The coupling consists of two half couplings connected by flanges. The traction motor and gear transmission device are connected by tooth coupling to compensate for the relative motion and installation error between the motor shaft and the driving gear shaft caused by the irregularity of the line, vertical, longitudinal and lateral displacement when passing through curves and corners, and the deflection change of a series of empty and loaded vehicles, etc. At the same time, the torque and rotational motion output by the traction motor are transmitted to the gear box.