The traditional automobile wheel bearings are composed of two sets of tapered roller bearings or ball bearings. The mounting, oiling, sealing and clearance adjustment of the bearings are all carried out on the automobile production line.This kind of structure makes it difficult to assemble in the automobile production plant, high cost, poor reliability, and when the automobile is maintained in the maintenance point, it also needs 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, in a truck also has a tendency to gradually expand the application.