Drive Line

8/12/2019 Drive Line

1/6

A,PTER

DRIVELINE

i-?'''- v,F,lli:-:IJ$,'"::tti,; :,*i::l*" An au'io{ "r:-1"TJi1*rrffiiumsg engine torqutffi:il,Hr:l'*t-:irf**i[tx:ir#t*t#''i'-,*r*H#,'"i#:T*ffiu ihe transmlsslc {hUniversalioint ;-Reat

drive axle

lmrerr*ssion\_-\,:{EUniversal ioint hear diive shaft

Differeritid carrier Control armr-i.- .:.*'Jy* / i, ),,\')J /,J Fronr/ c" '.f9iJ;i:5fi1ydrive snaft ur*veroq"- '-- - . -^-^^r inini and. rear dritle axleo* ,)-o two piece d'riueshaft wfth uniuersal ioint at rfts extendimry rhe engine tran'**r" u*o*u1v *:11'^"";. $il#'"i'' tn"* driveshafts or halfshaffiil;;;r,"u*I" to the front wheels (>e

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Sn6$neeringWheelI Strutirilr t Transaxlerl?lnboardflexiblejoint \

and types of sPlined Yokes' Universal iointUniversal ioint

Fig' 7'3' ProPeller shaft7.2.L TYPes of PnoPellen Shafts

trr" *iJai" of the shaft assembly' Fither zA chassis

Propeller shafts are of two types: 'ece, tubular steel or aluminiurc1. One and Two-piece Shafts : floqt common is the one-ptor composit" *ut"*iuiii"pJf", ,f..ft w'tf'-unlversal joints at each end as shown in Fig' 7'3'Tub,Iar shafts are light in weight.yet J;;;. Next is the two-piece' tubular propeller shaft'used on many long *"i.""ru""" iehitles. L ffi" a third o'iu""ul joint between the two shah,".tiors and a centre bearing to supp,ort 1.

\ Driveshatt

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Outboard flexible iointFig. 7.2' Front-wheel driueshafts

Varioustypesofdriveshaftsorpropellershafts,universaljointsandslipjointsareusedtocarry engine power from the transmissio;;;-;;;;;rx1e to the wheels' The following sectionsdescribe ttre different drive lines'::., 7.2 PROPELLER SHAFTPropellershaftordriveshaft(SeeFig.7.3)isastee.l.tubethattransmitspowerfromthetransmissio. ortprt-.t ufi to tire d'ive a# "i tf't" '"f itle' To take care of different models'wheelbase and transmission combinationi,"r;;,;"' thafts have different lengths' diameters

thlit Fits intotransmission

Irr" "r Jrrt may be exposed or enclosed R-/ii;J.**iilatln*o,As used,n tl" (rgoi-rgoipontiac Tempest models,this \-5d- -i:"-,tl* rransr(ission"frrfl it a flexible steel rope not unlike " :=1-. T'>ar axleiuigu ai.*",er version of a speedometer +- \ Rear wheelcable. It use, ,ro ,rrtr,""*lioi"t' U"t*"ul fts' r'f, Transmission i1^st1'lt;nar -while rear wheeisiil"'";"*i#';;^-;h" rear mounted moue up an. dou'ntransaxle.


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The propeller shaft's job is made di{ficult by the fact that, while the transmission is stationary,:he rear axll assembly is mounted on springs. This means that the rear axle assembly can moverp and down as the vehicle moves over bumps and holes. The drive line must be able to make.hung". in both angle and length (see Fig' 7.4). This can be accommodated by using a slip yoke11 th; propeller shaft or by using a ball-and-trunnion type of universal joints at one end of thepropeller shaft.Figure 7.5 showsa slip yoke design:,-.-rilt into the front; ropeller shaft1-tion. The slip yokelan be located at ther:ntre of two piece

Double cardanFis. 7.5. Propeller shaft with slip yoke joint

it,sign. or at eiiher end but usually is found at the front, behind the universai joint flange.Ball-and-trunnion U-joint operation follows in the universal joints section.\Iost propeller shafts tend to vibrate because ofuniversaljoint action and other factors. To*,-ninate vibration, cardtroard tubes are sometimes pressed into the steel tubes. Some propeller*,:"at'ts have r*bber biscuits moulded on the outside of the smaller diameter steel tube' Thisilssmbly is then pressed into the propeller shaft tube.7.3 uNrvEIsAL. jolN-rs

l.-:-,,-ersal joints or U-joints, allow the propeller shaft to transmit rotation at varying angles. On&r*iigns using U-joints, forged steel yokes or companion flanges for the joints are welded ontory*,:r end of the propeller shaft. The common types of universal joints are:i. Hooke,s Joint or Cross-and-Yoke Joint: (See Fig.7.6) It is the most common type ofr,.-i-rrsal joint and is widely used because of the fact that is simple and compact in constructionrm.,j reasonably efficient at small angles of propeller shaft movement up and down' It consist ofinrr : y-shaped yokes connected by a cross member called a cross or spider. The arms of the crossrur' :alled trunnions.

-{n improved form of the Hooke's joint uses needle roller bearings to support the cross ortui i=r in the yokes (see Fig. 7.7). The bearing outer race is a cap deep enough to hold a reserve*au:n : Lr of iubricant. A seal between the cap and cross holds in the iubricant'

SealFront q^ia^. Bearinffi-o- Retainerslip yoke ^ -& :r'':"' retainin.q ring s*Seal\ l9{.ia/ I }" ffi-Bearinqd":*& H I m''1.*l':,fl,q?3iEearings/ I i-.+ronj"g ^ \ ** Jo'nISeal- ]1 iuniversal pl.,&" Y6 .iBearins cap ;ffi --, ,f9 -d*$fu *{;earins cip - -J " ffi;; Kk *..Tr ''Bearing cap -1-3r ---ti- )B Lf' ni'-Retaining (i\9 -"." AY ,---""" Rear axleetaining ring.-.'.' ,{Y --^,"" Rehr axle'--rn^-- ?,./- k^ drive| #P;_, - --"? *rF*rPinion yoke," *l-";,ir" jnrtt *fr1clamo straotrig. 7.6. Hoohe's Joint Fig. 7.7. Exploded, uiew of front uniuersal ioint

Trunnion


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. ,. -r .." . .t .":'2. Ball-and-Trunnion Joint : (See Fig. 7.9) This type of joint used on older Chrysler:orporation vehicles and some Jeeps. A pin is fitted at one end of the propeller shaft. On the pinare two spherical bushings on needle bearings. The bushings slide into longitudinal grooves in:he universal joint housing, bolted to a companion flange.

Trunnion cap

s\Prooellershaft

Retainer Trunnionplate housingf.,,.{dl:(rri$

Fig. 7.9. Ball and trunnion JointI Constant Velocity Universal Joints : (See Fig. 7.10) When the angles of the universal1rmmrr.s a-ne very large, a constant velocity universal joint is required. Such joints are designed torilh*ilir--ain a constant shaft speed, regardless of operating angle. A constant velocity universalynmnr ":sed in most large, rear wheel drive vehicles with low propeller shaft tunnels are doublerl,umr.an universal joints (see Fig. 7.11). It uses two universal joints closely connected by a,,mmfi,*ring socket yoke and a centre yoke. On some vehicles, the double joint is used at both endsml mr* pmpeller shaft. On other vehicles, the double joint is used only on the drive end of [email protected]* :[slt. In some uses, it is placed in the centre of a very long propeller shaft.

shaftyoke bearingsff,{f ;.f0. Constant uelocity uniuersal joint Fig. 7.11.. Exploded uiew of a constant uelocityuniuersal joint( Bzeppa Joints : The Rzeppa joint is another type of constant velocity joint that aliowsn m,:peller shaft angles. Drive is transmitted via steel balls operating in a cage and spherical

Need bearingsSocket ball retainer Thrust

Socket spring

mrL.et. It is used in front wheel drive vehicles.


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5. Rotoflex coupling : It is a flexible rubber coupling. The coupling boits between trvotriangular bolt flang; urr? i, steel reinforced around its outer diameter and through boltsleeves. It is found mainly in British urra ftufiu" 'fo'ts cars' Beside from greasing its centeringbushing on installation, ihe Rotoflex coupling needs no routine lubrication., 7:4 SLIP JO|NTSThe front yoke of the universal joint,the slip joint, is splined to the externalsplines of the transmission outputshaft as shown in Fig. 7.12'When going over bumPs, the rearaxle assemblY moves uP and down onthe suspension system, changing thedistance between the transmission and

Output shaft

Bushing SealFie. 7.12. SliP jointPropeller shaft

the rear axle. The slip joint moves inand out on the t"ur.riirrion shaft to a11ow this change of distance. This is why the propellershaft is not anchored at the front. The spline of the Jtlp ioi"t fits snugly to the transmissionoutput shaft and is free to move in and out'The slip joint spline is lubricated by the transmission's lubricant' This lubricant permitsthe yoke to move in and out easily under all driving conditions'; 7.5. FINAL. DRtvE

The function of the finai drive is to turn the power flowat a.right angle from the propeller shaftto the rear axle. The final drive also prorria"t the mechanical advantage or leverage from thepropeller shaft to the rear axle'The final drive usually consists of a bevel pinion and a crown wheei (see Fig' 7'13) oralternatively, worm and w-heel arrangement. Th; bevel pinion is mounted on a shaft which isconnected to the propeller shaft through a rear universal yoke (see Fig' 7'1a)' The drive fromthe crown wheel goes to the differential'Bevel pinion

Crown wheel

Bevel pinion

Fig. 7.13. Beuel pinion is meshed with ffown. wheel Fig' 7'14' Beuel pinion is d'riuen by propeller shaftThecrownwheelalwaysturnsslowerthanthedrivebevel,pinion.Thisl:,".111^T".7

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wheel trade speecl for torque. Thus, the drive axle multiplies the torque received from thetransmission. A 2.8 ' i."r*1r-*ftu"l to bevel pinion ratio is common with automatic transmission


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2 8 : 1 ratio means the bevel pinion must turn 2.8 times to rotate the ring gear 1 time. This ismonly referred to as the gear ratio, rear axle ratio or final drive ratio'With manuai transmission more torque multiplication is needed. Then a 3.5 : l final driveio is normal. For faster acceleration some sports cars use 4 : 1 final drive ratios. Trucks alsofrnal drives with 4 : 1 or 5 : 1 ratios. This allows them to puII heavy loads.Final drives with ratios around 2.5 : 1 will take longer to accelerate but will'give a faster top

. Such cars are said to be high geared. At the other end of the scale, a 4.ll : 1 ratio will giveer acceleration with a lower top speed. This is low greaing. Since the emphasis on fuelmy in the 1970s, most cars have tended toward high gearing.There are three different types of arrangements for the crown wheel and pinion of theshaft :

1. Straight Bevel Gears: This type of arrangement is used in older vehicles, such that theve and driven gear centrelines must meet each other as shown in Fig. 7.15. In this type, atI 1- - i-- ---^L^ ^L ---L:^l^ -^^^-.1+^e instant only one pair of teeth of pinion and the crown wheel will be in contact, which resultsuneven transmission of motion. Hence high wear and noise occurs during transmission,2. Spiral Bevel Gears : These have curved teeth hence greater contact of the teeth. Thesestronger and silent in operation than straight bevel gears (see Fig. 7.16).

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Fig. 7.15. Straight beuel gears Fig. 7.16. Spiral beuel gearsanother type ofbevel gear, the hypoid gear3. Hypoid Gears: In order to lower the pinion,Fig. 7.17), was developed. The teeth ofid gears are curved in a spiral. It is notssary to match the centrelines of hypoidrs, as the pinion can be set below thetreline of the crown wheel. The pinion canlowered so that the tunnel of the car and thetire vehicle can be lowered.

Hypoid gears also allow an end-wise slidingion between the pinion teeth and crown wheelh along with the rolling action. Because ofsliding action, it is possible to lap the crown

and pinion gears. This gives them morematch, smoother action and quieter

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Bevel oear ofstraighl teeth

I:I:-I:I

Fig. 7.17. Hypoid crown and pinion gears

Drive Line

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