Wheel Bearing
A set of steel balls or rollers housed in a metal ring that allows the wheel to spin smoothly with minimal friction.
A wheel bearing is a critical component of the wheel assembly that enables the wheel to rotate smoothly and with minimal friction around the axle shaft. It consists of high-precision steel balls or rollers held together by a metal ring (cage) and packed with heavy lubricating grease inside a sealed metal housing.
Wheel bearings must support the entire weight of the vehicle while subject to radial and lateral forces during cornering. They are designed to last for a long time, often over 100,000 miles, but can fail prematurely if the protective seal is damaged, allowing water, dirt, and road salt to enter and corrode the bearing surfaces.
The classic symptom of a failing wheel bearing is a loud, humming, growling, or roaring noise that increases in pitch as the vehicle speeds up. This noise often changes in volume when steering from side to side, as the weight shifts onto or off the damaged bearing. A severely worn wheel bearing can also cause steering wheel vibration or play in the wheel assembly.
Driving with a failed wheel bearing is highly dangerous; in extreme cases, the bearing can seize or break, causing the wheel to lock up or detach from the vehicle while driving. Defective wheel bearings should be replaced immediately.