Two-step sine movable tooth drive

For sine movable tooth drive, the movable tooth number must be increased to obtain large speed ratio of the drive which increases largely radial size of the drive. Here, a two-step sine movable tooth drive is proposed. For the drive, a small radial size and large speed ratio can be realized simultaneously. For the drive, three-dimensional design is done; the forces and the torque in the drive system are investigated; and changes in the output torque along with the main parameters are analyzed. Results show that the output torque of the two-step sine movable tooth drive is much larger than that of the single-step sine movable tooth drive. In the drive, the output torque fluctuation occurs. To reduce the output torque fluctuation, a large speed ratio, large axial amplitude of the sine ball tracks, and a reasonable speed ratio distribution should be used.