Sliding Thrust Bearing Internals

[siddiq191]

How the total weight of the Vertical Pump shafts is supported by sliding thrust bearing on the top.Can anybody explain the internals of the bearing where it exactly supports the shaft and How shaft is lifted during its impeller clearance adjustment in pumps which have rigid coupling and sliding thrust bearing? Is there any adjustment thread or nut to facilitate the impeller lift? If so how it is measured?

 

[rotw]

do you mean thrust-slide bearing ?

Does this help:

[URL unfurl="true"]http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2686&context=icec[/url]

"If you want to acquire a knowledge or skill, read a book and practice the skill".

 

[JJPellin]

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

 

[electricpete]

How the total weight of the Vertical Pump shafts is supported by sliding thrust bearing on the top.

Assuming the machine has a rigid coupling, then it acts like one long shaft. If not other thrust bearings in the machine (other bearings allow float), the thrust bearing will take the thrust.

Can anybody explain the internals of the bearing where it exactly supports the shaft

Sliding thrust bearing on a motor would be in an oil reservoir at the top of the motor. The thrust pads pivote to form a hydrodynamic oil wedge which is thicker at the leading edge than the trailing edge. Kingsbury style have a system of equalizing pads / pins / spacers below the thrust pads which act to ensure load is shared (if you push down on one pad the equalizing pads cause the adjacent pads to move up). Other styles rely on fine adjustment of pad height to assure load sharing (I never liked this). You should have oil level indication and temperature indication, along with periodic oil sampling and periodic vib monitoring.

How shaft is lifted during its impeller clearance adjustment in pumps which have rigid coupling and sliding thrust bearing? Is there any adjustment thread or nut to facilitate the impeller lift? If so how it is measured?

On the rigid vertical pump couplings I have seen, the coupling includes an adjustment nut above the pump side hub. The lift is measured as distance between pump resting on bottom and pump in coupled position. Measured on the pump hub (which remains stationary with respect to shaft… only the nut above it is adjusted).


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