PD pump Shaft bend what could be the causes ?

[bmw318be]

I received a complaint of new oumo supplied that it shaft bend and This application is pumping light oil, I would like to kbow what caused the pump's shaft to bend ?

And woul that be possible
To straighten the pump's shaft and would That be an issue of lower flow than normap after repairing.

 

[MikeHalloran]

The most likely cause is that the installer dropped the pump on the shaft, or dropped something heavy on the shaft.

A machinist might be able to straighten it to within the coupling's misalignment range.
That operation, and any remaining imbalance, will probably shorten the bearing life.

None of that should affect the flow.




Mike Halloran
Pembroke Pines, FL, USA

 

[btrueblood]

I think you might be able to bend some shafts, by ingesting something non-fluid and incompressible into the cylinder.

 

[electricpete]

Long thin rotor stored long time horizontally without rotation might bow. It can also be result of poor manufacturing, possibly residual stresses lead initially straight shaft to bow

Shop may be able to straighten with heat applied inside the bow. I'd look for a shop I trust and ask them whether they think they can do it successfully on this shaft

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(2B)+(2B)' ?

 

[GaTechTheron]

To intelligently reply to this post, it is required to know what type of PD pump you are referring to?

Gear?
Twin Screw?
Three Screw?
Reciprocating?
Sliding Vane?
Double Lobe?

If the pump performed well on the test stand, but the customer is complaining about a bent shaft, I would expect that the customer closed a valve on the discharge of the pump causing very, very high pump shaft torque or a high moment on the shaft. Quite often, operators do not understand how these pumps truly operate.

 

[bmw318be]

Hi theron this is internal gear pump

 

[electricpete]

If torque overload could cause bent shaft (I havne't heard of it, but that doesn't say much), then a logical followup question would be: does the system have unisolable relief valves on pump discharge. (That's the norm from the limited set I have seen).

Another possibility to consider would be unusual heating of shaft during operation.


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(2B)+(2B)' ?

 

[electricpete]

Maybe foreign material being sucked through the pump

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(2B)+(2B)' ?

 

[MikeHalloran]

Wait a sec: The goo you're pumping starts out at 30000cp in the tank, and >solidifies in the heat exchanger downstream<, and you're wondering why the shaft bent?

Or did I misunderstand something from your other related discussion?




Mike Halloran
Pembroke Pines, FL, USA

 

[bmw318be]

Hi mike, thats my other thread and nothing to do with this shaft bend. I just would like pointed out some possibility of shaft bend on the pump.

Thanks for the inputs