Self-aligning ball bearing outer ring raceway is processed into spherical shape, the inner raceway with two double row deep groove ball bearings, aligning performance. It is mainly used to bear radial load, radial load at the same time, it can withstand a small amount of axial load, but generally can not bear the pure axial load, the speed limit lower than the deep groove ball bearings. This kind of bearings are used for the load prone to bending under the double bearing shaft, and dual bearings coaxial holes can not guarantee that the parts in the strict, but the inner ring and outer ring center line of the relative steepness of the center line of not more than 3 degrees.