Automobile Clutch Functions & Types.ppt

Clutch Functions & Types

1. CLUTCHES

2. Anautomobileclutchisamechanicaldevicethat
connectsanddisconnectstheengine'spowerfrom
thetransmission.It'sanessentialcomponentof
manualtransmissions,servingastheintermediary
betweentheengineandthewheels

3. Functions of the clutch
Toconnectanddisconnecttheshafts
Tostartorstopamachine(orarotatingelement)
withoutstartingandstoppingtheprimemover.
Tomaintainconstantspeed,torqueandpower.
Toreduceshockstransmittedbetweenmachine
shafts.
Forautomaticdisconnect,quickstartandstop,
gradualstarts,andnon-reversingandoverrunning
functions.

4. Principles of operation of clutch
Whentwofrictionsurfacesarebroughtinconnectwith
eachotherandpressed,theyareunitedduetothefriction
betweenthem.
Thefrictionbetweenthetwosurfacesdependsuponthe
areaofthesurfaces,pressureapplieduponthemand
coefficientoffrictionofthesurfacematerials.
Thetwosurfacescanbeseparatedandbroughtinto
contactwhenrequired.Onesurfaceisconsideredas
drivingmemberandtheotherasdrivenmember.
Thedrivingmemberiskeptrotating.Whenthedriven
memberisbroughtincontacttothedrivingmember,Itis
alsostartsrotating.

5. Required qualities of a good
friction material
Ahighanduniformcoefficientoffriction.
Theabilitytowithstandhightemperatures,together
withgoodheatconductivity.
Goodresilience.
Highresistancetowear,scoring.
Resistanceagainstenvironmentalconditions,suchas
moisture,saltwaterorfungi.
Adequatemechanicalandthermalstrengths.

6. Commonly used Friction Materials
Wood
Cork
Leather
Asbestosbasedfrictionmaterials–asbestos
fibres,wovenaroundbrass,copperorzinc
wires.Mouldedorcompositetype.
Powdered(orsintered)metalfrictionmaterials

7. Classification of clutches

8. Friction Clutches
Thefrictionclutchesworkonthefactthatfrictionis
causedwhentworotatingdiscscomeintocontactwith
eachother

9. Principle of Friction Clutches

10. Let the shaft A and Disc C be revolving at some speed say N
rpm. Shaft B and disc D keyed to it are stationary, initially
when the clutch is not engaged.
Now apply some axial force W to disc D , so that it comes in
contact with Disc C.
As soon as the contact is made the force of friction between
C and D will come into play and consequently the disc D will
also start revolving
The speed of D depends upon friction force present, which in
turn is proportional to the force W applied.
If W is increased gradually , the speed of D will be increased
correspondingly till the stage comes when speed of D
becomes equal to speed of C. Then clutch is said to be fully
engaged.

11. Continue…
Let
W = axial load applied.
= coefficient of friction
R = effective mean radius of friction surface.
Then ,
T = W R

12. PLATE CLUTCHES
Types:
Single Plate clutch
Multi plate clutch
Cone clutch
Semi-centrifugal clutch
Centrifugal clutch

13. SINGLE PLATE CLUTCH

14. Working of Single plate clutch
Basically,theclutchneedsthreeparts.Thesearetheengine
flywheel,africtiondisccalledtheclutchplateandapressure
plate.
Therearespringswhichprovideaxialforcetokeeptheclutch
inengagedposition.
Whentheengineisrunningandtheflywheelisrotating,the
pressureplatealsorotatesasthepressureplateisattachedto
theflywheel.Thefrictiondiscislocatedbetweenthetwo.
Whenthedriverhaspusheddowntheclutchpedalthe
clutchisreleased.Thisactionforcesthepressureplateto
moveawayfromthefrictiondiscagainsttheforceofsprings.
Withthismovementofpressureplate,thefrictionplateis
releasedandtheclutchisdisengaged.

15. Advantages
Simple and inexpensive
Easy to operate
Smooth engagement and disengagement
Efficient power transmission
Better heat dissipation
Better load withstanding capacity
Less pedal movement
More reliable
Smooth nature between load and speed

16. Disadvantages
As compare to cone clutch, the springs have to be more
stiff and this means greater force is required to be
applied by the driver while disengaging.
The size of single plate clutch is much larger then
other clutches, because it have single disc of friction
plate.
Compare to multi-plate clutch sliping ratio in the
single plate clutch is more.
Single-plate clutch can’t be used in heavy load
vehicles.

17. Multiplate Clutch

18. Multiplate Clutch
Themultiplateclutchisanextensionofsingleplatetype
wherethenumberoffrictionalandmetalplatesis
increased.
Increaseinnumberoffrictionsurfacesobviouslyincreases
capacityoftheclutchtotransmittorque.
Alternatively,theoveralldiameteroftheclutchisreduced
forthesametorquetransmissionasasingleplateclutch
Thistypeofclutchisthereforeusedinsomeheavytransport
vehiclesandracingcarswherehightorqueistobe
transmitted.
Thisfindsapplicationincaseofscootersandmotorcycles,
wherethespaceavailableislimited

19. •Whenyourfootisoffthepedal,thespringspushthe
pressureplateagainsttheclutchdisc,whichinturnpresses
againsttheflywheel.Thislockstheenginetothe
transmissioninputshaft,causingthemtospinatthesame
speed.
•Theamountofforcetheclutchcanholddependsonthe
frictionbetweentheclutchplateandtheflywheel,andhow
muchforcethespringputsonthepressureplate
•Whentheclutchpedalispressed,pistonpushesonthe
releasefork,whichpressesthethrow-outbearingagainstthe
middleofthediaphragmspring.Asthemiddleofthe
diaphragmspringispushedin,aseriesofpinsnearthe
outsideofthespringcausesthespringtopullthepressure
plateawayfromtheclutchdiscThisreleasestheclutchfrom
thespinningengine.

20. Advantages
Hightorquetransmission:Multi-plateclutchescantransmit
hightorquesduetotheirmultiplefrictionsurfaces.
Compactsize:Multi-plateclutchescanachievethesamepower
transmissionassingle-plateclutcheswhilebeingsmaller.
Fasterengagement:Multi-plateclutcheshavefaster
engagement.
Enhanceddurability:Multi-plateclutchesaremoredurable.
Reducedclutchpedaleffort:Multi-plateclutchesrequireless
effortontheclutchpedal.
Variabletorquetransmission:Multi-plateclutcheshave
variabletorquetransmission.
AbilitytohandlehighRPM:Multi-plateclutchescanhandle
highRPM.

21. Disadvantages
Moreexpensive:Multi-plateclutchesaremore
expensivethanothertypesofclutches.
Heavierandmorecomplex:Multi-plateclutchesare
heavierandmorecomplexthanothertypesof
clutches.
Heatdissipation:Thecompactarrangementofmulti-
plateclutchescanmakeheatdissipationaproblem.

22. Cone Clutch

23. Cone Clutch

24. 1.Cones: female= green, male= blue
2.Shaft: male cone is sliding on splines
3.Friction material
4.Spring: brings the male cone back after using the
clutch control
5.Clutch control: separating both cones by pressing
6.Rotating direction: both direction of the axis are
possible

25. Intheengagedpositionthefrictionsurfacearein
completecontact.Thisisdonebymeansofspring
whichkeepthemaleconepressedallthetime.
Whentheclutchisengagedthetorqueistransmitted
fromengineviatheflywheelandthemaleconeto
splinedgearboxshaft.
Fordisengagingtheclutch,themaleconeispulledout
bymeansofleversystemoperatedthroughclutch
pedaltherebyseparatingthecontactsurfaces.

26. Advantage
Theadvantageofconeclutchisthatthenormalforce
actingoncontactsurfaceinthiscaseislargerthan
axialforce(ascomparedtosingleplateclutchin
whichthenormalforceactingoncontactsurfacesis
equaltotheaxialforce)

27. Disadvantages
Thistypeofclutchispracticallyobsoletebecauseof
followingreasons:
1)Iftheangleofconeismadelessthanabout20degree,
itwillbedifficulttodisengagetheclutch.
2)Asmallamountofwearontheconesurfaceresultsin
considerableamountofaxialmovementofthemale
coneforwhichitwillbedifficulttoallow.

28. Centrifugal clutch
Infullycentrifugaltypeclutches,thespringsareeliminatedaltogether
andonlycentrifugalforceisusedtoapplytherequiredpressurefor
keepingtheclutchinengagedposition

29. Whentheengineisinmotion,theinternalcomponentsof
thecentrifugalclutchbegintoundergorotational
motionwhilethedrumremainsstationary,resultinginno
powertransmission.
Atlowerspeeds,thegeneratedcentrifugalforceisn't
sufficienttoovercometheopposingspringforce,keeping
theclutchdisengaged.However,asthespeedincreases,the
centrifugalforcesurpassesthespringforce.Thisenables
theslidingshoestomoveoutward,engagingwiththeinner
surfaceofthedrum.
Consequently,thedrumcommencesrotation,facilitating
thetransferofrotationalpowerfromtheenginetothe
transmission'sdrivenshaft.Whentheengineencounters
anincreasedload,itsspeeddecreases,causingtheclutch
todisengage.

30. Advantages of centrifugal clutches
Automatic Operation: Engages and disengages without
manual input, simplifying use.
Smooth Engagement: Provides gradual power transfer,
reducing wear on components.
Overload Protection: Safeguards the engine and
transmission from damage.
Ease of Use: No manual clutch pedal or lever, making it
user-friendly.
Prevents Stalling: Reduces engine stalling at low speeds.
Enhanced Safety: Minimizes sudden stalls, contributing to
safer operation.
Low Maintenance: Requires minimal upkeep compared to
other clutch types.

31. Disadvantages
Limited Control: Offers limited control over clutch
engagement, which may not be suitable for all applications.
Reduced Efficiency: Can lead to power loss due to partial
engagement at low speeds.
Engagement RPM: Engagement speed is fixed and may not
match the engine's optimal performance range.
Slippage: In some cases, slippage may occur during
engagement, reducing efficiency.
Heating: Continuous engagement can generateheat
energyand wear on clutch components.
Not Suitable for Heavy Loads: Less suitable for high-
torqueapplications and heavy loads.

32. Hydraulic Clutch
Ahydraulicclutchisanautomotiveclutchvariantthat
reliesonhydraulicfluidinsteadofacableforclutchplate
actuation.Inthissystem,amastercylinderis
interconnectedwiththeclutchpedal,exertinghigh-
pressurehydraulicforcetodisengagetheclutchwhenthe
driverdepressesthepedal.

34. Working Principle of Hydraulic Clutch
Whenavehicleisrunning(nopedalpressed),theclutchisinthe
engagedposition.Whenthedriverpressestheclutchpedal,thepiston
ofthemastercylinderforcesthefluid.Itcausesfluidtoflowfromthe
mastercylindertotheslavecylinderthroughthehose/pipe.
Whenfluidenterstheslavecylinder,thepistonrodoftheslave
cylindermovesout.Thispistonrodpushesthereleasefork.
ThenthereleaseforkpushesthereleaseBearingtopressthemiddle
portionofthediaphragmtomovetowardtheleftside.
Whenthemiddleportionofthediaphragmispushed(towardstheleft
side),theoutsidepartofthediaphragmmovesintheopposite
direction(towardstherightside)andthepressureplatemovestowards
therightside.
Thereforepressureonthefrictionplateisremoved.Sonofriction
betweentheplates&flywheelandtheclutchdisengages.Henceno
powertransmissionwilltakeplace.

35. Advantages
Smoother pedal feel
Self-adjusting
Consistent pedal feel
Less muscle needed
Little maintenance needed
More flexible
More reliable

36. Disadvantages
Potential for leaks
Difficult to repair
Pipes can rot
Must use correct fluid
Higher cost
More complex design
Requires more maintenance