Semi Final Hydraulics Lecture

7/24/2019 Semi Final Hydraulics Lecture

1/78

Hydraulic system


2/78

Advantages

It is almost 100 percent efficient. The slight loss of

efficiency (a fraction of 1 percent) is due to internal

friction in the system machinery.

Moving parts of a hydraulic system are lightweight and

can uic!ly "e put into motion or "rought to rest. The

valves in a hydraulic system uic!ly start or stop the

flow of fluid under pressure# very little effort is neededto operate them. $or these reasons% the system Is easy

for the operator to control.


3/78

Hydraulic lines can "e routed almost anywhere. &nli!e

mechanical systems which must follow straight

pathways% the lines of a hydraulic system can easily "e"ent around o"structions. Also% ma'or parts of hydraulic

systems can "e located in a wide variety of places.

ince components of a hydraulic system are smaller

than those of other systems% the space reuirement issmall.

Most of the parts of a hydraulic system operate in a

"ath of oil% ma!ing the system practically self

lu"ricating.


4/78

* physical ualities

Incompressi"ility

+,pansion and contraction

-ressure transmission


5/78

elationship "etween pressure%

force and area


6/78

elationship "etween area%

distance and volume


7/78

-ascal/s law


8/78


9/78


10/78

Important properties of hydraulic

fluids

iscosityis internal resistance to flow.

hemical sta"ilityit is the a"ility of the liuid2fluid to

resist o,idation and deterioration for long periods.

$lash pointthe temperature at which a liuid gives off

vapor in sufficient uantity to ignite momentarily when

a flame is applied.

$ire pointis the temperature at which a su"stance givesoff vapor in sufficient uantity to ignite and continue to

"urn when e,posed to a spar! or flame.


11/78

Types of hydraulic fluid

egeta"le"ase fluid

MI3H4566 fluid was used in the past. This fluid is

essentially castor oil and alcohol. And is used primarily in

older aircraft. 7yed "lue for identification.


12/78

Mineral"ase fluids

MI3H8505 is the most widely used hydraulic fluid in

general aviation aircraft today. It is "asically a !erosene

type petroleum product% having good lu"ricating

properties and additives to inhi"it foaming and prevent

the formation of corrosion.

ROYCO 756


13/78

ynthetic fluid2phosphate ester

9onpetroleum "ase hydraulic fluids. $ire resistant

Most common type is Skydrol.

Dyed light purple


14/78

Hydraulic eals


15/78


16/78


17/78


18/78


19/78


20/78


21/78


22/78


23/78


24/78


25/78


26/78

Hydraulic Fluid Contamination

Two general contaminants are:

A"rasives% including such particles as core sand% weld

spatter% machining chips% and rust.

9ona"rasives% including those resulting from oil

o,idation and soft particles worn or shredded from seals

and other organic components.


27/78

Contamination Check

To determine which component is defective% liuid

samples should "e ta!en from the reservoir and various

other locations in the system.


28/78

Hydraulic Sampling Schedule

; outine sampling


29/78

Contamination Control

As an aid in controlling contamination% the following maintenance and servicing procedures

should "e followed at all times:

Maintain all tools and the wor! area (wor!"enches and test euipment) in a clean% dirtfree

condition.

A suita"le container should always "e provided to receive the hydraulic liuid that is spilled

during component removal or disassem"ly procedures.

=efore disconnecting hydraulic lines or fittings% clean the affected area with dry cleaning

solvent.

All hydraulic lines and fittings should "e capped or plugged immediately after

disconnecting.

=efore assem"ly of any hydraulic components% wash all parts in an approved dry cleaningsolvent.

After cleaning the parts in the dry cleaning solution% dry the parts thoroughly and lu"ricate

them with the recommended preservative or hydraulic liuid "efore assem"ly. &se only

clean% lintfree cloths to wipe or dry the component parts.


30/78

All seals and gas!ets should "e replaced during the

reassem"ly procedure. &se only those seals and gas!ets

recommended "y the manufacturer.

All parts should "e connected with care to avoidstripping metal slivers from threaded areas. All fittings

and lines should "e installed and torued in accordance

with applica"le technical instructions.

All hydraulic servicing euipment should "e !ept cleanand in good operating condition.


31/78

Health and Handling

!ydrol> fluids are phosphate ester"ased fluids

"lended with performance additives. -hosphate esters

are good solvents and dissolve away some of the fatty

materials of the s!in. epeated or prolonged e,posure

may cause drying of the s!in% which if unattended%

could result in complications% such as dermatitis or even

secondary infection from "acteria.


32/78

!ydrol> fluids could cause itching of the s!in "ut have

not "een !nown to cause allergictype s!in rashes.

Always use the proper gloves and eye protection when

handling any type of hydraulic fluid.

?hen!ydrol>2Hy'et mist or vapor e,posure is possi"le%

a respirator capa"le of removing organic vapors and

mists must "e worn. Ingestion of any hydraulic fluid

should "e avoided. Although small amounts do not

appear to "e highly ha@ardous% any significant amountshould "e tested in accordance with manufacturer/s

direction% followed with hospital supervised stomach

treatment.


33/78

a!ic Hydraulic Sy!tem!


34/78

Hydraulic system components

eservoir The reservoir is a

tan! in which an adeuate

supply of fluid for the system is

stored. $luid flows from the

reservoir to the pump% where it

is forced through the system

and eventually returned to the

reservoir. The reservoir not only

supplies the operating needs ofthe system% "ut it also

replenishes fluid


35/78


36/78

Re!er%oir pre!!ure relie& %al%e prevents over pressuri@ation of the

reservoir. alve opens at preset value.

Sight gla!!e! 'lo( and o%er&ull)provides visual indications for flight

crews and maintenance personnel that

the reservoir needs to "e serviced.

Re!er%oir !ample %al%e used to

draw sample of hydraulic fluid fortesting.

Re!er%oir drain %al%e used to drainthe fluids out of reservoir for

maintenance operation.

Re!er%oir temperature tran!ducerprovides hydraulic fluid temperature

information for the flight dec!


37/78


38/78


39/78


40/78

$I3T+


41/78

$I3T+ I A ++9I9B C TAI9I9B

7+I+ &+7 TC 3+A9 TH+ HD7A&3I

$3&I7% -++9TI9B $C+IB9 -ATI3+A97 C9TAMI9ATI9B &=TA9+ $CM

+MAI9I9B I9 TH+ DT+M.


42/78

The filtering elements in fluid filters are normally made of

paper or stainless steel. Paper elements are used mostly in

low-pressure systems and are thrown away when removed.Stainless steel elements are used in both high-pressure and

low-pressure systems and may be reused.

$I3T+ 7I$$++9TIA3 -+&+ I97IATC

+lectrical switches% continuous reading visual indicators

(gauges)% and visual indicators with memory. isual indicators

with memory usually ta!e the form magnetic or mechanically

latched "uttons or pins that e,tend when the differential

pressure e,ceeds that allowed for a servicea"le element.


43/78


44/78

Hand pump


45/78


46/78

-ower driven pumps

+nginedriven pump

+lectricaldriven pump

Airdriven pump

-ower transfer unit (-T&)

-ower driven "y AT (am Air Tur"ine)


47/78

Berator pump


48/78

lassification of pumps

-ositive displacement

9onpositive displacement

C t t Di l t P


49/78

Constant-Displacement Pumps

A constantdisplacement pump% regardless of pump

rotations per minute% forces a fi,ed or unvarying

uantity of fluid through the outlet port during each

revolution of the pump

They deliver a fi,ed uantity of fluid per revolution%

regardless of the pressure demands.

G T P P


50/78

Gear-Type Power Pump


51/78


52/78

+lectric motor pump


53/78

Piston Pump

-iston pumps can "e constantdisplacement or varia"ledisplacement pumps.


54/78


55/78

ane pump


56/78


57/78


58/78

*al%e!

Flow Control Valves

Selector Valves


59/78

elector valve


60/78

poppet type selector valve


61/78


62/78

ervo valve


63/78


64/78

hec! valve


65/78

euence valve


66/78


67/78


68/78

huttle valve


69/78

huttle valve


70/78

-ressure relief valve


71/78

Pressure Regulators

The term pressure regulator is applied to a device used

in hydraulic systems that are pressuri@ed "y constant

delivery type pumps. Cne purpose of the pressureregulator is to manage the output of the pump to

maintain system operating pressure within a

predetermined range. The other purpose is to permit

the pump to turn without resistance (termed unloading

the pump) at times when pressure in the system iswithin normal operating range.


72/78


73/78

Pressure Reducers

-ressure reducing valves are used in hydraulic systemswhere it is necessary to lower the normal system

operating pressure "y a specified amount


74/78


75/78


76/78

The function of an accumulatoris to:

Dampen pressure surges in the hydraulicsystemcaused by actuation of a unit and the eortof thepump to maintain pressure at a preset level.

Aid or supplement the power pump whenseveral units are operatingat once bysupplying extra power from its accumulated,or stored, power.

tore power for the limited operation of a

hydraulic unit when the pump is notoperating.

upply !uid under pressure to compensatefor small internal or external "not desired#lea$s that would cause the system to cycle

continuously by action of the pressure


77/78


78/78

am air tur"ine

Semi Final Hydraulics Lecture

Documents

Transcript of Semi Final Hydraulics Lecture