Common Fluid Power Formulas - WIT
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Common Fluid Power Formulas

By   –  Published 9/12/2008

Force of a cylinder

Force = A x PSI
Key:
A = Area of piston (sq. in.)

Speed of hydraulic cylinder piston

Speed = O ÷ A
Key:
O = Volume of oil into cylinder (cu. in. per minute)
A = Area of piston (sq. in.)

Side load (lbs) on pump or motor shaft

Side load = (HP x 63024) ÷ (RPM x R)
Key:
HP = Horsepower
RPM = Speed (rev. per minute)
R = Pitch radius of sheave on shaft (in.)

Effective force cylinder at an angle to direction of the load travel

Force = C x sin A
Key:
C = Cylinder force (lbs)
A = Least angle between cylinder axis and load direction (in degrees)

Heat of fluid power in BTUs

BTU = PSI x GPM x 1 1/2
Key:
PSI = Gauge pressure (lbs / sq. in.)
GPM = Oil flow (gal. per min.)

Velocity of oil in hydraulic line

Velocity = (GPM x 0.3208) ÷ A
Key:
F = Force (in lbs)
A = Inside area of pipe (sq. in.)

Hydraulic power flowing through the pipes

Horsepower = (PSI x GPM) ÷ 1714
Key:
PSI = Gauge pressure (lbs / sq. in.)
GPM = Oil flow (gal. per min.)

Torque

Torque = (HP x 5252) ÷ RPM
Key:
HP = Horsepower
RPM = Speed (rev. per minute)

Horsepower

Horsepower = (T x RPM) ÷ 5252
Key:
T = Torque
RPM = Speed (rev. per minute)

RPM (revolutions per minute)

RPM = (HP x 5252) ÷ T
Key:
HP = Horsepower
T = Torque
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