gpm vs displacement

[jswiontek]

I have a White HB series hydraulic motor with a displacement of 24.9 in^3/rev, flow rating of 20 gpm, and pressure rating of 2500 psi. Needed RPM is approx 200. I have been told that since I do not need the entire 24.9 in^3/rev of displacement to achieve the 200 rpm I need I can up the amount of flow higher than what is recommended. Is this true? If so, how much flow could I send through the motor? I would be interested in any formulas that relate RPM, GPM, and displacement.

 

[rbcoulter]

This seems to be a power issue. The product of the displacement rate (volumetric flowrate) and the pressure is the horsepower consumed. Of course, there are efficiency losses so the motor HP sizing needs to include that.

 

[ve7brz]

Your problem is not very clear. To achieve a motor speed of 200 RPM you need 200*24.9 in³/min. of oil flow. At 231 in³/gal. (I'm assuming US, if Imperial use 270) your required flow is 21.56 gal./min..

The formula used is GPM = RPM x Displacement in gallons.

In this example I've used in³/min = RPM x Displacement in in³ then converted in³ to gallons.