Failure prevention – Spicer Drive Axles Failure Analysis Service Manual User Manual
Page 6
Failure Prevention
5
Controlled Traction Differential
A controlled traction differential is a biasing unit designed into the axle wheel differential. It provides the truck with effective trac-
tion control under adverse driving conditions, especially off the highway. A controlled traction differential is especially effective in
minimizing the possibility of spinout.
2-Speed (Dual Range) Gearing
See Spicer Driver Instruction AXDR-0134.
Spicer drive axles are equipped with 2-speed gearing to provide maximum operating efficiencies in two extreme situations:
•
Off-highway fully loaded
•
On-highway fully loaded
The low range provides deep reduction and maximum torque when off-highway or on steep grades. The high range provides a
faster ratio for cruising and fuel economy.
Premature failures of shifting parts, drive axles, and other drive train components can be prevented by proper driving per manual
instructions and training. There are two important rules to follow:
•
Do not abuse axle-shifting parts. Follow the instructions for shifting the axle.
•
Do not abuse the drive train components. Use low range when torque requirements are high such as on rough roads, on
steep grades, and under other adverse conditions.
Drive Axle Wheel Differential Lock
See Spicer Drive Instruction AXDR-0130.
The drive axle wheel differential lock is an air-actuated clutch which positively locks the differential gearing in the rear axle. When
this clutch is engaged, power flows to the tires without any differential action, giving each wheel all the torque the road conditions
will permit.
A cab-mounted valve moves the wheel differential lock in or out of engagement. This motion also trips an electrical switch that
activates a light in the cab or sounds an audible device to indicate that the wheel differential lock is engaged.
When the clutch is disengaged, the differential operates normally, dividing torque equally between the tires and compensating nor-
mally for cornering or tire size variations.