Subject: Driveline Angles No.: tts Date: Iday 15, L9?9 Models: au Page-of- Effective Date: N/A (Supercedes TSB 60) Description of Change(s):
1. The Necessitv for Equal Universal Joint Working A.ngles so that working angles of transmission, rear axle a:ra (if applicable) inter-axle universal joints are as nearly equal as possible. Equal working angles compensate for the variations in velocity found between two angled universal joints rotating together.
As a1 example, consider the diagram below. Note that the first universal jointr because it is coupling two angled shafts, will not transmit a constant speed. In this particular positiont the drive line is moving slower than the transmission output shaft. The second universal jointt however, 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 will move at the same speed as the transmission shaft, and the net result is a constant velocity system. \.,/'
Tronsmission Angle
Driveline Angle
Joint Working Ang les Reor Axle Angle
In one complete revolution, the drive line will first move slower than the transmission shaft, then faster. The exact opposite condition will exist betwe6-?EE drive line and pinion shaft, tnerJl:"-Gulting in constant velocity.
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Eaton Corporation Axle & Brake Division Field Service Dept. P.O. Box 4008 Kalamazoo, M149003 Print€d in U.S.A. Form E31 -739 laev.7 l78l Reprinted 3/82 Unequal working angles cause the rotating members of the drive train to work without this cancellati-on elfect, resulting in noiie, vibration and premature-universal joint or diive"p.ui shaft wear. In severe cases axle and transmission failures can also result. z. Axle Installation Methods @ionaltoinstalltransmissionandaxlesothatuniversaljointswere mod.ern truck design with its emphasis on the use of tandem axles made parallel to each other, -As ihi" .pp.oach impractical in some cases. 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,butworking angles 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" I Characteristics of Unequal Drive Line Angles tified 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 drive line angle problem. Noise or vibration which is consistent throughout the vehicle's entire operating r€rnger varying only in intensity with change of speed, is generally related to an 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 is restored and the vehicle tested before continuing with angularity checking.
4. Checking Driveline Angles Universal joint working angles can be checked by measuring them with a bubble protractor from the machined surfaces present on most driveline components. This measurement process normally requires partial disassembly of the driveline to expose machined surfaces. A chart made-up beforehand showing each component and universal joint in the drive train will simplify the checking procedure by providing a place to record all critical angles. Appendix A shows measuring tools and procedures for measuring from various universal joints. Before checking angles, the vehicle must be parked on level ground. Tires should have normal air pressures. The transmission must be in neutral with the parking brake "off". If the vehicle has a movable body (such as a dump), it should be placed in normal operating position. Ideally angles should be checked with the vehicle both loaded and unloaded. A l\ CAUfiON: Insure the vehicle is secured from rolling by means of blocks before continuing. \-/
5. Points of Measurement Driveline angle readings should be made from machined surfaces of the following components and 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 vehicle 1. 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). I 5. Both main and inter-axle drive shafts.
6. Computing Drive Line Angles Once component angles have been established, universal joint working angles can be compared. to allow determination of the adequacy of drive line angles. To compute for correct anglgs (tandem axle) angle is the 1. The ai?terence uetween tJIe drive shaft angle and the transmission v. *o"kitg *el* t"*"ryioitt joint z. ThE airference between IG6il. shaft angle and the power divider input working angle is the forward axle ioint -w.orki+g anglg 3.Thedifferencebetweenandtheforwardaxleangle joint angle' is the output shaft Yorking . 4. The difference between lE;-a;Ae-angle and the inter-axle drive line angle is the rear axle joint working angle' output shaft and Compare the transmission and forward axle joint working angles' Compare the-se paired axle joint working algles. For optimum component life, the working angles in rear maximum stouta be withiri 1o J0' and not exceed the U-joint manufacturer's recommended ioirrts combinations' working angle. See the charts contained in this bulletin for various driveline
Forward axle angle Rear axle angle 10'30'
Driveline. angle 6'45'
Y
Working angles 3'45'
\4iorking angles were computed as follows:
Inter-axle driveline angle: loo+s' Less forward axle angle: -J
30 45' 5oittt working angle
Rear axle angle: Loo 30' Less inter-axle &iveline angle: -60 45'
30 45' joint working angle
Working angles are equal at 30 45'.
the drive 7. An "uphill" drive line exists when the engine/transmission inclination.is_dolvP whilg Yl 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 f,y addine co-pott6t-ao-gles rather than subtracting as is the case with a (example "o*prriud"dorinhiu" arilffit- irr"t^"tt"tiorr. Ii "do*nhillu drive line installation C & D) the joint working angles will normally decrease as the chassis is loaded' Typical Uphill Drivelines
\/ A.
B.
Typical Downhill Drivelines
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8. Correcting Unequal Drive Line Angles Follow the vehicle manufacturer's recommendations for adjustment of mounting angles in drive axles, transmissions and other components. When reassembling the drive line insure that yokes and slip joints have been phased properly. Note: Male/Female driveline members should be marked before disassembling to allow accurate reassembly of yokes and slip joints. After completing adjustments, test the vehicle in both loaded arrd unloaded condition. It should be free of excessive noise and vibration. at, (D (tl C I I lo) (]lr lx \z lr)< .=.- L: lrl ! st() o; UJ lrJ ;3via JJ o) z.- (9(9 * =i 4{ lo z.z o '6U O')-3 2Z l+ o) c E t'- ro \__D- It LI -(9J=A
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