Lesson 2/Learning Event 2
The top and bottom of the round end of the housing contain mounting points for the
spindle or knuckle bearing. Around the outside and partly covering most of the round
ends of the axle housing are the steering knuckle housings. The steering knuckle housing
is connected to the end of the axle housing by upper and lower knuckle bearings.
On this type axle, a kingpin cannot be used to hold the bearings in position, because it
cannot pass completely through the housing of a live axle. Two short kingpins are used
on the top and bottom of each end of the axle to align the bearings. These kingpins may
be mounted on the axle housing or on a plate that bolts to the top and bottom of the
steering knuckle housing.
Tapered roller bearings help support the vehicle and keep the steering knuckle in proper
alignment. The bearings also provide a pivot or turning point for steering the wheels.
Shims are used at the bearing mounting surfaces to ensure proper adjustment. An oil
seal, mounted on the inner side of the steering knuckle housing, rides on the round
surface at the ends of the axle housing. The spindle has a flange that bolts to the outside
of the steering knuckle housing. The spindle also serves as a mounting point for the
wheel hub and bearings.
CONSTANT VELOCITY JOINTS (CV JOINTS)
The axle shafts operate in the hollow tube sections on each end of the axle housing. The
inner end of the axle shaft is splined to a side gear in the differential assembly. On most
tactical military vehicles, the outer end of the axle shaft is splined to a flange. This
flange is bolted to the wheel hub and provides the means of driving the front wheel.
The front axle shafts must be able to pivot in the steering knuckle, and there must be a
universal joint to transmit power at an angle. A single, conventional universal joint (the
type used in the propeller shaft) does not meet military requirements for use on the front
axle assembly. During steering, the axle shaft in the front live axle assembly must
operate at angles up to 30 and has to drive the output the same as the input without
speed changes.
The type used on military vehicles is called a constant velocity (CV) joint. There are
three types of CV joints used in military vehicles. These are the Rzeppa, Bendix-Weiss,
and Tracta.
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