Inoperative Conditions

In the event the axle fails to operate, there will be obviously broken or jammed-up parts. It is important to try to analyze why the parts broke to prevent the condition from recurring.

Broken Axle Shaft

Inspect a broken axle shaft for a twist in the spline next to the break.

Breaks that occur away from the spline, or that are not accompanied by a twist in the spline, may be caused by forging flaws and/or fatigue of the shaft.

Conditions that can cause a broken axle shaft include forging flaws or excessive impact load to the shaft as a result of a collision, etc.

Broken Pinion Stem

The drive pinion stem is subject to conditions that can break it anytime the pinion bearing preload is not set up properly. If there is no preload, the front bearing cone and roller will turn relative to the shaft. This galls the roller shaft and generates heat, which can draw the temper away from the shaft.

Too much preload also generates bearing heat with the same result. The break normally occurs between the two bearings.

Broken Welds

Axle housing welds, if completely broken, call for replacement of the housing.

Wheel Bearing Malfunctions

Because of the severe loads they must handle, wheel bearings may require replacement at high mileage. If a wheel bearing fails at low mileage, it is often caused by overloading.

Axle Lockup

Lockup or seizure of the axle is usually associated with a low lubricant condition. The lubricant, of course, prevents friction and helps cool the parts as they heat up. Without enough lubricant, the heated parts get soft and may eventually weld together. Check for lubricant leaks after servicing.