Bearing Load Calculations

The largest load on the bearings in a typical reciprocating pump will probably come from the fluid pressure on the pistons, as modified by the crank/slider mechanism.

The bearings will also care very much about their rotating speed.

Don't forget the 'belt pull' if the crank is driven by a belt, or the gear separation force if it driven by gears.

Even if the crank has only one throw, there may be harmonic oscillations traveling along it.

Can the pump be backdriven by the pumped fluid if the motor loses power? That's a failure scenario that you'd want to mitigate.

How accurately can you make all the crank bearings align with each other? Can you make the crankcase straight and rigid enough to maintain that alignment, or is it flexible enough to need shimming to get it straight? What if the skid underneath the crankcase is warped?

I don't care about the answers to all those questions, but you should.




Mike Halloran
Pembroke Pines, FL, USA

If you are looking to select bearings for a new pump product I would consult very closely with a bearing manufacturer.