Figure 13-22.-Three-quarter floating rear axle.
Figure 13-23.-Full floating rear axle.
The axle shafts in a three-quarter floating axle
(fig. 13-22) may be removed with the wheels, keyed to
the tapered outer ends of the shafts. The inner ends of
the shaft are carried as in a semifloating axle. The axle
housing, instead of the shafts, carries the weight of the
vehicle because the wheels are supported by bearings
on the outer ends of the housing. However, axle shafts
must take the stresses caused by the turning, skidding,
and wobbling of the wheels. Three-quarter floating
axles are used in some trucks, but in very few passenger
cars. Most heavy trucks have a full floating axle
(fig. 13-23). These axle shafts may be removed and
replaced without removing the wheels or disturbing the
differential. Each wheel is carried on the end of the axle
tube on two ball bearings or roller bearings, and the axle
shafts are not rigidly connected to the wheels. The
wheels are driven through a clutch arrangement or
flange on the ends of the axle shaft that is bolted to the
outside of the wheel hub. The bolted connection between
the axle and wheel does not make this assembly a true
full floating axle, but nevertheless, it is called a floating
axle. A true full floating axle transmits only turning
effort, or torque.
Chapter 13 explained how power developed by the
engine is transmitted to perform the work required of it.
It discussed the following mechanisms of the power
The clutch is incorporated in the powertrain to
provide a means of disconnecting the power of
the engine from the driving wheels and
The transmission transfers engine power from the
clutch shaft to the propeller shaft and allows the
operator to control the power and speed of the
vehicle by selecting various gear ratios.
Transfer cases provide the necessary offsets for
additional propeller shaft connections to drive
Propeller shaft assemblies provide a flexible
connection through which power is transmitted
from the transmission to the axle.
Axles are used to support part of the weight of a
vehicle; they also drive the wheels connected to