Engineering tools
Hydraulic cylinder calculator
In a double-acting cylinder the oil pushes on the whole piston to extend, and only on the ring around the rod to retract. That's why a cylinder pushes harder than it pulls, and retracts faster than it extends.
Calculator
Results
Push force (extending)
12.8 t
- Pull force (retracting)
- 8.8 t
- Area ratio φ
- 1.46
- Extending speed
- 84.9 mm/s
- Retracting speed
- 124 mm/s
- Time to extend
- 5.89 s
- Time to retract
- 4.04 s
- Oil to extend
- 3.93 L
- Oil to retract
- 2.7 L
Push force (extending): 12.8 t · Pull force (retracting): 8.8 t
An estimate, not an engineering certification. Our engineers check every figure before a machine is quoted.
Worked example
A Ø100 mm bore with a Ø56 mm rod at 160 bar and a 40 L/min pump pushes 126 kN (12.8 t) and pulls 86 kN (8.8 t). It extends at 85 mm/s and retracts at 124 mm/s, so a 500 mm stroke takes 5.9 s out and 4.0 s back.
Assumptions
- Theoretical values: no friction, pressure losses or leakage.
- The pump flow is constant and all of it reaches the cylinder.
- Buckling of long rods isn't checked here; an engineer checks it for your mounting.
The formulas
Where
- D
- cylinder bore
- d
- rod diameter
- P
- working pressure
- A
- piston area
- Q
- pump flow
- v
- speed
- s
- stroke
- t
- stroke time
- V
- oil volume
- φ
- area ratio
Related products
Questions
Why does a cylinder pull with less force than it pushes?
When it retracts, the oil acts only on the ring around the rod, which is smaller than the whole piston. The area ratio φ shows by how much.
How do I make a cylinder faster?
Give it more pump flow, or use a smaller bore at a higher pressure for the same force: speed is flow divided by area.
How big should the oil tank be?
At least the difference between the oil to extend and to retract, plus room for cooling; tanks usually hold several times the pump's flow per minute. Ask an engineer for your duty cycle.
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