Eaton Positive Locking Differentials - GMC 1982 Light Duty Truck Service Manual

4B6-12 REAR AXLE
EATON POSITIVE LOCKING DIFFERENTIAL
PINION SHAFT
CAMFORM SIDE GEAR
CAM PLATE
WAVE SPRING
SHIM
r THRUST RING
G EN E R A L D ESCRIPTIO N
Trucks equipped with locking differentials use one of
the Eaton locking units in Figure 4B 6-1H , 2H. These
differentials provide true differential action and also
incorporates a speed sensitive device which automatically
and positively locks both rear wheels together if either wheel
should spin excessively during slow vehicle operation.
Locking is accomplished through the use of a flyweight
governor mechanism, cam system, and multi-disc clutch.
The flywheights on the governor mechanism move outward
to engage a latching bracket whenever the wheel-to-wheel
speed varies by approximately lOOjpm or more. This action
retards a cam which, in turn, compresses a multi-disc clutch
locking one side gear to the case. At wheel-to-wheel
differentials of less than approximatley 100 rpm, the unit
operates as a standard or open differential.
At vehicle speeds above approximately 20 mph (32
km /h), the latching bracket overcomes a spring preload and
LOCKSCREW
LOCK WASHER
___________
PINION THRUST —^
WASHER (2)
GOVENOR ASSEMBLY
1/2 TON LOCKING DIFFERENTIAL
Fig. 4B6-1H--1 /2 Ton Unit
B U S H IN G ^ BUSHING
EARED DISC (3)
SPLINED DISC(2)
THRUST BLOCK
PINION GEAR{2)
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swings away from the flyweights. At this vehicle speed or
greater, the differential will not lock as the added traction is
not necessary.
Service Test Procedure
1. Place the Truck on a frame-contact hoist, allowing free
rotation of the rear wheels.
2. Raise hoist until wheels clear floor. Holding one wheel
stationary, slowly rotate other wheel approximately 1 /2
revolution per second, in both the forward and reverse
directions. Wheel should rotate freely. If both wheels
attempt to turn together the differential is locking and
is defective.
Rapid wheel rotation will cause a properly operating
differential to lock and both wheels will rotate in the
same direction.
3. Raise hoist to maximum height with one person in
vehicle.
GUIDE CLIP(4)
LATCHING BRACKET ASSEMBLY