Hydraulic Motor Calculations - Pneumatic and Hydraulic Company

GPM of Flow Needed for Fluid Motor Speed

Motor Displacement (in3 per rev)

Formula: Motor Displacement x Motor RPM ÷ 231 = gpm

Motor RPM

Example: How many GPM are needed to drive a 3.75 cubic inch motor at 1500 rpm?

GPM Flow Required (GPM)

Fluid Motor Speed from GPM Input

Gallons per Minute (GPM)

Formula: 231 x GPM ÷ Fluid Motor Displacement = RPM

Fluid Motor Displacement (in3)

Example: How fast will a 0.75 cubic inch motor turn with 6 gpm input?

RPM

Fluid Motor Torque from Pressure and Displacement

Pressure (PSI)

Formula: PSI x Motor Displacement ÷ (2 x π) = torque in inch pounds

Motor Displacement (in3)

Example: How much torque does a 2.5 cubic inch motor develop at 2,000 psi?

Torque (Inch Pounds)

Fluid Motor Torque from Horsepower and RPM

Horsepower

Formula: Horsepower x 63025 ÷ RPM = torque in inch pounds

Motor RPM

Example: How much torque is developed by a motor at 12 horsepower and 1750 rpm?

Torque (Inch Pounds)

Fluid Motor Torque from GPM, PSI and RPM

Gallons per Minute (GPM)

Formula: GPM x PSI x 36.77 ÷ RPM = torque in inch pounds

Motor PSI

Example: How much torque does a motor develop at 1,200 psi, 1500 rpm, with 10 gpm input?

Motor RPM

Torque (Inch Pounds)

*Pneumatic and Hydraulic Company, LLC assumes no liability for errors in data nor in safe and/or satisfactory operation of equipment designed from this information.