5.1.2 Three-Quarter Floating Axles
The axle shafts in a three-quarter floating axle may be removed with the wheels that are
keyed to the tapered outer ends
of the shaft (
Figure 8-105
). The
inner ends of the shafts are
carried as in a semi-floating 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 or skidding of the wheels.
Three-quarter floating axles are
used in some trucks but in very
few passenger cars.
5.1.3 Axles
A full-floating axle is used on
large, slow moving off-road
equipment with a drive wheel on
each end of the axle housing.
Figure 8-106
shows two large
tapered roller bearings that are
mounted to the wheel hub and
carry the full weight of the
equipment and load. On larger
equipment, the bearings are
mounted on spindle bolts to the
axle housing. The axle itself only
transmits torque of the engine
through it and does not carry any
weight; hence the term "floating"
is used to describe its function.
On smaller equipment, the axle is
connected to the drive wheels
through a bolted flange that can
be removed to gain access to the
axle without removing the wheels.
On larger equipment with
outboard planetary drives, the
axle is floating and held in place
with a thrust plate that can be
removed to gain access to the
planetary drive gears for
servicing. The axles are easily
removed when the equipment
needs to be towed in a non-run
Figure 8-105 - Three-quarter floating axle.
Figure 8-106 - Typical heavy-duty full-
floating axle.
NAVEDTRA 14050A
8-94