Mechanical failure
1. Motor bore cleaning: the space between the motor stator and rotor is very small, which simply leads to the collision between the stator and rotor. Once the phenomenon of different axes of the base, end cover and rotor occurs, it will cause the collision between the stator and rotor, which is often referred to as bore sweeping. Common factors causing different shaft centers are: severe out of tolerance of motor bearing, wear of inner hole of end cover, wear and deformation of end cover and base stop hole. If these phenomena are found, replace the bearing, or replace the end cover or brush plating.
2. Motor oscillation: it should be distinguished that the oscillation is caused by the motor itself, or caused by the poor transmission device, or transmitted from the mechanical load end, and then it should be cleaned according to the specific situation. Most of the oscillations caused by the motor itself are due to poor dynamic balance of the rotor, poor bearing, winding shaft, or different shaft centers of the end cover, base, and rotor, or the foundation of the motor device is uneven, the device is not in place, and fasteners are loose. Oscillation will generate noise and additional load.
3. Abnormal bearing operation: if the bearing operation is abnormal, it can be judged by experience with hearing and temperature. Touch the bearing box with a listening stick (copper bar). If you hear an impact sound, it means that one or more balls may be broken. If you hear a hissing sound, it means that the bearing is lack of lubricating oil. It is not easy to add too much grease. If too much grease is added, there will be a lot of friction between the rotating part of the bearing and the grease, which will heat up. Generally, the grease in the bearing box is about one-half to two-thirds of the total solution. If the bearing device is not correct and the cooperative service is too tight or too loose, it will also cause bearing heating.

The variable eccentric sealing structure of pneumatic butterfly valve with variable eccentric sealing is different from the above two. It has a unique feature that the valve rod shaft with butterfly plate is a three section shaft type, that is, the two shaft sections are concentric, and the center line of the central section shaft will deviate from the axis at both ends, so the butterfly plate will be installed on this intermediate shaft section. If the eccentric structure is in the fully open state, it can become a double eccentric structure. If the butterfly plate is turned to the closed state, it will appear as a single eccentric structure. In this way, the pneumatic butterfly valve which can switch the sealing structure can also reduce the extrusion pressure and ensure the sealing performance.