Our largest vertical pumps have two methods of dealing with lift and thrust. In all cases, the thrust of the pump is supported by the thrust bearing in the motor. All of our motors use a tapered roller bearing for thrust bearing.
In our deep well pumps, the motor thrust bearing is on the top. A threaded nut lifts the shaft. The lift procedure specifies the lift based on thread pitch and nut rotation angle. Once the shaft is lifted by the specified amount, the nut is locked.
For our largest cooling tower pumps, the motor thrust bearing is on the bottom. The adjustment is at the rigid coupling. The threaded nut on the motor is shimmed by the amount of lift specified. The nut is rotated to lift the shaft until it turns free. Then the shim is removed which lifts the shaft by the thickness of the shim.
The lift setting is specified by the pump manmanufacturer. Lift is based on impeller configuration, wear ring configuration, rotor weight, shaft length, process temperature and pressure.
Johnny Pellin