(BCD) - TechAV · WHAT MINOR DISADVANTAGES DO "VEE-SECTION" BELTS HAVE? o A certain amount of...

BELTS AND CHAIN DRIVES (BCD)

Learner Guide

TABLE OF CONTENTS

BCD-1: OVERVIEW OF BELT AND CHAIN DRIVES PROCEDURES FOR RUNNING THIS COURSE PAGE 1 RESOURCE NOTES: FLEXIBLE DRIVES PAGE 2 REVIEW BREAK: FLEXIBLE DRIVES PAGE 4 RESOURCE NOTES: VEE SECTION BELTS PAGE 5 REVIEW BREAK: VEE SECTION BELTS PAGE 11 RESOURCE NOTES: ROLLER CHAINS PAGE 12 REVIEW BREAK: ROLLER CHAINS PAGE 19 RESOURCE NOTES: SAFETY PAGE 20 REVIEW BREAK: SAFETY PAGE 22 BCD-2: VEE AND WEDGE BELT MAINTENANCE PROCEDURES FOR RUNNING THIS COURSE PAGE 23 RESOURCE NOTES: VEE & WEDGE BELTS PAGE 24 REVIEW BREAK: VEE & WEDGE BELTS PAGE 25 RESOURCE NOTES: BELT REPLACEMENT PAGE 26 REVIEW BREAK: BELT REPLACEMENT PAGE 32 RESOURCE NOTES: MAINTENANCE TIPS PAGE 33 REVIEW BREAK: MAINTENANCE TIPS PAGE 34 BCD-3: BASIC ROLLER CHAIN MAINTENANCE PROCEDURES FOR RUNNING THIS COURSE PAGE 35 RESOURCE NOTES: ISOLATION & SAFETY PAGE 36 REVIEW BREAK: ISOLATION & SAFETY PAGE 37 RESOURCE NOTES: REMOVAL & CHANGING PAGE 38 REVIEW BREAK: REMOVAL & CHANGING PAGE 39 RESOURCE NOTES: INSPECTION PAGE 40 REVIEW BREAK: INSPECTION PAGE 43 RESOURCE NOTES: INSTALLATION &ADJUST CHAIN PAGE 44 REVIEW BREAK: INSTALLATION &ADJUST CHAIN PAGE 47 RESOURCE NOTES: CHAIN TENSION PAGE 48 REVIEW BREAK: CHAIN TENSION PAGE 50 RESOURCE NOTES: LUBRICATION PAGE 51 REVIEW BREAK: LUBRICATION PAGE 52 SUPPLEMENTARY INFORMATION PAGE 53

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Back to Table of Contents 1

BCD-1: AN OVERVIEW OF BELT & CHAIN DRIVES TRAINING AIDS REQUIRED

o Tech AV Video programme No. BCD-1. PROCEDURE

1. Obtain the video programme from your Course Controller. 2. When you see the "REVIEW" signal on the video:

o Stop the video. o Read the Resource Notes. o Perform any practical or theoretical exercises suggested in the "Review"

section. TIPS

o If you experience any problems, ask your Course Controller to assist you.

BEGIN THE PROGRAMME NOW BY TURNING THE PAGE.



PART ONE: A GENERAL OVERVIEW OF FLEXIBLE DRIVES WHAT IS A FLEXIBLE DRIVE?

o It is the means of transmitting power (i.e. torque or turning force) from one shaft to another by means of non-rigid components such as chains or belts.

WHAT IS A NON RIGID COMPONENT?

o Any device which is free to bend, twist or "flex" during operation. WHAT ARE THE MAIN (POPULAR) TYPES OF FLEXIBLE DRIVES?

o Rubber belts. o Fabric impregnated rubber belts. o Synthetic belts. o Metal link-chains.

WHAT TYPE OF BELTS IS MOST COMMONLY USED?

o Wedge belts. o Vee-belts (Classical V). o Toothed or "synchronous" belts.

WHAT TYPES OF METAL LINK CHAINS ARE COMMONLY USED?

o Roller-chains. WHAT ADVANTAGES DO BELTS HAVE OVER CHAINS?

o Belts are less expensive. o Maintenance is easier. o Belts are more "flexible". o High speed drives at low torque.

WHAT ADVANTAGES DO ROLLER-CHAINS HAVE OVER BELTS?

o Chains can operate in higher ambient temperatures. o Chains can drive several shafts synchronously (NB: So can tooth-belts). o Low speed drives at high torque.

WHAT MINOR DISADVANTAGES DO "VEE-SECTION" BELTS HAVE?

o A certain amount of "slip" may occur, especially under heavy loading. o Static electricity may be generated. o Belts can be damaged by oils and greases. o Vee-belts cannot be used for accurate "timing" (due to the "slip" possibility).


WHAT MINOR DISADVANTAGES DO "ROLLER-CHAINS" HAVE? o Chains tend to be noisy in operation. o Chains require frequent lubrication. o Chains are more costly than belts. o Chains, generally, cannot attain the speeds that belts can.

PROCEED NOW TO THE "REVIEW" SECTION OVER THE PAGE.


PART ONE: REVIEW BREAK NO. 1 Having now watched the first section of the video and read the resource notes we suggest you do the following: Under the guidance of your Course Controller:

o Look around your plant, factory or worksite and notice how many machine types there are that use flexible drives.

o SAFETY TIP! DON'T TOUCH ANY MACHINERY AND OSERVE ALL LOCAL SAFETY SIGNS, REGULATIONS ETC. WHEN ON SITE.

o Continue watching the video up to the next "Review" break.

TURN PAGE TO BEGIN PART 2 (BELTS).



PART TWO: "VEE" SECTION BELTS WHAT DOES THE TERM "VEE-BELT" MEAN?

o The term refers to the cross-sectional shape of such a belt.

WHAT IS THE DIFFERENCE BETWEEN "CLASSICAL" AND WEDGE" BELTS? o Classical, or Classical-Vee, was the original design of such components. These belts

have a standard 40 degree Vee-angle and have rather narrowside faces (contact areas).

o Wedge belts by comparison are "deeper", slightly narrower and have a wider face area.

o N.B.: Both types are in common use. However, wedge type belts are gaining greater popularity for various reasons. The most common reason is that they are capable of transmitting higher loads for a comparable "size" of classical-vee.

HOW ARE VEE SECTIONED BELTS CONSTRUCTED? o As a rule "rubber-compounds" form the greater part of construction. o "Load carrying cords" are laid into the rubber compounds into the areaofhighest

"flex". These load carrying cords are immensely strong and constitute the main strength of the belt.

o Some belts (not all) are covered with a rubberised fabric known as thejacket. o N.B.: A belt without a jacket is known as a "raw-edge" belt.


o In operation a belt is subjected to several forces: Tension the area of the cords. Compression the area below the cords. Stretch or pull the cords themselves. Friction the contact I face area.

HOW IS POWER TRANSMITTED THROUGH A VEE TYPE BELT?

o Through the "frictional contact" of the two contact areas (faces) of the belt onto (or against) the sides of the grooves in the pulleys (also known as "sheeves").

o It is therefore the "wedging" action between the belts "vee" and the "vee" shaped grooves machined into a pulley that ensures transfer of power.

o NB -A belt must never contact the bottom of the pulley groove -if it does then either the wrong size belt is being used or the pulley is badly worn.

o Pulley grooves (usually) are machined in such a way that a 2 to 3 degree

"interference-angle" is introduced (i.e. a 40 degree belt angle is made to fit into a 38 degree pulley angle).

o NOTE: Wedge type belts will not operate in "old style" pulleys designed for classical vee. However classical vee-belts can be used on wedge pulleys -more about pulleys later.


HOW IS THE CORRECT AMOUNT OF FRICTION MAINTAINED BETWEEN BELT AND PULLEYS? o By applying the necessary "tension" into the belt upon installation, and by

subsequent re-adjustment after initial "running-in". o Correct tension is paramount to:

Optimum transfer of power. Belt life. Mechanical component life (e.g. shaft-bearings etc.).

o N.B.: Procedures covered in BCD-2. ARE CLASSICAL VEE AND WEDGE BELTS INTERCHANGEABLE?

o As a rule the answer is NO. o On no account should the two types be installed together onto one drive (i.e. onto

a "multiple-pulley groove" unit). HOW ARE THE TWO TYPES OF BELTS IDENTIFIED?

o By reading the manufacturers label is the safest way. o Wedge belts have the prefix "SP" on the label. o Classical Vee belts do not bear the letters SP.

WEDGE DESIGNATION (typical)

VEE DESIGNATION (typical)

WHAT DO THE LETTERS ON A BELT LABEL MEAN?

o Belts are manufactured in a variety of sizes and lengths, and the label information gives us this detail -plus more.

o Concerning belt size - this refers to a belts "cross-section" and for purposes of keeping this simple we shall only concern ourselves with belts intended for industry (not agricultural or automotive types).

o Each type of belt has five categories The diagrams show representations of the types, to scale.

1. CLASSICAL BELT SIZES The chart gives the physical dimension, to approximate scale, of the 5 ratings. (Note that sizes given are approximate in millimetres -original dimensions are in the "inch" system).


2. WEDGE BELT SIZES

On wedge belts, the belt size and width is also provided, (e.g.SPA -13N). The letter "A" tells us that it is of "A" section, 13 means it is 13 mm measured across the top edges and "N" means "Narrow" type.

The belts "nominal-length" is also given as the figure following the sectional information e.g. SPA 13N 1600 the figure 1600 tells us that the belts circumference, measured at a point via the "cord area," (i.e. its pitch length) is 1600 millimetres. It is not the circumference around the outer or inner edge.

o On classical belts, the information given on the label gives its section (e.g.A, B, C or D) then the nominal length in millimetres.


o In the example we read as follows: The belt is B section. The nominal length of the belt is 1690 mm.

o The design B65 is the IMPERIAL size rating which is no longer valid in our country. However, for interests sake it means B section, 65 inches long, measured around the INSIDE circumference.

WHAT DO I NEED TO KNOW ABOUT PULLEYS? Several points are worth noting about pulleys such as type, size, diameter and number of grooves. 1. TYPES OF PULLEYS

o Two main types are generally used in industry namely the cast or spoked type, and soid disc type.

o A third type, known as "formed-steel" type, is seldom used in industry ... but often used in automotive applications.

o Pulleys of both spoked and solid disc type are obtained in single-groove and multiple-groove variations.

o Spoked pulleys are sometimes made of aluminium (e.g. light duty compressors).

2. SIZES OF PULLEYS o Size refers to the "section" of belt that the pulley grooves are made for. o Nowadays most pulleys are of the "SP" type, those designed to

accommodate SP belts. SP pulleys will also accept Classical Vee belts. o Pulleys are available in SPZ, SPA, SPB and SPC sizes. (Note all Fenner types

pulleys bear the designation stamped near the boss area).


3. DIAMETER o Pulleys are provided in a variety of diameters ranging from around 60 mm up

to above 1000 mm. o A pulley's diameter is given as the "Pitch diameter" which means the

diameter measured across the contact area of the face of the belt.

For example if you measure a pulley's diameter from edge to edge and find it to be, let's assume 105 mm, you will find that the manufacturers size given will be 100 mm (pitch diameter).

4. NUMBER OF GROOVES o As previously mentioned pulleys can be obtained in single groove version or

multi-groove version. o Obviously the more grooves, the more belts can be fitted and therefore

higher loads transmitted. You may encounter as many as 8 belts on one drive, and on specially designed drives, as many as 36 belts.

o Other belt types you may encounter are as illustrated below.


PART TWO: REVIEW BREAK Having now watched the second section of the video and read the resource notes we suggest you do the following:

o Examine different Vee and Wedge belts. o Examine various pulleys (but not on live machinery!). o See how belts fit into pulleys. o Examine the label information on various belts and interpret the information. o Get hold of a manufacturerschart and study the information given, this can greatly

assist your understanding of belts AND pulleys. o With the permission of the necessary Supervisors or Engineers, take a look at the

various belt drives in your plant, factory or premises. SAFETY TIP! Don't touch ANY live equipment -keep away from rotating machinery and under no circumstances try to remove a safety guard.

o Continue watching the video up to the next "Review" break.

TURN PAGE TO BEGIN PART 3 (ROLLER CHAINS).



PART THREE: ROLLER-CHAINS WHAT IS A ROLLER-CHAIN? Basically it is a flexible drive component that comprises of a series of metal "links". Within the links are ROLLERS which are designed to engage the "pitches" of sprockets.

WHAT ARE THE MAIN COMPONENTS OF A ROLLER CHAIN? The two main components are:

o an inner-link which houses the rollers. o an outer-link which interconnects the inner-links.

Let's take a closer look at these parts.


HOW ARE THE TWO ENDS OF A LENGTH OF ROLLER-CHAIN JOINED TOGETHER? This is normally achieved using a "master-link" which is really a modified outer-link.

o Note that the "master-links" require the use of retainers, some use a CLIP, and others use SPLIT-PINS.

WHAT PREVENTS THE SIDE-BARS FROM FALLING OFF?

o Most roller-chains rely on a tight "press-fit" of the bushes into the side bars. o The ends of the pins (on outer links) are usually riveted upon assembly at


ARE ONLY SINGLE CHAINS AVAILABLE? o No, there are 3 basic types known by their number of "strands" namely: Simplex,

Duplex, and Triplex.

ARE THERE SPECIAL SPROCKETS TO MATCH DIFFERENT CHAINS? Very definitely -sprockets are made to suit a chains pitch, size and type.

o Sprockets may have odd or even numbers of "teeth". o Sprockets are made in several diameters. o Sprockets are made in different basic designs.

The following illustrations will help to describe some important facts about sprockets. 1. BASIC SPROCKETS (FORMS)


2. SPROCKET NOMENCLATURE (DESCRIPTION) When purchasing a sprocket from your dealer it is important that you provide an accurate description of exactly what you require. The minimum information necessary is:

o The type or form you require (e.g. Taper-lock, through-bore, or plate-wheel). o The number of strands (e.g. Simplex, Duplex or Triplex). o The "tooth-pitch" which corresponds to the pitch of the chain. o The "shaft diameter" onto which the sprocket will be fitted. o The number of teeth on the sprocket require. o The "pitch-diameter".

Below is a typical engineering drawing of a sprocket describing the various physical dimensions.


WHAT IS A "DOUBLE-PITCH" CHAIN? This is a roller-chain that has double lengthened side bars thus creating a chain which only has half the number of rollers of a "standard" roller-chain.

WHAT ARE DOUBLE PITCHED CHAINS USED FOR? Owing to their relative "inexpensiveness" double pitched chains are often used for:

o Light duty drives. o Conveyor systems. o Agricultural machinery.

In conveyor systems the side bars are often made with flat edges onto which a load can be supported (many conveyor chains are "roller-less"). Shown in the following illustrations are types of chains typically used for conveyor and elevator applications.


WHAT MAINTENANCE DO CHAINS REQUIRE? All chains, especially in "drive" applications, require two basic conditions namely:

o Lubrication, o Tensioning (sag adjustment).

Let's first consider lubrication. LUBRICATION is usually provided in the form of oil and may be applied manually or by semi-automatic and automatic feed methods.

Let's now discuss tensioning. TENSIONING of a chain actually refers to the amount of "slack" or "sag" that should exist in a strand of chain ... this occurs between the sprockets.

o A chain that is too loose will "whip" and tend to jump off the sprockets. o A chain that is too tight will "bind", wear faster and result in damage to all related

components. o As a general rule a chain should have a "slack" movement of approximately 2% -3%

of its longest span, between centres of sprockets.


An automatic tensioning device may be installed to: o Reduce down time for maintenance. o Help absorb shock loading. o Maintain correct tension, especially when chain is operating between "fixed

centres".

PROCEED NOW TO THE "REVIEW" SECTION.


PART THREE: REVIEW BREAK Having now watched the third section of the video and read the resource notes we suggest you do the following:

o Examine different chain drive mechanisms in your own workplace (not on live machinery).

o See the various types of chains used in your workplace. o Study a good chain catalogue (i.e. for roller and conveyor chains).

SAFETY TIP! Don't touch any equipment -keep away from rotating machinery and under no circumstances attempt to remove a safety guard.

o Continue watching the video up to the end of the programme.

TURN PAGE TO BEGIN PART FOUR (SAFETY).



PART FOUR: SAFETY WHAT IS THE MOST IMPORTANT SAFETY ASPECT WHEN WORKING ON ROTATING EQUIPMENT? The answer is ISOLATE! WHAT IS ISOLATION? This means making it impossiblefor anyone to accidentally (or deliberately!) start up a machine that you are busy workingon. HOW IS ISOLATION DONE? On electrically powered equipment it can be:

o Removal of the power plug from a wall socket. o Tripping the main switch at the distribution board

... and then placing a lock over the tripped switch. o Having an electricianLOCK OUT a switch gear unit

and YOU placing your OWN LOCK on it. HOW IS ISOLATION ENSURED? By trying to start the machine AFTER you have performed the necessary isolation procedure. If it STARTS then it’s NOT isolated! CAN A WORKER BE SURE OF TOTAL SAFETY, EVEN AFTER ISOLATION? The answer is NO! You are still at risk of having your fingers, loose-clothing, jewellery etc. trapped or caught-up in the machine parts, especially if you have to rotate components manually! WHAT IS A "SAFE" METHOD OF ROTATING A MACHINE MANUALLY? There are several ways in which you can do this:

o By using a spanner or wrench onto a hub bolt. o By turning a shaft (e.g. between plumber block bearings as demonstrated in DVD). o By turning a coupling at the gearbox.

WHAT OTHER "SAFETY" POINTS SHOULD A WORKER KEEP IN MIND?

o Wear the proper attire such as zipped up (or buttoned up) overalls I dust coat etc. o Don't wear loose articles (e.g. ties, necklaces, wrist-chains etc.). o Never re-connect the power until:

All tools and equipment have been removed.


The safety guards have been securely installed. You have notified your supervisor (if applicable) that the work is completed.

o If practical, TEST RUN the machine to make sure all is well. o NOTE: This step will depend largely on the type of machinery AND your companies

safety regulations. o Safety is a combination of:

Common sense. Knowledge of your equipment. Your companies rules.

PROCEED NOW TO THE "REVIEW" SECTION.


PART FOUR: REVIEW BREAK Having now completed this overview programme we suggest that you now proceed to:

o Learn about Vee-belt and Wedge-belt maintenance in programme BCD-2. OR o Learn about Roller-chain maintenance in programme BCD-3.

Please ensure that you have done the following:

o Returned the video to your library or Course Controller. Join us again for more technical training programmes produced in the interests of improving YOUR technical knowledge and technical skills, by TECH AV.

END.


BCD-2: AN OVERVIEW OF VEE-BELT MAINTENANCE TRAINING AIDS REQUIRED?

o Tech AV video programme No. BCD-2. o Assorted belt driven machinery and equipment. o Basic hand tools. o Straight-edge (1 metre). o Fenner Tension gauge.

PROCEDURE

1. Obtain the video programme from your Course Controller. 2. When you see the "REVIEW" signal on the video: o Stop the video. o Read the Resource Notes. o Perform any practical or theoretical exercises suggested in the "Review" section.

TIPS o If you experience any problems, ask your Course Controller to assist you.




PART ONE: INTRODUCTION TO VEE & WEDGE BELTS WHAT TYPES OF BELTS WILL THIS PROGRAMME CONCENTRATE ON?

o Classical Vee and "Wedge" belts for industrial applications. WHAT IS THE PRIMARY DIFFERENCE BETWEEN THE TWO TYPES?

o Wedge belts are slightly narrower and "deeper" in section than Classical types (see also Programme BCD-1).

WHAT SIZES ARE PRODUCED IN EACH TYPE?

o In "classical" section there are 5 sizes in common use, namely Z, A, B, C and D sections.

o In ''Wedge'' there are also 5 commonly used sizes, namely SPZ, SPA, SPB, SPC and "DELTA" sections.

WHAT DOES THE LETTER "N" DENOTE? (On Wedge Belt Label)

o This is a South African Bureau of Standards designation to denote NARROW, as compared to classical vee types.

WHY IS "WEDGE" TYPE BELTS MORE POPULAR THAN "CLASSICAL-VEE"?

o Owing to their construction they are capable of carrying higher loads. This comes about as a result of their greater frictional surface area. (See Study guide BCD-1 for extra detail on this subject).

ARE PULLEYS MADE FOR BOTH BELT TYPES?

o Yes, but be careful!Old style pulleys were designed only to accommodate EITHER "classical belts" or "wedge belts", not both.

o These pulleys, called "single-duty" types are largely being superseded by "dual-duty" type which can accommodate both classical and wedge types.

o Dual-duty pulleys are identifiable by the marking "SP" followed by a letter (e.g. SPA = dual duty pulley for "A" type belt).

CAN BOTH CLASSICAL VEE AND WEDGE BELTS BE USED TOGETHER ON THE SAME DRIVE?

o No, this is definitely NOT a recommended situation.

PROCEED TO THE REVIEW SECTION OVER PAGE.


PART ONE: REVIEW BREAK NO. 1 Having now viewed the first section of the video and read the resource notes we suggest you do the following:

o Inspect various belts and pulleys on ISOLATED machinery or on models in your work place. Get familiar with belt types, sizes and pulley grooves.

o Look for pulley type identifications that may be stamped or etched into pulley bosses.

o Continue watching the video up to the next "Review" section.

TURN PAGE TO BEGIN PART TWO (REPLACEMENT).



PART TWO: BELT REPLACEMENT WHAT IS THE STANDARD PROCEDURE TO FOLLOW WHENEVER A BELT, OR BELTS, NEEDS REPLACEMENT?

1. ISOLATE the power source FIRST! 2. Remove the old belt(s). 3. Inspect pulleys. 4. Select new belts. 5. Install belts. 6. Set tension and pulley alignment.

SAFETY TIP: Forget Step One and it may be the LAST thing you do! WHAT ARE THE PROCEDURES FOR STEP 2 -REMOVAL?

o Remove the safety guard. o Mark the position of the moveable unit so that you can reposition it later when we

come to belt selection. o Slacken the hold-down fasteners of the moveable unit. o Slacken, or move, the unit until the belts are fully slack. Ensure that any

adjustingscrews are wound back to allow for full slackening. o Lift belts off the drives.

WHAT ARE THE PROCEDURES FOR STEP 3 -INSPECTING PULLEYS?

o Visually inspect pulleys for damage. o Check the pulley grooves for wear -using a profile or groove gauge if possible (see

illustrations for explanation).

NOTE: SP pulleys of LARGE diameter have a 38 degree groove angle whereas small diameter pulleys have a 34 degree groove angle.


o If necessary, clean the grooves with a suitable non-flammabledegreaser/ solvent. NB! DO NOT introduce any form of "lubricant" to the grooves as this will affect the belts frictional quality and could also degenerate the belt material.

o Rotate the pulleys carefully and observe that they are running "true". o Renew or repair damaged or bent pulleys.

HOW ARE NEW BELTS SELECTED? (STEP FOUR) Firstly let's consider multiple belts, which must be "MATCHED".

o All belts intended for multiple use bear a number that has been stuck on near the printed label.

o The "optimum" number is "50". The number 50 indicates that the ACTUAL nominal belt length is precisely that as printed on its label (e.g. SPB 16N 1900 ... 50 ... means that the belt IS 1900 mm on its nominal circumference).

o For every "unit" above, or below, the optimum figure of 50 the ACTUALbelt circumference will differ by 2 mm.

Examples:

1. Belt length 1900 has a 51 sticker. Then the actual nominal length is 1902 mm.



o Ideally all belts should be EXACTLY the same length, but during manufacture,

machine tolerances may create slight differences in lengths, which although are "within limits", could create problems on the drive. Each belt is quality inspected and measured, and then a label giving its manufacturers "tolerance" is affixed.

o When selecting multiple belt SETS, the variations should not exceed the figures provided by the manufacturer for given belt lengths.

For example: Belts of between 800 mm and 1800 = MAX variation 2 mm. Belts of between 1801 mm and 3170 mm = MAX variation 4 mm. (N.B.: Refer to Fenner Chart, if available, for other details). RIGHT! BUT WHAT ABOUT THE ACTUAL BELT-LENGTHS NEEDED FOR MYJOB, HOW DO I FIND THIS OUT? There are 3 ways to do this:

1. Refer to the machine's manual. 2. From the label (if readable) of an old belt. 3. By calculation using a standard formula.


HOW CAN ONE "CALCULATE" A BELT LENGTH?

Providing that the pulleys are of different diameters then, use THIS formula:

Explanation by example:

NOTE - The movable unit must be set to original marks (or approx. 1/4 of adjustment) in order to measure the C factor. Calculate required belt length where: d = 185 mm D = 240 mm c = 615mm Substituting figures in formula:

=

=

= =

Length required =

o Using this figure, consult your belt chart and locate the manufactured belt that most closely matches your calculated length.

In addition.... o It is assumed that you know what SECTION (i.e. Z, A, B, C or D) belt you require.

WHAT IF BOTH PULLEYS ARE THE SAME DIAMETER ... DOES THE FORMULA STILL WORK? Yes it does, however calculate in the following way using the simple formula:

Example: Calculate belt length where D = 240 m c = 615 mm then 3,1412 x 240 + 2 x 615 = 1984,08 mm


WHAT IS THE NEXT PROCEDURE? (FIT BELTS) o Step 5 -Begin by replacing the moveableunit back to its "full-slack" position. o Feed the belts over the pulleys, without force!Locate each belt into the respective

grooves. N.B.: SAFETY!

o Do NOT try to stretch belt across pulleys using levers or force. o If a belt won't fit easily over the pulleys check:

That adjustment is fully backed off. Your calculated length is correct. That you are not trying to "jump" too many pulley grooves at a time.

o When all belts are positioned into their respective grooves then go onto Step 6.

WHAT IS THE CORRECT WAY TO ADJUST BELT TENSION? STEP 6 The correct way to do ANY job is to follow the procedures and methods provided by the manufacturers. We would like to explain the procedure in the manner recommended by "Fenner Power Transmission".

o Adjust the moveable unit ... using the adjuster screws if equipped ... and at the same time keeping a check on the "face alignment" of the pulleys to make sure the moveable unit does not "twist".

o Using a safe method (e.g. with a spanner or by a convenient shaft I coupling, ROTATE the pulleys during the adjusting process ... this will ensure that the belts "seat" properly in their grooves.

o At a time when the belts are visually taught,i.e. not sagging, check the tension using the "tension-gauge".

HOW DO I USE AND READ THIS TENSION GAUGE? Follow the manufacturer’s instructions which appear below.

As the high performance of Fenner Precision Built belts require correct tension, we recommend using the Fenner Belt Tension Indicator. METHOD OF BELT TENSIONING

1. Multiply the centre distance in metres by 16 to obtain the deflection distance in mm. 2. Set the lower marker ring at the deflection distance required in mm on the lower

scale.


3. Set the upper marker ring against the bottom edge of the top tube. 4. Place the belt tension indicator on top of the bell at the centre of span, and apply a

force at right angles to the belt deflecting it to the point where the lower marker ring is level with the top of the adjacent bell.

5. Read off the force value indicated by the top edge of the upper marker ring. 6. Compare this force to the kgf value shown in the table. If the measured force falls

within the values given, the drive should be satisfactory. A measured force below the lower value indicates under-tensioning. A new drive should be tensioned to the higher value to allow for the normal drop in tension during the running-in period.

NOTE: For single belt drives a straight edge should be placed across the two pulleys to act as a datum for measuring the amount of deflection.

TENSIONING FORCES

Belt Section

Force required to deflect belt 16 mm per metre of span

Mall Pulley Diameter (mm) Newton (N) Kilogram Force

(kgf)

10N (SPZ) 67 to 95 10 to 15 1.0 to 1.5

100 to 140 15 to 20 1.5 to 2.0

13N (SPA) 100 to 132 20 to 27 2.0 to 2.7

140 to 200 28 to 35 2.8 to 3.6

16N (SPB) 160 to 224 35 to 50 3.6 to 5.1

236 to 315 50 to 65 5.1 to 6.6

22N (SPC) 224 to 355 60 to 90 6.1 to 9.2

375 to 580 90 to 120 9.2 to 12.2

25N (DELTA) 355 & above 150 to 200 15.3 to 20.4

13x8 (A) 80 to 140 10 to 15 1.0 to 1.5


17x11 (B) 125 to 200 20 to 30 2.0 to 3.1

22x14 (C) 200 to 400 40 to 60 4.1 to 6.1

32x19 (D) 355 to 600 70 to 105 7.1 to 10.7

WHAT MUST I LOOK FOR WHEN CHECKING PULLEY ALIGNMENT? Again we refer you to the manufacturer’s information,

Good alignment of Pulleys is important otherwise the belt flanks will wear quickly.

The dotted lines emphasise the faults by indicating the correct position.

o Remember to re-check tension after:

Any adjustment made to correct an alignment fault. The correct "running in" period.

o N.B.: Running in period is approximately 30 minutes; on load for Fenner "PB" brands. For other types allow up to 4 hours.

PROCEED NOW TO THE "REVIEW" SECTION OVER PAGE.


PART TWO: REVIEW BREAK NO. 2 Having now viewed the second section of the video and read the RESOURCE NOTES we suggest you do the following:

o Under the supervision of your Course Controller or responsible person replace and adjust belts on various pieces of machinery.

o Select new belts by CALCULATION of length as demonstrated in the video and explained in the resource notes.

SAFETY!

o Observe all safety regulations applicable to your workplace and the ruling "machinery acts" in force in your area or country.

TURN PAGE TO BEGIN PART THREE (MAINTENANCE TIPS).



PART THREE: MAINTENANCE TIPS WHAT CAN BE DONE TO ENSURE THAT I HAVE NO "COMEBACK" ON A BELT REPLACEMENT JOB?

o Firstly -the correct tension is critical for long and trouble free service life. o Alignment of pulleys, if correct will also greatly improve service life of belts.

WHAT CAN GO WRONG WITH BELT DRIVES, PRESUMING THAT BELTS WERE CORRECTLY INSTALLED?

o Oil leaks, from machinery seals or gaskets or other contaminants, could get onto the belts during operation. When belts are contaminated they may:

1. Slip -even when correctly tensioned. 2. Swell or soften.

o On some machinery, especially where long belt spans are encountered, belts may "whip" when on load. Such conditions are out of the control of maintenance personnel, but a "jockey-pulley" could help to reduce the problem.

NOTE: In such cases it is often more practical to fit "Banded-Vee belts".

WHY WERE THE "OLD BELTS", THAT I REMOVED, COVERED IN SMALL CRACKS ALONG THE SIDES AND THE BASE?

o This is usually a sign that they had been operating: In a hot environment. Where chemical fumes were in the air. Or incorrect (loose) tension was given.

AFTER A FEW HOURS OF RUNNING -THE BELT SNAPPED! WHAT CAUSED THIS? o The most likely cause is that the belt had been "forced" onto the pulleys with a lever.

This action tends to break a few of the "load carrying cords" inside the belt thus severely weakening it.

o The next possible reason is that it was not properly tensioned, i.e. it was OVER tensioned.

o Severe overload or "jam" in the driven machine. CAN I REPLACE JUST ONE BELT ON A MULTIPLE DRIVE?

o Definitely NOT! o The ONE new belt will end up taking theENTIRE load, with inevitable results! o Always replace ALL belts -with matched sets, from the SAME MANUFACTURER.



PART THREE: REVIEW BREAK NO. 3

o This basically concludes the programme -from now on your experience in the maintenance of belt drives will improve as you get to work on such units in your workplace.

o It will inevitably happen that at some time you will come across other types of belt drives. However, the principles that you have learned in this programme -PLUS the information given by the machinerymanufacturer in the "shopmanual" will ensure that you will be able to cope with any maintenance or repair task.

o Read the notes in this study guide whenever you need a "refresher" on the subject, and, if need be, review the video.

o Please return the video to your Course Controller.

o Join us again in other Tech AV technical instructional programmes, designed to assist YOU in improving your knowledge and technical skills as you progress in your chosen trade.


BCD-3: AN OVERVIEW OF ROLLER-CHAIN MAINTENANCE TRAINING AIDS REQUIRED

o Tech AV video programme no. BCD-3. o Assorted roller-chain driven machinery. o Basic hand tools (fitter). o Straight edge. o Engineers steel rule. o Cleaning materials.

PROCEDURE

1. Obtain the video programme from your Course Controller. 2. When you see the "Review" signal on the video:

Stop the video. Read the resource notes. Perform any practical or theoretical exercises suggested in the "Review"

section. TIPS If you experience any problems ask your Course Controller to assist you.




PART ONE: "ISOLATION AND SAFETY" PRIOR TO ANY MAINTENANCE ON ROLLER-CHAIN DRIVES (OR LOAD CARRYING CONVEYOR CHAIN) WHAT MUST WE FIRST DO:

o Ensure that the machine is isolated in such a way that it cannot be started by any person.

ONCE ISOLATED WE MUST STILL BE AWARE OF HAZARDS IN THE FORM OF:

o Finger tips -where necessary use tools or other safe means to rotate a drive. Never turn a drive using your hands on the sprockets or chain itself.

o Location -always wear the prescribed personal safety equipment (e.g. helmet, safety shoes, goggles etc.) relevant to the area in which work takes place.

HAVE YOU THE "RIGHT" TO STOP / START UP MACHINERY?

o Always obtain the necessary permission/authority to stop or start a machine. o Obtain (if applicable) the necessary permit to do work on a machine.

DO YOU KNOW YOUR COMPANIES POLICIES AND PROCEDURES?

o Take time now to review your company’s regulations regarding maintenance on their machinery.

PROCEED TO THE REVIEW SECTION OVER THE PAGE.


PART ONE: REVIEW BREAK NO. 1 Having now viewed the first section of the video and read your notes, we suggest you do the following:

o Ask your Course Controller / Facilitator to show you which piece of plant / machinery will be allocated to you for your practical exercises.

o Study the machinery and (as applicable) learn the location of the isolation device and its operation.

o Have a responsible person demonstrate the lock-out procedure (if applicable). NOTE: "Responsible person" is one who is qualified and has the authority to connect or disconnect power to / from moving equipment.

o Continue watching the video up to the next "Review" section.

TURN PAGE TO BEGIN PART TWO (REMOVAL / CLEANING).



PART TWO: "REMOVAL AND CLEANING" WHAT ARE THE GENERAL PROCEDURES FOR REMOVING A ROLLER-CHAIN ON A TYPICAL DRIVE UNIT?

o Locate the master link (connecting link) and mark it with chalk. o Rotate the drive until the master link is located on a sprocket (preferably the largest

sprocket). o Remove the retainer-clip (or split-pins), side-bar and then disengage the link. o Place loose items in a container to avoid loss. o Lift chain off the drive and place into a container for purposes of cleaning.

WHAT "CLEANING-PROCEDURES" ARE NORMALLY NECESSARY?

o Chain is "soaked" in a de-greasing fluid (we do not recommend petrol, thinners, etc. However paraffin / kerosene used with care is often the most effective cleaning medium).

o Whilst chain is soaking, clean / de-grease the sprocket-wheels. o If necessary, use a stiff brush to remove stubborn deposits when cleaning the chain. o Dry off components (with careful and safe use of compressed air). o Lay chain out on a clean, flat surface for inspection.

PROCEED NOW TO THE "REVIEW" SECTION OVER THE PAGE.


PART TWO: REVIEW BREAK NO. 2 Having now viewed the second section of the video and read the Resource Notes we suggest you do the following:

o On your allocated machine -remove the chain and clean all components. o Layout the chain ready for an inspection. o Continue watching the video.

TURN PAGE TO BEGIN PART 3 (INSPECTION).



PART THREE: "INSPECTION" WHAT DO WE LOOK FOR WHEN INSPECTING SPROCKET-WIIEELS?

o Signs of wear and / or damage. WHAT "TYPICALLY" MAY WE EXPECT TO FIND?

o Worn tooth-pockets which in extreme cases results in a "hook-shaped" tooth-profile (see illustration).

o Side-wear, caused from severe misalignment. o Broken / cracked teeth. o Wheel "wobble" or run-out -this is checked with a dial-test-indicator if suspected.

WHAT INSPECTION DOES THE CHAIN RECEIVE?

o Inspect a "laid out" chain for "twist". A twisted chain has been over-stressed and must be renewed.

o Link flexibility -every link must be "free" to swivel. A stiff or solid (frozen) link joint points to severe wear from poor lubrication -and from over loading conditions.

o Wear marks -on inside surfaces of side-bars, as a result of severemisalignment. o "Stretch" as a result of "wear" between bushings and pins.

WHAT IS THE EFFECT OF A BADLY ELONGATED (STRETCHED) CHAIN?

o Most notable effect is that the chain will tend to "jump" sprocket teeth as it tends to ride "higher and higher" onto the teeth (see illustration below). This occurs owing to the "pitch" becoming elongated.


DESCRIBE A TYPICAL METHOD OF DETERMINING CHAIN STRETCH:

o The chain is placed under load -preferably laid out flat on a flat work surface. o Whilst under a loadthe specified number of "pitches" are measured -from pin centre

to pin centre. o The measurement is compared to the "nominal specification" and the "elongation

percentage" calculated'. NOTE: It is generally accepted that 2% is the maximum allowable wear.

EXAMPLE: A new simplex chain of 1/2 inch (12,7mm) pitch has a nominal length of 12 inches (304,8 mm) over span of 24 pitches. A used simplex chain was measured over 24 pitches and the length was found to be 12,4 inches (315 mm). By what percentage has the chain elongated (i.e. worn)? METHOD OF CALCULATING Measured length (L) minus nominal length (l) divided by nominal length (l) times 100 OR

For our purposes L = 305, l = 315 our calculation is

which equals 3.27 %

CONCLUSION By calculation we have discovered that our example chain has a stretch in excess of 3%, which is beyond "allowable". The chain needs to be renewed.


NOTE i) All roller chain specifications are given in the imperial measuring standard (the "inch"

system). For purposes of calculating and measuring in the metric system we use the conversion of one inch (1") as being 25,4 mm.

ii) Maximum chain elongation figures (Le. percentage wear) change in respect of the number of teeth on the largest sprocket in the drive. As a guide we provide a typical manufacturers "table" for various chain sizes and the "replacement" limits".

ANSI Pitch-Inches

No. of Pitches

Nominal Length-Inches

Up to 67 68-79 74-81 82-90 91-

103 104-118

119-140

141-173

35 .375 32 12.00 12.38 12.34 12.31 12.28 12.25 12.22 12.19 12.16

40 .500 24 12.00 12.38 12.34 12.31 12.28 12.25 12.22 12.19 12.16

50 .625 20 12.50 12.88 12.85 12.81 12.78 12.75 12.72 12.69 12.66

60 .750 16 12.00 12.38 12.34 12.31 12.28 12.25 12.22 12.19 12.16

80 1.000 24 24.00 24.75 24.69 24.63 24.56 24.50 24.44 24.38 24.31

100 1.250 20 25.00 25.75 25.69 25.63 25.56 25.50 25.44 25.38 25.31

HOW DOES ONE "READ" THIS CHART? By our example earlier -look at chain No.40 (ANSI 40) which has a "nominal pitch" of .500 inches (12.7 mm). Under the column "Measuring length" we see that we must measure over 24 pitches and this will have a "nominal" (new) length of 12.00 inches (304.8 mm or 305 mm rounded out). The last 8 columns give us the number of teeth on the largest sprocket. If for example, our drive had a 67 tooth sprocket -then the "length of chain replacement required" is 12,38 inches (314.4 mm). However, if our largest sprocket has 120 teeth then the "length for replacement" figure reduces to 12,19 inches (309.6 mm).



PART THREE: REVIEW BREAK NO. 3 Having now viewed the third section of the video, and read your "Resource Notes", we suggest that you do the following:

o Make a thorough inspection of the sprockets. o Check for run-out and play in the sprocket. o Inspect the chain for damage. o Perform an "elongation" (stretch) check on your chain (refer to table on Page 8 ) for

your specifications). o Continue watching the video.

TURN PAGE TO BEGIN PART 4 (INSTALL AND ADJUST).



PART FOUR: "INSTALL & ADJUST CHAIN" WHAT IS THE FIRST CONSIDERATION TO MAKE WHEN YOU DECIDE TO RENEW A CHAIN? Replacement chain must be of the correct:

o Pitch. o Roller diameter. o Inside width. o Length (Le. number of pitches).

WHAT ARE THE BASIC PROCEDURES FOR CHAIN REPLACEMENT?

o Move adjustable unit to minimum centres (Le. reduce distance between centres). o Wrap chain around sprockets beginning with one open end on largest sprocket. o Join chain, on sprocket, using the master (connecting) link. o Set centre distance to create the required slack or sag. o Ensure that sprocket face alignment is correct.

HOW IS "CORRECT TENSION" ACHIEVED? (Simple Drive Unit) N.B.: The term "tension" is technically incorrect when we refer to chain adjusting. The correct term is "chain slack" or "sag".

o Centres are adjusted to increase distance until, o A small amount of "slack" can be felt.

N.B.: All the slack must be taken up in one strand -opposite strand is"taut". o A straight-edge (or a tight string line) is laid across sprockets. o An engineer’s rule is used to measure the sag, in comparison to the "reference-edge"

of the rule (or line).

WHAT IS THE CORRECT "AMOUNT" OF SAG (SLACK)? o For horizontal and inclined drives we aim to provide sag amounting to approximately

2% - 4% of the sprocket “centre distance”. o For your convenience a table is provided below giving you a “quick reference” for the

more common centres, at a 2% factor.


SPROCKET CENTRES SAG

INCHES MILLIMETRES INCHES MILLIMETRES

20 508 .50 13

30 762 .63 16

40 1016 .88 22

60 1524 1.25 31

80 2032 1.63 41

100 2540 2.00 51

125 3175 2.50 63 NOTE: For drives on vertical centres, or those subject to conditions such as shock

loads, rotation reversals, or dynamic braking, install chain almost taut. It is essential to inspect such drives regularly for correct chain tension.

WHAT IS "SPROCKET ALIGNMENT"?

o In effect sprockets are aligned when, Adjacent shafts are parallel, and Sprocket edges (facings) lie on a common axis.

o If sprocket-wheels are not in alignment the chain will run "skew" resulting in wear between the teeth and inner surfaces of the chain's side-bar (plates).

o Typical alignment situations are illustrated below.

RIGHT

Check Point

Position of sprockets on shafts – Axially square

check with dial indicator

Lateral movement of sprockets on shaft – none

Alignment of sprockets on shafts - exactly

opposite; check with straight edge


WRONG

RIGHT

Check Point

Shafts parallel – check with Vernier, callipers,

or feeler bars

Shaft level – use machinists level

Shaft end float – minimum possible

WRONG

WHAT ACTION IS TAKEN TO CORRECT ANY MISALIGNMENT?

o The quickest method of checking is with a straight-edge. You will however usually need to remove the chain in order that the straight-edge can lie "flush" against sprocket wheel facings.

o Using appropriate methods (e.g. shims and side-adjuster screws) the "moveable unit" can be manipulated in such a way that the sprocket facing is coincident with the "fixed" unit’s sprocket facing.

o Having made any adjustment -the chain is replaced and the sag re-checked and, if necessary, re-adjusted.

N.B.: 1) Care, during adjustment, must be taken to maintain correct alignment (e.g. turn adjuster screws by equal amounts). 2) Make sure that the moveable units “hold down” bolts/screws have been secured.



PART FOUR: REVIEW BREAK NO. 4 Having now watched the video and read the resource notes we suggest you do the following:

o Practice the installation of your roller-chain on your assigned unit. o Adjust the chain to provide a 2% slack. o Check all alignment parameters. o Continue with video.

TURN PAGE TO BEGIN PART 5 (CHAIN TENSIONER).



PART FIVE: "CHAIN TENSIONER" WHAT IS THE MAIN PURPOSE OF A CHAIN TENSIONER?

o The primary function of an automatic chain tensioner is to increase a chains effective working life.

o A tensioner ensures correct tension in the drive. o It also absorbs shock loads and dampens vibration.

HOW AND WHERE ARE TENSIONERS FITTED? Most usually (and ideally) a tensioner is fitted in such a way that:

1. It is on the outer side of the "slack" span. 2. It is as close as possible (minimum 4 pitches) to the "driven" sprocket. 3. The swinging arm lies in the same direction as chain travel (i.e. the idler sprocket or

chain rider "trails" the chain).

Normal Positioning ROSTA tensioning elements are always fitted on the slack side, as close as possible to the big wheel and guide the chain from the outer side.The arm position of the tensioner should be ideally as parallel as possible to the chain drive.

Reversible Chain Drives On reversible chain drives, tensioning elements must be placed on both sides. An oversizing of the ROSTA tensioning elements is recommended for reversible function since they require more pressure on load and slack side.


Chain Engagement When tensioning for the first time, at least 3 teeth of the sprocket wheel should engage with the chain. The free chain length between the tensioning wheel and the following sprocket wheel should be at least 4 chain links.

WHAT ARE THE BASIC INSTALLATION / ADJUSTING PROCEDURES?

o Chain slack I sag is adjusted in the normal way to provide the recommended 2% -4%, with tensioner in the loose position.

o Tensioner body is turned to bring the idler sprocket (or chain rider) up against chain. o Further rotation of tensioner body is made whilst observing the angle scale. Turn to

+/- 15 degrees for initial adjustment. o Tighten control locking screw -then torque to specification (see below).

SCREW SIZE

(MM -METRIC) TORQUE

(NEWTON METRES) M6 10Nm

M8 25Nm

M10 50Nm

M12 86Nm

M16 210Nm

o Loosen both "lock nuts" (on either side of sprocket or chain rider). o Run the unit and allow idler (or chain rider) to "centralise". o Stop the unit . o Tighten either lock nuts against the idler (or chain rider) without disturbing the

centralised unit. o Run the unit to observe its behaviour (Le. that it operates smoothly).

WHAT FINAL ADJUSTMENTS NEED TO BE MADE?

o When the drive is operating, at normal load, observe whether any vibration exists in the chain; in the area between the idler and the driven sprocket.

o To decrease vibration -the tensioners angle may be increased up to, but not exceeding, 30 degrees.

N.B.: DO NOT MAKE ADJUSTMENTS WHILST MACHINE IS OPERATING.

PROCEED NOW TO THE REVIEW SECTION OVERPAGE.


PART FIVE: REVIEW BREAK NO. 5 Having now watched the video and read the resource notes we suggest you do the following:

o Practice the set-up and adjusting of the tensioning device on your chain-driven unit. o Adjust the devise to ensure a minimum vibration under load. o Have your Facilitator check your work. o Continue with video.

TURN PAGE TO BEGIN PART 6 (LUBRICATION).



PART SIX: "LUBRICATION" WHY IS LUBRICATION IMPORTANT FOR A CHAIN DRIVE?

o A chain, being a series of mechanical links, is subject to friction and thus to wear. o Movement occurs between pins, bushings and side-plates and of course as each

roller enters and leaves a sprocket-tooth. o Lubrication, normally in the form of a light viscosity oil, is therefore necessary in

order to reduce friction. N.B.: Grease is seldom recommended for chain lubrication, as it cannot "flow" into the

small cavities between pins / bushings and rollers. WHAT METHOD OF LUBRICATING IS RECOMMENDED? Basically there are three methods of lubrication, namely:

i) Hand lubrication (manual method). ii) Automotive feed lubrication. iii) Enclosed system lubrication.

o Manual Lubrication - Is performed on a "stationary chain" using a clean brush

dipped in oil or with an oil can. This method is employed mostly on light duty drives that are "open" or "exposed". Lubrication is necessary at around 4 -8 hour intervals.

o Automatic Feed Systems - Or "drip feeders· direct oil onto the chain at a determined "rate" (i.e. so many drops per minute). These systems are normally "encased" to prevent oil spray. Maintenance is usually limited to "topping up" the oil reservoir periodically.

o Enclosed Systems - (Splash feeds -pressurised systems) are usually employed on high-speed drives.

o "Splash" fed systems rely upon one of the sprockets, or a "disc", to "throw up" oil onto the chain.

o Overfilling of "splash type" systems can lead to a build up of heat -oil levels therefore must be correctly maintained.

o Pressurised systems direct a jet of oil spray at the chain's lower strand. Oil is contained in a "reservoir" or "sump". Oil levels should always be correctly maintained.

o Oil leaks should be rectified where applicable to prevent oil loss and possible chain failure.

o Manually lubricated chains will require cleaning at regular intervals, especially those exposed to dusty or dirty environments.

PROCEED NOW TO THE REVIEW BREAK SECTION OVER THE PAGE.


PART SIX: REVIEW BREAK NO. 6 Having now watched the video and read the resource notes we suggest you do the following:

o Inspect various chain drives, under the supervision of your facilitator, and look at the lubrication systems present in the equipment.

o Find out what type of lubricants are used. o Find out what level and topping-up methods are employed on various machines.



PART SEVEN: SUPPLEMENTARY INFORMATION The video programmes offered you visual information regarding most typical maintenance procedures. This section of the programme has been provided for your information on less typical topics which however may be of value to you in your place of work (No video information on this section). CHAIN STORAGE

o New chains should always be stored in a protective box or wrapping. Store away from heat or moisture and in a clean environment.

o Chains on idle equipment should be kept loose, i.e. provide plenty of slack and grease ton prevent the ingress of moisture. Ideally the chain should be removed, greased, wrapped and stored in the same conditions as a new chain.

o Sprockets should be greased to prevent corrosion during long storage periods. CHAIN LINK REMOVING

o A simple chain-detaching tool comprises a fork and an anvil-block. (see illustration). o The fork supports the link side-bars and a pin-punch is used to drive out the pins.

The following notes may contain useful reference to you when you are confronted with problems in chain-driven equipment: A. EXCESSIVE NOISE POSSIBLE CAUSES

1. Misalignment of sprockets. 2. Too little or too much slack. 3. Inadequate lubrication. 4. Loose casings or bearings. 5. Chain or sprocket worn out. 6. Too large a chain pitch size.


WHAT TO DO 1. Check alignment and correct. 2. Adjust centres for proper slack, or idler take-up. 3. Lubricate properly, check lubricating mechanism to be sure oil is reaching

working parts. 4. Draw up all bolts, and brace casings if necessary. 5. Replace chain and / or sprocket (some sprockets can be reversed). 6. Check chain drive recommendation chart.

B. WEAR ON CHAIN SIDE-BARS OR LINK PLATES AND SIDES OF SPROCKET TEETH POSSIBLE CAUSES

1. Misalignment. WHAT TO DO

1. Remove chain and correct alignment of sprockets and shafts. C. CHAIN CLIMBS SPROCKETS POSSIBLE CAUSES

1. Poor fitting of chains on sprockets. 2. Chain worn out. 3. Insufficient chain wrap. 4. Excessive chain slack. 5. Material build-up in sprocket tooth pockets.

WHAT TO DO

1. Make sure sprocket bottom diameters are not oversized. 2. Replace chain and sprockets (some sprockets can be reversed). 3. Revise driver arrangement to get more sprocket teeth in contact with chain,

or use idler take-up to increase wrap. 4. Adjust centres or take-up for proper slack. 5. Remove material build-up protect drive from contact with foreign material, or

use sprockets with mud relief, pitch line clearance. D. BROKEN PINS, BUSHINGS OR ROLLERS POSSIBLE CAUSES

1. Chain speed too high for pitch and sprocket size. 2. Heavy shock or suddenly applied loads. 3. Material build-up in sprocket tooth pockets. 4. Inadequate lubrication. 5. Chain or sprocket corrosion. 6. Poorly fitting sprockets.


WHAT TO DO 1. Use shorter pitch chain of equivalent or greater strength and 1or check

number of sprocket teeth to be sure it is within recommended limits for speed involved. Select a sprocket with increased number of teeth, if necessary.

2. Reduce shock loads (easy starts assure longer life). 3. Remove material build-up. 4. Lubricate properly. 5. Protect from corrosion. 6. Check sprockets for wear and correct bottom diameter .

E. CHAIN CLINGS TO SPROCKETS POSSIBLE CAUSES

1. Incorrect application or badly worn sprockets. 2. Heavy or tacky lubricants. 3. Material build-up on Drive "r” sprocket tooth pockets.

WHAT TO DO

1. Replace chain and sprockets (some sprockets can be reversed). 2. Clean and lubricate properly. 3. Remove material build-up.

F. CHAIN WHIP POSSIBLE CAUSES

1. Excessive chain slack. 2. High pulsating loads. 3. One or more stiff chain joints.

WHAT TO DO

1. Install chain take-up or idler, or adjust centres. 2. Reduce load where possible or replace chain with one of suitable strength. 3. Remove stiff links, or drive back on pins to provide proper clearance between

side plates. G. CHAIN GETS STIFF POSSIBLE CAUSES

1. Misalignment. 2. Inadequate lubrication -causes wear. 3. Corrosion. 4. Excessive overloads. 5. Material build-up in chain joint.


6. Peening of side plate edges. WHAT TO DO

1. Check sprocket and shaft alignment. 2. Remove chain if dirty or corroded ...clean and lubricate properly'. 3. Protect chain from corrosion. 4. Reduce excessive loads. 5. Protect chain with case ... clean and lubricate more often. 6. Check for chain interference, and correct.

H. BROKEN SPROCKET TEETH POSSIBLE CAUSES

1. Obstructions or foreign material in chain cases. 2. Excessive shock loads, especially with small, cast iron sprockets. 3. Chain climbing sprocket teeth.

WHAT TO DO

1. Check chain and sprocket clearances, remove foreign material. 2. Reduce excessive shock loads, or use steel sprockets.

I. COTTER'S COME OUT POSSIBLE CAUSES

1. Vibration. 2. Obstructions striking cotters. 3. Cotters not installed properly (should be properly spread and drawn back

snugly against side plate). WHAT TO DO

1. Reduce vibration. 2. Eliminate obstruction, or tap in ends back until cotter fits snugly against side

plates, or use riveted chain. 3. Correct faulty installation.

(BCD) - TechAV · WHAT MINOR DISADVANTAGES DO "VEE-SECTION" BELTS HAVE? o A certain amount of...

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