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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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r>
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.
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- 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
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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
-. -. I I I.-.~--I , ,-.I
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;L1 I L2 L3fo i :P'----+. .; ; ; e2
--+;; ~el
i
I L4! L5 iY It Y
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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
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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
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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
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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
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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.