Thrust ball bearings are made of three parts of the seats/shaft rings, balls, and cage. The one matched with the shaft is called a shaft ring, and the one matched with the shell is called the seat ring. They can be divided into single direction thrust ball bearing and bi-direction thrust ball bearing according to force. Single direction thrust ball bearing can withstand a single axial load while double direction thrust ball bearing can withstand bi-direction axial load. The ring should match with the shaft for a bi-direction thrust ball bearing. The bearing with the seat ring in the spherical mounting surface has the capacity of self-aligning. The impact caused by installation error can be less. Thrust ball bearings cannot bear radial load and have low limiting speed.