Spherical roller bearing consists of an outer ring with spherical raceway and an inner ring with double-raceway, one or two cages, and one group of spherical rollers. Due to the center of the spherical raceway of the outer ring which is coinciding with the center of bearing, this makes it have a self-aligning property. This kind of bearing can adjust angular error or deflection caused by the angle of the axle and bearing housing or axle bend. spherical roller bearing has a high load carrying capacity for radial load and axle load in two directions. It is especially suitable for carrying heavy loads and impact loads, but this type of bearing permits a lower limiting speed. The permissible aligning angle of the spherical roller bearing working in normal conditions is 1° ～2.5°. If bearings of this type have seals, then this function would be reduced.