a project report on autoclutch

8/17/2019 A Project Report on Autoclutch

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A PROJECT REPORT ON

AUTOCLUTCH FOR AUTOMOBILESubmitted in partial fulfilment of the requirements

For the award of

BTEC! EN"#NEER#N"

#N

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ EN"#NEER#N"

S%B&#TTE' B(

)))))))))))))))))))) *))))))))))))))+

))))))))))))))))))))) *)))))))))))))))+

))))))))))))))))))))) *)))))))))))))))+

'EPART&ENT OF $$$$$$$$$$$$$$$$$$$$$$$ EN"#NEER#N"

$$$$$$$$$$CO,,E"E OF EN"#NEER#N"

AFF#,#ATE' TO $$$$$$$$$$$ %N#-ERS#T(

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CERTIFICATE

This is to .ertif/ that the dissertation wor0 entitled

1AUTOCLUTCH FOR AUTOMOBILE”

is the wor0 done b/

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$submitted in partial

fulfilment for the award of 2'#P,O&A #N EN"#NEER#N"3 in

$$$$$$$$$$$$$$$$$$$$$$$$$$En4ineerin4 from$$$$$$$$$$$$$$ SC!OO, of

En4ineerin4 affiliated to $$$$$$$$$ %ni5ersit/6

________________ ____________

(Head of the department,______) (Assstant !rofessor)

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AC"#O$LE%&EME#T

The satisfa.tion and euphoria that a..ompan/ the su..essful .ompletion of an/

tas0 would be in.omplete without the mentionin4 of the people whose .onstant

4uidan.e and en.oura4ement made it possible 7e ta0e pleasure in presentin4

before /ou6 our pro8e.t6 whi.h is result of studied blend of both resear.h and

0nowled4e

7e e9press our earnest 4ratitude to our internal 4uide6 Assistant Professor

$$$$$$$$$$$$$$6 'epartment of $$$$$$$$$$6 our pro8e.t 4uide

$$$$$$$$$$$$$$$$$$$$$6 for his .onstant support6 en.oura4ement and

4uidan.e 7e are 4rateful for his .ooperation and his 5aluable su44estions

Finall/6 we e9press our 4ratitude to all other members who are in5ol5ed either

dire.tl/ or indire.tl/ for the .ompletion of this pro8e.t

3



%ECLARATIO#

7e6 the undersi4ned6 de.lare that the pro8e.t entitled 'AUTOCLUTCH

FOR AUTOMOBILE6 bein4 submitted in partial fulfilment for the

award of B)te.h in En4ineerin4 in $$$$$$$$$$$$$$$$$$$$$$$$$En4ineerin46

affiliated to $$$$$$$$$ %ni5ersit/6 is the wor0 .arried out b/ us

$$$$$$$$$$ $$$$$$$$$ $$$$$$$$$

$$$$$$$$$$ $$$$$$$$$ $$$$$$$$$

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ABTRACT

Our main fo.us in this pro8e.t is to desi4n a small auto).lut.h for automobile s/stem or for a

.ar s/stem

#n this pro8e.t we ha5e to studied the automati. .lut.h me.hanism in 5ehi.les The fabri.ation

part of it has been .onsidered with almost .ase for its simpli.it/ and e.onom/6 su.h that this

.an be a..ommodated as one of the essential tools on automobile 4ara4es

7ith automati. .lut.h s/stem for .ar /ou .an .on5ert a manual .ar to semi)automati. at the

tou.h of button This automati.all/ a.ti5ates the .lut.h pedal mo5ement in a .ompletel/

.ontrolled s/stem Then the .ar will be dri5en b/ usin4 8ust the bra0e and a..elerator

Features of usin4 this t/pe of s/stem is .han4in4 4ear without usin4 /our foot to operate the

.lut.h and more fuel e.onomi.al then an automati.

Auto).lut.h .omprises of two units first is elaborate ele.troni. .ontrol and the se.ond is

ele.tri. motor

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I#TRO%UCTIO#

Automati. transmission .ars are 4ettin4 in.reasin4l/ popular within the urban)s.ape as

.rammed streets ma0e shiftin4 4ears an undesirable 8ob Sure6 /ou would lo5e to use that

shifter as /ou steer /our bab/ around a set of twisties6 ma0in4 that re5 needle dan.e within

the power band6 but the pra.ti.e is quite harassin4 within the .lo44ed .onfines of the .it/

The simple alternati5e to those irritatin4 manual shifts is to 4o with a .ar with an auto trann/

Twist the 0e/6 put the sele.tor in ' and /ou won3t ha5e to tou.h the 4ear shifter or depress

the .lut.h le5er before /ou rea.h /our destination

So what e9a.tl/ is this auto transmission: #s there an/ substantial differen.e between 5arioust/pes of auto transmissions a5ailable toda/: 7hi.h .ars .ome with the option of an Auto

2bo9 and what are the asso.iated ad5anta4es and disad5anta4es: ,et3s tr/ and find the

answers to some of these questions

So what e9a.tl/ is an automati. 4earbo9: 7ell6 an automati. 4earbo9 .an .han4e 4ear ratios

on its own as the 5ehi.le mo5es without the dri5er ha5in4 to shift 4ears manuall/ Now this

fun.tion of shiftin4 4ears automati.all/ .an be a.hie5ed 5ia 5arious means Based on the

method applied to shift the 4ears automati.all/6 these transmissions are di5ided in four basi.

.ate4ories ; Automati. transmissions6 C-Ts *Continuousl/ -ariable Transmissions+6 Semi)

Automati. transmissions6 and 'CTs *'ual Clut.h Transmissions+

Automati. Transmissions differ in operation to C-Ts or semi)automati.s Auto transmissions

use somethin4 .alled a torque .on5erter6 instead of .lut.h to mana4e the relation between

en4ine speeds and transmission 4ears On the other hand6 a semi)automati. transmission

fa.ilitates the shift in 4ear ratios throu4h a .lut.h)li0e setup6 whi.h is .ontrolled throu4h

ele.tro)h/drauli. means6 and not a torque .on5erter This s/stem allows the dri5er to o5er)

ride auto shifts manuall/ if he so desires6 althou4h the final shiftin4 is still ta0en .are of b/

the h/drauli.s

A 'CT or a dual).lut.h transmission is an ad5an.ed 5ersion of a semi)automati. s/stem that

utili<es two separate .lut.hes for odd and e5en 4ear sets The s/stem is .apable of shiftin44ears more qui.0l/ than .on5entional automati. transmission6 and hen.e has appli.ation in

.ars where dri5in4 pleasure and qui.0 shiftin4 response .annot be .ompromised This s/stem

.osts substantiall/ more than /our usual automati. transmissions

Finall/6 a C-T uses a belt or some other means of torque transmission to allow an infinite

number of 4ear ratios between two fi9ed hi4hest and lowest ratios The fle9ibilit/ of a C-T

allows it to be tuned for better fuel e.onom/ or performan.e

6



There is ample e5iden.e that more and more .ar .ompanies are reali<in4 the need of

presentin4 an auto option in their .ars6 espe.iall/ for the urban mar0et Althou4h an auto

transmission is not as popular in #ndia as in the more de5eloped nations6 its popularit/ will

in.rease as awareness spreads and traffi. s.enario be.omes e5en more anno/in4 Considered

an option onl/ for the females in #ndia6 the usabilit/ of auto transmission a.tuall/ .uts a.ross

4enders and a4e 4roups After all6 who doesn3t want to add a bit of .on5enien.e to his dri5e

#n this report the d/nami. beha5iour of an automoti5e .lut.h is anal/<ed usin4 d/nami.al

models The en4a4ement of the .lut.h is then simulated usin4 the a.quired model Based on

this anal/sis a .ontrol strate4/ is su44ested and the desi4ned .ontrol law is implemented

AUTOMATIC CLUTCH

Automati. .lut.h6 automati. .lut.h s/stem6 .ar automati. .lut.h6 auto .lut.h s/stem for .ar

whi.h is mainl/ de5eloped to mat.h he.ti. traffi. .ondition suitable to all 0ind of .ars The

auto .lut.h .on5erts the manual .ar into semi)automati. b/ pressin4 a button #t .an be

a5ailable in an/ t/pes of .ar and the .ar .an be dri5en b/ usin4 8ust the bra0e and a..elerator

This is an intelli4ent ele.troni.all/ .ontrolled me.hanism whi.h enables the dri5er to sele.t

the 4ears simpl/ b/ pressin4 the button on the 4ear le5el and shiftin4 This automati.all/

a.ti5ate the .lut.h pedal mo5ement in a .ompletel/ .ontrolled s/stem Then the .ar .an be

dri5en b/ usin4 8ust the bra0e and a..elerator #n traffi. when releasin4 the bra0e pedal .ar

.reeps forward li0e an automati. Auto).lut.h ta0es the fati4ue awa/ from ha5in4 to operate

the .lut.h pedal .ontinuousl/6 parti.ularl/ in traffi. situations

Auto).lut.h is mainl/ .omprised of two units The first elaborate ele.troni. .ontrol unit

.ontrols the se.ond .ompa.t ele.tri. motor The ele.tri. motor is me.hani.all/ .onne.ted to

the .lut.h to the .lut.h pedal with a .able The a..elerator pedal6 bra0e pedal6 hand bra0e and

8



road speed are monitored for si4nals whi.h result in automati. a.ti5ation of the s/stem The

entire s/stem is installed in the interior .ompartment of the .ar

F#"%RE ??

Automati. .lut.h

#EE% FOR AUTOMATIO#*

Automation .an be a.hie5ed throu4h .omputers6 h/drauli.s6 pneumati.s6 roboti.s et.6 of

these sour.es6 pneumati. form an attra.ti5e medium for low .ost automation

Automation pla/s an important role in automobile

Nowada/s almost all the automobile 5ehi.le is bein4 atomi<ed in order to produ.t the human bein4 The automobile 5ehi.le is bein4 atomi<ed for the followin4 reasons

9



set of 4ear ran4es6 often with a par0in4 pawl feature that lo.0s the output shaft of the

transmission stro0e fa.e

Similar but lar4er de5i.es are also used for hea5/)dut/ .ommer.ial and industrial 5ehi.les

and equipment Some ma.hines with limited speed ran4es or fi9ed en4ine speeds6 su.h as

some for0lifts and lawn mowers6 onl/ use a torque .on5erter to pro5ide a 5ariable 4earin4 ofthe en4ine to the wheels

Besides automati.s6 there are also other t/pes of automated transmissions su.h as

a .ontinuousl/ 5ariable transmission *C-T+ and semi)automati. transmissions6 that free the

dri5er from ha5in4 to shift 4ears manuall/6 b/ usin4 the transmissionDs .omputer to .han4e

4ear6 if for e9ample the dri5er were redlinin4 the en4ine 'espite superfi.ial similarit/ to

other transmissions6 automati. transmissions differ si4nifi.antl/ in internal operation and

dri5erDs feel from semi)automati.s and C-Ts An automati. uses a torque .on5erter instead of

a .lut.h to mana4e the .onne.tion between the transmission 4earin4 and the en4ine #n.ontrast6 a C-T uses a belt or other torque transmission s.heme to allow an infinite number

of 4ear ratios instead of a fi9ed number of 4ear ratios A semi)automati. retains a .lut.h li0e a

manual transmission6 but .ontrols the .lut.h throu4h ele.tro)h/drauli. means

A .on5entional manual transmission is frequentl/ the base equipment in a .ar6 with the option

bein4 an automated transmission su.h as a .on5entional automati.6 semi)automati.6 or C-T

The abilit/ to shift 4ears manuall/6 often 5ia paddle shifters6 .an also be found on .ertain

automated transmissions6 semi)automati.s and C-Ts

AUTOMATIC TRA#MIIO# MO%E

#n order to sele.t the transmission operatin4 mode6 the dri5er mo5es a sele.tion le5er lo.ated

either on the steerin4 .olumn or on the floor *as with a manual on the floor6 e9.ept that most

automati. sele.tors on the floor do not mo5e in the same t/pe of pattern as a manual le5er

most automati. le5ers onl/ mo5e 5erti.all/+ #n order to sele.t modes6 or to manuall/ sele.tspe.ifi. 4ear ratios6 the dri5er must push a button in *.alled the shift lo.0 button+ or pull the

11



handle *onl/ on .olumn mounted shifters+ out Some 5ehi.les position sele.tor buttons for

ea.h mode on the .o.0pit instead6 freein4 up spa.e on the .entral .onsole -ehi.les

.onformin4 to %S "o5ernment standards must ha5e the modes ordered P)R)N)'), *left to

ri4ht6 top to bottom6 or .lo.0wise+

Prior to this6 quadrant)sele.ted automati. transmissions often used a P)N)'),)R la/out6 or

similar Su.h a pattern led to a number of deaths and in8uries owin4 to dri5er error .ausin4

unintentional 4ear sele.tion6 as well as the dan4er of ha5in4 a sele.tor *when worn+ 8ump into

Re5erse from ,ow 4ear durin4 en4ine bra0in4 manoeu5res

A+tomat transmssons ha-e -aro+s modes dependn. on the mode/ and

ma0e of the transmsson1 ome of the ommon modes n/+de*

!ar0 (!)

This sele.tion me.hani.all/ lo.0s the output shaft of transmission6 restri.tin4 the 5ehi.lefrom mo5in4 in an/ dire.tion A par0in4 pawl pre5ents the transmission from rotatin46 and

therefore the 5ehi.le from mo5in46 but the 5ehi.leDs dri5en wheels ma/ still rotate

indi5iduall/ *be.ause of the differential+6 as well as the non)dri5en road wheels ma/ still

rotate freel/ For this reason6 it is re.ommended to use the hand bra0e * parking brake+

be.ause this a.tuall/ lo.0s *in most .ases+ the wheels and pre5ents them from mo5in4

This also in.reases the life of the transmission and the par0 pin me.hanism6 be.ause par0in4

on an in.line with the transmission in par0 without the par0in4 bra0e en4a4ed will .ause

undue stress on the par0in4 pin A hand bra0e should also pre5ent the .ar from mo5in4 if aworn sele.tor a..identall/ drops into re5erse 4ear while idlin4

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#t should be noted that lo.0in4 the transmission output shaft with par0 does not definiti5el/

lo.0 the dri5in4 wheels #f one dri5in4 wheel has little 5erti.al load it will tend to slip6 and

will rotate in the opposite dire.tion to the more hea5il/ loaded non)slippin4 wheel Onl/ a

par0in4 bra0e .an be relied upon to positi5el/ lo.0 both of the par0in4)bra0ed wheels #t is

t/pi.al of front)wheel)dri5e 5ehi.les for the par0in4 bra0e to lo.0 the rear *non)dri5in4+

wheels6 so use of both the par0in4 bra0e and the transmission par0 lo.0 pro5ides the 4reatest

se.urit/ a4ainst unintended mo5ement on slopes Buses in !on4 Gon4 (Kowloon Motor

Bus) do not ha5e Par0in4 mode *!+6 instead6 the/ are usin4 a sin4le le5er to pre5ent the whole

bus from mo5in4

A .ar should be allowed to .ome to a .omplete stop before settin4 the transmission into par0

to pre5ent dama4e %suall/6 Par0 *!+ is one of onl/ two sele.tions in whi.h the .arDs en4ine

.an be started6 the other bein4 Neutral *#+ *Buses in !on4 Gon4 mentioned abo5e has to be

in Neutral mode *#+ ON,( before the en4ine .an be started+

#n man/ modern .ars and tru.0s6 the dri5er must ha5e the foot bra0e applied before the

transmission .an be ta0en out of par0 The Par0 position is omitted on busesH.oa.hes *and

some road tra.tors+ with automati. transmission *on whi.h a par0in4 pawl is not pra.ti.al+6

whi.h must be pla.ed in neutral with the air)operated par0in4 bra0es set Ad5i.e is 4i5en in

some ownerDs manuals that if the 5ehi.le is par0ed on a steep slope usin4 the par0 lo.0 onl/6

it ma/ not be possible to release the par0 lo.0 *mo5e the sele.tor le5er out of !+ Another

5ehi.le ma/ be required to push the stu.0 5ehi.le uphill sli4htl/ to remo5e the loadin4 on the

par0 lo.0 pawl

&ost automobiles require ! or # to be set on the sele.tor le5er before the en4ine .an be

started This is t/pi.all/ a.hie5ed 5ia a normall/ open inhibitor swit.h *sometimes .alled a

neutral safet/ swit.h+ wired in series with the starter motor en4a4ement .ir.uit6 whi.h is

.losed when ! or # is sele.ted6 .ompletin4 the .ir.uit *when the 0e/ is turned to the start

13



position+6 alon4 with an/ other safet/ de5i.es whi.h ma/ be present on newer .ars *su.h as a

foot)bra0e appli.ation+

Re-erse (R)

This en4a4es re5erse 4ear within the transmission6 permittin4 the 5ehi.le to be dri5en

ba.0ward6 and operates a swit.h to turn on the ba.0up li4hts for impro5ed 5isibilit/ *the

swit.h ma/ also a.ti5ate a beeper on deli5er/ tru.0s or other lar4e 5ehi.les to warn other

dri5ers and nearb/ pedestrians of the dri5erDs re5erse mo5ement+ To sele.t re5erse in most

transmissions6 the dri5er must .ome to a .omplete stop6 depress the shift lo.0 button *or

mo5e the shift le5er toward the dri5er in a .olumn shifter6 or mo5e the shifter sidewa/s alon4

a not.hed .hannel in a .onsole shifter+ and sele.t re5erse Not .omin4 to a .omplete stop ma/

.ause se5ere dama4e to the transmission Some modern automati. transmissions ha5e a

safet/ me.hanism in pla.e6 whi.h does6 to some e9tent6 pre5ent *but not .ompletel/ a5oid+

inad5ertentl/ puttin4 the .ar in re5erse when the 5ehi.le is mo5in4 forward su.h a

me.hanism ma/ .onsist of a solenoid).ontrolled ph/si.al barrier on either side of the Re5erse

position6 ele.troni.all/ en4a4ed b/ a swit.h on the bra0e pedal Therefore6 the bra0e pedal

needs to be depressed in order to allow the sele.tion of re5erse

Some ele.troni. transmissions pre5ent or dela/ en4a4ement of re5erse 4ear alto4ether while

the .ar is mo5in4

Some shifters with a shift button allow the dri5er to freel/ mo5e the shifter from R to # or %6

or simpl/ mo5in4 the shifter to # or % without a.tuall/ depressin4 the button !owe5er6 the

dri5er .annot shift ba.0 to R without depressin4 the shift button6 to pre5ent a..idental

shiftin46 espe.iall/ at hi4h speeds6 whi.h .ould dama4e the transmission

#e+tra/ 2 #o .ear (#)

This disen4a4es all 4ear trains within the transmission6 effe.ti5el/ dis.onne.tin4 the

transmission from the dri5en wheels6 allowin4 the 5ehi.le to .oast freel/ under its own

14



wei4ht and 4ain momentum without the moti5e for.e from the en4ine Coastin4 in idle down

lon4 4rades *where law permits+ should be a5oided6 thou4h6 as the transmissionDs lubri.ation

pump is dri5en b/ non)idle en4ine RP&s Similarl/6 emer4en./ towin4 with an automati.

transmission in neutral should be a last resort &anufa.turers understand emer4en./

situations and list limitations of towin4 a 5ehi.le in neutral *usuall/ not to e9.eed == mph and

=> miles+ This is the onl/ other sele.tion in whi.h the 5ehi.leDs en4ine ma/ be started

%r-e (%)

This position allows the transmission to en4a4e the full ran4e of a5ailable forward 4ear

ratios6 allowin4 the 5ehi.le to mo5e forward and a..elerate throu4h its ran4e of 4ears The

number of 4ear ratios within the transmission depends on the model6 but the/ initiall/ ran4ed

from three to four and fi5e speeds Si9)speed automati. transmissions are probabl/ the most

.ommon offerin4 in .ars and tru.0s

O-erdr-e (3%3, 3O%3, or a 4o5ed 6%7 or the a4sene of an //+mnated 3O2%

OFF3)

This mode is used in some transmissions to allow earl/ .omputer).ontrolled transmissions to

en4a4e the automati. o5erdri5e #n these transmissions6 'ri5e *'+ lo.0s the automati.

o5erdri5e off6 but is identi.al otherwise O' *O5erdri5e+ in these .ars is en4a4ed under

stead/ speeds or low a..eleration at appro9imatel/ I=;= mph *=K;L@ 0mHh+ %nder hard

a..eleration or below I=;= mph *=K;L@ 0mHh+6 the transmission will automati.all/

downshift

Other 5ehi.les with this sele.tor *e9ample li4ht tru.0s+ will not onl/ disable up)shift to the

o5erdri5e 4ear6 but 0eep the remainin4 a5ailable 4ears .ontinuousl/ en4a4ed to the en4ine for

use of .ompression bra0in4 -erif/ the beha5iour of this swit.h and .onsider the benefits of

15



redu.ed fri.tion bra0e use when .it/ dri5in4 where speeds t/pi.all/ do not ne.essitate the

o5erdri5e 4ear

Thrd (8)

This mode limits the transmission to the first three 4ear ratios6 or sometimes lo.0s the

transmission in third 4ear This .an be used to .limb or 4oin4 down) hill Some 5ehi.les will

automati.all/ shift up out of third 4ear in this mode if a .ertain re5olutions per minute *RP&+

ran4e is rea.hed in order to pre5ent en4ine dama4e This 4ear is also re.ommended while

towin4 a trailer

eond (9 or )

This mode limits the transmission to the first two 4ear ratios6 or lo.0s the transmission in

se.ond 4ear on Ford6 Gia6 and !onda models This .an be used to dri5e in ad5erse .onditions

su.h as snow and i.e6 as well as .limbin4 or 4oin4 down hills in winter #t is usuall/

re.ommended to use se.ond 4ear for startin4 on snow and i.e6 and use of this position

enables this with an automati. transmission Some 5ehi.les will automati.all/ shift up out of

se.ond 4ear in this mode if a .ertain RP& ran4e is rea.hed in order to pre5ent en4ine

dama4e

Althou4h traditionall/ .onsidered se.ond 4ear6 there are other names used Chr/sler models

with a three)speed automati. sin.e the late ?M>s ha5e .alled this 4ear 8 while usin4 the

traditional names For Drive and Low Oldsmobile has .alled se.ond 4ear as the DSuperD ran4e

whi.h was first used on their )speed !/dramati. transmissions6 althou4h the use of this

term .ontinued until the earl/ ?M>s when "&Ds Turbo !/dramati. automati. transmissions

were standardi<ed b/ all of their di5isions /ears after the )speed !/dramati. was

dis.ontinued

Frst (: or L 6Lo;7)

This mode lo.0s the transmission in first 4ear onl/ #n older 5ehi.les6 it will not .han4e to an/

other 4ear ran4e Some 5ehi.les will automati.all/ shift up out of first 4ear in this mode if a.ertain RP& ran4e is rea.hed in order to pre5ent en4ine dama4e This6 li0e se.ond6 .an be

16



used durin4 the winter season6 for towin46 or for downhill dri5in4 to in.rease the en4ine

bra0in4 effe.t

As well as the abo5e modes there are also other modes6 dependent on the manufa.turer and

model Some e9amples in.lude

%<

#n !ondas and A.uras equipped with fi5e)speed automati. transmissions6 this mode is used

.ommonl/ for hi4hwa/ use *as stated in the manual+6 and uses all fi5e forward 4ears

%=

This mode is also found in !onda and A.ura four or fi5e)speed automati.s6 and onl/ uses the

first four 4ear ratios A..ordin4 to the manual6 it is used for stop)and)4o traffi.6 su.h as .it/

dri5in4

%8 or 8

This mode is found in !onda6 A.ura6 -ol0swa4en and Pontia. four)speed automati.s and

onl/ uses the first three 4ear ratios A..ordin4 to the manual6 it is used for stop)and)4o traffi.6

su.h as .it/ dri5in4

%9 and %:

These modes are found on older Ford transmissions *CK6 et.+ #n '?6 all three 4ears are used6

whereas in '@ the .ar starts in se.ond 4ear and up)shifts to third

17



Fortuner6 Pre5ia and #nno5a &itsubishi and some Audi models *Audi TT+6 meanwhile do not

ha5e the &6 and instead ha5e the Q and )6 whi.h is separated from the rest of the shift modes

the same is true for some Peu4eot produ.ts li0e Peu4eot @>K &eanwhile6 the dri5er .an shift

up and down at will b/ to44lin4 the *.onsole mounted+ shift le5er similar to a semi)automati.

transmission This mode ma/ be en4a4ed either throu4h a sele.torHposition or b/ a.tuall/

.han4in4 the 4ears *e46 tippin4 the 4ear)down paddles mounted near the dri5erDs fin4ers on

the steerin4 wheel+

$nter ($)

#n some -ol5o6 &er.edes)Ben<6 B&7 and "eneral &otors Europe models6 a winter mode

.an be en4a4ed so that se.ond 4ear is sele.ted instead of first when pullin4 awa/ from

stationar/6 to redu.e the li0elihood of loss of tra.tion due to wheel spin on snow or i.e On

"& .ars6 this was '@ in the ?M=>s6 and is Se.ond "ear Start after ?MM> On Ford6 Gia6 and

!onda automati.s6 this feature .an be a..essed b/ mo5in4 the 4ear sele.tor to @ to start6 then

ta0in4 /our foot off the a..elerator while sele.tin4 ' on.e the .ar is mo5in4

Bra0e (B)

A mode sele.table on some To/ota models #n non)h/brid .ars6 this mode lets the en4ine do

.ompression bra0in46 also 0nown as en4ine bra0in46 t/pi.all/ when en.ounterin4 a steepdownhill #nstead of en4a4in4 the bra0es6 the en4ine in a non)h/brid .ar swit.hes to a lower

4ear and slows down the spinnin4 tires The en4ine holds the .ar ba.06 instead of the bra0es

slowin4 it down "& .alled this !R *hill retarder+ and "R *4rade retarder+ in the

?M=>s For h/brid .ars6 this mode .on5erts the ele.tri. motor into a 4enerator for the batter/

*Re4enerati5e Bra0in4+ #t is not the same as downshiftin4 in a non)h/brid .ar6 but it has the

same effe.t in slowin4 the .ar without usin4 the bra0es

H@%RAULIC AUTOMATIC TRA#MIIO#

The predominant form of automati. transmission is h/drauli.all/ operated usin4 a fluid

.ouplin4 or torque .on5erter6 and a set of planetar/ 4ear sets to pro5ide a ran4e of 4ear ratios

19



!arts and operaton

A h/drauli. automati. transmission .onsists of the followin4 parts

• Tor+e on-erter* A t/pe of fluid .ouplin46 h/drauli.all/ .onne.tin4 the en4ine

to the transmission #t ta0es the pla.e of a me.hani.al .lut.h6 allowin4 the transmission to

sta/ in 4ear and the en4ine to remain runnin4 while the 5ehi.le is stationar/6 without

stallin4 A torque .on5erter differs from a fluid .ouplin46 in that it pro5ides a 5ariable

amount of torque multipli.ation at low en4ine speeds6 in.reasin4 brea0awa/ a..eleration

This is a..omplished with a third member in the .ouplin4 assembl/ 0nown as the stator6

and b/ alterin4 the shapes of the 5anes inside the .ouplin4 in su.h a wa/ as to .ur5e the

fluidDs path into the stator The stator .aptures the 0ineti. ener4/ of the transmission fluid6

in effe.t usin4 the lefto5er for.e of it to enhan.e torque multipli.ation

• !+mp* Not to be .onfused with the impeller inside the torque .on5erter6 the pump is

t/pi.all/ a 4ear pump mounted between the torque .on5erter and the planetar/ 4ear set #t

draws transmission fluid from a sump and pressuri<es it6 whi.h is needed for transmission

.omponents to operate The input for the pump is .onne.ted to the torque .on5erter

housin46 whi.h in turn is bolted to the en4ineDs fl/wheel6 so the pump pro5ides pressure

whene5er the en4ine is runnin4 and there is enou4h transmission fluid Earl/ automati.

transmissions also had a rear pump6 allowin4 push)startin4

• !/anetar .earset* A .ompound epi)./.li. planetar/ 4ear set6 whose bands and

.lut.hes are a.tuated b/ h/drauli. ser5os .ontrolled b/ the 5al5e bod/6 pro5idin4 two or

more 4ear ratios *Not part of some manufa.turer3s transmissions durin4 some eras6

!onda bein4 but one+

• C/+thes and 4ands* to effe.t 4ear .han4es6 one of two t/pes of .lut.hes or

bands are used to hold a parti.ular member of the planetar/ 4ear set motionless6 while

allowin4 another member to rotate6 thereb/ transmittin4 torque and produ.in4 4earredu.tions or o5erdri5e ratios These .lut.hes are a.tuated b/ the 5al5e bod/ *see below+6

20



their sequen.e .ontrolled b/ the transmissionDs internal pro4rammin4 Prin.ipall/6 a t/pe

of de5i.e 0nown as a spri4 or roller .lut.h is used for routine up)shiftsHdownshifts

Operatin4 mu.h as a rat.het6 it transmits torque onl/ in one dire.tion6 free)wheelin4 or

o5errunnin4 in the other The ad5anta4e of this t/pe of .lut.h is that it eliminates the

sensiti5it/ of timin4 a simultaneous .lut.h releaseHappl/ on two planetaries6 simpl/

ta0in4 up the dri5e train load when a.tuated6 and releasin4 automati.all/ when the ne9t4earDs spri4 .lut.h assumes the torque transfer The bands .ome into pla/ for manuall/

sele.ted 4ears6 su.h as low ran4e or re5erse6 and operate on the planetar/ drumDs

.ir.umferen.e Bands are not applied when dri5eHo5erdri5e ran4e is sele.ted6 the torque

bein4 transmitted b/ the spri4 .lut.hes instead Bands are used for bra0in4 the "&

Turbo)!/drometri.s in.orporated this

• Da/-e 4od* h/drauli. .ontrol .entre that re.ei5es pressuri<ed fluid from the main

pump operated b/ the fluid .ouplin4Htorque .on5erter The pressure .omin4 from this pump is re4ulated and used to run a networ0 of sprin4)loaded 5al5es6 .he.0 balls

and ser5o pistons The 5al5es use the pump pressure and the pressure from a .entrifu4al

4o5ernor on the output side *as well as h/drauli. si4nals from the ran4e sele.tor 5al5es

and the throttle valve or modulator + to .ontrol whi.h ratio is sele.ted on the 4ear set as

the 5ehi.le and en4ine .han4e speed6 the differen.e between the pressures .han4es6

.ausin4 different sets of 5al5es to open and .lose

The h/drauli. pressure .ontrolled b/ these 5al5es dri5es the 5arious .lut.h and bra0e

band a.tuators6 thereb/ .ontrollin4 the operation of the planetar/ 4earset to sele.t the

optimum 4ear ratio for the .urrent operatin4 .onditions !owe5er6 in man/ modern

automati. transmissions6 the 5al5es are .ontrolled b/ ele.tro)me.hani.al ser5os whi.hare .ontrolled b/ the ele.troni. en4ine .ontrol unit *EC%+ or a separate transmission

.ontrol unit *TC%6 also 0nown as transmission .ontrol module *TC&+

• Hdra+/ /+4ratn. o/* .alled automati. transmission fluid *ATF+6 this

.omponent of the transmission pro5ides lubri.ation6 .orrosion pre5ention6 and a

h/drauli. medium to .on5e/ me.hani.al power *for the operation of the transmission+

Primaril/ made from refined petroleum6 and pro.essed to pro5ide properties that promote

smooth power transmission and in.rease ser5i.e life6 the ATF is one of the few parts of

the automati. transmission that needs routine ser5i.e as the 5ehi.le a4es

21



The multitude of parts6 alon4 with the .omple9 desi4n of the 5al5e bod/6 ori4inall/ made

h/drauli. automati. transmissions mu.h more .ompli.ated *and e9pensi5e+ to build and

repair than manual transmissions #n most .ars *e9.ept %S famil/6 lu9ur/6 sport)utilit/

5ehi.le6 and mini5an models+ the/ ha5e usuall/ been e9tra).ost options for this reason &ass

manufa.turin4 and de.ades of impro5ement ha5e redu.ed this .ost 4ap

Ener. effen

!/drauli. automati. transmissions are almost alwa/s less ener4/ effi.ient than manual

transmissions due mainl/ to 5is.ous and pumpin4 losses6 both in the torque .on5erter and the

h/drauli. a.tuators A relati5el/ small amount of ener4/ is required to pressuri<e the

h/drauli. .ontrol s/stem6 whi.h uses fluid pressure to determine the .orre.t shiftin4 patterns

and operate the 5arious automati. .lut.h me.hanisms

&anual transmissions use a me.hani.al .lut.h to transmit torque6 rather than a torque

.on5erter6 thus a5oidin4 the primar/ sour.e of loss in an automati. transmission &anual

transmissions also a5oid the power requirement of the h/drauli. .ontrol s/stem6 b/ rel/in4 on

the human mus.le power of the 5ehi.le operator to disen4a4e the .lut.h and a.tuate the 4ear

le5ers6 and the mental power of the operator to ma0e appropriate 4ear ratio sele.tions Thus

the manual transmission requires 5er/ little en4ine power to fun.tion6 with the main power

.onsumption due to dra4 from the 4ear train bein4 immersed in the lubri.atin4 oil of the

4earbo9

The on)road a..eleration of an automati. transmission .an o..asionall/ e9.eed that of an

otherwise identi.al 5ehi.le equipped with a manual transmission in turbo).har4ed diesel

appli.ations Turbo)boost is normall/ lost between 4ear .han4es in a manual whereas in an

automati. the a..elerator pedal .an remain full/ depressed This howe5er is still lar4el/

dependent upon the number and optimal spa.in4 of 4ear ratios for ea.h unit6 and whether or

not the elimination of spool downHa..elerator lift off represent a si4nifi.ant enou4h 4ain to

.ounter the sli4htl/ hi4her power .onsumption of the automati. transmission itself

22



CLUTCH

Clut.h is a me.hanism for transmittin4 rotation6 whi.h .an be en4a4ed and disen4a4ed

Clut.hes are useful in de5i.es that ha5e two rotatin4 shafts #n these de5i.es6 one shaft is

t/pi.all/ dri5en b/ a motor or pulle/6 and the other shaft dri5es another de5i.e ,et us ta0e an

instan.e where one shaft is dri5en b/ a motor and the other dri5es a drill .hu.0 The .lut.h.onne.ts the two shafts so that the/ .an either be lo.0ed to4ether and spin at the same speed

*en4a4ed+6 or be de.oupled and spin at different speeds *disen4a4ed+ 'ependin4 on the

orientation6 speeds6 material6 torque produ.ed and finall/ the use of the whole de5i.e6

different 0inds of .lut.hes are used The .lut.h in itself is a me.hanism6 whi.h emplo/s

different .onfi4urations and different prin.iples in 5arious models a5ailable #n the followin4

lines6 we ha5e pro5ided the different 0inds of .lut.hes that are a5ailable

Clut.hes are used whene5er the transmission of power or motion must be .ontrolled either in

amount or o5er time *e46 ele.tri. s.rewdri5ers limit how mu.h torque is transmitted throu4h

use of a .lut.h .lut.hes .ontrol whether automobiles transmit en4ine power to the wheels+

#n the simplest appli.ation6 .lut.hes .onne.t and dis.onne.t two rotatin4 shafts *dri5e

shafts or line shafts+ #n these de5i.es6 one shaft is t/pi.all/ atta.hed to a motor or other

power unit *the dri5in4 member+ while the other shaft *the dri5en member+ pro5ides output

power for wor0 7hile t/pi.all/ the motions in5ol5ed are rotar/6 linear .lut.hes are also

possible

#n a torque).ontrolled drill6 for instan.e6 one shaft is dri5en b/ a motor and the other dri5es a

drill .hu.0 The .lut.h .onne.ts the two shafts so that the/ ma/ be lo.0ed to4ether and spin

at the same speed *en4a4ed+6 lo.0ed to4ether but spinnin4 at different speeds *slippin4+6 or

unlo.0ed and spinnin4 at different speeds *disen4a4ed+

Re+rement of a /+th*

:) Tor+e transmsson*

The .lut.h should be able to transmit ma9imum torque of the en4ine

9) &rad+a/ en.a.ement*

The .lut.h should en4a4e 4raduall/ to a5oid sudden 8er0s

23



3) Heat dsspaton*

The .lut.h should be able to dissipate lar4e amount of heat whi.h is 4enerated durin4

the .lut.h operation due to fri.tion

= ) %nam 4a/ann.*

The .lut.h should be d/nami.all/ balan.ed This is parti.ularl/ required in the .ase of

hi4h speed en4ine .lut.hes

<) D4ratn. dampn.* The clutch should have suitable mechanism to damp vibrations and to

eliminate noise produced during the power transmission

6) e* The clutch should be as small as possible in si!e so that it will occup"

minimum space

7) Free peda/ p/a* -

The clutch should have #ree pedal pla" in order to reduce e$ectiveclamping load on the carbon thrust bearing and wear on it

G) Eas n operaton* The clutch should be eas" to operate re%uiring as little e&ertionaspossible on the part o# the driver

9) L.htness*

The driven member o# the clutch should be made as light as possible sothat it

will not continue to rotate #or an" length o# time a#ter the clutch has been disengaged

!RI#CI!LE OF O!ERATIO#*

24



Clut.h wor0s on the prin.iple of fri.tion 7hen two fri.tion surfa.es are

brou4ht in .onta.t with ea.h other and pressed the/ are united due to the fri.tion between

them if now one is re5ol5ed the other will also be re5ol5ed

The fri.tion between the two surfa.es depends upon the area of the surfa.es6

pressure applied on them and .o)effi.ient of fri.tion of the surfa.e material The twosurfa.es .an be separated and brou4ht into .onta.t when required

One surfa.e is .onsidered as a dri5in4 member the other as a dri5en member

The dri5in4 member is 0ept rotatin46 when the dri5en member is brou4ht in .onta.t with

the dri5in4 member it also rotates 7hen the dri5en member is separated from the dri5in4

member it does not rotate This is the prin.iple on whi.h the .lut.h operates

MAI# !ART OF CLUTCH*The main parts of .lut.h are di5ided into three 4roups

? 'ri5in4 member

@ 'ri5en member

I Operatin4 member

%RIDI#& MEMBER*

The dri5in4 members .onsist of a fl/wheel mounted on the en4ine .ran0shaftThe fl/wheel bolted to a .o5er whi.h .arries a pressure plate or a dri5in4 dis.6 the pressure

sprin4s and releasin4 le5ers Thus the entire assembl/ of the fl/wheel and the .o5er rotates

all the time The .lut.h housin4 and the .o5er pro5ided with openin4s dissipate the heat

4enerated b/ the fri.tion durin4 the .lut.h operation

The dri5in4 members .onsist of a fl/wheel mounted on the en4ine .ran0shaft

25



F/;hee/ o+p/e ;th /+th

%RIDE# MEMBER*

The dri5en member .onsists of a dis. or plate6 .alled the .lut.h plate #t is free to slide

len4thwise on the splines of the .lut.h shaft #t .arries fri.tion materials on both of itssurfa.es 7hen it is 4ripped between the fl/wheel and the pressure plate6 it rotates the

.lut.h shaft throu4h the splines

The dri5en member .onsists of the dis. or plate6 .alled the .lut.h plate

F/;hee/ o+p/e ;th /+th

26



O!ERATI#& MEMBER*

The operatin4 members .onsist of a foot pedal6 lin0a4e6 release or throw)out bearin46

release le5ers and the sprin4s ne.essar/ to insure the proper operation of the .lut.h

The operatin4 members .onsist of a foot pedal6 lin0a4e6 release or throw out

bearin46 release le5ers and sprin4s

!eda/, Bearn. and sprn.

27



Man !arts Of n./e !/ate C/+th

$OR"I#& OF CLUTCH*

#f /ou dri5e a manual transmission .ar6 /ou ma/ be surprised to find out that it has more than

one .lut.h And it turns out that fol0s with automati. transmission .ars ha5e .lut.hes6 too #n

fa.t6 there are .lut.hes in man/ thin4s /ou probabl/ see or use e5er/ da/ &an/

.ordless drills ha5e a .lut.h6 .hain saws ha5e a .entrifu4al .lut.h and e5en some /o)/os ha5e

a .lut.h

#n this arti.le6 /ouDll learn wh/ /ou need a .lut.h6 how the .lut.h in /our .ar wor0s and find

out some interestin46 and perhaps surprisin46 pla.es where .lut.hes .an be found

Clut.hes are useful in de5i.es that ha5e two rotatin4 shafts #n these de5i.es6 one of the shafts

is t/pi.all/ dri5en b/ a motor or pulle/6 and the other shaft dri5es another de5i.e #n a drill6

28



for instan.e6 one shaft is dri5en b/ a motor and the other dri5es a drill .hu.0 The .lut.h

.onne.ts the two shafts so that the/ .an either be lo.0ed to4ether and spin at the same speed6

or be de.oupled and spin at different speeds

#n a .ar6 /ou need a .lut.h be.ause the en4ine spins all the time6 but the .arDs wheels do not

#n order for a .ar to stop without 0illin4 the en4ine6 the wheels need to be dis.onne.ted from

the en4ine somehow The .lut.h allows us to smoothl/ en4a4e a spinnin4 en4ine to a non)

spinnin4 transmission b/ .ontrollin4 the slippa4e between them

To understand how a .lut.h wor0s6 it helps to 0now a little bit about frton6 whi.h is a

measure of how hard it is to slide one ob8e.t o5er another Fri.tion is .aused b/ the pea0s and

5alle/s that are part of e5er/ surfa.e )) e5en 5er/ smooth surfa.es still ha5e mi.ros.opi.

pea0s and 5alle/s The lar4er these pea0s and 5alle/s are6 the harder it is to slide the ob8e.t

(ou .an learn more about fri.tion in !ow Bra0es 7or0

29



A .lut.h wor0s be.ause of fri.tion between a .lut.h plate and a fl/wheel 7eDll loo0 at how

these parts wor0 to4ether in the ne9t se.tion

O!ERATIO# OF THE CLUTCH

7hen the .lut.h pedal is depressed6 throu4h pedal mo5ement6 the .lut.h

release bearin4 presses on the .lut.h release le5er plate6 whi.h bein4 .onne.ted to the

.lut.h release le5ers6 for.es these le5ers forward This .auses the Pressure Plate to

.ompress the Pressure Sprin4s6 thus allowin4 it to mo5e awa/ from the Clut.h 'ri5en

Plate This a.tion releases the pressure on the 'ri5en Plate and Fl/wheel6 the fl/wheel is

now free to turn independentl/6 without turnin4 the transmission

7hen the .lut.h pedal is released6 re5erse a.tion ta0es pla.e the dri5en plate is

a4ain for.ed a4ainst the fl/wheel b/ the pressure plate) be.ause of the for.e e9erted b/ the

pressure sprin4s

The pressure plate will 0eep on .ompressin4 the fa.in4s of the dri5en plate until

the fri.tion .reated be.omes equal to the resistan.e of the 5ehi.le An/ further in.rease in

pressure will .ause the .lut.h plate and the transmission shaft to turn alon4 with the

fl/wheel thus a.hie5in4 5ehi.le mo5ement

30



n./e !/ate C/+th

CLUTCH CO#TRUCTIO#*

The .lut.h is the first dri5e train .omponent powered b/ the en4ine .ran0shaft The .lut.h

lets the dri5er .ontrol power flow between the en4ine and the transmission or transa9le

Before understandin4 the operation of a .lut.h6 /ou must first be.ome familiar with the parts

and their fun.tion This information is 5er/ useful when learnin4 to dia4nose and repair the

.lut.h assembl/

C/+th Re/ease Mehansm

31



A .lut.h release me.hanism allows the operator to operate the .lut.h "enerall/6 it .onsists of

the .lut.h pedal assembl/6 either me.hani.al lin0a4e6 .able6 or A h/drauli. .lut.h release

me.hanism *fi4 )=+ uses a simple h/drauli. .ir.uit to transfer .lut.h pedal a.tion to the

.lut.h for0 #t has three basi. parts) master ./linder6 h/drauli. lines6 and a sla5e ./linder

&o5ement of the .lut.h pedal .reates h/drauli. pressure in the master ./linder6 whi.h

a.tuates the sla5e ./linder The sla5e ./linder then mo5es the .lut.h for0

C,%TC! CAB,E &EC!AN#S&

C/+th For0

32



The .lut.h for06 also .alled a .lut.h arm or release arm6 transfers motion from the release

me.hanism to the release bearin4 and pressure plate The .lut.h for0 sti.0s throu4h a square

hole in the bell housin4 and mounts on a pi5ot 7hen the .lut.h for0 is mo5ed b/ the release

me.hanism6 it PR#ES on the release bearin4 to disen4a4e the .lut.h

A rubber boot fits o5er the .lut.h for0 This boot is desi4ned to 0eep road dirt6 ro.0s6 oil6

water6 and other debris from enterin4 the .lut.h housin4

Re/ease Bearn.

The release bearin46 also .alled the throw)out bearin46 is a ball bearin4 and .ollar assembl/ #tredu.es fri.tion between the pressure plate le5ers and the release for0 The release bearin4 is

a sealed unit pa.0 with a lubri.ant #t slides on a hub slee5e e9tendin4 out from the front of

the manual transmission or transa9le

The release bearin4 snaps o5er the end of the .lut.h for0 Small sprin4 .lips hold the bearin4

on the for0 Then for0 mo5ement in either dire.tion slides the release bearin4 alon4 the

transmission hub slee5e

!ress+re !/ate C/+th Ho+sn.

The .lut.h housin4 is also .alled the bell housin4 #t bolts to the rear of the en4ine6 en.losin4

the .lut.h assembl/6 with the manual transmission bolted to the ba.0 of the housin4 The

lower front of the housin4 has a metal .o5er that .an be remo5ed for fl/)wheel rin4 4ear

inspe.tion or when the en4ine must be separated from the .lut.h assembl/ A hole is pro5ided

in the side of the housin4 for the .lut.h for0 #t .an be made of aluminium6 ma4nesium6 or

.ast iron

The pressure plate is a sprin4)loaded de5i.e that .an either en4a4e or disen4a4e the .lut.h

dis. and the fl/wheel #t bolts to the fl/wheel The .lut.h dis. fits between the fl/wheel and

the pressure plate There are two t/pes of pressure plates) the .oil sprin4 t/pe and the

diaphra4m t/pe

33



Co/ sprn. press+re p/ate* #t uses small .oil sprin4s similar to 5al5e sprin4s *fi4

)K+ The fa.e of the pressure plate is a lar4e6 flat rin4 that .onta.ts the .lut.h dis. durin4

.lut.h en4a4ement The ba.0side of the pressure plate has po.0ets for the .oil sprin4s and

bra.0ets for hin4in4 the release le5ers 'urin4 .lut.h a.tion6 the pressure plate mo5es ba.0

and forth inside the .lut.h .o5er The release le5ers are hin4ed inside the pressure plate to pr/

on and mo5e the pressure plate fa.e awa/ from the .lut.h dis. and fl/wheel Small .lip)t/pe

sprin4s fit around the release le5ers to 0eep them rattlin4 when full/ released The pressure

plate .o5er fits o5er the sprin4s6 the release le5ers6 and the pressure plate fa.e #ts main

purpose is to hold the assembl/ to4ether !oles around the outer ed4e of the .o5er are for

boltin4 the pressure plate to the fl/wheel

'iaphra4m pressure plate *fi4 )L+ uses a sin4le diaphra4m sprin4 instead of .oil

sprin4sThis t/pe of pressure plate fun.tions similar to that of the .oil sprin4 t/pe Thediaphra4m sprin4 is a lar4e6 round dis. of sprin4 steel The sprin4 is bent or dished and has

pie)shaped se4ments runnin4 from the outer ed4e to the .entre The diaphra4m sprin4 is

mounted in the pressure plate with the outer ed4e tou.hin4 the ba.0 of the pressure plate fa.e

The outer rim of the diaphra4m is se.ured to the pressure plate and is pi5oted on rin4s *pi5ot

rin4s+ appro9imatel/ ? in.h from the outer ed4e

34



F+ntons of a /+th are as fo//o;s*

• 7hen the .lut.h is en4a4ed6 the power flows from the en4ine to the rear wheels

throu4h the transmission s/stem and the 5ehi.le mo5es

• 7hen the .lut.h is disen4a4ed6 the power is not transmitted to the rear wheels and the

5ehi.les stops while the en4ine is still runnin4

• The .lut.h is disen4a4ed when startin4 the en4ine6 when shiftin4 the 4ears6 when

stoppin4 the 5ehi.le and when idlin4 the en4ine

• The .lut.h is 0ept en4a4ed when the 5ehi.le is mo5in4

• The .lut.h also permits the 4radual ta0in4 up of the load 7hen properl/ operated6 it

pre5ents 8er0/ motion of the 5ehi.le

T@!E OF CLUTCHE*

The .lut.hes used in motor 5ehi.les are almost 5er/ similar in .onstru.tion andoperation There are some differen.es in the details of a lin0a4e as well as in the pressure

plate assemblies Some .lut.hes are operated b/ h/drauli. means The dri5e plate .lut.h

operates dr/ without usin4 oil The wet .lut.h operates in a bat.h of oil &ost desi4n of the

.lut.hes use number of .oil sprin4s but some uses a diaphra4m or .oni.al t/pe sprin4s

36



%fferent tpes of /+thes are as fo//o;s*

? Fri.tion .lut.h

a+ Sin4le plate .lut.h

b+ &ulti plate .lut.h

?+ 7et @+ 'r/

.+ Cone .lut.h

?+ E9ternal @+ #nternal

@ Centrifu4al .lut.h

I Semi).entrifu4al .lut.h

Coni.al sprin4 .lut.h or diaphra4m .lut.h

*a+ Tapered fin4er t/pe

*b+ Crown sprin4 t/pe

= Positi5e .lut.h ; 'o4 and spline .lut.h

K !/drauli. .lut.h

L Ele.tro)ma4neti. .lut.h

-a.uum .lut.h

M O5er runnin4 .lut.h or free wheeled unit

FRICTIO# CLUTCH

The 5ast ma8orit/ of .lut.hes ultimatel/ rel/ on fri.tional for.es for their operation The

purpose of fri.tion .lut.hes is to .onne.t a mo5in4 member to another that is mo5in4 at a

different speed or stationar/6 often to s/n.hronise the speeds6 andHor to transmit power

%suall/ as little slippa4e *differen.e in speeds+ as possible between the two members are

desired

37



&er.edes tru.0 e9amples A .lamp load of II 0N is normal for a sin4le plate I> The >>

Twin appli.ation offers a .lamp load of a mere @I 0N Bursts speeds are t/pi.all/ around

=6>>> rpm with the wea0est point bein4 the fa.in4 ri5et

Man+fat+rn.

&odern .lut.h de5elopment fo.uses its attention on the simplifi.ation of the o5erall assembl/

andHor manufa.turin4 method For e9ample dri5e straps are now .ommonl/ emplo/ed to

transfer torque as well as lift the pressure plate upon disen4a4ement of 5ehi.le dri5e 7ith

re4ard to the manufa.ture of diaphra4m sprin4s6 heat treatment is .ru.ial ,aser weldin4 is

be.omin4 more .ommon as a method of atta.hin4 the dri5e plate to the dis. rin4 with the

laser t/pi.all/ bein4 between @)IG7 and a feed rate ?mHminute

%O& CLUTCH

A do. /+th is a t/pe of .lut.h that .ouples two rotatin4 shafts or other rotatin4 .omponents

not b/ fri.tion but b/ interferen.e The two parts of the .lut.h are desi4ned su.h that one will push the other6 .ausin4 both to rotate at the same speed and will ne5er slip

'o4 .lut.hes are used where slip is undesirable andHor the .lut.h is not used to .ontrol

torque 7ithout slippa4e6 do4 .lut.hes are not affe.ted b/ wear in the same wa/ that fri.tion

.lut.hes are

'o4 .lut.hes are used inside manual automoti5e transmissions to lo.0 different 4ears to the

rotatin4 input and output shafts A s/n.hromesh arran4ement ensures smooth en4a4ement b/

mat.hin4 the shaft speeds before the do4 .lut.h is allowed to en4a4e

$et and dr /+th

A Dwet .lut.hD is immersed in a .oolin4 lubri.atin4 fluid6 whi.h also 0eeps the surfa.es

.lean and 4i5es smoother performan.e and lon4er life 7et .lut.hes howe5er6 tend to lose

some ener4/ to the liquid A Ddr/ .lut.hD6 as the name implies6 is not bathed in fluid Sin.e the

surfa.es of a wet .lut.h .an be slipper/ *as with a motor./.le .lut.h bathed in en4ine

oil+6 sta.0in4 multiple .lut.h dis0s .an .ompensate for the lower .oeffi.ient of fri.tion and

so eliminate slippa4e under power when full/ en4a4ed

39



Cone /+th

A one /+th ser5es the same purpose as a dis0 or plate .lut.h !owe5er6 instead of matin4

two spinnin4 dis0s6 the .one .lut.h uses two .oni.al surfa.es to transmit torque b/ fri.tion

The .one .lut.h transfers a hi4her torque than plate or dis0 .lut.hes of the same si<e due to

the wed4in4 a.tion and in.reased surfa.e area

Cone .lut.hes are 4enerall/ now onl/ used in low peripheral speed appli.ations althou4h the/

were on.e .ommon in automobiles and other .ombustion en4ine transmissions

The/ are usuall/ now .onfined to 5er/ spe.ialist transmissions in ra.in46 rall/in46 or in

e9treme off)road 5ehi.les6 althou4h the/ are .ommon in power boats This is be.ause the

.lut.h doesnDt ha5e to be pushed in all the wa/ and the 4ears will be .han4ed qui.0er

Be/t /+th

%sed on a4ri.ultural equipment and some piston)en4ine)dri5en heli.opters En4ine power is

transmitted 5ia a set of 5ee)belts that are sla.0 when the en4ine is idlin46 but b/ means of a

ten)sioner pulle/ .an be ti4htened to in.rease fri.tion between the belts and the shea5es

Centrf+.a/ /+th

A entrf+.a/ /+th is a .lut.h that uses .entrifu4al for.e to .onne.t two .on.entri. shafts6

with the dri5in4 shaft nested inside the dri5en shaft

Centrifu4al .lut.hes are often used in mopeds6 lawnmowers6 4o)0arts6 .hainsaws6 and mini

bi0es

F/+d o+p/n.

A f/+d o+p/n. is a h/drod/nami. de5i.e used to transmit rotatin4 me.hani.al

power #t has been used in automobile transmissions as an alternati5e to a me.hani.al .lut.h

#t also has widespread appli.ation in marine and industrial ma.hine dri5es6 where 5ariable

speed operation andHor .ontrolled start)up without sho.0 loadin4 of the power transmission

s/stem is essential

$rapsprn. /+thes

40



These ha5e a heli.al sprin4 wound with square).ross)se.tion wire #n simple form the sprin4

is fastened at one end to the dri5en member its other end is unatta.hed The sprin4 fits

.losel/ around a ./lindri.al dri5in4 member #f the dri5in4 member rotates in the dire.tion

that would unwind the sprin4 the sprin4 e9pands minutel/ and slips althou4h with some dra4

Rotatin4 the dri5in4 member the other wa/ ma0es the sprin4 wrap itself ti4htl/ around the

dri5in4 surfa.e and the .lut.h lo.0s up

Hdra+/ /+th

The dri5in4 and dri5en members are not in ph/si.al .onta.t .ouplin4 is h/drod/nami.

#n a h/drauli. .lut.h s/stem6 the .ouplin4 is h/drod/nami. and the shafts are not a.tuall/ in

.onta.t The/ wor0 as an alternati5e to me.hani.al .lut.hes The/ are 0nown to ha5e

.ommon problems asso.iated with h/drauli. .ouplin4s6 and are a bit unstead/ in transmittin4

torque

afet C/+th

Also 0nown as the torque limiter6 this de5i.e allows a rotatin4 shaft to slip or disen4a4e

when hi4her than normal resistan.e is en.ountered on a ma.hine An e9ample of a safet/

.lut.h is the one mounted on the dri5in4 shaft of a lar4e 4rass mower #f a stone or somethin4

else is en.ountered b/ the 4rass mower6 it stops immediatel/ and does not hamper the blades

O-err+nnn. C/+th

Also 0nown as the freewheel me.hanisms6 this t/pe of .lut.h disen4a4e the dri5eshaft from

the dri5en shaft6 when the dri5en shaft rotates faster than the dri5eshaft An e9ample of su.h a

situation .an be when a ./.list stops peddlin4 and .ruises !owe5er6 in .ase of automobiles

4oin4 down the hill6 /ou .annot ta0e /our feet off the 4as pedal6 as there is no free wheel

s/stem #f /ou do so6 the whole en4ine s/stem .an be dama4ed

E/etroma.net /+th

Ele.troma4neti. .lut.hes operate ele.tri.all/6 but transmit torque me.hani.all/ This is wh/

the/ used to be referred to as ele.tro)me.hani.al .lut.hes

41

http://en.wikipedia.org/wiki/Fluid_coupling

http://en.wikipedia.org/wiki/Fluid_coupling



To help in.rease life in appli.ations6 fri.tion material is used between the poles on the fa.e of

the rotor This fri.tion material is flush with the steel on the rotor6 sin.e if the fri.tion material

was not flush6 4ood ma4neti. tra.tion .ould not o..ur between the fa.es Some people loo0 at

ele.troma4neti. .lut.hes and mista0enl/ assume that6 sin.e the fri.tion material is flush with

the steel that the .lut.h has alread/ worn down but this is not the .ase Clut.hes used in most

mobile appli.ations6 *automoti5e6 a4ri.ulture6 .onstru.tion equipment+ do not use fri.tion

material Their ./.le requirements tend to be lower than industrial .lut.hes6 and their .ost is

more sensiti5e Also6 man/ mobile .lut.hes are e9posed to outside elements6 so b/ not ha5in4

fri.tion material6 it eliminates the possibilit/ of swellin4 *redu.ed torque+6 that .an happen

when fri.tion material absorbs moisture

$OR"I#& OF ELECTROMA&#ETIC CLUTCH

The .lut.h has four main parts field6 rotor6 armature6 and hub *output+ 7hen 5olta4e is

applied the stationar/ ma4neti. field 4enerates the lines of flu9 that pass into the rotor *The

rotor is normall/ .onne.ted to the part that is alwa/s mo5in4 in the ma.hine+ The flu9

*ma4neti. attra.tion+ pulls the armature in .onta.t with the rotor *the armature is .onne.ted to

the .omponent that requires the a..eleration+6 as the armature and the output start to

a..elerate Slippin4 between the rotor fa.e and the armature fa.e .ontinues until the input and

output speed is the same *?>> lo.0up+ The a.tual time for this is quite short6 between

?H@>>th of a se.ond and ? se.ond

'isen4a4ement is 5er/ simple On.e the field starts to de4rade6 flu9 falls rapidl/ and the

armature separates One or more sprin4s hold the armature awa/ from the rotor at a

predetermined air 4ap

En.a.ement tme

There are a.tuall/ two en4a4ement times to .onsider in an ele.troma4neti. .lut.h The first

one is the time that it ta0es for a .oil to de5elop a ma4neti. field6 stron4 enou4h to pull in an

armature 7ithin this6 there are two fa.tors to .onsider The first one is the amount of ampereturns in a .oil6 whi.h will determine the stren4th of a ma4neti. field The se.ond one is air

43



hea5/ dut/ appli.ations su.h as tru.0s and .ompetition .ars use .erami. plates that ha5e a

4reatl/ in.reased fri.tion .oeffi.ient !owe5er6 these ha5e a 4rabb/ a.tion 4enerall/

.onsidered unsuitable for passen4er .ars The sprin4 pressure is released when the .lut.h

pedal is depressed thus either pushin4 or pullin4 the diaphra4m of the pressure plate6

dependin4 on t/pe !owe5er6 raisin4 the en4ine speed too hi4h while en4a4in4 the .lut.h

.auses e9.essi5e .lut.h plate wear En4a4in4 the .lut.h abruptl/ when the en4ine is turnin4at hi4h speed .auses a harsh6 8er0/ start This 0ind of start is ne.essar/ and desirable in dra4

ra.in4 and other .ompetitions6 where speed is more important than .omfort

A+tomo4/e po;ertran

This plasti. pilot shaft 4uide tool is used to ali4n the .lut.h dis0 as the sprin4)loaded pressure

plate is installed The transmissionDs dri5e splines and pilot shaft ha5e a .omplementar/

shape A number of su.h de5i.es fit 5arious ma0es and models of dri5etrains

#n a modern .ar with a manual transmission the .lut.h is operated b/ the left)

most pedal usin4 a h/drauli. or .able .onne.tion from the pedal to the .lut.h me.hanism Onolder .ars the .lut.h mi4ht be operated b/ a me.hani.al lin0a4e E5en thou4h the .lut.h ma/

ph/si.all/ be lo.ated 5er/ .lose to the pedal6 su.h remote means of a.tuation are ne.essar/ to

eliminate the effe.t of 5ibrations and sli4ht en4ine mo5ement6 en4ine mountin4s bein4

fle9ible b/ desi4n 7ith a ri4id me.hani.al lin0a4e6 smooth en4a4ement would be near)

impossible be.ause en4ine mo5ement ine5itabl/ o..urs as the dri5e is ta0en up

The default state of the .lut.h is engaged ) that is the .onne.tion between en4ine and 4earbo9

is alwa/s on unless the dri5er presses the pedal and disen4a4es it #f the en4ine is runnin4

with .lut.h en4a4ed and the transmission in neutral6 the en4ine spins the input shaft of the

transmission6 but no power is transmitted to the wheels

45



The .lut.h is lo.ated between the en4ine and the 4earbo96 as disen4a4in4 it is required to

.han4e 4ear Althou4h the 4earbo9 does not stop rotatin4 durin4 a 4ear .han4e6 there is no

torque transmitted throu4h it6 thus less fri.tion between 4ears and their en4a4ement do4s The

output shaft of the 4earbo9 is permanentl/ .onne.ted to the final dri5e6 then the wheels6 and

so both alwa/s rotate to4ether6 at a fi9ed speed ratio 7ith the .lut.h disen4a4ed6 the 4earbo9

input shaft is free to .han4e its speed as the internal ratio is .han4ed An/ resultin4 differen.ein speed between the en4ine and 4earbo9 is e5ened out as the .lut.h slips sli4htl/ durin4 re)

en4a4ement

Clut.hes in t/pi.al .ars are mounted dire.tl/ to the fa.e of the en4ineDs fl/wheel6 as this

alread/ pro5ides a .on5enient lar4e diameter steel dis0 that .an a.t as one dri5in4 plate of the

.lut.h Some ra.in4 .lut.hes use small multi)plate dis0 pa.0s that are not part of the

fl/wheel Both .lut.h and fl/wheel are en.losed in a .oni.al bellhousin46 whi.h *in a rear)

wheel dri5e .ar+ usuall/ forms the main mountin4 for the 4earbo9

A few .ars6 notabl/ the Alfa Romeo Alfetta6 Pors.he M@6 and Che5rolet Cor5ette *sin.e?MML+6 sou4ht a more e5en wei4ht distribution between front and ba.0 b/ pla.in4 the wei4ht

of the transmission at the rear of the .ar6 .ombined with the rear a9le to form a transa9le

The propeller shaft between front and rear rotates .ontinuousl/ as lon4 as the en4ine is

runnin46 e5en if the .lut.h is disen4a4ed or the transmission is in neutral

Motor/es

A basket clutch

46



&otor./.les t/pi.all/ emplo/ a wet .lut.h with the .lut.h ridin4 in the same oil as the

transmission These .lut.hes are usuall/ made up of a sta.0 of alternatin4 plain steel and

fri.tion plates Some plates ha5e lu4s on their inner diameters that lo.0 them to the en4ine

.ran0shaft Other plates ha5e lu4s on their outer diameters that lo.0 them to a bas0et thatturns the transmission input shaft A set of .oil sprin4s or a diaphra4m sprin4 plate for.e the

plates to4ether when the .lut.h is en4a4ed

On motor./.les the .lut.h is operated b/ a hand le5er on the left handlebar No pressure on

the le5er means that the .lut.h plates are en4a4ed *dri5in4+6 while pullin4 the le5er ba.0

towards the rider disen4a4es the .lut.h plates throu4h .able or h/drauli. a.tuation6 allowin4

the rider to shift 4ears or .oast Ra.in4 motor./.les often use slipper .lut.hes to eliminate the

effe.ts of en4ine bra0in46 whi.h6 bein4 applied onl/ to the rear wheel6 .an .ause instabilit/

A+tomo4/e nonpo;ertran

Cars use .lut.hes in pla.es other than the dri5e train For e9ample6 a belt)dri5en en4ine

.oolin4 fan ma/ ha5e a heat)a.ti5ated .lut.h The dri5in4 and dri5en members are separated

b/ a sili.one)based fluid and a 5al5e .ontrolled b/ a bimetalli. sprin4 7hen the temperature

is low6 the sprin4 winds and .loses the 5al5e6 whi.h lets the fan spin at about @> to I> of

the shaft speed As the temperature of the sprin4 rises6 it unwinds and opens the 5al5e6

allowin4 fluid past the 5al5e6 ma0es the fan spin at about K> to M> of shaft speed Other.lut.hessu.h as for an air .onditionin4 .ompressorele.troni.all/ en4a4e .lut.hes usin4

ma4neti. for.e to .ouple the dri5in4 member to the dri5en member

pea/t /+thes and app/atons

n./ere-o/+ton /+th

7hen ina.ti5e it is disen4a4ed and the dri5en member is stationar/ 7hen tripped6 it lo.0s

up solidl/ *t/pi.all/ in a few to tens of millise.onds+ and rotates the dri5en member 8ust one

full turn #f the trip me.hanism is operated when the .lut.h would otherwise disen4a4e the

.lut.h remains en4a4ed -ariants in.lude half)re5olution *and other fra.tional)re5olution+

47



t/pes These were an essential part of printin4 tele4raphs su.h as tele)printer pa4e printers6 as

well as ele.tri. t/pewriters6 notabl/ the #B& Sele.tri. The/ were also found in motor)dri5en

me.hani.al .al.ulators the &ar.hant had se5eral of them The/ are also used in farm

ma.hiner/ and industr/ T/pi.all/6 these were a 5ariet/ of do4 .lut.h

Sin4le)re5olution .lut.hes in tele)printers were of this t/pe Basi.all/ the sprin4 was 0epte9panded *details below+ and mostl/ out of .onta.t with the dri5in4 slee5e6 but ne5ertheless

.lose to it One end of the sprin4 was atta.hed to a slee5e surroundin4 the sprin4 The other

end of the sprin4 was atta.hed to the dri5en member inside whi.h the dri5e shaft .ould rotate

freel/ The slee5e had a pro8e.tin4 tooth6 li0e a rat.het tooth A sprin4)loaded pawl pressed

a4ainst the slee5e and 0ept it from rotatin4 The wrap sprin4Ds torque 0ept the slee5eDs tooth

pressin4 a4ainst the pawl To en4a4e the .lut.h6 an ele.troma4net attra.ted the pawl awa/

from the slee5e The wrap sprin4Ds torque rotated the slee5e6 whi.h permitted the sprin4 to

.ontra.t and wrap ti4htl/ around the dri5in4 slee5e ,oad torque ti4htened the wrap so it did

not slip on.e en4a4ed #f the pawl were held awa/ from the slee5e the .lut.h would .ontinue

to dri5e the load without slippin4 7hen the .lut.h was to disen4a4e power was dis.onne.tedfrom the ele.troma4net and the pawl mo5ed .lose to the slee5e 7hen the slee5eDs tooth

.onta.ted the pawl the slee5e and the loadDs inertiaun wrapped the sprin4 to disen4a4e the

.lut.h Considerin4 that the dri5e motors in some of these *su.h as tele)printers for news wire

ser5i.es+ ran @ hours a da/ for /ears the sprin4 .ould not be allowed to sta/ in .lose .onta.t

with the dri5in4 ./linder wear would be e9.essi5e The other end of the sprin4 was fastened

to a thi.0 dis. atta.hed to the dri5en member 7hen the .lut.h lo.0ed up the dri5en

me.hanism .oasted and its inertia rotated the dis. until a tooth on it en4a4ed a pawl that 0ept

it from re5ersin4 To4ether with the restraint at the other end of the sprin4 .reated b/ the trip

pawl and slee5e tooth6 this 0ept the sprin4 e9panded to minimi<e .onta.t with the dri5in4

./linder These .lut.hes were lubri.ated with .on5entional oil6 but the wrap was so effe.ti5ethat the lubri.ant did not defeat the 4rip These .lut.hes had lon4 operatin4 li5es6 ./.lin4 for

tens6 ma/be hundreds of millions of ./.les without need of maintenan.e other than

o..asional lubri.ation with re.ommended oil

Casadedpa;/ sn./ere-o/+ton /+thes

These superseded wrap)sprin4 sin4le)re5olution .lut.hes in pa4e printers6 su.h as tele) printers6 in.ludin4 the Telet/pe &odel @ and its su..essors6 usin4 the same desi4n

48



The .ondition of the fri.tion surfa.e of the fl/wheel is important for proper .lut.h fun.tion

The surfa.e should be smooth and free of burned spots and surfa.e .ra.0s %sed fl/wheels

.an be re)surfa.ed This should be done b/ 4rindin4 rather than lathe turnin4 as less material

is remo5ed The amount of material remo5ed from the fa.e .an affe.t whi.h .lut.h release

bearin4 should be used A fl/wheel should alwa/s be .he.0ed for runout on the en4ine it will be used on Fa.e runout should not e9.eed >>= *fi5e thousandths+ of an in.h

Thou4h not a .omposite part of the .lut.h '"wheel is what the .lut.h deri5es power from

and deli5ers it to the 4ear bo9

@+ CLUTCH %IC*

A .lut.h dis. .onsists of sprin4s between the hub and the dis. to absorb the sho.0 when the

.lut.h is en4a4ed

This is the dri5en part of the .lut.h #t has a fri.tion material ri5eted to ea.h side of a wa5/

sprin4 *.alled a mar.el+ This is atta.hed to a splined hub that the transmission input 4ear protrudes into

50



There are basi.all/ two t/pes of fri.tion material used for .lut.h linin4 These are or4ani. and

metalli. The or4ani. is best for all around use The metalli. is preferred b/ some for se5ere

dut/ appli.ations but requires hi4h sprin4 pressures and is hard on the fl/wheel and pressure

plate fri.tion surfa.es A5oid solid hub .lut.hes and .lut.hes without mar.el as the/ will

alwa/s .hatter when used in 5ehi.les with a rear differential mounted on sprin4s *as opposedto a transa9le desi4n+

I+ !REURE !LATE*

As the name defines a pressure plate is present to redu.e pressure when the power transfero..urs it .onsists of .oil sprin4s6 anti)rattle .lip6 release fin4er6 strut6 e/e bolt W a ful.rum

pin

51



+ CLUTCH CODER*

The .lut.h .o5er is used to .o5er the entire .lut.h assembl/

=+ HUB A#% RELEAE FOR"*

The hub is where the power from the fl/ wheel is transferred to the 4ear bo9 and

the release for0 releases the .lut.h from en4a4ed position on.e the transmission

is .omplete

) !ILOT BUHI#&

#n most .ases6 this is a porous bron<e6 pre)lubed bushin4 rather than an a.tual bearin46 as it isoften .alled A few appli.ations still use an a.tual bearin4 and others use a needle roller t/pe

bearin46 but b/ far6 the most .ommon t/pe is bron<e (ou .annot use a roller bearin4 on a

transmission shaft ori4inall/ desi4ned for a bron<e bushin4 due to different t/pe of heat

treatment on the shafts

The pilot bushin4 is seldom thou4ht of as a part of the .lut.h s/stem but it is one of the most

5ital parts of the s/stem #t pilots the end of the transmission input 4ear in the .ran0shaft #f it

is worn or not runnin4 true6 it .an .ause serious .lut.h problems or transmission failure

Pilot bushin4 bore runout should alwa/s be .he.0ed with a dial indi.ator and should be

within >>@ total The bron<e bushin4 t/pe should be a press fit in the .ran0shaft bore #t must be installed .arefull/ #t should ha5e between >>? and >>I .learan.e on the transmission

shaft when installed The pilot bushin4 is onl/ fun.tional when the .lut.h is disen4a4ed but it

is a fa.tor in input 4ear ali4nment at A,, times

52



) CLUTCH RELEAE BEARI#&

As its name implies6 this is the bearin4 that releases the .lut.h #t is often referred toas a

throw)out bearin4 The/ .ome on a number of different st/le .arriers The .arriers6 in some

.ases6 5ar/ .onsiderabl/ with the parti.ular en4ineBe.ause the release bearin4 onl/ wor0s

when the .lut.h is bein4 released it usuall/ lasts quite a lon4 time !owe5er6 improper

lin0a4e ad8ustment or ridin4 the .lut.h with /our foot when dri5in4 .an wear the bearin4

prematurel/ Normall/ there should be a minimum of ?H?K .learan.e between the fa.e of the

bearin4 and the three release fin4ers or diaphra4m sprin4 of the pressure plate when the

.lut.h is en4a4ed This fa.t is important and will be dis.ussed further when we 4et to the part

about settin4 up the .lut.h lin0a4e

G) TRA#MIIO# FRO#T BEARI#& RETAI#ER

This 4reat de5i.e has three .riti.al fun.tions This first is as its name implies The se.ond is

to pro5ide a re4ister on whi.h the bell housin4 must .entre This is feature is sometimes

o5erloo0ed with e9pensi5e .onsequen.es Thirdl/6 its tubular snout is the surfa.e on whi.h

the throw out bearin4 rides on its wa/ into to depress the sprin4s of the pressure plate

Con5ersions often require spe.ial and modified retainers to a.hie5e .ompatibilit/

53



These t;o da.rams n/+de e-er parts of the /+th1

54

a project report on autoclutch

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