In the past, most of the wheel hub bearings for cars were used in pairs of single-row tapered rollers or ball bearings. With the development of technology, car hub units have been widely used in cars. The scope and amount of use of wheel hub bearing units are increasing day by day, and they have now developed to the third generation: the first generation is composed of double-row angular contact bearings. The second generation has a flange on the outer raceway for fixing the bearing, which can simply be put on the axle and fixed with nuts. This makes the maintenance of the car easier. The third generation of wheel hub bearing units uses a bearing unit and an anti-lock brake system. The wheel hub unit is designed with an inner flange and an outer flange. The inner flange is bolted to the drive shaft, and the outer flange installs the entire bearing together.