Tower crane slewing ring is the main parts to help the tower crane do slewing working. Usually Tower Crane Slewing Bearing is made of 42-42CrMo, 40-40Cr or 50-50Mn material. Slewing bearing is mainly made up of inner and outer rings. It features of compact in design, and light in weight . The balls contact with the raceway at four point, via which the axial force, radial force and tilting moment may be transmitted simultaneously.