When the multi-stage pump is working, its rotor position is fixed to ensure:
A. The impeller outlet is aligned with the center of the vane (or pump casing).
B. The rotor components (such as the impeller) do not rub against the pump body.
The fixed method is:
1. A pump with a balance disc, the balance disc itself being a positioning device. Due to its automatic adjustment of the axial thrust, the rotor position is limited to a small variable range.
2. For pumps without balance discs, thrust rolling bearings should be provided. At this time, the axial thrust of the pump itself is balanced by the symmetric arrangement of the impeller or the opening of the balance hole. The remaining axial thrust is very small, and radial rolling bearings are generally used instead of thrust bearings.
Even so, in reality, the left and right tilt of the pump shaft will be encountered. For a pump with a balance disc, most of its turbulence occurs when the pump is started or stopped, because the axial thrust disappears and the balance disc does not function. In normal operation, the movement is very small and it is difficult to see. If the balance disc wears, the rotor will gradually move toward the entrance - tending to a new working position, but the amount of wear will take a long time to see.
For pumps that are positioned for rolling bearings, the cause of the turbulence is:
1. The bearing is not pressed against the end cap, that is, there is a gap.
2. The thrust bearing is damaged.
In addition to the above two reasons, the normal rolling bearing will also cause turbulence due to the axial clearance, which is roughly between 0.20 and 0.50 mm. The larger pump turbulence is larger, and the smaller pump turbulence is smaller.
