Lesson 2/Learning Event 2
More than one type of axle housing is used on wheeled vehicles. Some early vehicles
used an axle housing that was made of two sections. These consisted of a right and left
section that were joined in the center with bolts. Axles using this type of housing are
called split type. The split construction requires that the axle be removed first and then
completely disassembled for inspection or repair of the differential. A standard-type
differential assembly is supported by tapered roller bearings in the right and left housings.
The drive pinion and shaft are mounted in the front of either the right or left section.
Most present-day vehicles use a banjo-type rear axle. With this type of construction, the
differential and final drive assemblies are made as a single unit. The axle housing is a
large single unit with a large opening in the center to receive the differential assembly.
The differential and final drive are bolted into the front of the housing, and the axle
shafts are installed from the right and left ends. It is possible to remove and repair the
differential without complete disassembly of the axle assembly.
Two different banjo-type axle housings are presently in use on military wheeled vehicles.
One type mounts the final drive assembly in the front or rear of the housing. The
second type of banjo axle mounts the final drive gearing on the top of the axle housing.
This type axle assembly is used on most of the military tandem axle trucks. It is used as
a front steering and drive axle as well as for both rear driving axles. On military vehicles,
this type axle uses the double-reduction final drive gearing.
OPERATION OF LIVE REAR AXLES
As the vehicle operator engages the clutch, the rotating motion of the engine is
transmitted through the transmission and transfer case to the axle by the propeller shafts.
The propeller shaft is connected to the pinion shaft by means of a flange or yoke at the
front of the axle and turns the pinion shaft and gear of the final drive. This forces the
ring gear, which is in mesh with the pinion gear, to turn in the direction driven by the
pinion. Since the ring gear has more teeth than the pinion, it will rotate more slowly.
There is, therefore, a loss of speed and a gain in torque between the pinion and ring gear.
The ring gear is solidly fastened to the differential case. Therefore, the entire differential
assembly turns when the ring gear turns. The spider or differential pinion shafts that are
mounted in the case are carried along at the same speed as the case.