What is the procedure for checking evidence of impending wheel, hub, or bearing failure?

The procedure for checking evidence of impending wheel, hub, or bearing failure involves inspecting the hub-oil in the sight glass because this inspection can reveal critical information about the condition of the hub assembly. The presence of clear, properly filled oil indicates that the hub is well-lubricated and functioning properly. Conversely, low oil levels or contaminated oil may suggest leaks or deterioration, which could lead to hub or bearing failure.

Monitoring the hub-oil is crucial as proper lubrication is essential for the safe operation of the wheel bearing, reducing friction and wear. Without adequate lubrication, bearings can overheat, leading to potential failure that can affect vehicle safety.

While tire pressure, transmission fluid, and brake pads are important parts of a vehicle's operation, they do not directly indicate the health of the wheel hub or bearings in the same way that checking the hub-oil does. Each of those checks focuses more on different systems within the vehicle rather than the immediate condition of the wheel hub and associated components.