Asking for advice on adjusting the distance between the pump impeller and the suction inlet
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For the pump as shown in the picture, if you adjust the distance between the pump impeller and the suction inlet, a set of soft material (mild steel or elastic paper) gaskets should be filled between the bearing end cover and the end face of the bearing seat.； When adjusting, first install the water pump shaft and bearing end cover without placing the gasket. While tightening the screws on the bearing end cover evenly, turn the shaft by hand until the bearing rolling element contacts the outer ring and there is no gap inside the shaft. Then use the gasket to adjust the impeller 1-2mm toward the motor side. I don't quite understand two points: 1. If there is no gasket, use the bearing gland to push the rotor to the pump side and then add the gasket to move back to the motor side. At this time, the gland is also moving. How can the rotor also move the same distance to the motor side? 2. If there is a bearing gland pressing the outer ring of the bearing, the maintenance document package also requires that the fitting gap between the bearing gland and the bearing be measured to 10-15 wires during reassembly. Then the subsequent adjustment is to use the bearing gland to push the entire rotor forward, and then add a shim and move it back 1-2mm. Doesn't the fitting gap between the bearing gland and the bearing change again?
Adjusting the clearance is to adjust the clearance. Leave 10-15 wires to allow for thermal expansion of the bearing.
Judging from the drawing, the right side is a pair of angular contact ball bearings starting with 7, which bear the axial force and are positioned by it. On the left is the nu bearing. This bearing has separate inner and outer rings. It only bears radial force and has no axial positioning. The bearing on the right is installed in the bearing box. The impeller clearance can be found by adjusting the axial relative position of the bearing box. The 10 or so wires you mentioned are determined when the bearing is installed in the bearing box, and do not conflict with the adjustment. Under the condition that the large cover gasket does not change, the pump only needs to be adjusted when the shaft or impeller is replaced. Normally, you can add as much thickness as the original pad when replacing the bearing.
This post was last edited by CHANGBAISHI on 2020-8-1 07:53 The bearing gland circled in red is only for the installation clearance requirements of this bearing and the bearing on the other end. It is understood that it is improper to adjust the gap between the impeller and the pump casing. If you do not pay attention to this gap during installation, it is very likely that an artificial axial force will be exerted on the bearing, causing the bearing to be unable to rotate normally. This is done by positioning and locking the bearing gland at the impeller end, and adjusting the bearing gland at the other end, thereby regulating the axial positioning of the entire rotor. For reference.
You regard the rear bearing gland (also called the bearing box) and the bearing as a whole, and move them forward and backward together to position the rotor system. As for the rear bearing clearance, it has been adjusted before being installed into the rear bearing gland and is fixed relative to the rear bearing gland. Adjusting the rear bearing gland front and back will not affect the change in the size of the rear bearing clearance, but only changes the front and rear position of the rotor system.