However, when the concentricity is different, the output shaft must bear the radial force from the input side of the reducer. The radial force will cause the output shaft of the motor to be bent for a long time, and the direction of the bending will change along with the rotation of the output shaft. For each rotation of the output axis, the direction of the lateral force changes 360 degrees. If the error of concentricity is large, the radial force will increase the output shaft temperature of the motor, and the metal structure will be destroyed. Finally, the radial force will exceed the radial force that the output shaft of the motor can bear, and finally lead to the breaking of the output shaft of the driving motor. When the error of concentricity is greater, the shorter the time of the drive motor output shaft is broken.