Angular contact ball bearings which can bear radial load and axial load. Can work under high speed. The contact angle is bigger, the higher the axial bearing capacity. Under the action of axial force, contact angle will increase. Single row angular contact ball bearings can only bear the axial load in one direction, the radial load to bear, will cause the additional axial force. And only limit shaft or to the casing in a direction of the axial displacement. If the duplex mounting, so that a pair of bearing outer ring relatively, namely wide face to face wide, narrow end face narrow face. It can avoid the additional axial force, and in a two direction so that the shaft or the outer limits in axial clearance range.