Angular contact ball bearing consists of an outer ring, an inner ring, one-row balls and a cage. This bearing can carry radial load and axial laod simultaneously, even pure axial load operating with higher rotation speed. Although this bearing only can carry axial load in one direction, yet it can be mounted with the other bearing carrying a load in contrary direction. This kind of bearing is most used in applications with high rotation speed, high precision and samll axial load such as main shaft of airplane motor, gas turbine, oil pump, air compressor, printing machines, etc.