Thrust bearing location?

[471akm]

I have a general question regarding multi-stage horizontal split case pumps. What determines the location of the thrust bearing along the shaft? The majority of the time, I've seen the thrust bearing located on the non-drive end, however occassionaly it is on the drive end. Why the difference and reasoning for locatoin?
Any help would be greatly appreciated. Thanks!

 

[Tmoose]

I'd pick a location based on as much of the following criteria as I could:
- Lets thermal expansion occur painlessly and not "use up" the axial expansion capabilities of the coupling or force the sleeve bearing motor off magnetic center
- Keeps the bearing at a more comfortable temperature
- Makes sealing or maintenance easier
- Reduces manufacturing costs
- Makes the machine look techno-cool

I know that method is in direct conflict with the document I had to sign in order to get the ME degree diploma

 

[JJPellin]

In most of our pumps of this type, the thrust bearing is on the non-drive end. Axial thermal growth can be accommodated in either arrangement. For the non-drive end installation, the case is usually pinned at the coupling end and keyed to allow growth to expand toward the non-drive end. The thrust bearing fixes the shaft to the case at the NDE, allowing it to grow toward the DE. The two thermal growths almost cancel each other out. The gap at the coupling changes only slightly. The thrust bearing housing tends to be larger. It has more parts inside that will eventually require maintenance. For the sake of maintainability, I prefer to have the thrust bearing at the non-drive end,

Johnny Pellin

 

[Spud6414]

Short question, long answer. Depending on the design of the pump is what determines the placement of the thrust bearing and type. Is it a 'balanced' pump? Does it pump hot fluids or nominal temp fluids? What types of pressures is the pump designed to generate? Thermal growth plays a huge roll in type and placement of the thrust package and so on.

The answers to these questions determine the placement of the thrust package and the type.

A majority of the pumps will have the thrust on the NDE or outboard end.

Spud says; Meticulous effort and willingness to learn are honorable traits.