Hydraulic Motor Calculations

GPM of Flow Needed for Fluid Motor Speed

Motor Displacement X Motor RPM / 231
How many GPM are needed to drive a 2.51 cubic inch motor at 1200 rpm?

Motor Displacement = 2.51 cubic inches per revolution
Motor RPM = 1200
Motor Displacement X Motor RPM / 231 = 2.51 X 1200 / 231 = 13.04 gpm

Fluid Motor Speed from GPM Input

231 X GPM / Fluid Motor Displacement
How fast will a 0.95 cubic inch motor turn with 8 gpm input?

GPM = 8
Motor Displacement = 0.95 cubic inches per revolution
231 X GPM / Fluid Motor Displacement = 231 X 8 / 0.95 = 1,945 rpm

Fluid Motor Torque from Pressure and Displacement

PSI X Motor Displacement / (2 X PI)
How much torque does a 2.25 cubic inch motor develop at 2,200 psi?

Pressure = 2,200 psi
Displacement = 2.25 cubic inches per revolution
PSI X Motor Displacement / (2 x PI) = 2,200 X 2.25 / 6.28 = 788.22 inch pounds

Fluid Motor Torque from Horsepower and RPM

Horsepower X 63025 / RPM
How much torque is developed by a motor at 15 horsepower and 1500 rpm?

Horsepower = 15
RPM = 1500
Horsepower X 63025 / RPM = 15 X 63025 / 1500 = 630.25 inch pound

Fluid Motor Torque from GPM, PSI and RPM

GPM X PSI X 36.77 / RPM
How much torque does a motor develop at 1,250 psi, 1750 rpm, with 9 gpm input?

GPM = 9
PSI = 1,250
RPM = 1750
GPM X PSI X 36.7 / RPM = 9 X 1,250 X 36.7 / 1750 = 235.93 inch pounds second
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