The spherical roller bearings are the roller bearings with two row inner ring raceways and self-aligning outer ring raceway. Therefore, it is provided with the function of self-aligning. It can auto adjust the eccentricity due to the mounting error or shaft bending. The bearing can still work normally when the centerlines of the outer and inner rings are within 1- 2.5 degree relatively. It can bear the radial load and bidirectional axial load and it is more applicable to heavy load and shock load.