Spicer Drive Axles Failure Analysis Service Manual - Manual (Page 5)

Failure Prevention
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Driving Practices
Driving practices have a large influence on the service life of a truck axle. Good driving practices can eliminate shock and prevent
undue strain not just on the axle, but on the entire truck.
There are two driver practices that are detrimental to axle parts life:
• Subjecting the vehicle to undue rough handling
• Driving under road conditions not specified
Either of these practices could cause premature axle failure.
Even conscientious drivers may encounter an unusual adverse situation of an exceptionally rough road. The driver should be
trained to regulate speed and brake application according to road conditions.
Training is Essential
Driving a truck is an important job that can be performed more effectively with thorough training. The driver needs to know all the
specifics about the hauling job such as payload characteristics, anticipated road conditions, and roads to be avoided. The driver
must also be well informed about the equipment. For example, the driver should know answers to such questions as:
• What was the truck designed for?
• Why does the truck have a differential lockout?
• What is the function of a controlled traction differential?
• What are the benefits of 2-speed gearing in the drive axle?
A well-informed driver with proper training will eliminate many drive axle failures.
Failure-Preventing Equipment
Spicer tandem axles incorporate design features that can help prevent axle failures. Four important equipment features are:
• Inter-axle Differential Lockout
• Controlled Traction Differential
• 2-Speed (Dual Range) Gearing
• Drive Axle Wheel Differential Lock
The driver must know the purpose as well as the proper use of these important design features.
Inter-axle Differential Lockout
See Spicer Driver Instruction AXDR-0126.
The inter-axle differential lockout increases traction effort under adverse road conditions.
When engaged, the lockout provides positive drive to both axles. When the drive wheels of one axle are subjected to a condition
of wheel spinning, the drive will continue to the other axle (to the wheels with traction) and move the truck.
Proper use of this lockout feature is important:
• Do not engage lockout while wheels are spinning.
• Do not engage lockout when driving conditions are good.
Improper use of the lockout could result in unnecessary axle parts failure.