The function of the torque arm of the reducer is mainly to install the torque arm horizontally. The gravity of the motor reducer will not be deformed for a long time, when all the gravity of the motor reducer is pressed on the shaft. It increases the torque and the balance transition of the rotation angle, which plays a good role in the protection and stability of the motor. The reducer has no feet or flanges, and is mounted on the shaft to the shaft, and the load is all on the shaft. There is a torsion arm on the reducer housing, and one end is connected to a fixed position to prevent the reducer housing from rotating. There are many advantages, as high speed ratio and high efficiency, compact structure, small volume, stable operation, low noise, reliable use, long life, strong overload capacity, impact resistance, small moment of inertia, etc.