Spherical roller bearings are principally provided with two rows of symmetrical spherical rollers and a common sphere raceway in out ring, the two inner ring raceways are included at an angle to the bearing axial. The bearings have good self-aligning ability and can operate when the shaft deflection under load or the shaft deflection under load or the shaft misaligningment in mounting. This type of bearings has heavy load carrying capacity and anti-impact ability, in addition to radial loads, they also can carry axial loads in two directions. In general, this type of bearings permit a low limiting speed.