The principal function of Wheel Hub Unit is to carry load and to provide precise guidance for the rotating wheel hub, it withstands both axial load and radial load, is a very important parts. Traditional automotive wheel bearing is a combination of two single row bearings, the installation, oiling, sealing, and clearance adjustment are carried out in the automotive production line. This structure makes it difficult in the automotive assembly plants, high cost, poor reliability, the bearings must be cleaned, greased and adjusted during car maintenance. The Wheel Hub units combined two sets of bearings as a whole and integrated the spline, ABS sensors and other parts. The Wheel Hub units are with following advantage: light weight, compact structure, big load capacity, bearings with grease and seal, without wheel hub seal, good installation performance, the users needn¡¯t adjust the clearance and free from maintenance. The Wheel Hub Units have been widely used in cars, and gradually to be widely applied into trucks.