B.The hub bearing unit is developed on the basis of standard angular contact ball bearings and tapered roller bearings. It integrates two sets of bearings, has good assembly performance, can eliminate clearance adjustment, light weight, compact structure, and load capacity. Large, sealed bearings can be pre-installed with grease, omitting the external hub seal and maintenance-free, etc., has been widely used in cars, there is also a trend of gradually expanding the application in trucks.