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Fluid Power Formulas Cylinder Speed and Motor Torque
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Fluid Pressure Pounds/Square Inch |
Pressure=Force (pounds) /Unit
Area (Square Inches) |
P=F/A or
psi=F/A |
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Cylinder Area Square Inches |
Area= p
x Radius2 inches |
A=pr2 |
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Area=(p/4)x
Diameter2 inches |
A=pD2/4
or A=0.785D2 |
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Cylinder Force Pounds |
Force= Pressure (psi)
x Net Area (square inches) |
F=psi x A or
F=PA |
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Cylinder Speed Feet/second |
Velocity= (231 x Flow rate (gpm))/(12x60xNet
Area (square inches)) |
V=231Q/720A or
V=0.3208Q/A |
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Cylinder
Volume Capacity Gallons |
Volume=(pxRadius2(inches)x
Stroke (inches)
)/231 |
V=pr2L/231 |
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Volume=Net Area (square inches) x
Stroke (inches)/231 |
V=AL/231 L=stroke
length |
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Cylinder Flow Rate Gallons per minute |
Flow Rate=(12x60xVelocity(feet/sec)
xNet Area(square inches))/231 |
Q=720vA/231 or Q=3.117vA |
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Fluid Motor Torque Inch pounds |
Torque=(Pressure(psi)xF.M.Displacement(cubic
inch/rev))2p |
T=psi d/2p
or T=Pd/2p
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Torque=(Horsepowerx63025/RPM |
T=63025 HP/n |
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Torque=Flow Rate(gpm)xPressure(psi)x36.77/RPM |
T=36.77QP/n or
T=36.77psi/n |
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Fluid Motor Torque/100psi Inch pounds |
Torque/100psi=F.M. Displacement (cubic
inches/rev)/.0628 |
T100psi=d/.0628 |
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Fluid Motor Speed Revolutions/Minute |
Speed=231 x Flow rate (gpm)/F.M.
Displacement (cubic inches /revolution) |
n=231Q/d |
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Fluid Motor Power Horsepower Output |
Horsepower=Torque Output (inch pounds) x
RPM/63025 |
HP=Tn/63025 |
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Pump Outlet Flow Gallons per Minute |
Flow= RPM x Pump Displacement (cubic inches/revolution)/231 |
Q=nd/231 |
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Pump Input Power Horsepower required |
Horsepower input=Flow Rate Output (gpm)
x
Pressure (psi)/1714 x Efficiency (Overall) |
Hpin=QP/1714Eff or Hpin=GPM x psi/1714Eff |
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Flow Rate Through Pipe Feet/Second |
Velocity=0.3208 x Flow rate Through I.D. (gpm)/Internal
Area (square inches) |
V=0.3208/A |
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Compressibility of Oil Additional Oil required to reach Pressure |
Additional Volume=Pressure(psi)xVolumeof
Oil Under Pressure/250,000 |
VA=PV/250,000
Approximately ½% per 1000 psi |