No.: ttsDate: Iday 15, L9?9

Page-of-(Supercedes TSB 60)

1. The Necessitv for Equal Universal Joint Working A.nglesso that working angles of transmission,

rear axle a:ra (if applicable) inter-axle universal joints are as nearly equal as possible. Equalworking angles compensate for the variations in velocity found between two angled universaljoints rotating together.

As a1 example, consider the diagram below. Note that the first universal jointr becauseit is coupling two angled shafts, will not transmit a constant speed. In this particular positiontthe drive line is moving slower than the transmission output shaft. The second universal jointthowever, has the effect of causing the pinion shaft to move faster than the drive line.If the two working angles are equal, then the two effects will cancell the pinion shaft willmove at the same speed as the transmission shaft, and the net result is a constantvelocity system.

Tronsmission Angle

Driveline Angle

Subject: Driveline Angles

Models: auEffective Date: N/A

Description of Change(s):

Eaton CorporationAxle & Brake DivisionField Service Dept.P.O. Box 4008Kalamazoo, M149003

Form E31 -739 laev.7 l78l Reprinted 3/82

Joint WorkingAng les

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In one complete revolution, the drive line will firstthen faster. The exact opposite condition will existtnerJl:"-Gulting in constant velocity.

Reor AxleAngle

move slower than the transmission shaft,betwe6-?EE drive line and pinion shaft,

Print€d in U.S.A.

z.

Unequal working angles cause the rotating members of the drive train to work without this

"p.ui cancellati-on elfect, resulting in noiie, vibration and premature-universal joint ordiive shaft wear. In severe cases axle and transmission failures can also result.

Axle Installation Methods@ionaltoinstalltransmissionandaxlesothatuniversaljointswereparallel to each other, mod.ern truck design with its emphasis on the use of tandem axles made

ihi" .pp.oach impractical in some cases. -As a result, the non-parallel o_r_"broken-back"

installation method was developed for tandem inter-axle applications. Illustrated below are

examples of both parallel and broken-back installations'

PARALL E L INSTALLATION

parallel Installation: Axle assemblies are mounted at equal angles, resulting in parallel yokes

and equal working angles at each universal joint.

NON - PARALLEL INSTALLATION

Non-Parallellnstallation:Axleassembliesarenotmountedatequalangles,butworkingangles are equal at each universal joint. Ir this t1rye of installation, the forward axle must

be mounted parallel to the transmission. The *""i*u* mismatch for working angles is 1030"

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Characteristics of Unequal Drive Line Anglestified by the presence of noise or vibration

within certain speed ranges which diminish or disappear when the vehicle is not in those ranges.Persistent and otherwise unexplainable drive line component failure caJr also point out a driveline angle problem. Noise or vibration which is consistent throughout the vehicle's entireoperating r€rnger varying only in intensity with change of speed, is generally related toan unbalanced condition in one or more drive train members and is not necessarily related.to improper driveline angles. Should this condition exist, insure that driveline balance isrestored and the vehicle tested before continuing with angularity checking.

Checking Driveline AnglesUniversal joint working angles can be checked by measuring them with a bubble protractorfrom the machined surfaces present on most driveline components. This measurement processnormally requires partial disassembly of the driveline to expose machined surfaces. Achart made-up beforehand showing each component and universal joint in the drive train willsimplify the checking procedure by providing a place to record all critical angles. Appendix Ashows measuring tools and procedures for measuring from various universal joints. Beforechecking angles, the vehicle must be parked on level ground. Tires should have normal airpressures. The transmission must be in neutral with the parking brake "off". If the vehiclehas a movable body (such as a dump), it should be placed in normal operating position. Ideallyangles should be checked with the vehicle both loaded and unloaded.

Al\ CAUfiON: Insure the vehicle is secured from rolling by means of blocks before continuing.

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5. Points of Measurement

-

Driveline angle readings should be made from machined surfaces of the following componentsand recorded:

a. Single axle vehigle (or tandem with non-driving rear ax.]el

2. If present, transfer caser aux drive or retarder (input and output yoke).3. If present, central universal joint (input and output yoke).4. Drive Axle (input yoke).5. Drive-shafts.

b. Tandem axle vehicle1. Transmission (output yoke).Z. If present, transfer case, aux transmission or retarder (input or output yoke).3. Tandem forward axle (input yoke-inclinometer flat or pump cover).4. Tandem rear axle (drive pinion yoke).5. Both main and inter-axle drive shafts.

Computing Drive Line AnglesOnce component angles have been established, universal joint working angles can be compared.to allow determination of the adequacy of drive line angles.

4.

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6.

To compute for correct anglgs (tandem axle)

1. The ai?terence uetween tJIe drive shaft angle and the transmission angle is the v.t"*"ryioitt *o"kitg *el*

z. ThE airference between IG6il. shaft angle and the power divider input jointworking angle is the forward axle ioint -w.orki+g anglg

3.Thedifferencebetweenandtheforwardaxleangleis the output shaft joint Yorking angle'

.4. The difference between lE;-a;Ae-angle and the inter-axle drive line angle

is the rear axle joint working angle'

Compare the transmission and forward axle joint working angles' Compare output shaft and

rear axle joint working algles. For optimum component life, the working angles in the-se paired

ioirrts stouta be withiri 1o J0' and not exceed the U-joint manufacturer's recommended maximum

working angle. See the charts contained in this bulletin for various driveline combinations'

Forward axle angle Rear axle angle10'30'

Driveline. angle 6'45'

Y

Working angles 3'45'

\4iorking angles were computed as follows:

Inter-axle driveline angle:Less forward axle angle:

Rear axle angle:Less inter-axle &iveline angle:

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30 45' 5oittt

Loo 30'-60 45'

30 45' joint working angle

Working angles are equal at 30 45'.

An "uphill" drive line exists when the engine/transmission inclination.is_dolvP whilg the drive

line inclination is y2 (engine CL below axle input CL: example A & U), t this configuration,

working angles wiiiiend-to increase when the vehicle is loaded. Working angles must be

"o*prriud f,y addine co-pott6t-ao-gles rather than subtracting as is the case with a

"dorinhiu" arilffit- irr"t^"tt"tiorr. Ii "do*nhillu drive line installation (example C & D)

the joint working angles will normally decrease as the chassis is loaded'

working angle

7. Yl

Typical Uphill Drivelines

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B.

Typical Downhill Drivelines

Correcting Unequal Drive Line AnglesFollow the vehicle manufacturer's recommendations for adjustment of mounting angles in driveaxles, transmissions and other components. When reassembling the drive line insure that yokesand slip joints have been phased properly. Note: Male/Female driveline members should bemarked before disassembling to allow accurate reassembly of yokes and slip joints. Aftercompleting adjustments, test the vehicle in both loaded arrd unloaded condition. It should be freeof excessive noise and vibration.

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