EVALUATION OF LENGTH OF PROPELLER SHAFT

Mrs Archana S.Chavan I Mr.Chavan S. S2. Prof. Patil R N3.

I Research Scholar 2 Research Scholar 3 Assistant Professor

Department Of Mechanical Engineering Bharati Yidyapeeth University, College of Engineering,

Dhankawadi, Pune-43. Ph. [0] (020) 24371378 exrn. 298 [M] 9226794076 Fax: (020) 24372998

E-mail: -sachin77887(aJ.rediffmail.com

Abstract

The power from Transmission shaft should be transmitted to the Rear axle of the vehicle. The axisof the Transmission and the connecting member of Rear axle are at an angle, which changes with thevariation in load or the road condition. To facilitate the power transmission at a variable angle a Propellershaft is used. With respect to the geometrical construction the Propeller shafts are categorized into singlepiece two-piece and three-piece propeller shafts.

In case of two or multi stage propeller shaft length of the rear propeller shaft is subjected tovariation while the remaining propeller shafts are rigid members; i.e. do not change in length. The variationin the length of rear propeller shaft is allowed using a splined shaft. Generally length of the propeller shaftis decided after freezing the remaining aggregates. It is assumed that the inclination of cross memberbracket (in case of multistage propeller shaft) is also decided based on the requirement criteria such as betaequivalent angle. The maximum and minimum length of the propeller shaft required is found in this paperthere by finding the slip required for the particular vehicle. The main objective of the paper is to find thelength of the propeller sha ft.

A Microsoft Excel program is made which reveals the calculation. Hence, if a parameter ischanged, its effect in the other output values can be easily seen.

Keywords: Propeller Shaft, Splined Shaft, Universal Joint,

1. INTRODUCTIONWhere the engine and axles are separated

from each other, as on four-wheel-drive and rear-wheel-drive vehicles, it is the propeller shaft thatserves to transmit the drive force generated bythe engine to the axles. For its usage, the optimalshaft is a short, bar-like product. The longer thebar, the more liable it is to sag and sagging isfurther promoted when rotation is applied.Sagging causes vibration and results in anincrease in noise, to such an extent that the shaftis likely to break when the critical speed isexceeded. The propeller shaft is naturallydesigned not to break when used within theservice limits expected of use. In addition. it isis subjected to variation while the remainingpropeller shafts are rigid members; i.e. do not

designed to suppress vibrations arising from awide range of causes [I].

Defining the length of the propeller shaftis an important task in the production of anyvehicle. The power is transmitted from Gearboxto differential by means of propeller shaft.Depending on the length of the vehicle there is anecessity to make the propeller shaft in stages.The orientation of the propeller shaft is a criticalfactor defining the length of the propeller shaft.In case of multistage propeller shaft theintermittent pieces are supported by centerbearings. which are mounted on the bracket ofcross member [2]. In case of two or multi stagepropeller shaft length of the rear propeller shaftchange in length. The variation in the length ofrear propeller shaft is allowed using a splinedshaft [I].

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Where the engine and axles are separatedfrom each other, as on four-wheel-drive and rear-wheel-drive vehicles, it is the propeller shaft thatserves to transmit the drive force generated bythe engine to the axles.

The basic function of a driveshaft is totransmit power from one point to another in asmooth and continuous action. In automobiles.trucks and construction equipment the drive trainis designed to send torque through an angle fromthe transmission to the axle (or auxiliarytransmission).

The driveshaft must operate throughconstantly changing relative angJes between thetransmission and axle. It must also be capable ofchanging length while transmitting torque. Theaxle of a vehicle is not attached directly to theframe, but rides suspended by springs in anirregular, floating motion.

This means the driveshaft must be able tocontract. expand and change operating angleswhen going over bumps or depressions. This isaccomplished through universal joints. whichpermit the driveshaft to operate at differentangles, and slip joints which permit contractionor expansion to take place [4]. Fig. 1 shows theSchematic representation of vehicle.

Fig. 1 Schematic Representation of vehicle

To fmd the length of the propeller shaftthereby finding the slip required for theparticular vehicle in,

Bump condition ,Rebound condition. Flatcondition.

The inputs parameters of the program are as.Engine block, Gear Box housing, Frame,Rear axle Rear suspension, Propeller shaft.

The output parameters of the program are as,Maximum length of the propeller shaft.Minimum length of the propeller shaft.

2. TYPES OF PROPELLER SHAFT 13)

2.1 Single piece propeller shaftVehicle models: - This type is used invehicles with a short distance between theengine and axles, MR base four-wheel-drivevehicles.Characteristics: - The friction weldingadopted at the junction has contributed to animprovement in the strength, quality, anddurability of the junction.- A reduction in the number of componentparts and in the weight has been achieved.

_Fig. 2 Single piece type propeller shaft(Courtesy)

2.2 Two piece Propeller shaftVehicle models: - This type is used in vehicleswith a long distance between the engine andaxles, Front engine front drive base four-wheel-drive vehicles, and the like.Characteristics: - The division of the propellershaft into two parts has allowed the critical speedto be prevented from falling and the vibrationproblem from occurring, which would otherwisebe the case when the overall length of the shaft isincreased.

Fig. 3 Two piece type propeller shaft

(CourtesY)

- The dynamic damper inserted into the pipereduces the vibration and noise.

- A reduction in the number of componentparts and in the weight has been achieved.-Two piece drive lines, with two propeller'shafts and an intermediate support bearingShown in fig. 3 are generally used on truckswith wheel bases from 3.4 to 4.8m.2.3 Three piece propeller shaftFor vehicles more than 4.8m wheel bases, athree piece drive line with two intermediatesupport bearings may be necessary as shownin fig. 4.

Fig. 4 Three piece type propeller shaft

3. EVALUATJON METHOD

3.1 MECHANJSM AFFECTJ GPROPELLER SHAFT LE GTH

Different mechanisms that affect the length ofthe propeller shaft are found to be

I. Axle path of the rear suspension system2. Static brake windup

I. Axle path of rear suspension systemThe length of the propeller shaft attains

the extreme conditions because of the motion ofthe suspension system. The path traced by theaxle is identified and at each configuration lenzthof the propeller shaft is foun-d. Differe;cebetween the maximum and minimum lengthsgives the slip that should be allowed.

As the spring leaves of constant crosssection properly stepped to approach thecondition of uniform strength is deflected, it willassume the shape of circular arc at all loadsbetween zero and maximum load, provided it hasa circular arc shape or is flat at no load or at anvgiven load.

It is observed that most of the springsapproximate these conditions closely enough sothat the circular arc shape can be used tocalculate their geometric properties. A set ofprocedure is used to reproduce the path traced bythe bottom of the spring with an accuracy of 1%.

When flexibility or deflection in a mechanicalsystem is specifically desired. some form of thespring can be used. Otherwise the elasticdeformation of an engineering body is usually adisadvantage.

Spring:Spring part made in a particular configuration toprovide a range of forces over a significantdeflection or to store potential energy.

Springs are employed to exert forces ortorques in a mechanism or to absorb the energyof suddenl_ applied loads. Springs frequentlyoperate with high values of working stresses andwith loads which are continuously varying.Helical and leaf springs are in widest use. Thesprings take care of two fundamental verticalactions: jounce & rebound. [ I I]JOUNCE (Bump) occurs when the wheel hits abump & moves up. It is upward displacement ofwheel relative to the car bodv. When thishappens. the suspension systems -acts to pull inthe top of the wheel, maintaining an equaldistance between the two front wheels &preventing a sideways scrubbing action as thewheel moves up and down. Road bumps orspeed breakers function as speed reducing byinducing jerks & vertical acceleration. The driverknov s that higher the speed. the greater thediscomfort S: forces on the 'vehicle. The degreeof comfort varies with the bump profile, heightgradient, length & vehicle parameters. (12]REBOUND (Droop) occurs when the wheel hitsa dip or hole and moves downwards. It isdownward displacement of wheel relative to thecar body. In this case. the suspension system actsto move the wheel in at both the top and bottomequally, while maintaining an equal distancebetween the wheels.The spring goes back & forth from jounce torebound. Each time, jounce & rebound becomesmaller &smaller. This is caused by the systemsmolecular structure and the suspension pivotjoints. A shock absorber is added to eachsuspension to dampen and stop the motion ofspring after each jounce.Cantilever Spring

For a spring of this type the center ofthe eye of the Berlin type moves in a path withradius of 0.751 central to the main leaf: I beingthe front length minus the inactive length onfront spring. If a distance 'e from centers-of themain leaf offsets the eye center. the center of arcwill be offset by 0.5e in the opposite direction.This construction reproduces the change of arc

height with an accuracy of I% up deflection of0.6\.

Two Point Deflecrion Method POJThis method is used for construction of the axlepath of circular spring. It has the advantage thatall of the layout work can be done within the overalllength of the spring. In cases where the unsymmetryfactor is small and the 0 point is far from the axlecenter, it is the only known procedure whichpermits construction within the confmes of thestandard layout board and straight edge.The principle of this method is based upon the

use of the two cantilever deflections correspondingto a given deflection at the center of the spring seat.These deflections may be computed for two verticalpositions of the spring seat, for example maximumcompression (metal-to-metal) and maximumrebound. When they are applied to the three-linkequivalent of the spring with the main leaf in the flatposition, the path of the axle and the angles of thespring seat can be determined entirely byconstruction.

4. METHODOLOGY

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Fig. 5 Ray Diagram of propeller shaft

The Location hole is taken as a referencealong the length of the vehicle. The top of theframe is the reference for vertical axis. Thecoordinates of the point is located using thedimensions of different aggregates. The end ofprop2 connected to differential is the criticalpoint deciding the length of the propeller shaft.To locate the point the input can be theinclination of spring stack with the vertical andthe distance of bottom of spring from the top of

the long member. The other dimensions aregiven with respect to the bottom of the spring.Based on geometry "the position of end of prop2can be found. In case of bump and reboundcondition the axle path curve is used to locate thepoint. The distance between the two ends of theprop2 is the length of the prop shaft

5. J PlJTS TO THE PROGRAM I) IThe basic components that affect the length ofthe propeller shaft are identified to be:

I. Engine block2. Gear Box housing3. Frame4. Rear axle5. Rear suspension6. Propeller shaft

The coordinate system:The top of the frame, centerline of location holeand vehicle centerline are considered as the threecoordinated of the body of the vehicle. In input.the locations of different components arereferred with respect to this coordinate system.1. Engine Block

I. The inclination of the engine withrespect to the top of the frame inclockwise direction.

2. The distance between the centerline ofthe engine and the rear face of theengine block

3. The distance of the crankshaft of theengine from top of the engine at thecenterline of engine.

4. Distance between the centerline oflocation hole and center line of engineblock

5. Length of flywheel housing2. Transmission

I. The length of clutch housing betweenthe flywheel and gear box

2. The length of gear box housing from theclutch face to the flange face

3. FrameI. Distance between the centerline of front

axle and the centerline of location hole2. Distance of Cross member from center

line of location hole along top of theframe

3. Inclination of cross member on theframe with respect to the vehiclecoordinates in anticlockwise direction

4. X coordinate of the Eye I of the rearleaf spring

5. Y coordinate of the Eye of the rearleafspring

6. X coordinate of pivot of shackle of rearleaf spring on frame from center line oflocation hole

7. Y coordinate of pivot of shackle of rearleaf spring on frame from the top of theframe

4. Rear axleI. Distance between the axle of the crown

wheel and pinion in side view2. Distance between the axle of the crown

wheel and pinion in plan3. Distance of spring bottom to the axle

center4. Distance of axle center to the flange

face on the pinion connected to thepropeller shaft

5. Inclination of mounting face of the rearaxle suspension with X axis inclockwise direction

5. Rear SuspensionI. Span of the spring III flat spring

condition2. Length of the shackle of rear suspension3. Stack height of the main spring in

suspension system4. Diameter of eye of the spring

6. Propeller Shaft

I. Distance between flange face and theUJ cross center

../ Two piece propeller shaft

I. Distance between flange face and theUJ cross center

2. Inclination of cross member bracket onthe frame

3. Distance of axis of center bearing to themounting bracket face

4. Distance between center bearing andflange face along the axis of propellershaft

5. Center bearing offset at the crossmember along x axis

../ Three piece propeller shaftI. The corresponding inputs for second

cross member need to be given as input.

../ Single piece propeller shaft

6. PROGRAM FOR LENGTH CALCULA TlON6.] Program Input

Vehicle 1-PROGRAM TO CALCULATE THE LENGTH OF PROPELLER SHAFT (2PIECE)

INPUTX coordinate of CL of Location hole XI 0X Coordinate of CL of front axle from CL of location hole (abs value) e2 25X coordinate of Eye I of Lf spring from CL of location hole Xl 2410

FRAME Y coordinate of Eye Iof Lf spring from top of frame YI ]3].5X coordinate of shackle pivot of Lf spring on frame from CL of locationhole X2 3980Y coordinate of shackle pivot of Lf spring on frame from top of frame Y2 131.5

Angle of inclination of Engine with the X axis(in degrees) Tl 2X Coordinate of CL of Engine from CL of location hole (abs value) el 70

ENG.Y coordinate of CL of Engine from frame top face L7 ]85MTG.Distance between CL of the Engine to the RFOB Ll 375Length of Flywheel Housing (RFOB TO RFOFH) L2 134.1

GEAR Length of Clutch Housing (RFOFH TO RFOCH) L3 ]76BOX Length of Gear Box (RFOCH TO GB Flange face) L4 596

PROP.SH. Distance from Prop. Shaft Flange face to Center of Yoke L5 83.3

Distance between the center of the rear axle and the flange face (in Zdirection) Lxz 45

REARDistance between the center line of rear axle and the flange face center(in y direction) zl 40

AXLE Distance of spring bottom to the axle center 88.5raDistance from center of Rear axle to the flange face zO 388Inclination of mounting face of rear axle (along x axis) T5 1.75Length of shackle of rear spring P2 ]00

SUSP.Length of Main leaf of leaf spring P3 ]600Stack height of rear spring ( Main spring) Hs 196Diameter of eye of spring De 30

r

Distance between the CL of Engine and the CLof front axle e 45Angle of inclination of Engine with the Xaxis(in radians) TI in radians 0.034906585Inclination of mounting face of rear axle( Inradians) T5 r 0.030543262Total Length between CL of front axle (0) andGB flange yoke center (B) OB 1319.372571Coordinates of 0 o (x, v. z) 0 186.57143Coordinates of B B(x,y,z) 1318.568844 232.61687Distance between two pivots of the spring PI 1570

P4 32.84375Inclination of spring with the line joiningpivotes on the frame ALFAI 0.060197223 3.4490468Angle between two pivotes on frame withrespect to top of the frame T3a 0 0Inclination of spring with the vertical axis ( Yaxis) Ts 0.060197223X coordinate of Center of main spring leaf (fromfront axle) Xr 3233.550955Y coordinate of Center of main spring leaf (fromfront axle) Yr ] 79.6286984X coordinate of bottom of spring/rear axlecenter Xb 3220.8570 I IY coordinate of bottom of spring/rear ax Iecenter Yb 390.2465129

Hsl 211Distance of rear axle center from top of theframeiby program) L8 438Length of differential housing from center ofaxle to the yoke z3 471.3Inclination of rear axle center with respect to xaxis T3 1.699046791 0.029654Distance between the bottom of spring and thepinion connected to the propeller shaft z l+ra 128.5

z2 114.5199903z4 3.395473595z5 471.5072965

OUTPUT

Distance between rear axle and center of theyoke along x axis DE-x 474.9027701X coordinate of 0 Ox 2745.954241Y coordinate of 0 Dy 504.7161549Z coordinate of 0 Dz 45X offset of bottom of spring and the center ofyoke of propeller shaft DBsx 474.9027701Y offset of bottom of spring and the center ofyoke of propeller shaft Dbsy 114.469642Coordinates of 0 o (x, v, z) 2745.95424 I 504.71615Length of propeller shaft 2 (yoke to yoke) 1453.785435

7. RESULT

RESULT

Prop2 I 1620.385435 ILength of propeller shaft 2 ( from flange end tothe flange end)-FLAT SPRING CONDITION

Minimum length of propeller shaft 2 2403.42849 IMaximum length of propeller shaft 2 2500.387487Slip required for propeller shaft spline shaft 96.95899546

Inclination of shackle with the s 1.536835Inclination of shackle with the s 88.05416

8. CONCLUSIO

The maximum and minimum length ofthe propeller shaft required is found in this paperthere by finding the slip required for theparticular vehicle. A Microsoft Excel program ismade which reveals the calculation. Hence, if aparameter is changed. its effect in the otheroutput values can be easily seen.

9. REFERE 'CES

I). H. I. F. Evernden, "The Propeller Shaft orHooke's Coupling and the Cardan Joint, ..Proceedings of the Institution of MechanicalEngineers. October, 1949. PP. 5-6.2). Thomas. D. Gillespie. 1994. Fundamentals ofVehicle Dynamics, PP. 24.3).http://v,,\w.showa/.com/enJProducts/4rs/Propeller. S. html.

4). Wagner. E. R. "Driveline and DriveshaftArrangements and Constructions, "UniversalJoint and Driveshaft Design Manual, Chapter

J, SAEAE-7. 1947,PP.440.5). P. J. Mazziotti, "Universal Joint and PropellerShaft. "Dana Corporation Bulletin J-1371,October 15, 1954.6). B. R. Reimer. Design and ApplicationConsiderations for Agricultural PTO Drivelines,SAE Paper 650680, 1965.7). http://w\vw.tpub.Com!Content!constructionlI4273/ css / 14273 182. html.8). Welded steel Tube Institute, Handbook ofWelded Steel Tubing, 1967.9). L. J. DiFrancesco, Better Needle Bearings forUniversal Joints, SAE Paper 660159, 1966.10). Spring Design Manual. AE-21.1I). John C Dixon. Tires, Suspension &handeling.12). Gawde, Mukherjee. Mohan. Sept 2004 .Wheel lift-off &ride comfort of three wheeledvehicle over bump. IE (I) Journal-MC.PP 78-87.