Abstract: A locking and slowing down device includes a central hole and a recess part, which are connected with each other. The central hole is inserted with an output shaft so that the spline shaft at one end of the output shaft extends into the recess part. The locking and slowing down device also includes an eccentric wheel set composed of a first eccentric wheel and a second eccentric wheel, which are connected with a first gear and a second gear, respectively, to move in opposite direction. The first gear and the second gear have a plurality of first through holes around a circle and second through holes around a circle, respectively. The protruding columns on the rotating plate penetrate through the first through holes and the second through holes, and each protruding column has an outer diameter smaller than the inner diameters of the first through holes and the second through holes. The first gear, the second gear, and the eccentric wheel set are placed within the recess part of the housing base.