Four ball ball bearings are a type of separable bearing that can withstand bidirectional axial loads. The outer raceway of the angular contact ball bearing is integral, but the contour of the raceway is composed of different concentric, same radius (or different radius) arcs, while the inner raceway is composed of two parts, and the centers of the contour of the inner raceway composed of these two parts do not coincide. The contour radius can be the same or different. The inner and outer race raceways have a peach shaped cross-section. When there is no load or pure radial load, the steel ball and the ring form a four point contact, hence the name four ball ball bearing. The application characteristics of this type of bearing are: it can withstand bidirectional axial forces and small radial forces, and is suitable for high-speed situations.