Upthrust Taking out Turbine Bearing

[Cary Austin]

A question from an email.

what would cause this? Motor thrust upward taking out the bearing. Would assume if anything it would thrust in the downward direction.

[Cary Austin]

what type of vertical pump are you talking about and what is the configuration of pump/driver? this make a big difference to the discussion.

[Cary Austin]

4650gpm 1780rpm
6stage
4160v motor
1500hp
rigid coupling

correction to previous post should have read motor shaft thrust upward.

[Cary Austin]

It takes a lot of force to lift a 1500 hp motor. Are all the turbines lifting on the pump, or are they balanced for no axial thrust? Maybe a sudden water hammer affected the pump. Possibly an expansion happened, and up was the only way to go.

[Cary Austin]

yes, this is a pit type pump.
took out the top bearing but not the bottom.
shaft show signs of scoring/gouging on only one side.

[Cary Austin]

motor upper guide bearing was wiped out
thrust bearing was smeared

sorry for short answers info is slow and confusing as it comes in

[Cary Austin]

If the pump rotation is wrong, you will still get a delivery pressure , but the upthrust will be excessive and wipe out your bearing. Indication of wrong motor rotation will be high motor current and low flowrate.

[Cary Austin]

sorry for the dalay but turns out this was not a pump problem.  after investigation of all mechanical possibilities we re-visited the electrical side of the equation.

long story short, stray voltage thru the lower motor bearing was found.

thanks to all for their responses.