A wheel hub assembly (WHA), also referred to as hub assembly，wheel hub unit,wheel hub bearing, is an automotive part used in most cars, passenger vehicles, and light and heavy trucks.

The main function of the hub bearing is to bear weight and provide precise guidance for the rotation of the hub. It bears both axial load and radial load, and is a very important component. Especially for the wheel hub bearings of trucks, due to the greater load it bears, the bearing capacity and precision of the wheel hub bearings are even more important.   

The WHA is located between the brake drums or discs and the drive axle. A wheel is bolted on it. Depending on the construction, the end of the hub comes equipped with the splined teeth. They mate the teeth on the axle shaft. The axle hub spins along with the wheels bolted to it and provide power to the wheels in order to rotate. 

A roller bearing between the axle hub and axle shaft ensures easy rotation of the non-drive wheels. On the axle side, it is mounted to the holding bracket from the chassis; on the disc side, the wheel is mounted to the bolts of the WHA. When replacing, a wheel hub assembly should be torqued to the vehicle's specifications to prevent failure.

Working principle:

Truck hub bearings are factory preconditioned, lubricated and sealed to simplify installation. Wheel bearing units are available for trucks, trailers and buses. Wheel bearing units are designed to withstand the typical severe operating conditions and require less maintenance than the traditional wheel bearing sets they replace. Some variants come with an integrated impulse ring, which makes them suitable for anti-lock braking systems. The unit also saves time and money on brake maintenance.