The self-aligning ball bearing has two structures: cylindrical hole and conical hole. The material of the cage is steel plate, synthetic resin, etc. Its feature is that the outer ring raceway is spherical and has automatic centering, which can compensate for errors caused by different centricity and shaft deflection, but the relative inclination of its inner and outer rings shall not exceed 3 degrees. Self-aligning ball bearings are suitable for bearing heavy load and impact load, precision instruments, low-noise motors, automobiles, motorcycles, metallurgy, rolling mills, mines, oil, paper, cement, sugar and other industries and general machinery.