The four-point contact ball bearing is the kind of bearing which can be separable. The 0000 type has a double semi-inner ring, and the OJ0000 type has a double semi-outer ring, and the contact angle is 35°. When there is pure radial load or no load, the steel ball and the ring are in four-point contact; under the action of pure axial load, the steel ball and the ring are in two-point contact and can withstand bidirectional axial load. This type of bearing can also withstand moment loads and combine the functions of single row and double row angular contact ball bearings. This kind of bearing can only guarantee normal operation when two-points contact is formed.