Thrust ball bearing by the seat ring.shaft ring and ball and cage assembly 
is composed of three parts,Coordinate with the axis of said shaft ring,cooperate with the 
housing of said seat,According to the force divided one-way thrust ball bearings and thrust
 ball bearings,Single direction thrust ball bearing,can beari axial load,thrust ball bearing,
can bear bi-directional axial load,Double dirction thrust ball bearings,in which the ring is 
matched with a shaft,Seat mounting surfaces show spherical bearings,with self-aligning capability,
can reduce the mounting error influence,Thrust ball bearing can bear radial load,limit rotational sped is low.