# 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

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

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

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

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

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