Hydraulic Cylinder Force and Speed Calculator
Push and pull force, speed, stroke time and hydraulic power for a double-acting hydraulic cylinder.
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How this calculator works
A hydraulic cylinder turns pressure into force and flow into speed. The push force is the pressure times the piston area. On the way back the rod takes up part of the piston area, so the pull force is lower and, for the same flow, the speed is higher.
The speed is the pump flow divided by the area. The hydraulic power is the pressure times the flow, which is what the pump and motor have to supply. A long, slender rod pushed hard can buckle, so check it with the column calculator.
Formulas used
- F = p\,A\,\eta
- A = \frac{\pi D^2}{4}
- v = Q / A
- P = p\,Q / 600\ (\mathrm{kW};\ p\ \text{in bar},\ Q\ \text{in L/min})
Worked example
With the default numbers in the calculator above:
- Piston area and annulus area: 7854 mm² and 2463 mm²
- Push (extend) force: 119.4 kN
- Pull (retract) force: 81.94 kN
- Extend speed: 0.06366 m/s
- Retract speed (faster: less area): 0.09275 m/s
- Time for the stroke, out and back: 13.24 s
- Hydraulic power at this flow and pressure: 8 kW
Change the numbers in the calculator to see the full working, every step, for your own case.
Common questions
Why is the retract force lower?
The rod takes up part of the piston area on the rod side, so the pressure acts on a smaller area.
How do I get the bar to newtons?
One bar is 0.1 N/mm², so force in newtons is pressure in bar times 0.1 times area in square millimetres.
What efficiency should I assume?
About 90 to 97 percent for a good cylinder, mostly seal friction.
Related calculators
Further reading: Fluid power texts, for example Esposito, Fluid Power with Applications; cylinder manufacturers' catalogues.
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