6.1.5 Wheel hub
The wheel hub (shown in Figure 6.4) is the link between the wheel and the steering knuckle/axle journal. The steering knuckle only transfers forces to the suspension elements, but it does not rotate itself. A hub is required in order to ensure free rotation of the wheel. A brake disc* (or brake drum) is installed on the hub. The wheel is attached to it, and the hub itself is installed in the steering knuckle in the case shown in Figure 6.4, on bearings that ensure smooth rotation of the wheel.
* The brake disc and brake drum are described in detail in the "Brake System" chapter.
Note
The brake disc can be structurally made as one piece with the wheel hub. Depending on the design, the hub bearings can be roller or ball bearings.
Good to know
Always after removing and installing a hub or replacing bearings, it is necessary to adjust the preload (which is, see the note below) of the hub bearings.
Note
In simple terms, the preload is the force with which the hub bearings are compressed while tightening the fastening nut. The amount of preload affects the force of resistance to wheel rotation. Each manufacturer provides its own recommendations regarding the value of the resistance to wheel rotation. Therefore, while performing repair works that are related to the removal of the hub, always ask whether or not the wheel hub bearing has been adjusted or not.
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