The double-raw ball slewing bearing can carry axial load, tilting moment and radial loads at the same time. The top ball mainly carries the axial load and positive tilting moment. The drop ball takes the opposite tilting moment. This is the reason for the loading capacity of the double raw ball slewing bearing being larger than the four-point contact ball slewing bearing; however, the frictional ratio is much larger. than the latter. The  double raw ball slewing bearing consists of a inner ring, outer ring, balls in double rows, spacers, sealing device, and other components. Due to the top ball mainly taking the axial load and tilting moment loads, the size of top balls are larger than the drop ball. In order to accommodate the various working condition at different axial load, tilting moments and axial load, the angle of contact would be adjusted accordingly. The rings structure can be divided into two types, integral type and split type. Generally, the integral type maintains a stronger rigidity. The split type is more convenient to adjust; the two segregate rings are fastened by bolts prior to delivery. The  Ｄouble raw slewing bearing has cages (or spacing blocks) among the balls. Only when large loading is requested would the full ball type be applied. Loading capacity for full ball type is definitely larger. However, the increased friction generated by this design allows for the balls to be easily scratched. The double raw slewing bearing is mainly for the working conditions when carrying an axial load, larger tilting moment, and where the mounting place is limited in radial direction. This structure provides good performance when fit into an installation when an amount of deformation may be allowed.