The torque arm is mainly to install the torsion arm horizontally. The gravity of the motor reducer is all pressed on the shaft for a long time without deformation, and the transition of the torsion and the angle balance is increased, which plays a good role in the protection of the motor and the stability of the motor. The reducer is that the reducer has no foot and no flange. The shaft is mounted on the shaft and the load is all on the shaft. The reducer arm has a torsion arm and one end is connected to a fixed position to prevent the reducer housing from rotating. High speed ratio and high efficiency, compact structure, small size, stable operation, low noise, reliable use, long service life, strong overload capability, impact resistance and small moment of inertia.