Two Spark Dual 177

Magnets, Forms of 160

Magnets, How Produced 162

704/821

Magnets, Properties of 159

Main Bearings, Fitting 448

Manifold, Intake 143

Master Multiple Jet Carburetor 133

Master Bod CJonstmction 310

Maximum Theoretical Efficiency 61

Meaning of Piston Speed * 241

Measures of Efficiency 61

Measuring Tools 397

Mechanical Efficiency 62

Mercedes Aviation Engine 543

Metering Pin Carburetor, Stewart 128

Micrometer Caliper, Reading 405

Micrometer Calipers, Types and Use 4(H

Mixture, Effeot of Altitude on 153

Mixture, Proportions of 151

Mixture, Starvation of 149

705/821

Monosoupape Gnome Engine 486

Mother Bod, Gnome Engine 305

Motor Misfires, Carburetor Faults Causing 374

Motor Misfires, Ignition Troubles Causing 370 /

Motor Baces, Carburetor Faults Causing 374'

Motor Starts Hard, Carburetor Faults Causing 374'

Motor Stops In Flight, Carburetor Faults 374

Motor Stops Without Warning, Ignition Troubles 370

Multiple Cylinder Engine, Why Best 83

Multiple Nozzle Vaporizers 129

Multiple Valve Advantages 286

N

iNoisy Engine Operation, Causes of 359

Noisy Operation, Carburetor Faults Causing 374

Noisy Operation, Summary of Troubles Causing ••• 365

O

Off-set Cylinders, Beason for 243

706/821

Oil Bi-pass, Function of 213

Oil, Draining From Crank-case 214

Oil Grooves, Cutting 448

Oil Pressure in Hall-Scott System 214

Oil Pressure Belief Bi-pass 213

Oiling System Defects 357

Oils for Cylinder Lubrication 206

Oils for Hall-Scott Engine 215

Oils for Lubrication 204

Operating Principles of Engines 37

Oscillating Piston Pin 295

Otto Four-cycle Cards 67

Overhauling Aviation Engines 412

Overhead Cam-shaft Location 252

Overheating, Causes of 359

PAGB

rd Concentric Valves 255

707/821

eum, Distillates of Ill

, Differential 291

Pin Betention : 293

Bing Construction 298

Bing Joints 299

Bing Manipulation . ^ 438

Bing Troubles 437.

Bings, Compound 301

Bings, Concentric 299

Bings, Eccentric 299

Bings, Fitting 439

Bings, Leak Proof 301

Bings, Beplacing .* 441

Speed in Airplane Engines 241

Speed, Meaning of 241

Troubles and Bemedies 436

8, Aluminum 296^

708/821

8, Details of 288

8 for Two-cycle Engines 289

ve Valve Systems 283

, Affected by High Altitude 145

Delivery in Multiple Cylinder Engines 91

, How Obtained From Heat 58

Needed in Airplane Engines 21

Used in Airplanes 2^

itions in Assembling Parts 452

ire Belief Fitting .- 213

ires and Temperatures 63

pies of Carburetion 112

pies of Magneto Action 163

pties of Cylinder Oils 2Q7

rties of Liquid Fuels , 110

Circulation Systems 226

Forms 226

709/821

B

I Cylinder Arrangement 103

ttg Indicator Cards 67

3rs, Types and Use 392

ambling Parts, Precautions in 451

irable Cylinder Head 239

It Air Cooled Engine '. 507

It Engine Details 508

ring Scored Cylinders 423

Bites for Best Power Effect 59

PiCB

Beseating and Truing Valves 426

Besistance, Influence of 22

Botary Cylinder Engines 107

Botary Engine^ Le Bhone 495

Botary Engines, Castor Oil for 211

Botary Engines, Installing 342

710/821

Botary Engines, Why Odd Number of Cylinders 109

Botary Engines, Why Odd Number of Cylinders Is Used 482

8

8. A. E. Engine Bed Dimensions 330

Salmson Nine-cylinder Engine 470

Scissors Joint Bods 310

Scored Cylinders, Bepairing 422

Scrapers, Types of Bearing 446

Scraping Bearings tp Fit 447

Second Law of Gases 50

Sequence of Engine Operation 84

Shebler Carburetor " 125

Six-cylinder Timing Diagram : 275

Sixteen Valve Duesenberg Engine 525

Skipping or Irregular Operation, Causes of 367

Sliding Sleeve Valves 266

Spark Plug Air Gaps, Setting 197

711/821

Spark Plug, Design of 193

Spark Plug, Mica 194

Spark Plug, Porcelain 193

Spark Plugs, Defects in 371

Spark Plugs for Two Spark Ignition '. 197

Spark Plug, Special for Airplane Engine 199

Spark Plug, Standard S. A. E 195

Spherical Combustion Chambers 76

Splash Lubrication 215

Split Pin Remover 3S4

Spraying Carburetors 120

Springless Valves 280

Springs, for Valves 263

Spring Winder 384

Sprung Cam-shaft, Testing 451

Stand for Supporting Engine 414

Starting Engine, Hints for 361

712/821

Starting Hall-Scott Engine 341

Starting System, Christensen 567

Starting Systems, Compressed Air 565

Starting Systems, Electric 569

Statistics, American Engines 546, 547

Statistic Sheet, Hall-Scott Engines 544

PAGB

:C8 of Benz Engine 551

Engine, Efficiency of , 59

Engine, Why Not Used 27

icale, Machinists' , 399

t Metering Pin Carburetor 128

; Battery, Defects in 372

and Bore Ratio 240

ant Model 5A Engine 515

ry of Engine Types 80

m Aviation Engines 588

713/821

m Eighteen-Cylinder Engine * 561

T

d Die Sets *. 397

or Thread Cutting 394

»ad Cylinders • 247

•ature Computations 52

•atures and Explosive Pressures 64

•atures and Pressures 63

•atures. Operating 221

f Bearing Parallelism 453

r Connecting Rod Alignment 454

f Fit of Bearings 446

f Sprung Cam-shaft 451

of Gas Engine 47

of Lubrication 203

)-8yphon Cooling System 227

a-Morse Aviation Engine 521

714/821

3-Morse Lubrication System ^10

Pitch Gauge » 403

f Ignition 273

Defects in ...: 373

of Explosion 56

Pixie Magneto 188

Gears, Effects of Wear 456

Magneto 179

Valves 267

atfits. Typical 408

'or Adjusting and Erecting 378

or Bearing Work 445

'or Curtiss Engines \ 408

for Grinding Valves 430

■or Hall-Scott Engines 410, 411

'or Measuring 397

for Reseating Valves ,. 426

715/821

B in Carburetion System ^ 355

e, Location of Magneto 181

fta

Troubles, Engine, How to Loeate ^

Troubles, Ignition ...••' 3^

Troubles in Oiling System 357

True High Tension Magneto 172

Twelve-Cylinder Engines 96

Two- and Fbur-Cycle Types, Comparison of 44

Two-Cycle Engine Action 41

Two-Cycle Three-Port Engine 43

Two-Cycle Two-Port Engine 42

Two-Spark Ignition 196

Two-Stage Carburetor 131

Types of Aircraft 17

Types of Internal Combustion Engines 30

V

716/821

Vacuum Fuel Feed, Stewart ., 119

Value of Compression 69

Value of Indicator Cards 66

Valve Actuation, Le Rhone 500

V-alve Design and Construction 256

Valve-Grinding Processes 429

Valve-Lifting Cams 259

Valve-Lifting "^lungers 260

Valve Location Practice 245

Valve Operating Means 252

Valve Operating System, Depreciation in ' 433

Valve Operation 25S

Valve Removal and Inspection 424

Valve Seating, How to Test 432

Valve Springs 263

Valve Timing, Exhaust 270

Valve Timing, Gnome Monosoupape* 278

717/821

Valve Timing, Intake 270

Valve Timing, Lag and Lead 269

Valve Timing Proceedure 277

Valve Timing Practice 267

Valves, Electric Welded : 25S

Valves, Flat and Bevel Seat 257

Valves, Four per Cylinder .* 2S4

Valves, How Placed in Cylinder 247

Valves in Cages 249

Valves in Removable Heads 249

Valves, Materials Used for 258

Valves, Reseating % 426

Vaporizer, Simple Forms of 120

V Engines, Cylinder Arrangement in 102

Vernier, How Used 401

w

w

718/821

PACK

Wall Cooling, Losses in 65

Water Cooling by Natural Circulation 227

Water Cooling System 224

Weight of Airplane Motors . • 21

Wiring, Defects in 373

Wiring Magneto Ignition System 179

Wisconsin Engines 531

Wrenches, Forms of 380

Wristpin Retention 293

Wristpin Betention Locks 295

Wristpin Wear and Bemedy 442

Z

Zenith Carburetor, Action of 137

Zenith Duplex Carburetor, Troubles in 356

Zenith Carburetor Installation 139

CATALOGUE

719/821

Of tfie LATEST and BEST

PRACTICAL and MECHANICAL

BOOKS

Including Automobile and Aviation Books

Any of these hooks will he sent prepaid to any part of the world, on re-ceipt of price. Remit hy Draft, Postal Order, Express

Order or Registered Letter

Published and For Sale By

The Norman W. Henley Publishing Co.,

2 West 45th Street, New York, U.S.A.

THE NORMAN W. HENLEY PUBLISHING C(

INDEX

FAOB8

Air Brakes 21, 24

Arithmetic 14. 25. 31

720/821

Autoau^ile Books 3. 4, 5, 6

Automobile Charts 6, 7

Automobile lotion Systems 5

Automobile Lighting 5

Automobile Questions and Answers 4

Automobile Repairing 4

Automobile Starting Systems 5

Automobile Trouble Coarts 5, 6

Automobile Welding 5

Aviation 7

Aviation Chart 7

Batteries, Storage 5

Bevel Gear 19

Boiler-Koom Chart 9

Bracing 7

Cams 19

Carburetion Trouble Chart 6

721/821

Change Gear 19

CharU 6, 7, 8

Coal 22

Coke &

Combustion 22

Compressed Air 10

Concrete 10, 11. 12

C-oncretc for Farm Use 11

Concrete for Shop Use 11

Cosmetics 27

Cyclecars 5

Dictionary 12

Dies '. 12. 13

Drawing 13, 14

Drawing for Plumbers 28

Drop Forging 13

Dynamo Building 14

722/821

Electric Bells 14

Electric Switchboards 14, 16

Electric Toy Making 15

Electric Wiring 14, 15, 16

Electricity 14. 15, 10. 17

Encyclopedia 24

E-T Air Brake 24

Every-day Engineering 34

Factory Management 17

Ford Automobile 3

Ford Trouble Chart 6

Formulas and Recipes 29

Fuel 17

Gas ConHtruction IS

Gas Engines 18, 19

Gh» Tractor 33

Gearing and Cams 19

723/821

Glossary of Aviation Terms 7, 12

Heating 31, 32

Horse-Power Chart 9

Hot-Water Heating 31. 32

House Wiring 15. 17

How to Run an Automobile 3

Hydraulics 5

Ice and Refrigeration : 20

Ignition Systems 6

Ignition-Trouble Chart 6

India Rubber 30

Interchangeable Manufacturing 24

Inventions 20

Knots 20

lAthe Work 20

Link Motknui

724/821

Liquid Air

Looomotive Boilers

Locomotive Broakdowns

Locomotive Encineerins 21

Madbinist Book

Magarine. Mechanical

Manual Training

Marine Engineerins

Marine Gasoline Engines

Mechanical Drawing

Mechanical Magasine

Mechanical Movements

Metal Work

Motorcycles

Patents

Pattern Making

Perfumery

725/821

Perspective

Plumbing

Producer Gas

Punches

itions and Answers on Automobil

itions on Heating

li'road Accidents

Railroad Charts

Recipe Book

Ref n^ration

Repairing Automobiles

Rope Work

Rubber

Rubber Stamps

SawFiUng

Saws, Management of

Shoet-Metal Works

726/821

Shop Construction

Shop Management

Shop Practice

Shop Tools

Sketching Paper

Soldering

Splices and Rope Work

Steam Engineering

Steam Heating

Steel

Storage Batteries

Submarine Chart

Switchboards

Tapers

Telegraphy, Wireless

Telephone

Thread Cutting

727/821

Tool Making

Toy Making

Train Rules

Tractive Power Chart

Tractor, Gas

Turbines

Vacuum Heating

Valve Setting

Ventilation

Watch Making

Waterproofing

Welding with Oxy-acetylene Flame...

Wireless Telegraphy

Wiring

Wiring Diagrams

Any of these books promptly sent prepaid to any add

the world on receipt of price.

728/821

HOW TO REMIT— By Postal Money Order, Express Mone:

Bank Draft or Registered Letter.

CATALOGUE OF GOOD, PRACTICAL BOOKS

AUTOMOBILES AND MOTOBCYOLES

lie Modem Gasoline AutomobUe—Its Design, Construction, and Oper-ation, 1918 Edition. By Victor W. Pag£, M.S.A.E.

Thb is the most complete, practical and up-to-date treatise on gasolineautomobiles and their component parts ever published. In the new re-vised and enlarged 1918 edition, all phases of automobile construction,operation and maintenance are fully and comjpletely described, and inlanguage anyone can understand. Every part of all types of automo-biles, from light cycle-cars to heavy motor trucks and tractors, are de-scribed in a thorough manner, not only the automobile, but every itemof it: equipment, accessories, tools needed, supplies and spare partsnecessary for its upkeep, are fully discussed.

It is clearly and concisely written by an expert familiar with everybranch of the automobile indtulry and the originator of the pro/Cticalsystem of self-education on technical svbjects. It is a liberal edur 'cation in the automobile artt useful to all who motor for nther busi-ness or pleasure. Anyone reading the incomparable treatise is in touchwith all improvements that have been made in motor-car construc-tion. All latest developments, such as high speed aluminum motorsand multiple valve and sleeve-valve engines, are considered in detail.The latest ignition, carburetor and lubrication practice is outlined.New forms of change speed gears, and final power transmission sys-tems, and all latest chassis improvements are shown and described.This book is used in all leading automobile schools and is conceded tobe the Standard Treatise. The chapter on Starting and Lighting

729/821

Systems has been greatly enlarged, and many automobile engineeringfeatures that have long puxzled laymen are explained so clearly thatthe underlsdng- principles can be understood bv anyone. This bookwas first published six years ago and so much new mJEitter has beenadded tnat it is nearly twice its orii^nal sise. The only treatise coveringvarious forms of war automobiles and recent developments in mo-tortruck design as well as pleasure cars. This book is not too technicalfor the layman nor too elementary for the more expert. It is an incom-parable work of reference for home or school. 1,000 6x9 pages, nearly1,000 iUustrations, 12 folding plates. Cloth bound. Price $3*00

WHAT IS SAID OF THIS BOOK:

" It is the best book on the Automobile seen up to date."—J. H. Pile,Associate Editor AutO' mobile Trade Journal.

" Every Automobile Owner has use for a book of this character."— TheTradesman. "This book is superior to any treatise heretofore publishedon the subject."— The Inventive Age, *' We know of no other volumethat is so complete in all its departments, and in which the wide fieldof automobile construction with its mechanical intricacies is so plainlyhandled, both in the text and in the matter of illustrations:"— TheMotorist.

** The book is very thorough, a careful examination failing to discloseany point in connection with the automobile, its care and repair, tohave been overlooked."— Iron Age. "Mr. Pag6 has done a great work,and benefit to the Automobile Field."—W. C. Hasford, Mgr. Y. M. C. A.Automobile School, Boston, Mass. ■ " It is just the kind of a book amotorist needs if he wants to understand his car."— AmericanThresherman.

730/821

lie Model T Ford Car, Its Construction, Operation and Repair. By Vict-or W. Pag6, M.S.A.E.

This is a complete instruction book. All parts of the Ford Model T Carare described and illustrated; the construction is fully described andoperating principles made clear to everyone. Every Ford owner needsthis practical book. You don't have to guess about the construction orwhere the trouble is, as it shows how to take all parts apart and how tolocate and fix all faults. The writer, Mr. Pag6, has operated a Ford carfor many years and writes from actual knowledge. ^ Among the con-tents are: 1. The Ford Car: Its Parts and Their Functions. 2. TheEngine and Auxiliary Groups. How the Engine Works—^The FuelSupply System— The Carburetor—Making the Ignition Spark—Coolingand Lubrication. 3. Details of Chassis. Change Speed Gear—;PowerTransmission—^Differential Gear Action—Steering Gear—FrontAxle—Frame and Springs—^Brakes. 4. How to Drive and Care for theFord. The Control System Explained—Starting the Motor—Driving theCar—Locating Roadside Troubles— Tire Repairs—Oiling theChassis—^Winter Care oi Car. 5. Systematic Location of Troubles andRemedies. Faults in Engine—Faults in Carburetor—^IgnitionTroubles—Cooling and Lubrication System Defects—^Adjustment ofTransmission Gear—General Chassis Repairs. 95 illustrations, 300pages, 2 large folding plates. Price $1*00

ow to Run an AutomobUe. By Victor W. Pao£, M.S.A.E.

This treatise gives concise instructions for starting and nmning allmakes of gasoline automobiles, how to care for them, and gives dis-tinctive features of control. Describes every step for shifting gears,controlling engines, etc. Among the chapters contained are: I.— Auto-mobile Parts and Their Functions. II.—General Starting and DrivingInstructions. III.—^Typical 1917 Control Systems. IV.—Care of Auto-mobiles. 178 pages. 72 specially made illustrations. IMce $1*00

731/821

•4 THE XORMAN W. HENLEY PUBLISHING CO

AntomoMle Bcyalrfiig Made Easjr. By Victor W. Pag£, M^A£

A eomprelifniflnre, prmctieal ezpositicMi of every phaae of modemantoiMifaile tiee. OutlincB every proeen incidental to nM>tor ear res-toration. Givca plai eoootruction, saneatiooB for equipoMnt, powerneeded, marhinriy and tools carry on buaneas succeasfully. Tells bowto orerfaaul and repair aO parts of al mobiies. Everythins is explainedso simpy that motorists and students can aeqoin

orkins knowledge of automobile repairing This work starts with theengine, thai ei

1 Ittbricati

carfooretioo. ignition, cooling and mbrication ssrstcms. The datch, _

and transmisBion system are considered in detail. Contains instruc-tions for repax types of axles, steering geare and other chassis parts.Many tables, diort cuts in SLod roles of practice are given for themechanic. Fxplainw folly valve and magneto

toning" engues. sjrstematic location of trooble. repair of ball and rollerbestfings. Ae^ first aid to injored and a multitude of sobjects of in-terest to all in the garage and repair b This book contain* special in-Mtructiona on eUetrie ttartimg, lighting and ignition syale repairingand rebuilding, avtogenout welding, brnziftg and soldering. heattreaimtent ef Met timing practice, eight and tvcelte-rylinder motors,etc. 5*4 xS. Ooth. Ij056paees, IJOI trations, 11 folding plates. Price

WHAT IS SAID OF THIS BOOK:

732/821

** *Aotomobile Repairing Made Easy' is the best book on the sobject Ihare ever si the only book I ever saw that is of any value in a gar-age."—Fred Jeffrey, ^klartinsbar "I wish to thank you for sending me aeop^ of 'Automobile Repairing Made Easy, not think it could be ex-celled."—3. W. Gisnel. Director of Instroction, T. M. C. A. ddphia. Pa.

Qaestlons and Answers Keating to Modem AntomobOe ConsfmDrlTlns and KefuOr. By Victor W. Pag£, M^A£.

A practical self-instroctor for students, mechanics and motorists, cxm-sisting of thirt lessons in the form of questions and answers, writtenwith special reference to the ments of the non-technical reader desir-ing easily understood, explanatory matter to all branches c^ auto-mobiling. The subject-matter is absolutely correct and exi^ simple lan-guage. If you can't answer all of the following qoesticHis, you need thiswor answers to these and over 2.000 more are to be found in its pages.Give the name d portant parts of an auttxnobile and describe theirfunctions. Describe action of late oi kerosene carburetors. What is thedifference between a ''double" ignition systeu "dual" ijpiition system?Name parts of an induction coil. How are valves ;::iined' is an electricmotor starter and how does it woric? What are advantages of wormdrr ing? .Vame all important types of ball and roller bearings. What isa **three-qaart» ing axle: What is a two-spe«l axle? What is the Vul-can electric gear shift? Name th of lost power in automc^iles. Describeall noises due to deranged mechanism and give How can you adjust acarburetor by the color of the exhaust gases? What causes "p in thecarburetor? What tools and supplies are needed to equip a car? How_do y< various mak*^ of cars? What i« a differential lock and where isit used? Xame c

Sstems of wire wheei construction, etc . etc. A popular work at a popu-lar fmce. £ oth. 6o0 pages, 3o0 illustrations. 3 folding plates. Price .....

733/821

WHAT IS SAID OF THIS BOOK:

"If you own a car—get this Ikk^-" — The Glassworker.

"Mr. Page has the faculty of maL-ing difficult subjects plain and un-dostandable.'*-

"We can name no writer better qualified to prepare a book of instruc-tion on auto than Mr. Victor W. Pag4."— Scientific American.

"The best automobile catechism that has appeared."— .\utomchiUTopics.

"There are few men. even with long experience, who will not find thisIxxdc useful.

The Aatomobnist's Poeket Companion and Expense Record. ArrangVictor W. Pag£, M.S.A.E.

This book is not only valuable as a convenient cost record but containsmuch information to motorists. Includes a condensed digest of autolaws of all States, a lubrication S4 hints for care of storage batter>-and care of tires, location of road troubles, anti-i solutions. horse-Dower table, driving hints and many useful tables and recipes of int allmotorists. Not a technical book in any sense of the word, just a collec-tion <^ p facts in simple language for the ever>-day motorist. Price .' •

lodern Starting, Lighting and Ignition Systems. By Victor W. Pagj^,M.E.

This practical volume has been written with special reference to the re-quirements of the non-techmcal reader desiring easily understood,

734/821

explanatory matter, relating to all types of automobile ignition, start-ing and lighting systems. It can be understood by anyone, evenwithout electrical knowledge, because elementary electrical principlesare considered before any attempt is made to discuss features of thevarious systems. These basic principles are clearly stated and illus-trated with simple diagrams. All the leading systems of starting, light-ing and ignition have been described and illustrated with the co-oper-ation of the experts employed by the manufacturers. Wiring diagramsare shown in both technical and non-technical forms. All symbols arefully explained. It is a comprehensive review of modern starting andignition system practice, and includes a complete exposition of storagebattery construction, care and re{>air. All types of starting motors,generators, magnetos, and all ignition or lighting system-units arefully explained. Every person in the automobile business needs thisvolumf. Among some of the subjects treated are: I.—^ElementaryElectricity; Current Production; Flow; Circuits; Measurements; Defini-tions; Magnetism; Battery Action; Generator Action. II.—Battery Igni-tion Systems. III.—Magneto Ignition Systems. IV.—Elementary Expos-ition of Starting System Principles. V.—^Tymcal Starting and LightingSystems; Practical Application; Wiring Diagrams; Auto-lite, Bijur,Delco, Dyneto-Entz, Gray and Davis, Remy, U. S. L., Westinghouse,Bosch-Rushmore, Genemotor, North-^East, etc. VI.—Locating andRepairing Troubles in Starting and Lighting Systems. VII.—Auxiliary.Electric Systems; Gear-shifting by Electricity; Warning Signals; Elec-tric Brake; Entz-Transmission, Wagner-Saxon Circuits, Wagner-Studebaker Circuits. 53^x7)^. Cloth. 530 pages, 297 illustrations, 3folding plates. Price $1.50

.utomobUe Welding Witli tlie Oxy-Acetylene Flame. By M. KeithDunham.

735/821

This is the only complete book on the "why" and "how" of Weldingwith the Oxy-Acetyleno Flame, and from its pages one can gain in-formation so that he can weld anything that comes along.

No one can afford to be without this concise book, as it first explainsthe apparatus to be used, and then covers in detail the actual weldingof all automobile parts. The welding of aluminum, cast iron, steel, cop-per, brass and malleable iron is clearly explained, as well as the properway to burn the carbon out of the combustion head of the motor.Ajnong the contents are: Chapter I.—Apparatus Knowledge. ChapterII.—Shop Equipment and Initial Procedure. Chapter III.—Cast Iron.Chapter IV.—^Aluminum. Chapter V.— Steel. Chapter VI.—MalleableIron, Copper, Brass, Bronze. Chapter VII.—Carbon Burning and otherUses of Oxygen and Acetylene. Chapter VIII.—How to Figure Cost ofWelding. 167 pages, fully illustrated. Price $1.00

torage Batteries Simplified. By Victor W. Pag6, M.S.A.E.

A comprehensive treatise devoted entirely to secondary batteries andtheir maintenance, repair and use.

This is the most up-to-date book on this subject. Describes fully theExide, Edison, Gould» Willard, U. S. L. and other storage batteryforms in the types best suited for automobile, stationary and marinework. Nothing of importance has been omitted that the reader shouldknow about the practical operation and care of storage batteries. ^ Nodetails have been slighted. The instructions for charging and care havebeen made as simple as possible. Brief Synopsis of Chapters: ChapterI.—Storage Battery Development; Types of Storage Batteries; LeadPlate Types; The Edison Cell. Chapter II.—Storage Battery Construc-tion; Plates and Girds; Plants Plates; Faur6 Plates; Non-Lead Plates;Commercial Battery Designs. Chapter III.—Charging Methods; Recti-fiers; Converters; Rheostats; Rules for Charging. Chapter IV.—Battery

736/821

Repairs and Maintenance. Chapter V.—Industrial Application of Stor-age Batteries; Glossary of Storage Battery Terms. 208 Pages. VeryFully Illustrated. Price $1.50 net.

lotorcycles, Side Cars and Cyclecars; their Construction, Managementand Repair. By Victor W. Pag6, M.S.A.E.

The only complete work published for the motorcyclist and cyclecarist.Describes fully all leading types of machines, their design, construc-tion, maintenance, operation and repair. This treatise outlines fullythe operation of two- and four-cycle power plants and all ignition, car-buretion and lubrication systems in detail. Describes all representativetjnpes of free engine clutches, variable speed gears and power trans-mission systems. Gives complete instructions for operating and repair-ing all types. Considers fully electric self-starting and lighting systems,all types of spring frames and spring forks and shows leading controlmethods. For those desiring technical information a complete series oftables and many formulae to assist in designing are included. Thework tells how to figure power needed to climb grades, overcome airresistance and attain high speeds. ^ It shows how to select gear ratiosfor various weights and powers, how to figure braking eflBciency re-quired, gives sizes of belts and chains to transmit power safely, andshows how to design sprockets, belt pulleys, etc. This work also in-cludes complete formula for figuring horse-power, shows how dy-namometer tests are

^

6 THE NORMAN W. HENLEY PUBLISHING CO.

made, defines relative e£Sciency of air and water-cooled eneuieB,plain and anti-friction beai^ ings and many other data of a practical,helpful, en|^eering nature. Remembo' thtX yoo get this information in

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addition to the practical description and instructions which alone areworth several times the price of the book. 550 pages. 350 speciallymade illustraticMs, 5 folding plates. Cloth. Price $1«5#

WHAT IS SAID OF THIS BOOK:

"Here is a book that should be in the cycle repairer's kit."— AmericanBlaekMmith.

"The best way for any rider to thoroughly understand his machine, isto get a oc^n^ of tiui

book; it is worth many times its price."— Pacific Moiorcydiai.

AUTOMOBILE AND MOTORCYCLE CHARTS

Chart. Location of Gasoline Engine Troubles Made Easy—A CbartShowing Sectional View of Gasoline Engine. Compiled by Victob W.PagI, M.S.A.E.

It shows clearly^ all parts of a typical four-cylinder gasoline engiiM ofthe four-cycle type.

It outlines distmctly all parts liable to give trouble and also details thederang^ooents igi

to interfere with smooth engine operation.

Valuable to students, motorists, mechanics, repairmen, garagemen,automobile salesmeo,

chauffeurs, motorboat owners, motor-truck and tractor drivers, aviat-ors, motcvHsydistB,

738/821

and all others who have to do with gasoline power plants.

It simplifies location of all engine troubles, and while it will prove in-valuable to the novioey

it can be used to advantage by the more expert. It should be on thewalls of every jpublks

and private garage, automobile repair shop, club house or school. Itcan be caniea m the

automobile or pocket with ease, and will insure againct loss of timewhen engiiie troul^

manifests itself.

This sectional view of engine is a complete review of all motortroubles. It is prepared Inr a

practical motorist for all who motor. More information for the m<Hieythan ever before

offered. No details omitted. Sise 25x38 inches. Securely mailed on re-ceipt of ^ cmtS

Chart. Location of Ford Engine Troubles Made Easy. Ck>mpiled byVicttob W. Pag£, M.S.A.E.

This shows clear sectional views depicting all portions of the Fordpower plant and auxiliary | groups. It outlines clearly all parts of theengine, fuel supply S3nstem, ignition group and cooling system, thatare apt to give trouble, detailing all derangements that are liable tomake an engine lose power, start hard or work irregularly. This chartis valuable to students, owners, and drivefs, as it simplifies location of

739/821

all engine faults. Of great advantage ss ao instructor for the novice, itcan be used equally well by the more expert as a work of ref«^moe andreview. It can be carried in the tool-box or pocket with ease and willsave its cost in labor eliminated the first time engiiie trouble mamfestsitself. Prepared with special refer* ence to the average man's needsand is a practical review of all motor troubles because it is based onthe actual experience of an automobile engineer-mechanic with the tn-ft<«h»i.|T|iffiTi the chwrt ■ describes. It enables the nC>n-techmcalowner or operator of a Ford car to locate engine | derangements bysystematic search, guided by easily recognised symptoms instead offar • guesswork. It makes the average owner independent of the road-side repair i^op when touring. Must be seen to be appreciated. Size25x38 inches. Printed an heavy bond paper.

i*rice ; . . u cents

Chart. Lubrication of the Motor Car Chasi^s. Compiled by Victob W.Pag6, M.S.A.E.

This chart presents the plan view of a typical six-cylinder chassis ofstandard design and aD

f>arts are clearly indicated that demand oil, also the frequency withwhich they must be :

ubricated and the kind of oil to use. A practical chart for all interestedin motor-car main I

tenance. Size 24x38 inches. Price J^ CCOtS )

Chart. Location of Carbureton Troubles Made Easy. Compiled byVictob W. Pag6, M.S.A.E.

740/821

This chart shows all parts of a typical pressure feed fuel supply systemand gives causes of trouble, how to locate defects and means of rem-edying them. Siae 24x38 indiea Price Scents

Chart. Location of Ignition System Troubles Made Easy. Compiled by I

Victor W. Pag6, M.S.A.E.

In this diagram all parts of a typical double ignition system using bat-tery and magneto correal are shown, and suggestions are given forreadily finding ignition troubles and eliminatinf them when found.Size 24x38 inches. Price ^ etsM

\

CATALOGUE OF GOOD, PRACTICAL BOOKS

ihart. Location of Cooling and Lubrication System Faults. Compiled byVictor W. Pag6, M.S.A.E.

This composite diagram shows a typical automobile power plant usingpump circulated water-cooling system and the most popular lubrica-tion methoa. Gives suggestions for curing all overheating and loss ofpower faults due to faulty action of the oiling or cooling group. Size24x38 inches. Price Jjg CCUtS

ihart. Motorcycle Troubles Made Easy. Compiled by Victor W. Pag£,M.S.A.E.

A chart showing sectional view of a single-cylinder gasoline engine.This chart simplifies location of all power-plant troubles. A single-cyl-inder motor is shown for simplicity. It outlines distinctly all parts li-able to give trouble and also details the derangements apt to interferewith smooth engine operation. This chart will prove of value to all who

741/821

have to do with the operation, repair or sale of motorcycles. No detailsomitted. Size 30x20 inches.

Price 25 cents

AVIATION

vlatlon Engines, their Design, Construction, Operation and Repair. By

* Lieut. Victor W. Pag6, Aviation Section, S.C.U.S.R.

A practical work containing valuable instructions for aviation stu-dents, mechanicianSt squadron engineering officers and all interestedin the construction and upkeep of airplane power plants.

The rapidly increasing interest in the study of aviation, and especiallyof the highly developed internal combustion engines that make mech-anical flight possible, has created^ demand for a text-book suitable forschools and home study that will clearly and concisely explain theworkings of the various aircraft en^nes of foreign and domestic manu-facture. This treatise, written by a recognized authority on all of thepractical aspects of internal combustion engine construction, mainten-ance and repair fills the need as no other book does. The matter is lo-gically arranged; all descriptive matter is simply expressed and copi-ously illustrated so that anyone can understand airplane engine opera-tion and repair even if without previous mechanical training. Thiswork is invaluable for anyone desiring to become an aviator or avi-ation mechanician.

The latest rotary types, such as the Gnome, Monosoupape, and LeRhone, are fully explained, as well as the recently developed Vee andradial types. The subjects of carburetion, ignition, cooling and lubrica-tion also are covered in a thorough manner. The chapters on repairand maintenance are distinctive and found in no other book on this

742/821

subject. Invaluable to the student, mechanic and soldier wishing toenter the aviation service. Not a technical book, but a practical, easilyunderstood work of reference for all interested in aeronautical science.576 octavo pages. 253 specially made engravings. Price . ^.00 net

GLOSSARY OF AVIATION TERMS

ermes D'Aviation, English-French, French-English. Compiled byLieuts. Victor W. Pag6, A.S., S.C.U.S.R., and Paul Montariol of theFrench Flying Corps, on duty on Signal Corps Aviation School, Min-eola, L. I.

A complete, well illustrated volume intended to facilitate conversationbetween English-speaking and French aviators. A very valuable bookfor all who are about to leave for duty overseas.

Approved for publication by Major W. G. Kilner, 8.C., U.S.C.O. SignalCorps Aviation School. Hazlehurst Field, Mineola, L. I.

This book should be in every Aviator's and Mechanic's Kit for readyreference. 128 pages. Fully illustrated with detailed engravings. Price$1*00

vlatlon Chart. Location of Airplane Power Plant Troubles Made Easy.By Lieut. Victor W. Pag6, A.S., S.C.U.S.R.

A large chart outlining* all parts of a typical airplane power plant,showing the points where trouble is apt to occur and suggesting rem-edies for the common defects. Intended especially for Aviators andAviation Mechamcs on School and Field Duty. Price . . 50 CCntS

BRAZING AND SOLDERING

razing and Soldering. By James F. Hobart.

743/821

The only book that shows you just bow to handle any job of brazing orsoldering that comes along; it tells you what mixture to use, how tomake a furnace if you need one. Full of valuable kinks. The fifth edi-tion of this book has iust been published, and to it much new matterand a large number of tested formule for all kinds of solders and fluxeshave been added. Illustrated. Price 25 CCntS

8 THE NORMAN W. HENLEY PUBLISHING CO.

CHARTS

Avlatioii diart. Location of Airplane Power Plant Troubles Mide fiuj.]

By Lieut. Victor W. Pag6, A.S., S.C.U.S.R.

A large chart outlining all parts of a typical airplane power plant,showing the jxaan trouble is apt to occur and suggesting remedies forthe common defects. Cit^nded for Aviators and Aviation Mechanicson School and Field Duty. Price . . . . j

Gasoline Engine Troubles Made Easy—A Chart Showing SectionalYlew Gasoline Engine* Compiled by Lieut. Victor W. Pag6, A.S., S.CU

It shows clearly all parts of a typical four-cylinder gasoline engine ofthe four'47ctr t]

It outlines distinctly all parts liable to give trouble and also details thederan^emeoti

to interfere with smooth engine operation.

Valuable to students, motorists, mechanics, repairmen, garagemen.automobile

744/821

chauffeurs, motor-boat owners, motor-truck and tractor drivers,aviators, motor-CTti^

and all othcro who have to do with gasoline power plants. ^ ^

It simplifies location of all engine troubles, and while it will prove in-valuable to the Bna^

it can be used to advantage by the more expert. It should be on thewalla of every pUk

and private garage, automobile repair shop, club house or school. Itcan be carni<d laAi

automobile or pocket with ease and will insure against loss of timewhen engine trouble on

fests itself.

This sectional ^new of engine is a complete review of all motortroubles. It is prepandbfl

practical motorist for.all who motor. No details omitted. Sise 25x38inches. Price 25

Lubrication of the Motor Car Chassis.

This cnart presents the plan view of a typical six-cylinder chassis ofstandard desipai all parts are clearly indicated that demand oil, alsothe frequency with which they mini to lubricated and the kind of oil touse. A practical chart for all interoited in motor-car vitf tenance. Sise24x38 inches. Price 25 C<lli|

Location of Carburetlon Troubles Made Easy.

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This chart shows all parts of a typical pressure feed fuel supply systemand gives caoMl trouble, how to locate defects and means of remedy-ing them. Sise 24x38 inches. j

Price 25 ceu

Location of Ignition System Troubles Made Easy.

In this chart all parts of a typical <ioublc ignition system usins batteryand maRneto rortfl arc Bhown and nugRfstioua are pi von for readilyfinding ignition troubles and olimiMta them when found. Size 24x:jSinclu's. Price 25 WBI

Location of Cooling and Lubrication System Faults.

This coinpo.siti' ch.art shows a typical automobile power plant usingpump circulated w»U coolinjr system uikI the most popular lubrica-tion method. Gives suRgeations for curias i overheatini: and Ions ofpower faults due to faulty action of the oiling or cooling ffroup. S24x38 inches. Price ^ ffOi

Motorcycle Troubles Made Easy—A Chart Showing; Sectional View ofSlnidt Cylinder Gasoline Engine. Compiled by Victor \V. Vw,^:, M.SA.E.

TWin chart .*<iniplifies location of all power-plant troubles, and willprove invaluable to.* who hav<! to do with the oi>oration, repair orsale of motorcycles. No details omitt*-<i. Si 2ox3S inchca. Price 25CEnt

Location of Ford Engine Troubles Made Easy. Coinpiletl by Victor WP.\(;6, M.S.A.E.

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This .»howH ch'ur sectional views depicting all portions of thcTordpower plant and auxiitifl Kroup.s. It outlines charly all parts of the en-gine, fuel supply syatera, ifcuition uroop* coolinjf system, that arc ai>tto uive trouble, detailing ail derangements that are liable ■ make ;iiieii;:inc lox' power, start hard or work irregularly. This chart isvalu.'iblc to j«tuH«i* owTn rs. ari<l drivers, as it simplitics location ofall engine faults. Of great advantact^ fc *• instructoi for ili« novice, itcan l»<' us^hI <Hju:illy well by the more expert an a work of rffenrWianti icvltw. Ii ran be carried in the toolbox or pocket with ease and willsave it? c^'^ labor eliminated the first Time engine troul)Ie manifest-sit.self. Prepared with si^eci.-i! r*fiff enee to the a\eraL'e man's nct'dsand is a practical review of all motor trouble* bei-au«£ iti base*! onthe actual experience of an automobile engineer-mechanic with themechani-'in *-^ chart des'-ribes. If (-nabies the non-technical owneror ofx^rator of a Ford ear to locatf-f gine derangements bys>.<;ematie search, giiidetl by easily recognized symptoms instw'i ■ bygu<*s.swork. It makes the av»>rairc owner indejK'ndent of the road-s^iue repair shop *"!* touring. Must be seen to be appreciate. Size2ox'Sii inches. Printed on heavy bond psp** Price -25 CfB^

CATALOGUE OF GOOD, PRACTICAL BOOKS 9

Modern Submarine Chart—with Two Hundred Parts Numbered andNamed.

A cross-section view, showing clearlsr and distinctly all the interior ofa Submarine of the latest type. You get more information from thischart, about the construction and operation of a Submarine, than inany other way. No details omitted—everything is accurate and to scale.It is absolutely correct in every detail, having been approved by NavalEngineers.- AH the machinery und devices fitted in a modem Submar-ine Boat are shown, and to make the engraving more readily under-stood all. the features are shown in operative form, . with Officers and

747/821

Men in the act of performing the duties assigned to them in serviceconditions. This CHART IS REALLY AN ENCYCLOPEDIA OF ASUBMARINE. It is educational and worth many times its cost. Mailedin a Tube for J35 CeutS

Box Car Chart.

A chart showing the anatomy of a box car, having every part of the carnumbered and its proper name given in a reference list. Price 25 CeutS

Gondohi Car Chart. •

A chart showing the ^natomy of a gondola car, having every part ofthe car numbered and its proper reference name given in a referencelist. Price 25 CeUtS

I Passenger-Car Chart.

A chart showing the anatomy of a pa8sen^e^K^ar, having every partof the car numbered and its proper name given in a reference list t •135 CeutS

i

^ Steel Hopper Bottom Coal Car.

^ A chart showing the anatomy of a'steel Hopper Bottom Coal Car,having every part of the car numbered and its proper name given in areference list. Price ^ CentS

^ Tractive Power Chart.

^ A chart whereby you can find the tractive power or drawbar pull ofany locomotive without making a* figure. Shows what cylinders are

748/821

equal, how drivmg wheels and steam pressure aflfect the power. Whatsized engine you need to exert a given drawbar pull or anything yoiidesire in this line. Price 5Q centS

r

' Horse-Power Chart.

Shows the horse-power of any stationary engine without calculation.No matter what the f cylinder diameter of stroke,^ the steam pressureof cut-off, the revolutions, or whether condensing or non-condensing,it's all there. Easy to use, accurate, and saves time and calculations.Especially useful to engineers and designers. Price 5Q centS

BoUer Boom Chart. By Geo. L. Fowleb.

A chart—size 14x28 inches^-showing in isometric perspective themechanisms belonging in a modorn boiler room. The various parts areshown broken or removed, so that the internal construrtion is fully il-lustrated. Each part is given a reference number, and these, with thecorresponding name, are given in a glossary printed at the sides. Thischart is really a dictionary of the boiler room—^the names of morethan 200 parts being given. Price . 25 CentS

COKE

Modern Coking Practice, Including Analysis of Materials andProducts.

By J. E. Christopher and T. H. Byrom.

This, the standard work on the subject, has just been revised. It is apractical work for those engaged in Coke manufacture and the recov-ery of By-products. Fully illustrated with folding Dlates. It has been

749/821

the aim of the authors, in preparing this book, to produce one whichshall be of use and benefit to those who are associated vvith, or inter-ested in, the modem developments of the industry. Among theChapters contained in Volume I are: Introduction; Classification ofFuels; Impurities of Coals; Coal Washing; Sampling and Valuation ofCoals, etc.; Power of Fuels; History of Coke Manufacture; Develop-ments in the Coke Oven Design; Re?ent Types of Coke Ovens; Mech-anical Appliances at Coke Ovens; Chemical and Physical Examinationof Coke. Volume II covers fully the subject of By-Products. Price, pervolume $3.00 net

10 THE NORMAN W. HENLEY PUBLISHING CO.

COMPRESSED AIR

Compressed Air in All Its Applications. By Gardner D. Hiscox.

This is the most complete book on the subject of Air that has ever beenissued, and its thirty-five chapters include about every phase of thesubject one can think of. It may be cidled an encyclopedia of com-pressed air. It is written by an expert, who, in its 665 pages, has dealtwith the subject in a comprehensive manner, no phase of it beingomitted. Includes the physical properties of air from a vacuum to itshighest pressure, its thermodynamics, compression, transmission anduses as a motive power, in the Operation of Stationary and PortableMachinery, in Mining, Air Tools, Air Lifts, Pumping of Water, Acids,and Oils; the Air Blast for Cleaning and Painting the Sand Blast and itsWork, and the Numerous Appliances in which Compressed Air is aMost Convenient and Economical Transmitter of . Power for Mechan-ical Work, Railway Propulsion, Refrigeration, and the Various Uses towhich Compressed Air has been applied. Includes forty-four tables ofth^ physical properties of air, its compression, expansion, andvolumes required for various kin<u of work, and a list of patents on

750/821

compressed air from 1875 to date. Over 500 illustrations, 5th Edition,re-viBed and enlarged. Cloth bound. Price $5.M

JHalf Morocco. Pric# $6<M

CONCEETE

Concrete Workers' Reference Books. A Series of Popular Handbooksfor Concrete Users. Prepared by A. A. Houghton 50 cents

The author, in vreparing this Series, has not only treated on the usualtypfs of constradion, hut explains and illustrates molds and systemsthat are not -patented, but which are equal in value and often superiorto those restricted by patents. These molds are very easily and cheaplyconstructed and embody simplicity, rapidity of operation, and themost successful results in the molded concrete. Each of these books isfully illustrated,, and the subjects are exhaustively treated in plainEnglish.

Concrete Wail Forms. By A. A. Houghton.

A new automatic wall clamp is illustrated with working drawings. Oth-er types of wall forms,, clamps, separators, etc., are also illustrated andexplained. (No. 1 of Series) Price 50 CCntS

Concrete Floors and Sidewalks. By A. A. Houghton.

The molds for molding squares, hexagonal and many other styles ofmosaic floor and sidewalk blocks are fully illustrated and explained.(No. 2 of Series) Price 50 CCntS

Practical Concrete Silo Construction. By A. A. Houghton.

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Complete working drawings and specifications are given for severalstyles of concrete silos, with illustrations of molds for monolithic andblock silos. The tables, data, and information presented in this bookare of the utmost value in planning and constructing all forms of con-crete silos. (No. 3 of Series) Price • 50 CCntS

Molding Concrete Chimneys, Slate and Roof TUes. By A. A. Houghton.

The manufacture of all tjqpes of concrete slate and roof tile is fullytreated. Valuable data on all forms of reinforced conorote roofs arecontained "within its pages. The construction of concrete chimneys byblock and monolithic systems is fully illustrated and described. Anumber of ornamental designs of chimney construction with moldsare shown in this valuable treatise. (No. 4 of Series.) Price 50 CCntS

Molding and Curing Ornamental Concrete. By A. A. Houghton. |

The proper proportions of cement and aggregates for various finishes,also the method of j thoroughly mixing and placing in the molds, arefully treated. An exhaustive treatise on this subject that every concreteworker will find of daily use and value. (No. 5 of Series.)

Price 50 cents

Concrete Monuments, Mausoleums and Burial Vaults. By A. A.Houghton.

The molding of concrete monuments to imitate the most expensive cutstone is explained in this treatise, with working drawings of easilybuilt molds. Cutting inscriptions and designs are also fully treated.(No. 6 of Series.) Price '50 COntS

Molding Concrete Bathtubs, Aquariums and Natatoriums. By A. A.

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Houghton.

Simple molds and instruction are given for molding many styles ofconcrete bathtube, swim-ming-|>ools, etc. These molds are easily builtand permit rapid and successful work. (No. 7 of Series.) Price 50CCntS

CATALOGUE OF GOOD, PRACTICAL BOOKS 11

Concrete Bridges, Culverts and Sewers. By A. A. Houghton.

A number of ornamental concrete bridges with illustrations of moldsare given. A coUapEuble center or core for bridges, culverts and sew-ers is fully illustrated with detailed instructions for building. (No. 8 ofSeries.) Price 50 CentS

Constructing Concrete Porches. By A. A. Houghton.

^ A number of designs with working drawings of molds are fully ex-plained so any one can easily

\' construct different styles of ornamental concrete porch^ without thepurchase of expensive

molds. (No. 9 of Series.) Price 50 CCUtS

\ Molding Concrete Flower-Pots, Boxes, Jardinieres, Etc. By A. A.Houghton.

r The molds for producing many original designs of flower-pots, urns,flower-boxes, jardinieres, etc., are fully illustrated and explained, sothe worker can easily construct and operate same. (No. 10 of Series.)Price 50 CCntS

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Molding Concrete Fountains and Lawn Ornaments. ., By A. A.Houghton.

i The molding of a number of designs of lawn seats, curbing, hitchingposts, pergolas, sun dials and other forms of ornamental concrete forthe ornamentation of lawns and gardens, is fully illustrated and de-scribed. (No. 11 of Series.) Price 50 CCntS

•

Concrete ft*om Sand Molds. By A. A. Houghton.

A Practical Work treating on a process which has heretofore been heldas a trade secret by

the few who possessed it, and which will successfully mold every andany class of ornamental

> concrete work. The process of molding concrete with sand molds isof the utmost practical

value, possessing the manifold advantages of a low cost of molds, theease ^nd rapidity of

\ operation, perfect details to all ornamental designs, density and in-creased strength of the

• concrete, perfect curing of the work without attention and the easyremoval of the molds

regardless of any undercutting the design may have. 192 pages. Fullyillustrated

Pnce . .92.00

754/821

^Ornamental Concrete without Molds. By A. A. Houghton.

The process for making ornamental concrete without molds has longbeen held as a secret, and now, for the first time, this process is givento the public. The book reveals the secret and is the only book pub-lished which explains a simple, practical method whereby the concreteworker is enabled, by emi>lo3dng wood and metal templates of differ-ent designs, to mold or model in concrete any Cornice, Archivolt,Colunm, Pedestal, Base Cap, Urn or Pier in a monolithic form—rightupon the job. These may be molded in units or blocks and then builtup to suit the specifications demanded. This work !s fully illustrated,with detailed engravings. Price . . ^ ^.00

Concrete for the Farm and in the Shop. By H. Colin Campbell, C.E.,E.M.

"Concrete for the Farm and in the Shop" is a new book from cover tocover, illustrating and describing in plain, simple language many ofthe numerous applications of concrete within the range of the homeworker. Among the subjects treated are: Principles of Reinforcing;Methods of Protecting Concrete so as to Insure Proper Hardening;Home-made Mixers; Mixing by Hand and Machine; Form Construc-tion, Described and Illustrated by Drawings and Photographs; Con-struction of Concrete Walls and Fences; Concrete Fence Posts; Con-crete Gate Posts; Corner Posts; Clothes lane Posts; Grape Arbor Posts;Tanks; Troughs; Cisterns; Hog Wallows; Feeding Floors and Bari^-yard Pavements; Foundations; Well Curbs and Platforms; IndoorFloors; Sidewalks; Steps; Concrete Hotbeds and Cold Frames; Con-crete Slab Roofs; Walls for Buildings; Repairing Leaks in Tanks andCisterns; and all topics associated with these subjects as bearing uponsecuring the best results from concrete are dwelt upon at sufificientlen^h in plain every-day English so that the inexperienced person de-siring to undertake a piece of concrete construction can, by following

755/821

the directions set forth in this book, secure 100 per cent, success everytime. A number of convenient and practical tables for estimatingquantities, and some practical examples, are also given. (5x7.) 149paged. 51 illustrations. Price 75 CCntS

Popular Handbook for Cement and Concrete Users. By Mtron H.Lewis.

This is a concise treatise of the principles and methods employed inthe manufacture and use of cement in all classes of modem works. Theauthor has brought together in this work all the salient matter of in-terest to the user of concrete and its many diversified products. Thematter is presented in logical and systematic order, clearly written,fully illustrated and free from involved mathematics. ^ Everything ofvalue to the concrete user is given, including kinds of cement em-ployed in construction, concrete architecture, inspection and testing,waterproofing, coloring and painting, rules, tables, working and costdata. The book comprises thirty-three chapters, as follow: Introduct-ory. Kinds of Cement and How They are Made. Properties. Testing andRequirements of Hydraulic Cement. Concrete and Its Properties.Sand, Broken Stone and Gravel for Concrete. How to Proportion theMaterials. How to Mix and Place Concrete. Forms of Concrete Con-struction. The Architectural and Artistic Possibilities of Concrete. Con-crete Residences. Mortars, Plasters and Stucco, and How to Use Them.The Artistic Treatment of Concrete Surfaces. Concrete Building

12 THE NORMAN W. HENLEY PUBLISHING CO.

Blocks. The Making of Ornamental Concrete. Concrete Pipes, Fences,Posts, etc. Essen* tial Features and Advantages of Reenforced Con-crete. How to Design Reenfcreed Concrete Beams, Slabs and Columns.Explanations of the Methods and Principles in Designing ReenforcedConcrete, Beams and iSlabs. Systems of Reenforcement Employed.

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Reenforced Concrete in Factory and General Building Construction.Concrete in Foundation "Work. Concrete Retaining Walls, Abutmentsand Bulkheads. Concrete Arches and Arch Bridges. Concrete Beamand Girder Bridges. Concrete in Sewerage and Draining Works. Con-crete Tanks, Dams and Reservoirs. Concrete Sidewalks, Curbs andPavements. Concrete in Railroad Construction. The Utility of Concreteon the Farm. The Waterproofing of Concrete Structures. Grout ofLiquid Concrete and Its Use. Inspection of Concrete Work. Cost ofConcrete Work. Some of the special features of the book are: 1.—^TheAttention Paid to the Artistic and Architectural Side of Concrete Work.2.—The Authoritative Treatment of the Problem of WaterproofingConcrete. 3.—^An Excellent Summary of the Rules to be Followed inConcrete Construction. 4.—The Valuable Cost Data and Useful Tablesgiven. A valuable Addition to the Library of Every Cement and Con-crete User. Price . ^,50

WHAT IS SAID OF THIS BOOK:

"The field of Concrete Construction is well covered and the mattercontained is well within the understanding of any person."—Engineering-Contracting.

"Should be on the bookshelves of every contractor, engineer, and ar-chitect in the land."— National Builder.

Waterproofing Concrete. By Myron H. Lewis.

Modern Methods of Waterproofing Concrete and Other Structures. Acondensed statement of the Principles, Rules, and Precautions to beObserved in Waterproofing and Dampproofing Structures and Struc-tural Materials. Paper binding. Illustrated. Price .... 50 €entS

DICTIONARIES

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Aviation Terms, Termes D'Aviation, English-French, iVeneh-Engllsh.

Compiled by Lieuts. Victor W. Page, A.S., S.C.U.S.R., and Paul Mon-TARioL, of the French Flying Corps, on duty on Signal Corps AviationSchool, Mineola, L. I.

The lists contained are confined to essentials, and special foldingplates are included to show all important airplane parts. The lists aredivided in four sections as follows: 1.—Flying Field Terms. 2.—The Air-plane. 3.—The Engine. 4.—Tools and Shop Terms. A complete, well il-lustrated volume intended to facilitate conversation between English-speaking and French aviators. A very valuable book for all who areabout to leave for duty overseas.

Approved for publication by Major W. G. Kilner, S.C., U.S.CO. SignalCorps Aviation School, Hazolhurst Field, Mineola, L. I. This bookshould be in every Aviator's and Mechanic's Kit for ready reference.128 pages, fully illustrated, with detailed engravings. Price . . ^l.QQ

Standard Electrical Dictionary. By T. O'Conor Sloane.

An indispensable work to all interested in electrical science. Suitablealike for the student and professional. A practical handbook of refer-ence containing definitions of about 5,000 distinct words, terms andphrases. The definitions are terse and concise and include every termused in electrical science. Recently issued. An entirely new edition.Should be in the possession of all who desire to keep abreast with theprogress of this branch of science. Complete, concise and convenient.682 pages, 393 illustrations. Price $3*00

DIES—METAL WORK

Dies: Their Construction and Use for the Modern Worldng of SheetMetals.

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By J. V. WOODWORTH.

A most useful book, and one which should be in the hands of all en-gaged in the press working of metals; treating on the DesiKning, Con-structing, and Use of Tools, Fixtures and Devices, together with themanner in which they should be used in the Power Press, for the cheapand rapid production of the great variety of sheet-metal articles now inuse. It is designed as a guide to the production of • ^hcet-iiietal partsat the minimum of cost with the maximum of output. The hardeningand tempering of Press tools and the classes of work which may bejiroduced to the best atlvantage l)y the use of dies in the power pressare fully treated. Its 515 illustrations show dies, press fixtures andsheet-metal working devices, the descriptions of which are so clearand practical that all metal-working mechanics will be able to under-stand how to design, construct and use them. Many of the died andpress fixtures treated were either constructed by the author or underhis supervision. Others were built by skilful mechanics and are in usein large sheet-metal establishments and machine shops. 6th Revisedand Enlarged Edition. Price S3.00

CATALOGUE OF GOOD, PRACTICAL BOOKS 13

onches. Dies and Tools for Manufacturing In Presses. By J. V. Wood-worth.

This work is a companion volume to the author's elementary work en-titled "Dies: Their Construction and Use." It does not go into the de-tails of die-making to the extent of the author's previous book, butgives a comprehensive review of the field of operations carried on bypresses. A large part of the information given has been drawn from theauthor's personal experience. It might well be termed an Encyclopediaof Die-Making, Punch-Making, Die-Sinking, Sheet-Metal Working,and Making of Special Tools, Sub-presses, Devices and Mechanical

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Combinations for Punching, Cutting, Bendmg, Forming, Piercing,Drawing, Compressing and Assembling Sheet-Metal Parts, and alsoArticles of other Materials in Machine Tools. 2d Edition. Price $4.00

rop Forging, Dle-Slnklng and Machine-Forming of Steel. By J. V.

WOODWORTH.

This is a practical treatbe on Modem Shop Practice, Processes, Meth-ods, Machine Tools, and Details treating on the Hot and ColdMachine-Forming of Steel and Iron into Finished Shapes: togetherwith Tools, Dies, and Machinery involved in the manufacture ofDuplicate Forgings and Interchangeable Hot and Cold Pressed Partsfrom Bar and Sheet Metal. This book fills a demand of long standingfor information regarding drop-forgings, die-sinking and machine-forming of steel and the shop practice involved, as it actually exists inthe modern drop>-forging shop. The processes of die-sinking andforce-making, which are thoroughly described and illustrated in thisadmirable work, are rarely to be found explained in such a clear andconcise manner as is here set forth. The process of die-sinking relatesto the engraving or sinking of the female or lower dies, such as areused for drop-forgings, hot and cold machine-forging, swedging, andthe press working of metals. The process of force-making relates to theengraving or raising of the male or upper dies used in producing thelower dies for the press-forming and machine-forging of duplicateparts of metal.

In addition to the arts above mentioned the book contains explicit in-formation regarding the drop-forging and hardening plants, designs,conditions, equipment, drop hammers, forging machines, etc., ma-chine forging, hydraulic forging, autogenous welding and shop prac-tice. The book contains eleven chapters, and the informatipn con-tained in these chapters is just what will prove most valuable to the

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forged-metal worker. All operations described in the work are thor-oughly illustrated by means of perspective half-tones and outlinesketches of the machinery employed. 300 detailed illustrations. Price$2*50

DRAWING—SKETCHING PAPER

ractlcal Perspective. By Richards and Colvin.

Shows just how to make all kinds of mechanical drawings in the onlypractical perspective isometric. Makes everything plain, so that anymechanic can understand a sketch or drawing in this way. Saves timein the drawing room, and mistakes in the shops. Contains practical ex-amples of various classes of work. 4th Edition. Price 50 CentS

Inear Perspective Self-Taught. By Herman T. C. Kraus.

This work gives the theory and practice of linear perspective, as usedin architectural, engineering and mechanical drawings. Persons takingup the study of the subject by. themselves will be able, by the use ofthe instruction given, to readily grasp the subject, and by reasonablepractice become good perspective draftsmen. The arrangement of thebook is good; the plate IS on the left-hand, while the descriptive textfollows on the opposite page, so as to be readily referred to. The draw-ings are on sufficiently large 'scale to show the work clearly and areplainly figured. There is included a solf-exjilanatory chart which givesall information necessary for the thorough understanding of perspect-ive. This chart alone is worth many times over the price of the book.2d Revised and Enlarged Edition. Price $!S.50

Blf-Taught Mechanical Drawing and Elementary Machine Design. By

F. L. Sylvester, M.E., Draftsman, with additions by Erik Oberg, associ-ate editor of ''Machinery."

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This is a practical treatise on Mechanical Drawing and MachineDesign, comprising the first principles of geometric and mechanicaldrawing, workshop mathematics, mechanics, strength of materialsand the calculations and design of machine details. The author's aimhas been to adapt this treatise to the requirements of the practicalmechanic and young draftsman and to present the matter in as clearand concise a manner as possible. To meet the demands of this class ofstudents, practically all the important elements of machine designhave been dealt with, and in addition algebraic formulas have been ex-plained, and the elements of trigonometry treated in the manner bestsuited to the needs of the practical man. The book isdivided into 20chapters, and in arranging the material, mechanical drawing, pure andsimple, has been taken up first, as a thorough understanding of theprinciples of representing objects facilitates the further study of mech-anical subjects. This is followed by the mathematics necessary for thesolution of the problems in machine design which are presented later,and a practical introduction to theoretical mechanics and the strengthof materials. The various elements entering into machine design, suchas cams, gears, sprocket-wheels, cone pulleys, bolts, screws, couulings,clutches, shafting and fly-wheels, have been treated in such a way as tomake possible the use of the work as a text-book for a continuouscourse of study. It is easily comprehended and assimilated even bystudents of limited previous training. 330 pages, 215 engravings. Price$!S.OO

14 THE NORMAN W. HENLEY PUBLISHING CO. A New SketchingPaper.

A new specially ruled paper to enable you to make sketches or draw-ings in isometric perspective without any figuring or fussing. It is be-ing used for shop details as well as for assembly drawings, as it makesone sketch do the work of three, and no workman can help seeing Justwhat is wanted. Pads of 40 sheets, 6x9 inches. Price ^ CentS

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Pads of 40 sheets, 9x12 inches. Price 50 centS

40 sheets. 12x18 inches. Price fl.M

ELECTRICITY

Arithmetic of Electricity. By Prof. T. O'Conor Sloans.

A practical treatise on electrical calculations of all kinds reduced to aseries of rules, all of the simplest forms, and involving only ordinaryarithmetic; each rule illustrated by one or more practical problems,with detailed solution of each one. This book is classed among themost useful works published on the science of electricity, covering as itdoes the mathematics of electricity in a manner that will attract the at-tention of those who are not familiar with alge* braical formulas. 20thEdition. 160 pages. Price $l.tll

Commutator Construction. By Wm. Baxter, Jr.

The business end of any dynamo or motor of the direct current t3n;>eis the commutator. This book goes into the designing, building, andmaintenance of commutators, shows how to locate troublesandhow toremedy them; everyone who fusses with dynamos needs this. 4thEdition.

Price 25 cents

Dynamo Building for Amateurs, or How to Construct a Fifty-WattDynamo.

By Arthur J. Weed, Member of N. Y. Electrical Society.

A practical treatise showing in detail the construction of a small dy-namo or motor, the entire machine work of which can be done on a

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small foot lathe. Dimensioned working drawings are given for eachpiece of machine work, and each operation is clearly described. Thismachine, when used as a dynamo, has an output of fifty watts; whenused as a motor it will drive a small drill press or lathe. It can be usedto drive a sewing machine on any and all ordinary work. The book is il-lustrated with more than sixty original engravings, showing the actualconstruction of the different parts. Among the contents are chapterson: 1. Fifty-Watt Dynamo. 2. Side Bearing Rods. 3. Field Punching. 4.Bearings. 5. Commutator. 6. Pulley. 7. Brush Holders. 8. ConnectionBoard. 9. Armature Shaft. 10. Armature. 11. Armature Winding. 12.Field Winding. 13. Connecting and starting.

Paper. Price 50 CCUtS

Cloth. Price ^1.(1^

Electric BeUs. By M. B. Sleeper.

A complete treatise for the practical worker in Installing, Operatingand Testing Bell Circuits, Burglar Alarms, Thermostats, and other ap-paratus used with Electric Bells. Both the electrician and the experi-menter will find in this book new material which is essential in theirwork. Tools, bells, batteries, unusual circuits, burglar alarms, annunci-ator systems, thermostats, circuit breakers, time alarms, and other ap-paratus used in bell circuits are described from the standpoints oftheir application, construction and repair. The detailed instruction forbuilding the apparatus will appeal to the experimenter particularly.The practical worker will find the chapter on Wiring, Calculation ofWire Sizes and Magnet Winding, Upkeep of Systems, and the Locationof Faults, of the greatest value in their work. Among the chapters are:Tools and Materials for Bell Work; How and Why Bell Work; Batteriesfor Small Installations; Making Bells and Push Buttons; Wiring BellSystems; Construction of Annunciators and Signals; Burglarv Alarms

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and Auxiliary Apparatus; More Elaborate Bell Systems; Finding Faultsand Remedying Them. 124 pages, fully illustrated.

P"ce • • 50 cents

Electric Lighting and Heating Pocket Book. By Sydney F. Walker.

This book puts in convenient form useful information regarding theapparatus which is likely to be attached to the mains of an electricalcompany. Tables of units and eqiiivalents are included and useful elec-trical laws and formulas are stated. 438 pages, 300 engravings. Boundin leather. Pocket book form. Price $3*00

Electric Wiring, Diagrams and Switchboards. By Newton Harrison,with additions by Thomas Poppe.

A thoroughly practical treatise covering the subject of Electric Wiringin all its branches, including explanations and diagrams which.arcthoroughly explicit and greatly simplify the subject. Practical, every-day problems in wiring are presented and the method oi obtaining in-telligent results clearly shown. Only arithmetic is used. Ohm's law isgiven a simple explanation with reference to wiring for direct and al-ternating currents. The fundamental principle of drop of (potential incircuits is shown with its various applications. The simple circuit is de-veloped with the position of mains, feeders and branches; theirtreatment

CATALOGUE OF GOOD, PRACTICAL BOOKS 15

as a part of a wiring plan and their employment in house wiring clearlyillustrated. Some simple facts about testmg are included in connectionwith the wiring. Molding and conduit work are-given careful consider-ation; and switchboards are systematically treated, built up and illus-trated, showing the purpose they serve, for connection with the

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circuits, and to shunt and compound wound macnines. The simpleprinciples of switchboard construction, the development of the switch-board, the connections of tne various instruments, including the light-ning arrester, are also plainly set forth.

Alternating current wiring is treated, with explanations of the powerfactor, conditions calling for various sizes of wire, and a^ simple wayof obtaining the si^^ for single-phase, two-phase and three-phase cir-cuits. This is the only complete work issued showing and telling youwhat you should know about direct and alternating current wiring. Itis a ready reference. The work is free from advanced technicalities andmathematics, arithmetic being used throughout. It is in every respect ahandy, well-written, instructive, comprehensive volume on wiring forthe wireman, foreman, contractor, or electrician. 2nd Revised Edition.303 pages, 130 illustrations. Price $1*50

Slectric Furnaces and their Industrial Applications. By J. Wright.

This is a book which will prove of interest to many classes of people;the manufacturer who desires to know what product can be manufac-tured successfully in the electric furnace, the chemist who wishes topost himself on the electro-chemistry, and the student of science whomerely looks into the subject from curiosity. New, Revised and En-lai^ed Edition. 320 pages. Fully illustrated, cloth. Price $3*00

Slectric Toy Making:, Dynamo Building, and Electric MotorConstruction.

By Prof. T. O'Conor Sloans.

This work treats of the making at home of electrical tojrs, electrical ap-paratus, motors, dynamos, and instruments in general, and is de-signed to bring within the reach of young and old the manufacture of

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genuine and useful electrical appliances. The work is especially de-signed for amateurs and young folks.

Thousands of our young people are daily experimenting, and busilyengaged in making electrical toys and apparatus of various kinds. Thepresent work is just what is wanted to give the much needed informa-tion in a plain, practical manner, with illustrations to make easy thecarrying out of the work. 20th Edition. Price $1*00

Practical Electricity. By Prof. T. O'Conor.Sloanb.

This work of 768 pages was previously known as Sloane's Electricians*Hand Book, and is intended -for the practical electrican who has tomake things go. The entire field of electricity is covered within itspages. Among some of the subjects treated are: The Theory of theElectric Current and Circuit, Electro-Chemistry, Primary Batteries, St-orage Batteries, Generation and Utilization of Electric Powers, Altern-ating Current, Armature Winding, Dynamos and Motors, Motor Gen-erators, Operation of the Central Station Switchboards, Safety Appli-ances, Distribution of Electric Light and Power, Street Mains, Trans-formers, Arc and Incandescent Lighting, Electric Measurements, Pho-tometry, Eleclric Railways, Telephony, Bell-Wiring, Electric-Plating,Electric Heating, Wireless Telegraphy, etc. It contains no useless the-ory; everything is to the point. It teaches you just what you want toknow about electricity. It is the standard work published on thesubject. Forty-one chapters, 556 engravings. Price |RiS«50

aectridty Simplified. By Prof. T. O'Conor Sloane.

The object of "Electricity Simplified" is to make the subject as plain aspossible and to show what the modern conception of electricity is; toshow how two plates of different * metal, immersed in acid, can send amessage around the globe; to explain how a bundle of copper wire

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rotated by a steam engine can be the agent in lighting our streets, totell what the volt, ohm and ampere are, and what high and low tensionmean; and to answer the questions that perpetually arise in the mindin this age of electricity. 13th Edition. 172 pages. Illustrated. Price •. . .$1*00

louse Wiring. By Thomas W. Poppe.

This work describes and illustrates the actual installation of ElectricLight Wiring, the manner in which the work should be done, and themethod of doing^ it. The book can be conveniently carried in thepocket. It is intended for the Electrician, Helper and Apprentice. Itsolves all Wiring Problems and contains nothing that conflicts with therulings of the National Board of Fire Underwriters. It gives just the in-formation essential to the Successful Wiring of a Building. Among thesubjects treated are: Locating the Meter. Panel-Boards. Switches. PlugReceptacles. Brackets. Ceiling Fixtures. The Meter Connections. TheFeed Wires. The Steel Armored Cable System. The Flexible Steel Con-duit System. The Ridig Conduit System. A digest of the National Boardof Fire Underwriters' rules relating to metallic wiring systems. ^ Vari-ous switching arrangements explained and diagrammed. The easiestmethod of testing the Three- and Four^way circuits explained. Thegrounding of all metallic wiring systenus and the reason for doing soshown and explained. The insulation of the metal parts of lamp fix-tures and the reason for the same described and illustrated. 125 pages.2nd Edition, revised and enlarged. Fully illustrated. Flexible

cloth. Price 50 cents

16 THE NORMAN W. HENLEY PUBLISHING CO. How to Become aSuccessful Electrician. Bv Prof. T. O'Conor Sloane.

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Every young man who wishes to become a successful electricianshould read this book. It tells in simple language the surest and easiestway to become a successful* electrician. The studies to be followed,methods of work, field of operation and the requirements of the sue*cessful electrician are pointed out and fully explainea. Every youn^;engineer will find this an excellent steppmg stone to more advancedworks on electricity which he must master before success can be at-tained. Many young men become discouraged at the very outstart byattempting to read and study books that are far beyond their compre-hension. This book serves as the connecting link between the rudi-ments taught in the public schools and the real study of e ectricity. It isinteresting from cover to cover. 18th Revised Edition, just issued. 205pages. Illustrated. Price $1.00'

Management of Dynamos* By Lummis-Paterson.

A handbook of theory and practice. This work is arranged in threeparts. The first part covers the elementary theory of the dynamo. Thesecond part, the construction and action of the different classes of dy-namos in common use are described; while the third part relates tosuch matters as affect the practical ipanagement and working of dy-namos and motors. 4th Edition. 292 pages, 117 illustrations. Price$1.50

Standard Electrical Dictionary* By T. O'Conor Sloane.

An indispensable work to all interested in electrical science. Suitablealike for the student and professional. A practical handbook of refer-ence containing definitions of about 5,000 distinct words, terms andphrases. The definitions are terse and concise and include every termused in electrical science. Recently issued. An entirely new edition.Should be in the possession of all who desire to keep abreast with theprogress of this branch of science. In Its arrangement and typography

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the book is very convenient. The word or term defined is printed inblack-faced type, which readily catches the eye, while the body of thepage is in smaller but distinct type. The definitions are well worded,and so as to be understood by the non-technical reader. The generalplan seems to be to give an exact, concise definition, and then amplifyand explain in a more popular way. Synonyms are also given, and ref-erences to other words and phrases are made. ^ A very complete andHccurate index of fifty page& is at the end of the volume; and as thisindex contains all synonyms, and as all phrases ait indexed in everyreasonable combination of words, reference to the proper place in thebody ot the book is readily made. It is difficult to decide how far abook of this character is to keep the dictionary form, and to what ex-tent it may assume the encyclopedia form. For some purposes, con-cise, exactly worded definitions are needed; for other purposes, moreextepded descriptions are required. This book seeks to satisfy both de-manas, and does it with considerable success. 682 pages, 393 illustra-tions. 12th Edition. Price 13,00

Storage Batteries Simplified. By Victor W. Pag^, M.E.

A complete treatise on storage battery operating principles, repairs"^and applications. The greatly increasing application of storage batter-ies in moaern engineering and mechanical work has created a demandfor a book that will consider this subject completely and exclusively.This is the most thorough and authoritative treatise ever published onthis subject. It is written in easily understandable, non-technical lan-guage so that any one may grasp the basic principles of storage batteryaction as well as their practical industrial applications. AH electric andgasoline automobiles use storage batteries. Every automobile repair-man, dealer or salesman should have a good knowledge of mainten-ance and repair of these important elements of the motor car mechan-ism. This book not only tells how to charge, care for and rebuild stor-age batteries but also outlines all the industrial uses. Learn how they

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run street cars, locomotives and factory trucks. Get an understandingof the important functions they perform in submarine boats, isolatedlighting plants, railway switch and signal systems, marine applica-tions, etc. This book tells how they are used in central station standbyservice, for startmK automobile motors and in ignition systems. Everypractical use of the naodem storage battery is outlined in this treatise.320 pages, fully illustrated. Price . . , ^1*50

Switchboards. By William Baxter, Jr.

This book appeals to every engineer and electrician who wants toknow the practical side of things. It takes up all sorts and conditions ofdynamos, connections and circuits, and shows by diagram and illus-tration just how the switchboard should be connected. Includes directand alternating current boards, also those for arc lightipg, incandes-cent and power circuits. Special treatment on high voltage boards forpower transmission. 2nd Edition. 190 pages, Illustrated. Price $1*50

Telephone Construction, Installation, Wiring, Operation andMaintenance*

By W. H. Radcliffe and H. C. Gushing.

This book is intended for the arnateur, the wireman, or the engineerwho desires to establish a means of telephonic communicationbetween the rooms of his home, office, or shop. It deals only with suchthings as may be of use to him rather than with theories. Gives theprinciples of construction and operation of both the Bell andIndependent instruments; approved methods of installing and wiringthem; the means of protecting them from lightning and abnormal cur-rents; their connection together for operation as series or bridging sta-tions; and rules for their inspection and maintenance. Line wiring andthe wiring and operation of special telephone systems are also treated.

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Intricate mathematics are avoided, and all apparatus, circuits and sys-tems are thoroughly described. The appendix

CATALOGUE OF GOOD, PRACTICAL BOOKS 17

•

contains definitions of units and terms used in the text. Selected wir-ing tables, which are very helpful, are also included. Among the sub-jects treated are Construction, Op>eration, and Installation of Tele-phone Instruments; Inspection and Maintenance of Telephone Instru-ments; Telephone Line Wiring; Testing Telephone Line Wires andCables; Wiring and Operation of Special Telephone Systems, etc. 2ndEdition, Rev^ped and Enlarged. 223 pages, 154 illustrations $1*00

Ireless Telegraphy and Telephony SImpIf Explained. By Alfred P.Morgan.

This is undoubtedly one of the most complete and comprehensibletreatises on the subject ever published, and a close study of its pageswill enable one to master all the details of tht wireless transmission ofmessages. The author has filled a long-felt want and has succeeded infurnishing a lucid, comprehensible explanation in simple language ofthe theory and practice of wireless telegraphy and telephony. _ ^ . ^Among the contents are: Introductory; Wireless Transmission and Re-ception—^The Aerial System, Earth Connections—The TransmittingAp^ratus, Spmrk Coils and Transformers, Condensers, Helixes, SparkGaps, Anchor Gaps, Aerial Switches—^The Receiving Apparatus,Detectors, etc.—^Tuning and Coupling, Tuning Coils, Loose Couplers,Variable Condensers, Directive Wave Systems—Miscellaneous Appar-atus, Telephone Receivers, Range of Stations, Static Interfer-ence—^Wireless Telephones, Sound and Sound Waves, The VocalCords and Ear—^Wireless Telephone, How Sounds Are Changed into

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Electric Waves—^Wireless Telephones, The Apparatus—Summary.154 pages, 156 engravings. Price $1*00

iring a House. By Herbert Pratt.

Shows a house already built; tells just how to start, about wiring it;where to begin; what wire to use; how to run it according to InsuranceRules; in fact, just the information you need. Directions apply equallyto a shop. 4th Edition. Price ....... ^ CentS

FACTORY MANAGEMENT, ETC.

m • ■

odern Machine Shop Constructiony Equipment and Management. By

O. E. Perrigo, M.E.

The only work published that describes the modem machine shop ormanufacturing plant from the time the grass is growing on the site in-tended for it until the finished product is shipped. By a careful study ofits thirty-two chapters the practical man may economically build, effi-ciently equip, and successfully manage the modern machine shop ormanufacturing establishment. Just the book needed by those contem-plating the erection of modern shop buildings, the rebuilding and re-organization of old ones, or the introduction of modem shop methods,time and cost systems. ' It is a book written and illustrated by a prac-tical shop man for practical shop men who are top busy to read theor-ies and want facts. It is the most complete all-around book of its kindever published. It is a practical bobk for practical men, from the ap-prentice in the shop to the president in the office. It minutely de-scribes and illustrates the most simple and yet the most efficient timeand cost system yet devised. 2nd Revised and Enlarged Edition, justissued. 384 pages, 219 illustrations. Price . . . ^.CO

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FUEL

imbustion of Coal and the Prevention of Smoke. By Wm. M. Barr.

This book has been prepared with special reference to the generationof heat by the combustion of the common fuels found in the UnitedStates, and deals particularly with the conditions necessary to the eco-nomic and smokeless combustion of bituminous coals in Stationaryand Locomotive Steam Boilers.

The presentation of this important subject is systematic and progress-ive. The arrangement of the book is in a series of practical questions towhich are appended accurate answers, which describe in language,free from technicalities, the several processes involved in the furnacecombustion of American fuels; it clearly states the essential requisitesfor perfect combustion, and points out the best methods for furnaceconstruction for obtaining the greatest quantity of heat from any givenquality of coal. Nearly 350 pages, fully illustrated. Price . . $1.00

noke Prevention and Fuel Economy. By Booth and Kershaw.

A complete treatise for all interested in smoke prevention and com-bustion, being based on the German work of Ernst Schmatolla, but itis more than a mere translation of the German treatise, much beingadded. The authors show as briefly as pKJssible the principles of fuelcombustion, the methods which have been and are at present in use,as well as the proper scientific methods for obtaining all the energy inthe coal and burning it without smoke. Considerable space is also giv-en to the examination of the waste gase.s, and several of therepresontutivo English and American mechanical stoker and similarappliances are described. The losses carried away in the waste gasesare thoroughly analyzed and discussed in the Ap-

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gendix, and abstracts are also here given of various patents on com-bustion apparatus. The ook is complete and contains much of value toall who have charge of large plants. 194 pages. Illustrated. Price $^.50

18 THE NORMAN W. HENLEY PUBLISHING CO.

GAS ENGINES AND GAS

Gas9 Gasoline and Oil Engines. By Gardner D. Hiscox. Revised byVictor W. Pag6, M.E.

Just issued New 1018 Edition, Reyised and Enlarged. Every user of agas engine needs this book. Simple, instructive and right up-to-date.The only complete work on the subject. Tells all about internal com-bustion engineering, treating eidiaustively on the design, constructionand practical application of all forms of gas, gasoline, kerosene andcrude petroleum-oil engines. Describes minutely all auxiliary systems,such as lubrication, carburetion and ignition. Considers the theory andmanagement of all forms of explosive motors for stationary and mar-ine work, automobiles, aeroplanes and motor-cycles. Includes alsoProducer Gas and Its Production. Invaluable instructions for allstudents, gas-engine owners, gas-. engineers, patent exports, design-ers, mechanics, draftsmen and all having to do witJi the m^ern power.Illustrated by over 400 engravings, many specially made from engin-eering drawings, all in correct proportion. 650 pages, 435 engravings.Price .... $2.50 net

The Gasoline Engine on the Farm: Its Operation, Bepair and Uses* By

Xeno W. Putnam.

This is a practical treatise on the Gasoline and Kerosene Engine inten-ded^ for the man who wants to know just how to manage his engineand how to apply it to all kinds of farm woric to the best advanta^^e.

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This book abounds with hints and helps for the farm and suggestionsfor the home and housewife. There is so much of value in this bookthat it is impossible to-adequately describe it in such small space. Suf-fice to say that it is the kind of a book every farmer will appreciate andevery farm home ought to have. Includes selecting the most suitableengine for farm work, its most convenient and efficient installation,with chapters on troubles, their remedies, and how to avoid them. Thecare and management of the farm tractor in plowing, harrowing, har-vesting and road grading are fully covered; also plain directions aregiven for handling the tractor on the road. Special attention is given torelieving farm life of its drudgery by applying power to the disagree-able small tasks which must otherwise be done by hand. Many home-made contrivances for cutting wood, supplying kitclten, garden, andbam with water, loading, hauling and unloading hay, delivering grainto the bins or the feed trough are included; also full directions formaking the engine milk the cows, churn, wash, sweep the house andclean the windows, etc. Very fully illustrated with drawings of workingparts and cuts showing Stationary, Portable and Tractor Engines do-ing all kinds of farm work. All money-making farms utilize power.Learn how to utilize power by reading the pages of this book. It is anaid to the result getter, invaluable to the up-to-date farmer, student,blacksmith, implement dealer and, in fact, all who can apply practicalknowledge of stationary gasoline engines or gas tractors to advantage.530 pages. Nearly 180 engravings. Price ^.0#

WHAT IS SAID OF THIS BOOK:

"Am much pleased with the book and find it to be very complete andup-to-date. I will heartily recommend it to students and farmerswhom I think would stand in need of such a work, as I think it is an ex-ceptionally good one."— N. S. Gardiner, Prof, in Charge, Clemson Agr.College of S. C; Dept. of Agri. and Agri. Exp. Station, Clemson College,S. C.

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"I feel that Mr. Putnam's book covers the main points which a farmershould know."— R. T. Burdick, Instructor in Agronomy, University ofVermont, Burlington, Vt.

Gasoline Eng:lnes: Their Operation, Use and Care. By A. Htatt Verrill.

The simplest, latest and most comprehensive popular work publishedon Gasoline Engines, describing what the Gasoline Engine is; its con-struction and operation; how to install it; how to select it; how to use itand how to remedy troubles encountered. Intended for Owners, Oper-ators and Users of Gasoline Motors of all kinds. This work fully de-scribes and illustrates tiie various types of Gasoline Engines used inMotor Boats, Motor Vehicles and Stationary Work. The parts, ac-cessories and appliances are described with chapters on ignition, fuel,lubrication, operation and engine troubles. Special attention is givento the care, operation and repair of motors, with useful hints and sug-gestions on emergency repairs and makeshifts. A complete glossary oftechnical terms and an alphabetically arranged table of troubles andtheir symptoms form moat valuable and unique features of this manu-al. Nearly every illustration in the book is original, having been madeby the author. Every page is full of interest and value. A book whichyou cannot afford to be without. 275 pages, 152 specially made engrav-ings. Price $1.50

Gas Eng:lne Construction, or How to Build a Half-horsepower GasEngine.

By Parsell and Weed.

A practical treatise of 300 pages describing the theory and principlesof the action of Gas Engines of various types and the design and con-struction of a half-horsepower Gas Engine, with illustrations of thework in actual progress, together with the dimensioned working

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drawings, giving clearly the sizes of the various details: for the student,the scientific investigator, and the amateur mechanic. This book treatsof the subject more from the standpoint of practice than that of theory.The principles of operation of Gas Engines are clearly and simply de-scribed, and then the actual construction of a half-horsepower engineis taken up, step by step, showing in detail the making of the GasEngine. 3rd Edition. 300 pages.

P"«« $2.50

f CATALOGUE OF GOOD, PRACTICAL BOOKS 19

How to Bun and Install Two- and Foiir-Cyde Marine GasolineEngines.

By C. Von Culin.

Revised and enlarged edition just issued. The object of this little bookis to furnish a pocket instructor for the beginner, the busy man whouses an engine for pleasure or profit, but who does not have the timeor inclination for a technical book, but simply to thoroughly under-stand how to properly operate, install and care for his own engine. Theindex refers to each * trouble, remedy, and subject alphabetically. Be-ing a quick reference to find the cause, remedy

I and prevention for troubles, and to become an expert with his ownengine. Pocket size.

|, Paper binding. Price 25 CentS

^ Modern Gas Engines and Producer Gas Plants. By R. E. Mathot.

•

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A guide for the gas engine designer, user, and engineer in the con-struction, selection, purchase, installation, operation, and mainten-ance of gas engines. More than one book on gas engines has been writ-ten, but not one has thus far even encroached on the field covered bythis book. Above all, Mr. Mathot's work is a practical guide. Recogniz-ing the need of a volume that would assist the gas engine user in un-derstanding thoroughly the motor upon which he depends for power,the author has discussed his subject without the help of any mathem-atics and within' out elaborate theoretical explanations. Every part ofthe gas engine is described in detail, tersely, clearly, with a thoroughunderstanding of the requirements of the mechanic. Help-I ful sugges-tions as to the purchase of an engine, its installation, care, and opera-tion, form a most valuable feature of the work. 320 pages, 175 detailedillustrations. Price . . . ^.50

The Modern Gas Tractor. By Victor W. Pag6, M.E.

A complete treatise describing all types and sizes of gasoline,-keroseneand oil tractors. Con-; siders design and construction exhaustively,gives complete instructions for care, operation and ^ repair, outlinesall practical applications on the road and in the field. The best andlatest work on farm tractors and tractor power plants. A work neededby farmers, students, blacksmiths, mechanics, salesmen, implementdealers, designers and engineers. 2nd Edition, Revised. 504 pages,228 illustrations, 3 folding plates. Price $^«00

i

■

GEARING AND CAMS

f Bevel Gear Tables. By D. Ag. Engstrom.

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A book that will at once commend itself to mechanics and draftsmen.Does away with all the trigonometry and fancy figuring on bevel gears,and makes it easy for anyone to lay them out or make them just right.There are 36 full-page tables that show every necessary dimension forall sizes or combinations you're apt to need. No puzzling, figuring orguessing. Gives placing distance, all the angles (including cuttingangles), and the correct cutter to use. A copy of this prepares you foranything in the bevel-gear line. 3rd Edition. 66 pages. Price $1.00

Change Gear Devices. By Oscar E. Perrigo.

A practical book for every designer, draftsman, and mechanic inter-ested in the invention and development of the devices for feed changeson the different machines requiring such niechanism. AH the neces-sary information on this subject is taken up, analyzed, classified,sifted, and concentrated for the use of busy men who have not the timeto go through the masses of irrelevant matter with which such a sub-ject is iisually encumbered and select such information as will be use-ful to them.

It shows just what has been done, how it has been done, when it wasdone, and who did it. It saves time in hunting up patent records andre-inventing old ideas. 88 pages. 3rd Edition. Price $1.00

I>rafting of Cams. By Louis Rouillign.

The laying out of cams is'a serious problem unless you know how to goat it right. This puts you on the right road for practically any kind ofcam you are likely to run up against. 3rd Edition. Price 35 CentS

HYDRAULICS

Hydraulic Eng:lneerlng. By Gardner D. Hiscox.

780/821

A treatise on the properties, power, and resources of water for all pur-poses. Including the measurement of streams, the flow of water inpipes or conduits; the horsepower of falling water, turbine and impactwater-wheels, wave motors, centrifugal, reciprocating and air-liftpumps. With 300 figures and dia^ams and 36 practical tables. ^ Allwho are interested in water-works development will find this book auseful one, because it is an entirely practical treatise upon a subject ofpresent importance and cannot fsiil in having a far-reaching influence,and for this reason should have a place in the working libranr of everyengineer. Among the subjects treated are: Historical Hydraulics; Prop-erties of Water; Measurement of the Flow of Streams;

23 THE NORMAN WL HENLEY PUBLISHING CO.

Flow from Sub-eurface Orifices and Nosslee; Flow of Water in Pipes;Siphons of Various Kinds; Dams and Great Storage Reservoirs; Cityand Town Water Supply; Wells and Their Reinforcement; Air-liftMethods of Raising Water; Artesian Wells; Irrigation of Arid IMs-tricts; Water Power; Water Wheels; Pumps and Pumping Machinery;Reciprocating Pumps; Hydraulic Power Transmission; Hydraulic Min-ing; Canals; Ditches; Conduits and Pipe Lmes; Marir.e Hydraulics;Tidal and Sea Wave Power, etc. 320 pages. Price . . . ^.00

ICE AND BEFRIGEBATION

Pocketbook of Befrigeratlon and Ice Making. By A. J. Wallis-Taylor.

This is one of the latest and most comprehensive reference books pub-lished on the subject of refrigeration and cold storage. It explains thepiY>perties and refrigerating effect of the different fluids in use. themanagement of refrigerating machineiy and the construction and in-sulation of cold rooms with their required pipe surface for differentdecrees of cold; freeling mixtures and non-freezing brines,

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temperatures of cold rooms for all lands of provisions, cold storagecharges for all classes of goods, ice making and storage of ice, data andmemoranda for constant reference by refrigerating engineers, withnearly one hundred tables containing valuable references to every factand condition required in the installment and operation of a refriger-ating plant. New edition just published. Price $1*50

INVENTIONS—PATENTS

Inventors' Manual: How to Make a Patent Pay.

This is a book designed as a guide to inventors in perfecting their in-ventions, taking out their patents and disposing of them. It is not inany sense a Patent Solicitor's Circular nor a Patent Broker's Advertise-ment. No advertisements of any description appear in the work. It is abook containing a quarter of a century's experience of a successful in-ventor, together with notes based upoft the experience of many otherinventors.

Among the subjects treated in this work are: How to Invent. Howto'Secure a Good Patent. Value of Good Invention. How to Exhibit anInvention. How to Interest Capital. How to Estimate the Value of aPatent. Value of Design Patents. Value of Foreign Patents. Value ofSmall Inventions. Advice on Selling Patents. Advice on the Formationof Stock Companies. Advice on the Formation of Limited LiabilityCompanies. Advice on Disposing of Old Patents. Advice as to PatentAttorneys. Advice as to Selling Agents. Forms of Assignments. Licenseand Contracts. State Laws Concerning Patent Rights. 1900 Census ofthe United States by Counts of Over 10,000 Population. Ilevised Edi-tion. 120 pages. Price $1M

KNOTS

Knots, Splices and Rope Work. By A. Hyatt Verrill.

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This is a practical book giving complete and simple directions for mak-ing all the most useful and ornamental knots in common use, withchapters on Splicing, Pointing, Seizing, Serving, etc. This book is fullyillustrated with 154 original engravings, which show how each knot, tieor splice is formed, and its appearance when finished. The book willbp found of the greatest value to Campers, Yachtsmen, Travelers, BoyScouts, in fact, to anyone having occasion to use or handle rope orknots for any purpose. The book is thoroughlv reliable and practical,and is not only a guide, but a teacher. It is the standard work on thesubject. Among the . contents are: 1. Cordage, Kinds of Rope. Con-struction of Rope, Parts of Rope Cable and

Bolt Rope. Strength of Rope, Weight of Rope. 2. Simple Knots andBends. Terms Used in Handling Rope. Seizing Rope. 3. Tics andHitches. 4. Noose, Loops and Mooring Knots. 5. Shortenings, Grom-mets and Salvages. 6. Lashings, Seizings and Splices. 7. Fancy Knotsand Rope Work. 128 pages, 150 original engravings. 2nd RevisedEdition.

Price 75 eents

LATHE WORK

Lathe Design, Construction, and Operation, with Practical Examplesof Lathe Work. By Oscar E. Perrigo.

A new, revised edition, and the only complete American work on thesubject, written by a man who knows not only how work ought to bedone, but who also know^s how to do it, and how to convey thi.sknowledpo to others. It is strictly up-tondate in its descriptions and il-lustrations. Lathe history and the relations of the lathe to manufactur-ing are given; also a description of the various devices for feeds andthread-cutting mechanisms from early efforts in this direction to the

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present time. Lathe design is thoroughly discussed, including backgearing, driving cones, thread-cutting gears, and all the essential ele-ments of the modern lathe. The classific^ation of lathes is taken up,giving the essential differences of the several types of lathes including,as is usually undferstood, engine lathes, bench lathes, 8pe«;d lathes,forge lathes, gap lathes, pulley lathes, forming lathesj multiple-epindlelathes, rapid-reduction lathes, precision lathes, turret lathes, speciallathes, electrically driven lathes,

CATALOGUE OF GOOD, PRACTICAL BOOKS 21

etc. In addition to the complete exposition on construction and design,much practical matter on lathe installation, care and operation hasbeen incorporated in the enlarged new-edition. All kinds of lathe at-tachments for drilling, milling, etc., are described and complete in-structions are given to enable the novice machinist to grasp the art oflathe operation as well as the principles involved in design. A numberof difficult machining operations are described at length and illus-trated. The new edition has nearly 500 pages and 350 illustrations.Price $/3«50

WHAT IS SAID OF THIS BOOK:

**This is a lathe book from beginning to end, and is just the kind of abook which one de* lights to consult—a masterly treatment of the sub-ject in hand."— Engineering News. "This work will be of exceptionalinterest to any one who is interested in lathe practice, a& one very sel-dom sees such a complete treatise on a subject as this is on thelathe."— Canor dian Machinery.

Practical Metal Turning. By Joseph G. Hobner. t

A work of 404 pages, fully illustrated, covering in a comprehensivemanner the modem practice of machining metal ^arts in the lathe,

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including the regular engine lathe, its essential design, its uses, itstools, its attachments, and the manner of holding the work and per-forming the operations. The modernized engine lathe, its methods,tools and great range of accurate work. The turret lathe, its tools, ac-cessories and methods of performing its functions. Chapters on specialwork, grinding, tool holders, speeds, feeds, modem tool steels, etc. Se-cond edition ^.50

Turning and Boring Tapers. By Fred H. Colvin.

There are two ways to turn tapers; the right way and one other. Thistreatise has to do with the right way; it tells you how to start the workproperly, how to set the lathe, what tools to use and how to use them,and forty and one other little things that you should know. Fourth edi-tion 25 CeutS-

LIQUID AIR

Liquid Air and the Liquefaction of Gases. By T. O'Conor Sloane.

This book gives the history of the theory, discovery and manufactureof Liquid Air, and

contains an illustrated description of all the experiments that have ex-cited the wonder of

audiences all over the country. It shows how liquid air, like water, iscarried hundreds of

miles and is handled in open buckets. It tells what may be expectedfrom it in the near

future.

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A book that renders simple one of the most perplexing chemical prob-lems of the century.

Startling developments illustrated by actual experiments.

It is not only a work of scientific interest and authority, but is intendedfor the general reader,

being written in a popular style—easily understood by every one. Se-cond edition. 36^

pages. Price $!3.06

LOCOMOTIVE ENGINEERING

Air-Brake Catecliism. By Robert H. Blackall.

This book is a standard text-book. It covers the Westinghouse Air-Brake. Equipmentr including the No. 5 and the No. 6 E.-T. LocomotiveBrake Equipment; the K (Quick Service) Triple Valve for Freight Ser-vice; and the Cross-Compound Pump. The operation of all parts of theapparatus is explained in detail, and a practical way of finding theirpeculiarities and defects, with a proper remedy, is given. It contains2,000 questions with their answers, which will enable any railroadman to pass any examination on the subject of Air Brakes. Endorsedand used by air-brake instructors and examiners on nearly every rail-road in the United States. Twenty-sixth edition. 411 pages, fully illus-trated with colored plates and diagrams. Price $!S*00'

786/821

American Compound Locomotives. By Fred H. Colvin.

The only book on compounds for the engineman or shopman thatshows in a plain, prac-^ tical way the various features of compound lo-comotives in use. Shows how they are made, what to do when theybreak down or balk. Contains sections as follows: A Bit of History.Theory of Compounding Steam Cylinders. Baldwin Two-CylinderCompound. Pittsburg Two-Cylinder Compound. Rhose Island Com-pound. Richmond Compound. Rogers Compound. Schenectady Two-Cylinder Compound. Vauclain Compound. Tandem Compounds. Bald-win Tandem. The Colvin-Wightman Tandem. Schenectady Tandem.Balanced Locomotives. I^aldwin Balanced Compound. Plans forBalancing. Locating Blows. Breakdowns. Reducing Valves. Drifting.Valve Motion. Disconnecting. Power of Compound Locomotives.Practical Notes.

Fully illustrated and containing ten special "Duotrtie" inserts on heavyPlate Paper, show-ing different types of Compounds. 142 pages. Price^LOO*

22 THE NORMAN W. HENLEY PUBLISHING CO.

Application of Highly Superheated Steam to Locomotives. By RobertGarbe.

A practical book which cannot be recommended too highly to thosemotive-power men who are anxious to maintain the highest efficiencyin their locomotives. Contains special chapters on Generation ofHighly Superheated Steam; Superheated Steam and the Two^ylinderSimple Engine; Compounding and Superheating; Designs of Locomot-ive Superheaters; Constructive Details of Ix)comotives Using HighlySuperheated Steam. Experimental and Working Results. Illustratedwith folding plates and tables. Cloth. Price .... ^^

Combustion of Coal and the Prevention of Smoke. By Wm. M. Barr.

This book has been prepared with si>ecial reference to the generationof heat by the combustion of the common fuels found in the UnitedStates and deals particularly with the conditions necessary to the eco-nomic and smokeless combustion of bituminous coal in Stationary andLocomotive Steam Boilers.

Presentation of this imi>ortant subject is systematic and progressive.The arrangement of the book is in a series of practical questions towhich are appended accurate answers, which describe in language freefrom technicalities the several processes involve in the furnace com-bustion of American fuels; it clearly states the essential requisites forperfect combustion, and points out the best methods of furnace con-struction for obtaining the greatest quantity of heat from any givenquality of coal. Nearly 350 pages, fully illustrated. Price $l.eO

Diary of a Bound-House Foreman. By T. S. Rei^lt.

This is the greatest book of railroad experiences ever published. Con-taining a fund of information and suggestions along the line of hand-ling men, organizing, etc., that one'cannot afford to miss. 176 pl&ges.Price $1.09

Link Motions, Valves and Valve Setting. By Fred H. Colvin, AssociateEditor of ** American Machinist."

A handy book for the engineer or machinist that clears up the myster-ies of valve setting. Shows the different valve gears in use, how theywork, and why. Piston and slide valves of different types are illustratedand explained. A book that every railroad man in the motive-powerdepartment ought to have. Contains chapters on Locomotive Link Mo-tion, Valve Movements, Setting Slide Valves, Analysis by Diagrams,Modem Practice, Slip of Block, Slice Valves, Piston Valves, Setting

788/821

Piston Valves, Joy-Allen-Valve Gear, Walscluiert Valve Gear, GoochValve Gear, Alfree-flubbell Valve Gear, etc., etc. Fully illustrated.

Price 50 cents

Locomotive Boiler Construction. By Frank A. Kleinhans.

The construction of boilers in general is treated and, following this, thelocomotive boiler is taken up in the order in which its various parts gothrough the shop. Shows all types of boilers used; gives details of con-struction; practical facts, such as life of riveting, punches and dies;work done per day, allowance for bending and flanging sheets and oth-er data. Including the recent Locomotive Boiler Inspection Laws andExamination Questions with' their answers for Government Inspect-ors. Contains chapters on Laying-Out Work; Flanging and Forging;Punching; Shearing; Plate Planing; General Tables; Finishing Parts;Bending; Machinery Parts; Riveting; Boiler Details; Smoke-Box De-tails; Assembling and Calking; Boiler-Shop Machinery, etc., etc.

There isn't a man who has anything to do with boiler work, either newor repair work, who doesn't need this book. The manufacturer, super-intendent, foreman and boiler worker— all need it. No matter what thetype of bioler, you'll find a mint of information that you wouldn't bewithout. Over 400 pages, five large folding plates. Price $3*00

Locomotive Breakdowns and their Remedies. By Geo. L. Fowler.Revised by Wm. W. Wood, Air-Brake Instructor. Just issued. Revisedpocket edition.

It is out of the question to try and tell you about every subject that iscovered in this pocket edition of Locomotive Breakdowns. Just ima-gine all the common troubles that an engineer may expect to happensome time, and then add all of the unexpected ones, troubles thatcould occur, but that you have never thought about, and you will find

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that they are all treated with the very best methods of repair. Wals-chaert Locomotive Valve Gear Troubles, Electric Headlight Troubles,as well as Questions and Answers on the Air Brake are all included.312 pages. 8th Revised Edition. Fully illustrated. Price $1.00

Locomotive Catechism. By Robert Grimshaw.

The revised edition of "Locomotive Catechism," by Robert Grimshaw,is a New Book from Cover to Cover. It contains twice as many pagesand double the number of illustrations of previous editions. Includesthe greatest amount of practical information ever published on theconstruction and management of modern locomotives. Specially Pre-pared Chapters on the Walschaert Locomotive Val>« Gear, the Air-Brake Equipment and the Electric Headlight are given.

i * ■

It commends itself at once to eveiy Engineer and Fireman, and to allwho are going in for examination or promotion. In plam language;with full, complete answers, not only all the questions asked by the ex-amining engineer are given, but those which thp youxig and less ex-perienced would ask the veteran, and which old hands ask as"stickers/' It is a veritable Encyclopedia of the Locomotive, is entirelyfree from mathematics, easily imderstood and thoroughly up to date.Contains over 4,000 Examinatii6n Questions with their Answers. 825pages, 437 illustrations, and 3 folding plates. 28th Revised Edition.Price ft9«50

Practical Instructor and Beference Book for LocomotlTe Firemen and£ng;ineers. By Chas. F. Lockhart..' ,..,.,:

An entirely new book on the Locomotive. It appeals to every railroadmto, as it tells him how things are done and the right way to do them.Written by a man who has had years of practical experience in

790/821

locomotive shops and on the road firinjg and running. The informa-tion given in this book cannot be found in any other simi|ar treatise.Eight hundred and fifty-one questions with their answers are in-cluded, which will prove specially^elpful to those preparing for exam-ination. Practical information on: The Construction and Operation ofLocomotives* Breakdowns and their Remedies, Air Brakes and ValveGears. Rules and Signals are handled in a thorough manner. As a bookof reference it cannot be excelled. The book is divided into six parts, asfollows: 1. The Firema^i's Duties. 2. General Description of the Loco-motive. 3. Breakdowns and their Remedies. 4. Air^ Brakes. 5. Extractsfrom Standard Rules. 6. Questions for Examination. The 851 qu^tionshave been carefully selected and arranged. These cover the examina-tions required by the different railroads.* 368 pages, 88 illustrations.Price $1.50

PreTention of Ballroad Accidents, or Safety in BaUroadlng. By GeorgbBradshaw.

This book is a heart-to-heart talk with Railroad Employees, dealingwith facts, not theories, and showing the men in the ranks, from every-day experience, how accidents occur and how they may be avoided.The book is illustrated with seventy^ original photographs and draw-ings showing the safe and unsafe methods of work. ' No visionaryschemes, no ideal pictures. Just Plain Facte and Practical Suggestionsare given. Every rulroad employee who reads the book is a better andsafer man to have in railroad service. It gives just the informationwhich will be the means of preventing many injuries and deaths. Allrailroad employees should procure a copy, read it, and do their part inpreventing accidents. 169 pages. Pocket size. Fully illustrated. Price 50CCntS

•

791/821

Train Bule Examinations Made Easy. By G. E. Collingwood.

This is the only practical work on train rules in print. Every detail iscovered, and puzzling

?oints are explained in simple, comprehensive language, making it apractical treatide for the 'rain Dispatcher, Engineman, Trainman, andall others who have to do with the movements of trains. Contains com-plete and reliable information of the Standard Code of Train Rules forsingle track. Shows Signals in Colors, as used on the different roads.Explains fully the . practical application of train orders, giving a clearand definite understanding of all orders which may oe used. Themeaning and. necessity for certain rules are explained in such a man-ner that the student may know beyond a doubt the rights conferredunder any orders he may receive or the action required by certainrules. As nearly all roads require trainmen to pass regular examina-tions, a complete set of examination questions, with their answers, areincluded. These will enable the student to pass the required examina-tions with credit to himself and the road for which he works. 2na Edi-tion, Revised. 256 pages, fully illustrated, with Train Signals in Colors.Price $1*!35

The Walscliaert and Otlier Modem Badial ValTe Qears forLocomotiTes*

By Wm. W. Wood.

If you would thoroughly understand the Walschaert Valve Gear youshould possess a copy of this book, as the author takes the plainestform of a steam engine—a stationary engine in the rough, that willonly turn its crank in one direction—and from it builds up, with thereader's help, a modern locomotive equipped with the WalschaertValve Gear, complete. The points discussed are clearly illustrated: _

792/821

Two large folding plates that show the positions of the valves of bothinside or outside admission type, as well as the links and other parts ofthe gear when the crank is at nine different points in its revolution, areespecially valuable in mak-mg the movement clear. These employ slid-ing cardboard models which are contained in a pocket in the cover.

The book is divided into five general divisions, as follows: 1. Analysisof the gear. 2. Designing and-erecting the gear. 3. Advantages of thegear. 4. Questions and answers relating to the Walschaert Valve Gear.5. Setting valves with the Walschaert Valve Gear; the three primarytypes of locomotive valve motion; modern rtidial valve gears otherthan the Walschaert ; the Hobart All-free Valve and Valve Gear, withquestions and answers on breakdowns: the Baker-Pilliod Valve Gear;the Improved Baker-Pilliod Valve Gear, with questions and answerson breakdowns.

The questions with full answers given will be especially valuable tofiremen and engineers in preparing for an examination for promotion.245 pages. 3rd Revised Edition. Price $1,50

24 THE NORMAN W. HENLEY PUBLISHING CO.

Westtnghouse E-T Air-Brake Instructton Pocket Book. By Wm. W.Wood, i Air-Brake Instructor. '

Here is a book for the railroad man, and the man who aims to be one.It is without doubt the only complete work published on theWestin^house £-T Locomotive Brake Equipment Written by anAir>Brake Instructor who knows just what is n e eded. It oovers thesubjeet thoroup^hly. Everything about the New Westinghouse Engin^and Tender Brake Equipment, including the standard No. 5 and thePerfected No. 6 style of brake, is treated in detail Written in plam Eng-lish and profusely illustrated with Colored Plates, which enable one to

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trace the flow of pressures throughout the entire equipment. The beetbo<^ ever published on the Air Brake. Equally good for the beginnerand the advanced engineer. Will pass any one through any ezamma-tion. It informs and enlightens you on every xxunt. Indiapoisabk toevery engineman and trainman. ^ ,

Contains examination questions and answers on the Ei-T equipment.Covering what the £«-T | Brake is. How it should be operated. What todo when defective. Not a question can be j asked of the engineman upfor promotion, on either the No. 5 or the No. 6 E-T equipment, | thatis not asked and answered in the book. If you want to thoroughly un-derstand the £-T 1 equipment get a copy of this book. It covers everydetail. Makes Air-Brake troubles and examinations easy. Price fltM

BIACHINE-SHOP PBACTICE

American Tool Makiiig and Interchangeable Manufacturing. By J. V.

WOODWORTH.

A "shoppy** book, containing no theorising, no problematical or ex-perimental devices. There are no badly proportioned and impossiblediagnuns, no catalogue cuts, but a valuable colleo> tion of drawingsand descriptions of devices, the nch fruits (» the author*s owne3q;>eriaice. In its 500-odd pages the one subject only, Tool Making,and whatever relates thereto, is dealt with. The work stands without arival. It is a complete, practical treatise, on the art of American ToolMaking and system of interchangeable manufacturing as carried onto-day in the United States. In it are described and illustrated all ofthe^ di£Ferent types and classes of small tools, fixtures, devices, andspecial appliances which are in general use in all machine* manufac-turing and metal-working establishments where economy, capacity,and interchan^ ability in the production of machined metal parts are

794/821

imperative. Tne science of jig making is exhaustively discussed, andparticular attention is paid to drill jigs, boring, proming and millingfixtures and other devices in which the parts to be machined are loc-ated and fasteped within the contrivances. All of the tools, fixtures,and devices illustrated and described have been or are used for the ac-tual production of work, such as parts of drill presses, lathes, patentedmachinery, typewriters, electrical apparatus, mechanical appliances,brass goods, composition

Sarts, mould products, sheet-metal articles, drop-forgings, jewelry,watches, medals, coins, etc. 31 pages. Price f4,M

HENLEY'S ENCTCLOPEDU OF PRACTICAL ENGINEERING ANDALLIED TRADES. Edited by Joseph G. Hornbr, A.M.I., M.E.

This set of five volumes contains about 2,500 pages with thousands ofillustraticHis, including diagrammatic and sectional drawings with fullexplanatory details. This work covers the entire practice of Civil andMechanical Engineering. The best known experts in all branches ofengineering have contributed to these volumes. The Cyclopedia is ad-mirably well adapted to the needs of the beginner and the self-taughtpractical man. as well^ as the mechanic^ engineer, designer, drafts-man, shop superintendent, foreman, and machinist.^ The work will befound a means of advancement to any progressive man. It>is encyclo-pedic m scope, thorough and practical in its treatment on technicalsubjects, simple and clear in its descriptive matter, and without unne-cessary technicalities or formulse. The articles are as brief^ as may beand yet give a reasonably clear and explicit statement of the subject,and are writt^i by men who have had ample practical experience inthe matters of which they write. It telb you all you want to know aboutengineering and tells it so simply, so clearly, so concisely, that onecannot help but understand. As a work of reference it is without apeer. Complete set of five volumes, price ^S5*M

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The Modern Machinist. By John T. Usher.

This is a book, showing by plain description and by profuse engravingsmade expressly for the work, all that is best, most adv^anced, and ofthe highest efficiency in modern machine-shop practice, tools and im-plements, showing the way by which and throuf[h which, as Mr. Max-im says, "American machinists have become and are the finest mech-anics in the world." Indicating as it does, in every line, the familiarityof the author with every detail of daily experience in the shop, it can-not fail to be of service to any man practically connected with theshaping or finishing of metals.

There is nothing experimental or visionary about the book, all devicesbeing in actual use and giving good results. It mi^ht be called a com-pendium of shop methods, showing a variety of special tools and ap-pliances which will give new ideas to many mechanics, from the super-intendent down to tne man at the bench. It will be found a yuuable ad-dition to any machinist's library, and should be consulted whenever anew or difficult job is to be done, whether it is boring, milling, turning,or planing, as they are all treated in a practical manner. Fifth edition.320 pages. 250 illustrations. Price $2*50

CATALOGUE OF GOOD, PRACTICAL BOOKS 25

THE WHOLE FIELD OF BIECHANICAL MOVEMENTS COVEREDBT MB. HISCOX'S TWO BOOKS

We puhliah two hooka by Chxrdner D. Hiscox that vnU keep you from''inventing" things that have been done before^ and euggeti ways ofdoing (hinge that you have not thought of before. Many a man spendstime and money pondering over some mechanical problem^ only tolearn, after he has solved the T^obiem, that the same thing has beenaccomplished and put in practice by others long before. Time and

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money spent in an effort to accomplish wtuU has abready been accom-plished are time and money LOST. The whale field of mechanics, everyknown mechanical movement, and practically every device are coveredby these tioo books. If the thing you want has been invented, it is iUus-trtUed in them. If it hasn't been invented, then you'll find in them thenearest things to wfuU you v>ant, some movements or devices thatwill apply in your case, verhaps; or which wiU give you a key fromwhich to work. No book or eet of books ever published is of more realvalue to the Inventor, Draftsman, or practical Mechanic than the twovolumes described below.

eehanlcal Movements, Powers, and Devices. By Gardner D. Hiscox.

This is a collection of 1,890 engravings of different mechanical mo-tions^ and appliances, ao-companied by appropriate text, making it ab(X>k of great value to the inventor, the draftsman, and to all reaoerswith mechanical tastes. The book is divided into eighteen sections orchapters, in which the subject-matter is classified under the followingheads: Mechanical Powers; Transmission of Power; Measurement ofPower; Steam Power; Air Power Appliances; Electric Power and Con-struction; Navigation and Roads; Gearing; Motion and Devices; Con-trolling Motion; Horological; Mining; Mill and Factory Appliances;Construction and Devices; Drafting Devices; Miscellaneous Devices,etc. 15th Edition. 400 'octavo pages. Price $3.00

eehanlcal Appliances, Mechanical Movements and Novdtles of Con-struction. By Gardner D. Hiscox.

This is a supplementary volume to the one upon mechanical move-ments. Unlike the first volume, which is more elementary in character,this volume contains illustrations and descriptions of many combina-tions of motions and of mechanical devices and appliances found indifferent lines of machinery, each device being shown by a line

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drawing with a description showing its working parts and the methodof operation. From the multitude of devices described and illustratedmight be mentioned, in passing, such items as conveyors and elevat-ors. Pony brakes, thermometers, various types of boilers, solarengines, oil-fuel burners, condensers, evaporators, Corliss and othervalve gears, governors, {^as engines, water motors of various descrip-tions, air ships, motors and dynamos, automobile and motor bicycles,railway lock signals, car couplers, link and gear motions, ball bearings,breech-block mechanism for heavy guns, and a large accumulation ofothers of equal importance. One thousand specially made engravings.396 octavo pages. Fourth edition. Price $3.00

achine-Shop Tools and Shop Practice. By W. H. Vandervoort.

A work of 555 pages and 673 illustrations, describing in every detailthe construction, oper& tion and manipulation of both hand and ma-chine tools. Includes chapters on filing, fitting and scraping surfaces;on drills, reamers, taps and dies; the lathe ana its tools: planers,shapers, and their tools; milling machines and cutters; ^ear cuttersand ^ear cutting; drilling machines and drill work; grinding machinesand their work; hardening and tempering; gearing, belting and trans-mission machinery; useful data and tables. Sixth edition. Price $3.00

achine-Shop Arithmetic. By Colvin-Cheney.

This is an arithmetic of the things you have to do with daily. It tellsyou plainly about: how to find areas in figures; how to find surface orvolume of balls or spheres; handy ways for calculating; about com-pound gearing; cutting screw threads on any lathe; drilling for tape;speeds of drills; taps, emery wheels, grindstones, milling cutters, etc.;all about the Metric system with conversion tables; properties ofmetals; strength of bolts and nuts; decimal equivalent of an inch. Allsorts of machine-shop figuring and 1,001 other things, any one of

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which ought to be worth more than the price of this book to you, as itsaves you the trouble of bothering the boss. 6th Edition. 131 pages.Price 50 CentS

odern Machlne-Shop Construction, Equipment and Management. By

Oscar E. Perrigo.

The only work published that describes the Modern Shop or Manufac-turing Plant from the time the grass is growing on the site intended forit until the finished prcxluct is shipped. Just the book needed by thosecontemplating the erection of modern shop buildings, the rebuildingand reorganization of old ones, or the introduction of Modern ShopMethods, time and cost systems. It is a book written and illustrated bya practical shop man for practical shop men who are too busy to readtheories and want facts. It is the most complete all-round book of itskind ever published. Second Edition, Revised. 384 large quarto pages.219 original and 8i>ecially made illustrations. 2nd Revised and En-larged Edition. Price $5.00

26 THE NORMAN W. HENLEY PUBLISHING CO.

* Modern Milling Machines: Their Design, Construction, andOperation. \

By Joseph G. Horner.

This book describes and illustrates the Milling Machine and its workin such a plain, clear and forceful manner, and illustrates the subjectso clearly and completely, that the up-to-date machinist, student ormechanical engineer cannot afford to do without the valuable inform-ation which it contains. It describes not only the early machines of thisclass, but notes their gradual development into the splendid machinesof the present dav,> giving the design and construction of the various

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types, forms, and special features proauced hy prominent manufactur-ers, American and foreign. 304 pages, 300 illustrations. Cloth. Price...^.M

** Shop Kinlcs." By Robert Grimshaw.

A book of 400 pages and 222 illustrations, being entirely differentfrom any other book on machine-shop practice. Departing from con-ventional style, the author avoids universal or common shop usageand limits nis work to showing special wasrs of doing things better,more cheaply and more rapidly than usual. As a result the advancedmethods of representative establishments of the world are placed atthe disposal of the reader. This book shows the proprietor where largesavings are possible, and how products may be improved. To the em-ployee it holds out suggestions that, properly applied, will hasten hisadvancement No shop can afford to be without it. It bristles with valu-able wrinkles and helpful suggestions. It will benefit all, from appren-tice to proprietor. Every machinist, at any age, should study its pages.Fifth edition. Trice $!iJ$

Threads and Thread Cutting. By Colvin and Stabel.

This clears up many of the mysteries of thread-cutting, such as doubleand^ triple threads, internal threaids, catching threads, use of hobs,etc. Contains a lot of useful hints and several tables. Third edition.Price 25 CCOtS

MANUAL TRAINING

Economics of Manual Training. By Louis Rouimjon.

The only book published that gives just the information needed by allinterested in Manual Training, regarding Buildings. Equipment, andSupplies. Shows exactly what is needed I for all grades of the work

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from the Kindergarten to the High and Normal School. Gives , item-ized lists of everything used in Manual Training Work and tells justwhat it ought to cost. Also shows where to buy supplies, etc. Contains174 pages, and is fully illustrated. Second edition. Price $1.56

MARINE ENGINEE RING '

The Naval Architect's and ShipbuUder's Poclcet Book of Formul»,Kules, | and Tables and Marine Engineer's and Surveyor's Handy Bookof Reference. By Clement Maokrow and Lloyd Woollard.

The eleventh Revised and Enlarged Edition- of this most comprehens-ive work has just been issued. It is absolutely indispensable to all en-gaged in the Shipbuilding Industry, as it eon-denses into a compactform all data and formulae that arc ordinarily required. The book iscompletely up to date, including among other subjects a section onAeronautics. 750 pages, limp leather binding. Price $5.00 n€t

Marine Eng:ines and Boilers: Their Design and Construction. By Dr.G.

Bauer, Leslie S. Robertson and S. Bryan Donkin.

In the words of Dr. Bauer, the present work owes its origin to an oftfelt want of a condensed treatise embodying the theoretical and prac-tical rules used in designing marme engines and boilers. The need ofsuch a work has been felt by most engineers engaged m the construc-tion and working of marine engines, not only by the younger men, butalso by those of greater experience. The fact that the original Germanwork was written by the chief engineer of the , famous Vulcan Works,Stettin, is in itself a guarantee that this book is m all respectsthoroughly up-to-date, and that it embodies all the information whichis necessanr for the design and construction of the highest types ofmarine engines and boilers. It may be said that the motive power

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which Dr. Bauer has placed in the fast German liners that have beenturned out of late years from the Stettin Works represent the very bestpractice in marme engineering of the present day. The work is clearlywritten, thoroughly systematic, theoretically sound; while the charac-ter of the plans, drawings, tables, and statistics is without reproach.The illustrations are careful reproductions from actual working draw-ings, with some well-executed photographic views of completed en-gines and boilers. 744 pages, 550 illustrations and numerous tables.Cloth. Price $9.00 net

CATALOGUE OF GOOD, PRACTICAL BOOKS 2

MINING

re Deposits, with a Cliapter on Hints to Prospectors. By J. P. Johnson.

This book gives a condensed account of the ore deposits at presentknown in South Africi It is also intended as a guide to the prospector.Only an elementary knowledge of geolog and some mining experienceare necessary in order to understand this work. With thej qualifica-tions, it will materially assist one in his search for metalliferous miner-al occurrenc< and, so far as simple ores arc concerned, should enableone to form some idea of the poss bilities of any he may find. Illus-trated.' Cloth. Price $2.,0

'actical Coal Mining. By T. H. Cockin.

An important work, containing 428 pages and 213 illustrations, com-plete with practical detail which will intuitively impart to the readernot only a general knowledge of the principl of coal mining, but alsoconsiderable insight into allied subjects. The treatise is positive up-to-date in every instance, and should be in the hands of every colliery en-gineer, geologL mine operator, superintendent, foreman, and all

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others who are interested in or connected w^ the industry. 3d Edition.Cloth. Price ^»,

lysics and Chemistry of Mining. By T. H. Byrom.

A practical work for the use of all preparing for examinations in min-ing or qualifying colliery managers* certificates. The aim of the authorin this excellent book is to place cle^. before the reader useful and au-thoritative data which will render him valuable assistance his studies.The only work of its kind published. The information incorporated init -^ prove of the greatest practical utility to students, mining engin-eers, colliery managers, ^ all others who are specially interested in thepresent-day treatment of mining problems. 1 pages, illustrated. Price ^^

PATTERN MAKING

•adacal Pattern Maldng. By F. W. Barrows.

This book, now in its second edition, is a comprehensive and entirelypractical treatise on tl subject of pattern making, illustrating patternwork in both wood and metal, and with definr instructions on the useof plaster of paris in the trade. It gives specific and detailed descriitions of the materials used by pattern makers, and describes the tools,both those for tr bench and the more interesting machine tools, havingcomplete chapters on the Lathe, tl Circular Saw, and the Band Saw. Itgives many examples of pattern work, each one full illustrated and ex-plained with much detail.' These examples, in their great variety, offermuc .that will be found of interest to all pattern makers, and especiallyto the younger ones, wh are seeking information on the more ad-vanced branches of their trade.

In this second edition of the work will be found much that is new, evento those who ha\ long practised this exacting trade. In the description

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of patterns as adapted to the Mouldir Machine many difl&cultieswhich have long prevented the rapid and economical production <castings are overcome; and this great, new branch of the trade is givenmuch space. Strii ping plate and stool plate work and the less expens-ive vibrator, or rapping plate work, ai all explained in detail.

Plain, every-day rules for lessening the cost of patterns, with a com-plete system of cos keeping, a detailed method of marking, applicableto all branches of the trade, with con plete information showing whatthe pattern is, its specific title, its cost, date of productioi material ofwhich it is made, the number of pieces and core-boxes, and its locationin tl pattern safe, all condensed into a most couftplete card record,with cross index. The book closes with an original and practical meth-od for the inventory and valuation < patterns. Containing nearly 350pages and 170 illustrations. Price $J8.0

PERFUMERY

^rfumes and Cosmetics: Tlieir Preparation and Manufacture. By G. \^

AsKiNSON, Perfumer.

A comprehensive treatise, in which there has been nothing omittedthat could be of vali to the perfumer or manufacturer of toilet prepara-tions. Complete directions for makir handkerchief perfumes, smelling-salts, sachets, fumigating pastilles; preparations for tl care of the skin,the mouth, the hair, cosmetics, hair dyes and other toilet articles aregivei also a detailed description of aromatic substances; their nature,tests of purity, and whol« some manufacture, including a chapter onsynthetic products, with formulas for their us A book of general as wellas professional interest, meeting the wants not only of the drui gistand perfume manufacturer, but also of the general public. Among thecontents ar 1. The History of Perfumery. 2. About Aromatic Substaiftes

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in General. 3. Odors froi the Vegetable Kingdom. 4. The Aromatic Ve-getable Substances Employed in Perfumer; 5. The Animal SubstancesUsed in Perfumery. 6. The Chemical Products Used in Perfumei^ 7.The Extraction of Odors. 8. The Special Characteristics of AromaticSubstances. 9. Tl Adulteration of Essential Oils and Their Recognition.10. Synthetic Products. 11. Tab of Physical Properties of AromaticChemicals. 12. The Essences or Extracts Employe in Perfumery. 13.Directions for Making the Most Important Essences and Extract

28 THE NORMAN W. HENLEY PUBLISHING CO.

14. The Division of Perfumerv. 15. The Manufacture of HandkerchiefPerfumes. 16. Formulas for Handkerchief Perfumes. 17. Ammoniacal.and Acid Perfumes. 18. Dry Perfumes. 10. Formulas for Dry Perfumes.20. The Perfumes Used for Fumigation. 21. Antiseptic and TherapeuticValue of Perfumes. 22. Classification of Odors. 23. Some Special | Per-fumerjr Products. 24. Hygiene and Cosmetic Perfumenr. 25. Prepara-tions for the Care of the Skin. 26. Manufacture of Casein. 27. Formulasfor Emulsions. 28. Formulae for Cream. 29. Formulas for Meals,Pastes and Vegetable Milk. 30. Preparations Used for the Hair. 31.Formulas for Hair Tonics and Restorers. 32. Pomades and Hair Oils.33. Formulas for the Manufacture of Pomades and Hair Oils. 34. HairDyes and Depilatories. 35. Wax Pomades, Bandolines and Bril-liantines. 36. Skin Cosmetics and Face Lotions. 37. Preparations forthe Nails. 38. Water Softeners and Bath Salts. 39. Preparations for theCare of the Mouth. 40. The Colors Used in Perfumery. 41. The UtensilsUsed in the Toilet. Fourth edition, much enlarged and brought up todate. Nearly 400 pages, illustrated. Price $^.M

WHAT IS SAID OF THIS BOOK:

^

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"The most satisfactory work on the subject of Perfumery that we haveever seen.*'

*'We feel safe in saying that here is a book on Perfumery that will notdisappoint you, for

it has practical and excellent formulae that are within your ability toprepare readily."

" We recommend the volume as worthy of confidence, and say that nopurchaser will be dis-

api>ointed in securing from its pages good value for its cost, and alarge dividend on the same,

even if he should use but one per cent, of its working formulse. Thereis money in it for evexy

user of its information."— PharmaceiUiccU Record.

PLUMBING

•

Mechanical Drawing for Plumbers. By R. M. Starbuck.

A concise, comprehensive and practical treatise on the subject ofmechanical drawing in its various modern applications to the work ofall who are in any wav connected with the plumbing trade. Nothingwill so help the plumber in estimating and in explaining work to cus-tomers and workmen as tt knowledge of drawing, and to the workmanit is of inestimable value if he is to rise above his position to positionsof greater resj^nsibility. Among the chapters contained are: 1. Value toplumber of knowledge of drawing; took required and their use;

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common views needed in mechanical drawing. 2. Perspective versusmechanical drawing in showing plumbing construction. 3. Correct andincorrect methods in plumbing drawing; plan and elevation explained.4. Floor and cellar plans and elevation; scale drawings; use of tri-angles. 5. Use of triangles; drawing of fittings, traps, etc. 6. Drawingplumbing elevations and fittings. 7. Instructions in drawing plumbingelevations. 8. The drawing of plumbing fixtures; scale drawings. 0.Drawings of fixtures and fittings. 10. Inking of drawings. 11. Shadingof drawings. 12. Shading of drawings. 13. Sectional drawings; drawingof threads. 14. Plumbing elevations from architect's plan. 15. Eleva-tions of separate parts of the plumbing system. 16. Elevations from thearchitect's plans. 17. Drawings of detail plumbing connections. 18.Architect's plans and plumbing elevations of residence. 19. Plumbingelevations of residence (.continued); plumbing plans for cottage. 20.Plumbing elevations; roof connections. 21. Plans and plumbing eleva-tions for six-flat building. 22. Drawing of various parts of the plumb-ing system; use of scales. 23. Use of architect's scales. 24. Special fea-tures in the illustrations of country plumbing. 25. Drawing of wrought-iron piping, valves, radiators, coils, etc. 26. Drawing of piping to illus-trate heating systems. 150 illustrations. Price '. . . ^1,50

Modern Plumbing Illustrated. By R. M. Starbuck.

This book represents the highest standard of plumbing work. It hasbeen adopted and used as a reference book by the United StatesGovernment in its sanitary work in Cuba, Porto Rico and the Philip-pines, and by the principal Boards of Health of the United States andCanada. . . »

It gives connections, sizes and working data for all fixtures and groupsof fixtures. It is helpful to the master plumber in demonstrating to hiscustomers and in figuring work._ It gives the mechanic and studentquick and easy access to the best modern plumbing i>ractice.

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Suggestions for estimating plumbing construction are contained in itspages. This book represents, in a word, the latest and best up-to-datepractice and should oe in the hands of every architect, sanitary engin-eer and plumber who wishes to keep himself up to the minute on thisimportant feature of construction. Contains following chapters, eachillustrated with a full-page plate: Kitchen sink, laundry tubs, vegetablewash sink; lavatories, pantry sinks, contents of marble slabs; bath tub,foot and sitz bath, shower bath; water cloeete. venting of water closets;low-down water closets, water closets operated by flush valves, watercloset range; slop sink, urinals, the bidet; hotel and restaurant sink,grease trap; refrigerators, safe wastes, laundry waste, lines of refriger-ators, bar sinks, soda fountun sinks; horse stall, frost-proof waterclosets; connections for S trapra, venting; connections for dnun traps;soil-pipe connections; supporting of soil pipe; main trap and fresh-airinlet; floor drains and cellar drains, subsoil drainage; water closetsand floor connections; local ventingj connections for bath rooms; con-nections for bath rooms, continued; examples of poor practice; rough-ing work ready for test; testing of plumbing systems; method of con-tinuous venting; continuous venting for two-floor work; continuousventing for two lines of fixtures on three or more floors; continuousventing of water closets; plumbing for cottage house; construction,forcellar piping; plumbing for residence, use of special fittings; plumbingfor two-flat house; plumbing for apartment building, plumbing fordouble apartment building; plumbing for office building; plumbing forpublic toilet rooms; plumbing for public toilet rooms, continued;plumbing for bath establishment; plumbing for engine house, factoryplumbing; automatic flushing for schools, factories, etc.; use of flush-ing valves; urinals for piiblic toilet rooms; the Durham system, the de-struction of nines bv electrolvsis: construction of work

CATALOGUE OF GOOD, PRACTICAL BOOKS 29

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without use of lead; automatic sewage lift; automatic sump tank;country plumbing; construction of cesspools; septic tank and automat-ic sewage^ siphon; water supply for country house; thawing of watermains and service by electricity; double boilers; hot water supply ofloiji^e buildings; automatic control of hot-water tank; suggestions forestimating plumbing construction. 407 octavo pages, fully illustrated\>y 57 full-page engravings. Third, revised and enlarged edition, justissued. Price . ^.00

;andard Practical Plumbing. By K. M. Starbuck.

A complete practical treatise of 450 pages, covering the subject ofModerr. Plumbing in al* its branches, a large amount of space bemgdevoted to a very complete and practical treatment. o€ the subject ofHot Water Supply and Circulation and Range Boiler Work. Its thirtychapters include about every phase of the subject one can think of,making it an indispensable work -t.o the master plumber, the journey-man plumber, and the apprentice plumber, containing i:ha.T>^ terson: the plumber's tools; wiping solder; composition and use; joint wip-ing; lead worfa^ traps; siphonage of traps; venting; continuous vent-ing; house sewer and sewer concectioxx:^ house drain; soil piping,roughing; main trap and fresh air inlet; floor, yard, cellar drai^cxi rainleaders, etc.; fixture wastes; water closets; ventilation; improvedplumbing connectios:^i residence plumbing; plumbing for hotels,Schools, factories, stables, etc.; modem coun-t:.-^ plumbing; filtrationof sewage and water supply; hot and cold supply; range boilers; cir-cvmJX tion; circulating pipes; range boiler problems; hot water forlarge buildings; water lift ^^.^ its use; multiple connections for hotwat^ boilers; heating of radiation by supply syst^^:] theory for theplumber; drawing for the plumber. Fully illustrated by 347 engravingsI*rice $3^i

BECIPE BOOK

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snlCF's Twentieth Century Book of Becipes» Formulas andProcess^^^

Edited by Gardner D. Hibcox.

The most valuable Techno-chemical Formula Book published, includ-ing over 10,000 selectti<{ scientific, chemical, technological, and prac-tical recipes and processes.

This is the most complete Book of Formulas»ever published, givingthousands of recipes for the manufacture of valuable articles for every-day use. Hints, Helps, Practical Ideas, and Secret Processes are re-vealed within its pages. It covers every branch of the useful arts andtells thousands of ways of making money, and is just the book every-one should have at his command.

Modern in its treatment of every subject that properly falls within itsscope, the book may truthfully be said to present the very latest formu-las to be found in the arts and indiistries, and to retain those processeswhich long experience has proven worthy of a permanent record. Topresent here even a limited number of the subjects which find a placein this valuable work would be difficult. Suffice to say that in its pageswill be found matter of intense interest and immeasurably practicalvalue to the scientific amateur and to him who wishes to obtain aknowledge of the many processes used in the arts, trades and manu-facture, a knowledge which will render his pursuits more instructiveand remunerative. Serving as a reference book to the small and largemanufacturer and supplying intelligent seekers with the informationnecessary to conduct a process, the work will be found of inestimableworth to the Metallurgist, the Photographer, the Perfumer, the Paint-er, the Manufacturer of Glues, Pastes, Cements, and Mucilages, theComijounder of Alloys, the Cook, the Physician, the Druggist, the Elec-trician, the Brewer, the Engineer, the Foundryman, the Machinist, the

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Potter, the Tanner, the Confectioner, the Chiropodist, the Manicurist,the Manufacturer of Chemical Novelties and Toilet Preparations, theDyer, the Electroplater, the Enameler, the Engraver, the Provisioner,the Glass Worker, the Goldbeater, the Watchmaker, the Jeweler, theHat Maker, the Ink Manufacturer, the Optician, the Farmer, the Dairy-man, the Paper Maker, the Wood and Metal Worker, the Chandler andSoap Maker, the Veterinary Surgeon, and the Technologist in general.

A mine of information, and up-to-date in eveiy respect. A book whichwill prove of value to EVERYONE, as it covers every branch of theUseful Arts. Every home needs this book; every office, every factory,every store, every public and private enterprise—^EVERYWHERE,—should have a copy. 800 pages. Price $3.00

WHAT IS SAID OF THIS BOOK:

"Your Twentieth Century Book of Recipes, Formulas, and Processesduly received. I am glad to have a copy of it, and if I could not replaceit, money couldn't buy it. It is the best thing of the sort I ever saw."(Signed) M. E. Trux, Sparta, Wis.

** There are few persons who would not be able to find in the booksome single formula that would repay several times the cost of thebook."— Merchants' Record and Show Window.

•' I purchased your book, * Henley's Twentieth Century Book of Re-cipes, Formulas and Processes,' about a year ago and it is worth itsweight in gold." — ^Wm. H. Murray, Bennington, Vt.

"ONE OF THE WORLD'S MOST USEFUL BOOKS"

" Some time ago I got one of your ' Twentieth Century Books of For-mulas,* and have made my living from it ever since. I am alone sincemy husband's death with two small children to care for and am trjring

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so hard to support them. I have customers who take from me ToiletArticles I put up, following directions given in the book, and I havefound everyone of them to be fine."— Mrs. J. H. McMaken, WestToledo, Ohio.

30 THE NORMAN W. HENLEY PUBLISHING CO.

RUBBER

Eubber Hand Stamps and the Manipulation of India Rubber. By T.

O'CoNOR Sloane.

This book gives full details on all points, treating in a concise andsimple manner the elements of nearly everything it is necessary to un-derstand for a commencement in any branch of the India RubberManufacture. The making of all kinds of Rubber Hand Stamps, SmallArticles of India Rubber, U. S. Government Composition, Dating HandStamps, the Manipulation of Sheet Rubber, Toy Balloons, India Rub-ber Solutions, Cements, Blackings, Renovating, Varnish, and Treat-ment for India Rubber Shoes, etc.; the Hektograph Stamp Inks, andMiscellaneous Notes, with a Short Account of the Discovery, Collectionand Manufacture of India Rubber, are set forth in a manner designedto be readily understood, the explanations being plain and simple. In-cluding a chapter on Rubber Tire Making and Vulcanizing; also achapter on the uses of rubber in Surgery and Dentistry. 3rd Revisedand Enlarged Edition. 175 pages. Illustrated $1.09

SAWS

Saw Filing and Management of Saws. By Robert Grimshaw.

A practical hand-book on filing, gumming, swaging, hammering, andthe brazing of band saws, the speed, work, and power to run circular

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saws, etc. A handy book for those who have charge of saws, or forthose mechanics who do their own filing, as it deals with the projiershape and pitches of saw teeth of all kinds and gives many useful hintsand rules for gumming, setting, and filing, and is a practical aid tothose who use saws for any purpose. Complete tables of proper shape,pitch, and saw teeth as well as sizes and number of teeth of varioussaws are included. 3rd Edition, Revised and Enlarged. Illustrated.Price ftj^j

STEAM ENGINEERING

American Stationary Engineering. By W. E. Crane.

This book begins at the boiler room and takes in the whole powerplant. A plain talk on every-day work about engines, boilers, and theiraccessories. It is not intended to be scientific or mathematical. All for-mulas arc in simple form so that any one understanding plain arith-metic can readily understand any of them. The author has made thisthe most practical book in print; has given the results of his years ofexperience, and has included about all that has to do with an engineroom or a power plant. You are not left to guess at a single point. Youare shown clearly what to expect under the various conditions; now tosecure the best results; ways of preventing "shut downs" and repairs;in short, all that goes to make up the requirements of a good engineer,capable of taking charge of a plant. It's plain enougn for practical menand yet of value to those high in the profession.

A partial list of contents is: The boiler room, cleaning boilers, firing,feeding; pumps, inspection and repair; chimneys, sizes and cost; pip-ing; mason work; foundations; testing cement; pile driving; engines,slow and high speed; valves; valve setting; Corliss engines, settingvalves, single and double eccentric; air pumps and condensers; dififer-ent types of condensers; water needed; lining up; pounds; pins not

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square in crosshead or crank; engineers* tools; pistons and pistonrings; bearing metal; hardened copper; drip pipes from cylinder jack-et; belts, how made, care of; oils; greases; testing lubricants; rules andtables, including steam tables; areas of segments; squares and squareroots; cubes and cube root; areas and circumferences of circles. Noteson: Brick work: explosions; pumps; pump valves; heaters, econom-izers; safety valves; lap, lead, and clearance. Has a complete examina-tion for a license, etc., etc. 3rd Edition. 345 pages, illustrated. Price ....^.00

Engine Runner's Catecliism. By Robert Grimshaw.

A practical treatise for the stationary engineer, telling how to erect, ad-just, and run the principal steam engines in use in the United States.Describing the principal features of various special and well-knownmakes of engines: Temper Cut-oflF, Shipping and Receiving Founda-tions, Erecting and Starting, Valve Setting, Care and Use, Emergen-cies, Erecting and Adjusting Special Engines.

The questions asked throughout the catechism are plain and to thepoint, and the answers are given in such simple language as to bereadily understood by anyone. All the instructions given are completeand up-to-date; and they are written in a popular style, without anytechnicalities or mathematical formulae. The work is of a handy sizefor the pocket, clearly and well printed, nicely bound, and profuselyillustrated.

To young engineers this catechism will be of great value, especially tothose who may be preparing to go forward to be examined for certific-ates of competency; and to engineers generally it will be of no littleservice, as they will find in this volume more really practical and usefulinformation than is to be found anywhere else within a like compass.387 pages. 7th Edition. Price $ZM

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CATALOGUE OF GOOD, PRACTICAL BOOKS 31

Modern Steam Engineering: In Theory and Practice. By Gardner D.Hiscox.

This is a complete and practical work issued for Stationary Engineersand Firemen, dealing with the care and management of boilers, en-gines, pumps, superheated steam, refrigerating machinery, dynamos,motors, elevators, air compressors, and all other branches with whichthe modern engineer must be familiar. Nearly 200 questions withtheir answers on steam and electrical engineering, likely to be askedby the Examining Board, are included. Among the chapters are: His-torical: steam and its properties; appliances for the generatioii ofsteam; types of boilers; chimney and its work; heat economy of thefeed water; steara pumps and their work; incrustation and its work;steam above atmospheric pressure; flovr of steam from nozzles; super-heated steam and its work; adiabatic expansion of steam; indicatorand its work; steam engine proportions; slide valve engines and valvemotion; Corliea engine and its valve gear; compound engine and itstheory; triple and multiple expansiot^ engine; steam turbine; refriger-ation; elevators and their management; cost of power; st&«fc.to en-gine troubles; electric power and electric plants. 487 pages, 405 en-gravings. 3rd Edit ion Price $^«^

Steam Engine Catecliism. By Egbert Grimshaw. •

This unique volume of 413 pages is not only a catechism on the ques-tion and answer prino Jp>i but it contains formulas and worked-outanswers for all the Steam problems that appertaixa ^ operation andmanagement of the Steam Engine. Illustrations of various valves andvaJi^* gear with their principles of operation are given. Thirty-fourTables that are indispensat>7^ to every engineer and fireman thatwishes to be progressive and is ambitious to become master of his

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calling are within its pages. It is a most valuable instructor in the ser-vice of Steain Engineering. Leading engineers have recommended it asa valuable educator for the begin, ner as well as a reference book forthe engineer:. It is thoroughly indexed for every detaii. Every essentialquestion on the Steam Engine with its answer is contained in thisvaluable work. 16th Edition. Price $Z*W

Steapi Engineer's Aritlimetic. By Colvin-Chenet.

a practical pocket-book for the steam engineer. Shows how to work theproblems of the engine room and shows "why." Tells how to figurehorsepower of engines and boilers; area of boilers; has tables of areasand circumferences; steam tables; has a dictionary of engineeringterms. Puts you on to all of the little kinks in figuring whatever there isto figure around a power plant. Tells you about the heat unit; absoluteaero; adiabatic expansion; duty of engines; factor of safety; and athousand and one other things; and everything is plain andsimple—not the hardest way to figure, but the easiest. 2nd Edition.Price . . 50 Ccntl^

Engine Tests and BoUer Efficiencies. By J. Buchetti.

This work fully describes and illustrates the method of testing thepower of steam engines* turbines and explosive motors. The proper-ties of steam and the evaporative power of fuels. Combustion of fueland chimney draft; with formulas explained or practically computed.255 pages, 179 illustrations. Price $3.00

Horsepower Cliart.

Shows the horsepower of any stationary engine without calculation.No matter what the cylinder diameter of stroke, the steam pressure ofcut-off, the revolutions, or whether condensing or non-condensing, it's

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all there. Easy to use, accurate, and saves time and calculations. Espe-cially useful to engineers and designers. Price 50 CcntS

STEAM HEATING AND VENTELATION

Practical Steam, Hot-Water Heating and Ventilation. By A. G. King.

This book is the standard and latest work published on the subject andhas been prepared for the use of all engaged in the business of steam,hot-water heating, and ventilation. It is an original and exhaustivework. Tells how to get heating contracts, how to install heating andventilating apparatus, the best business methods to be used, with"Tricks of the Trade" for shop use. Rules and data for estimating radi-ation and cost and such tables and information as make it an indis-pensable work for everyone interested in steam, hot-water heating,and ventilation. It describes all the principal systems of steam, hot-wa-ter, vacuum, vapor, and vacuum-vapor heating, together with the newaccelerated systems of hot-water circulation, including chapters onup-to-date methods of ventilation and the fan or blower system ofheating and ventilation. Containing chapters on: I. Introduction. II.Heat. III. Evolution of artificial heating apparatus. IV. Boiler surfaceand settings. V. The chimney flue. VI. Pipe and fittings. VII. Valves,various kinds. VIII. Forms of radiating surfaces. IX.

Every Practical Man Needs A Magazine Which Will Tell Him How ToMake And Do Things

Have us enter your suhscription to the best mechanical magazine onthe market Only one dollar a year for twelve numbers. Subscribe todayto

Everyday Engineering

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AMOXTIILY magazine devoted to practical mechanics for everydaymen. Its aim is to popularize engineering as a science, teaching theelements of applied mechanics and electricity in a straightforward andunderstandable manner. The magazine maintains its own experiment-al laboratory where the devices described in articles submitted to theEditor are first tried out and tested before they are published. This im-portant innovation places the standard of the publislied material veryhigh, and it insures accuracy and dependability.

The magazine is the only one in this country that specializes in practic-al model building. Artick's in past issues have given comprehensivedesigns for many model .boats, including submarines and chasers,model steam and gasoline engines, electric motors and generators,etc., etc. This feature is a permanent one in this magazine.

Another popular department is that devoted to automobile's and air-planes. Care, maintenance, and operation receive full and authoritat-ive treatment. Every article is written from the practical, everyday-man, standpoint rather than from that of the professional.

The magazine entertains while it instructs. It is a journal of practical,dependable information given in such a style that it may be readilyaasimiiated and applied by the man with little or no technical training.The aim is to placi before the man who leans toward practical mechan-ics, a series of concise, crisp, readable talks on what is going on andhow it is done. These articles are profusely illustrated with clear,snappy photographs, specially posed to illustrate the subject in themagazine's own studio by its own staff of technically-trained illustrat-ors and editors.

The subscription price of the magazine is one dollar per year of twelvenumbers. Sample copy sent on receipt of ten cents.

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