1. Caused by the imbalance of rotor, coupler, coupling, transmission wheel (brake wheel).

2. The iron core bracket is loose, the oblique keys and pins are invalid and loose, and the rotor is not tied tightly, which will cause the unbalance of the rotating part.

3. The shaft system of the linkage part is not centered, the center lines are not coincident, and the centering is incorrect. The cause of this failure is mainly caused by poor alignment and improper installation during the installation process.

4. The center line of the linkage part is coincident in the cold state, but after running for a period of time, due to the deformation of the rotor fulcrum and the foundation, the center line is damaged again, resulting in vibration.

5. The gears and couplings connected to the motor are faulty, the gears are poorly meshed, the gear teeth are seriously worn, the lubrication of the wheels is poor, the couplings are skewed and dislocated, the toothed couplings have incorrect tooth shape and pitch, and excessive clearance. Large or serious wear, will cause a certain amount of vibration.

6. Defects in the structure of the motor itself, the journal is elliptical, the shaft is bent, the gap between the shaft and the bearing bush is too large or too small, and the rigidity of the bearing seat, foundation plate, part of the foundation and even the entire motor installation foundation is not enough.

7. Installation problems, the motor and the base plate are not fixed firmly, the foot bolts are loose, the bearing seat and the base plate are loose, etc.

8. Too large or too small clearance between the shaft and the bearing bush can not only cause vibration, but also make the lubrication and temperature of the bearing bush abnormal.

9. The load driven by the motor conducts vibration, such as the vibration of the fan and water pump driven by the motor, causing the motor to vibrate.

10. Wrong connection of AC motor stator, short circuit of rotor winding of wound asynchronous motor, short circuit between turns of synchronous motor excitation winding, wrong connection of excitation coil of synchronous motor, broken rotor bar of cage type asynchronous motor, and deformation of rotor core, which causes air gap between stator and rotor to fail. Evenly, the air gap magnetic flux is unbalanced and vibration is caused.