Skateboard has pivoting wheels at front and back, non-pivoting wheel or two pairs of wheels on swiveling axles are mounted at center of board, pairs of wheels being clear of ground when board is parallel to it

摘要

The skateboard has pivoting wheels (3,2) at the front (1,2) and back. A non-pivoting wheel or two pairs of wheels (5,2) on swiveling axles are mounted at the center of the board. The pairs of wheels are clear of the ground when the board is parallel to it.