AXLE-REAR
MOTOR TRUCK SERVICE MANUAL
Fig. 10-Worn Support Case Hub.
Differential bearing hubs in axles that have been in
rapidity. At this point the bearing no longer functions
severe service are apt to be worn undersize as is the one
properly as the inner race is moving on the hub.
shown in Fig. 10.
A similar condition of wear may be the result of
When a truck is heavily overloaded, or subjected to
contaminated lubricant. If chips from broken parts are
excessive clutching, the pressures between the inner
left in an axle housing after a repair job, they will likely be
race of the differential bearing and the case hub are
picked up by the circulating lubricant and carried into the
exceedingly high. The bearings are forced to carry a
bearings. Foreign matter in the lubricant will temporarily
load greater than the capacity for which they were
lock the rolls of the bearing, forcing the inner race to turn
designed.
and wear the hub. The latter reason is by far the less
common of the two; and when it is, the evidence of
Consequently the hub is compressed and the race turns,
contaminated lubricant is generally present on other axle
wearing away the metal of the hub with increasing
parts.
67
