Spicer Single Drive Axles Service Manual: Single Reduction & Single Reduction with Differential Lock - Manual (Page 60)

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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
differential, 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 assemblies.
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 a axle shaft
and a fixed clutch which is splined to the differential
case hub.
The differential lock also includes a selector switch (electric)
which senses clutch engagement and sends an electrical sig-
nal to a cab mounted indicator light (or an audible signal
device).
1— Curvic clutch assembly
1a—Sliding clutch
1b—Fixed clutch
2— Shift fork and pushrod assembly
2a—Shift fork
2b—Pushrod
3— Shift cylinder assembly
3a—Piston driver
3b—Selector switch
1
1b
1a
2
2a
2b
3
3a
3b