The four-point contact ball bearing is separable bearing, it is generally consists of two structures as follows: QJ 0000 – one complete outer ring and two half inner rings; QJF 0000 – two half outer rings and one complete inner ring. The contact angle is usually 35. Each steel ball contacts the raceway at four points when carring pure radial loads. Each steel ball contacts the raceway at two points if there is only a unidirectional axial load. It can bear axial loads in two directions as well as a certain eccentric load, i.e. moment loads. Such kind of bearing has features and properties of both single-row and double-row angular contact ball bearings. If it is used in a high-speed scenario, two-point contact must be ensured for its normal working.