Spicer Single Drive Axles Service Manual: S170, S190, S590 - Manual (Page 68)

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Theory of Operation
Wheel Differential Lock
The Spicer Wheel Differential Lock is an optional feature for
spicer Axles. In operation, it positively locks the wheel differ -
ential, to provide improved traction under adverse road
conditions.
The differential lock is driver-controlled through an electric
switch or air valve mounted in the cab. The locking mecha-
nism is air-operated to engage a mechanical clutch and lock
the wheel differential. It is spring-operated to disengage the
lock and permit the wheel differential to function normally.
The wheel differential lock consists of three major assem-
blies.
• Shift Cylinder Assembly: Operates a shift fork and
push rod assembly.
• Shift Fork and Push Rod Assembly: Engages and
disengages the differential lock curvic clutch
assembly.
• Curvic Clutch Assembly: Consists of a sliding
clutch splined to an axle shaft and a fixed clutch
which is splined to the differential case hub.
The differential lock also includes a selector switch (elec-
tric) which senses clutch engagement and sends an electri-
cal signal to a cab mounted indicator light (or an audible
signal device) .
1 - Sliding clutch 5 - O-ring 9 - Pin
2 - Spring 6 - Piston cover 10 - Carrier
3 - Clutch fork 7 - Washer
4 - Piston and rod 8 - Switch
2
3
9
1
8
10
7
6
5
4