AXLE-REAR
MOTOR TRUCK SERVICE MANUAL
Fig. 15-Fatigue-At Axle Shaft Flange
Worn wheel bearings caused the failure of the axle shaft
ring to Fig. 15, the fatigue or progressive fracture is
shown in Fig. 15.
clearly seen extending from the outside diameter about a
third of the distance in toward the center of the shaft.
Looseness in wheel bearing adjustment, causing
This failure worked in slowly until the body was so
misalignment, if not immediately correcte4 will almost
reduced in size that it would no longer carry the load.
invariably result in a fracture of this kind. Misalignment
The remaining portion was then broken through in a
between the differential and the hub, such as that
single action. This last area to fracture is darker in color
caused by a bent axle housing, will also create such
and rougher in texture. In cases of this kind, it is not
failures. It is to be noted that housings may deflect
uncommon for final rupture to occur when a truck is
sufficiently under heavy load to create a temporary
moving unloaded on excellent surface conditions. The
misalignment that will be in effect the same as a sprung
failure may have started many miles previous to that
or bent unit. Not necessarily will it follow that the housing
time.
when not carrying load will remain sprung.
The best preventive measure against such failures is
Fractures from such conditions are of the fatigue type
correct lubrication and proper adjustment of wheel
and
are
readily
identified.
Refer
72
