Spicer Tandem Drive Axles Service Manual D170, D190, and D590 Series - Manual (Page 89)

85
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 mechanism
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 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
Theo
ry of Operation