spindle is stationary. The spindle simply extends
outward and provides a mounting surface for the wheel
bearings. hub. and wheel. With the vehicle moving, the
wheel and hub spin on the wheel bearings and spindle.
The hub simply freewheels.
Driving Wheel Assembly
The components of a driving wheel bearing and
hub assembly (fig. 8-40) includes the following:
OUTER DRIVE AXLEa stub axle shaft that
extends through the wheel bearings and is
splined to the hub.
WHEEL BEARINGSeither ball or roller type
bearings that allow the drive axle to turn in the
steering knuckle or bearing support.
STEERING KNUCKLE or BEARING
SUPPORTa suspension or steering com-
ponent that holds the wheel bearings, axle stub.
DRIVE HUBa mounting place for the wheel
which transfers driving power from the stub axle
to the wheel.
AXLE WASHERa special washer that fits
between the hub and locknut.
HUB or AXLE LOCKNUTa special nut that
screws onto the end of the drive axle stub shaft to
secure the hub and other parts of the assembly.
GREASE SEALprevents lubricant loss
between the inside of the axle and the steering
knuckle and bearing support.
The driving wheel bearing and hub assembly has
bearings mounted in a stationary steering knuckle or
bearing support. The drive axle fits through the center
of the bearings. The hub is splined to the axle shaft.
Instead of a stationary spindle. the axle shaft spins
inside the stationary support. With the hub splined to
the axle shaft, power is transferred to the wheels.
Leaks from a tubeless tire are located by filling the
tire with air and then placing the tire in a drum full of
water. Bubbles will show the location of any leaks. If a
drum of water is not available, coat the tire with soapy
water. Soap bubbles will show the location of the leak.
It has been common practice to attempt the repair
of some punctures without dismounting the tire
through the use of a rubber plug. However. this
practice is NO LONGER RECOMMENDED, because
of serious safety concerns. Using a plug to attempt tire
repair without dismounting is effective only 80 percent
of the time. The remaining 20 percent of such repairs
will result in TIRE FAILURE, which may take the
form of a dangerous sudden deflation (blowout).
The safe and correct procedure for tire repair is to
ALWAYS remove the tire from the wheel and make
the repairs from the inside of the tire. After the tire has
been dismounted.. it should be thoroughly
INSPECTED. During this inspection, check the inside
surface carefully, to locate the puncture and determine
the nature and extent of the damage.
The Rubber Manufacturer's of America list two
requirements for correctly repairing a puncturethe
repair MUST fill the injury to the tire and the repair
MUST soundly patch the inner liner. Various products
are available for repairing the puncture to the tire.
including plugs and liquid sealants.
The basic procedures for repairing a tubeless tire
are as follows:
Select a patch of sufficient size to extend well
beyond the damaged area, so it will adhere
properly and withstand the heat and mechanical
stress of the tire.
Figure 8-40.Disassembled view of a driving wheel bearing and hub assembly.