Drum-shaped cycloid gear structure

The utility model discloses a drum-shaped cycloid gear structure, comprising a cycloid gear; the cycloid gear is meshed with annularly arrayed needle teeth on a needle gear; the gear teeth at the outer peripheral surface of the cycloid gear form drum-shaped surfaces with middle outward convex structures. Correspondingly, the middles of the needle teeth are matched with the gear teeth to form inner concave curved surfaces. Needle teeth form the drum shape with the inner concave middle parts, the buses of the needle teeth are the inner concave curves, the cross section of each tooth profile is circle and the radii of the circle are axially changed. The contact surface between the cycloid gear and the needle teeth is large, the stress is uniform, the transmission efficiency of the cycloid gear is high and the service life is long.