Hydraulic Pump Output Flow
The gpm a pump delivers from its displacement and drive speed - the inverse of the hydraulic-motor speed relation and the flow the pump-horsepower tile takes as input: theoretical flow = disp x rpm / 231, delivered = theoretical x volumetric efficiency. A 2.0 in^3/rev pump at 1800 rpm and 0.95 vol eff makes 15.58 theoretical but delivers 14.81 gpm - the 0.78 gpm difference is internal slip that grows with pressure and wear. A sizing aid; the pump manufacturer's data govern.
Formula and source
q_theo = disp x rpm / 231; q_actual = q_theo x vol_eff; q_slip = q_theo - q_actual.
The fluid-power pump displacement-flow relation (theoretical flow = disp x rpm / 231), by name.
Audience
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