Spicer Drive Axles Failure Analysis Service Manual - Manual (Page 43)

Two Speed Planetary
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Pitting and Spalling Failures
Sliding Clutch - Pitting Planetary Gear - Spalling
Sliding Clutch - Shock Failure Planetary Gear - Shock Failure
General Description:
Pitting and spalling: Progressive destruction of gear teeth. An overload puts pressure between the
meshed surfaces. Repeated overloads result in teeth failure.
Shock: Damage from overstressing the gear teeth or shaft beyond the strength of the material. The fail-
ure can be immediate (as from a sudden shock) or progressive (as cracking of the teeth or shaft surface
following the initial shock).
Usual Causes:
Pitting and Spalling:
• Continuous overloading
• Contaminated lube
• Incorrect lube
• Low lube levels
Shock:
• Rough trailer hook-up
• Misuse of the lockouts
• Trying to free-up frozen brakes
• Spinning wheels grabbing on firm road surface
Failure Prevention:
• Vehicle Operation and Drive Practices - see Failure Prevention Section
Pitting
Granular
fracture surface