The outer ball bearing is a special type of bearing, which is a variant of the deep groove ball bearing. Its characteristic is that the outer diameter surface of the outer ring is spherical, which can be matched into the corresponding concave spherical surface of the bearing seat to play the role of self-alignment. This design enables the outer ball bearing to be used in the case of poor alignment between the axis of the shaft and the seat hole, long shaft and large deflection, and has the function of automatic self-alignment.