Self-Aligning ball bearing belongs to double-row ball bearing with spherical outer ring raceway and double-row raceway for its inner ring. It has self-aligning property, which could automatically compensate coaxial error due to shaft deflection and housing deformation. As different series, angle error is also different while the max value could not exceed 3 º. Mainly used to bear radial load and small axial load, but not to afford pure axial load.