Hub, also called rim, wheel, tire bell, is a cylindrical metal part, the center of which is mounted on the shaft and supports the tire inside. There are many kinds of wheels according to their diameters, widths, molding methods and materials.
In the past, the hub bearings of automobiles were mostly paired with single row tapered rollers or ball bearings. With the development of science and technology, automobile hub units have been widely used in automobiles. The application scope and usage of hub bearing unit are increasing day by day, and it has developed to the third generation: the first generation consists of double-row angular contact bearings. The second generation has a flange to fix the bearing on the outer raceway, which can simply cover the bearing on the axle and fix it with nuts. It makes the maintenance of the car easy. The third generation hub bearing unit adopts the cooperation of bearing unit and anti-lock braking system. The hub unit is designed with an inner flange and an outer flange. The inner flange is fixed on the transmission shaft by bolts, and the outer flange installs the whole bearing together.