The hub bearing unit is developed on the basis of standard angular contact ball bearings and tapered roller bearings. It combines two sets of bearings as a whole. It has good assembly performance, can omit clearance adjustment, light weight, compact structure, and load capacity. Large, sealed bearings can be pre-loaded with grease, omit external wheel hub seals, and are free from maintenance. They have been widely used in cars, and there is a trend to gradually expand their applications in trucks.