PURPOSE: To allow a wheel to rotate automatically by allowing the weight to be always set eccentrically on one side from the center, owing to the rotation and the revolution of the wheel weight.

CONSTITUTION: A wheel weight 2 is revolved by the descending gravitation. The weight 2 rotates (half rotation) through a geared bearing 3, and is stopped by autostoppers 8 and 11. Therefore, the weight of the wheel weight 2 is transferred outward. On the other hand, the weight 2 rotates (half rotation) through a geared bearing 4, and is stopped by autostoppers 8 and 11. Therefore, the weight of the wheel weight 2 is transferred inward. Accordingly, the weight is always set on the half surface from the center, and a wheel 1 is rotated automatically by the descending force.