AXLE-REAR
MOTOR TRUCK SERVICE MANUAL
Fig. 12-Fatigue Fracture-Differential Side Gears
Repeated stresses reaching the maximum strength of
driver regarding two-speed axle operation. Education of
differential side gears, causes progressive failures of the
the driver plays a very important part in the prevention
type shown in Fig. 1; Applied forces were not sufficiently
and elimination of failures like this. Abusive handling of
high to cause immediate complete rupture at first, b
equipment is usually unnecessary and must be stopped
continued applications further opened the original
if long life and trouble-free service are to be expected.
fracture until there was not sufficient strength to carry the
load in the remaining section. Portions of the gear teeth
When repairing a job of this kind, give attention to all
were then broken out fully. Fatigue or progressive
differential gears and pinions. Although they may not
fracture is most clearly seen at points A and B.
have ruptured completely, they may be cracked and on
their way toward failure. Careful repair work and the
"Frogging" or "bucking" the truck will tend to produce the
replacement of questionable parts is in the end the least
expensive way.
conditions of the job alone, but lack of knowledge on the
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