By means of sealing design of grease lubricated the tiny dust, impurities and cutting fluid can be prevented into the bearing effectively. Manufacturer added greases with high performance and long life in sealed bearings, which can achieve free maintenance, improve the service life of the bearings under normal use.

The elements of bearing group are produced by matching requirement, so that the bearings can get the predetermined preload and rigidity after installation. The inner and outer diameter and angle of the same bearing group can be controlled within the allowable tolerance. 

The load lines in a pair of bearings by back to back assembly (DB) are enlarging from the bearing axis. It can bear axial load in two directions and relative larger moment because of larger angular rigidity.