The main function of automobile wheel hub bearing is to bear weight and provide accurate guidance for the rotation of the wheel hub. It bears both axial load and radial load. It is a very important component. The traditional automobile wheel bearing is composed of two sets of tapered roller bearings or ball bearings. The installation, oiling, sealing and clearance adjustment of bearings are carried out on the automobile production line. This structure makes it difficult to assemble, high cost and poor reliability in the automobile production plant. Moreover, when the automobile is maintained at the repair point, it is also necessary to clean, grease and adjust the bearing. Wheel hub bearing unit is in the standard angular contact ball bearings and tapered roller bearings, on the basis of it will be two sets of bearing as a whole, has the assembly clearance adjustment performance is good, can be omitted, light weight, compact structure, large load capacity, for the sealed bearing prior to loading, ellipsis external wheel grease seal and from maintenance etc, and has been widely used in cars, There is also a trend of gradually expanding the application in the truck.