Changing pump

[Walter]

I need the formula for pully sizes. I am changing a pump and need it to spin at 1765 RPM. The old pump spun at 1415 RPM. Thanks.

 

[Russ Johnson]

Motor pulley OD X Motor speed = Pump Pulley OD X Pump speed
So: Measure your engine pulley, multiply by 3400 (optimum engine rpm) and divide by pump rpm.

 

[Justin]

Walter,

Take your known pump rpm which I think you stated 1765 (must be the rating for the pump) and take your known or rated engine rpm (3600). 1765 divided by (your rated engine rpm) multiply by your pump pulley's O.D. (outside diameter) and that will give you your pulley size.

Example, I have a 1765 pump rpm rating and a 3600 rpm engine. 1765 divided by 3600 = .490277777 Now multiply .49027777 by my pump pulley which is 9 inches. 49027777 x 9 = 4.4125.

4.4125 being the optimum pulley size. Generally the way they manufacture is that your pump pulley should be about twice the size or your engine pulley.

Hope this helps.

 

[Justin]

when measuring pulleys, measure by outside diameter.

 

[mattia]

Hello Walter, I just asked John to e-mail about this myself.

Here is what he sent.

 

[Justin]

Walter,

What pump, ie: name and brand and model, do you have that has to spin at 1765.

Just curious.

 

[Walter]

Cat pump #51. 4.8 gpm/3K