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 AXLE - a stub axle shaft that extends through the wheel bearings and is splined to the hub.

WHEEL BEARINGS - either ball or roller type bearings that allow the drive axle to turn in the steering knuckle or bearing support.

STEERING KNUCKLE or BEARING SUPPORT - a suspension or steering com- ponent that holds the wheel bearings, axle stub. and hub.

DRIVE HUB - a mounting place for the wheel which transfers driving power from the stub axle to the wheel.

AXLE WASHER - a special washer that fits between the hub and locknut.

HUB or AXLE LOCKNUT - a special nut that screws onto the end of the drive axle stub shaft to secure the hub and other parts of the assembly.

GREASE SEAL - prevents 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.

TIRE REPAIR

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 puncture - the 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.