Hydraulic Cylinder Force and Speed Calculator

How is hydraulic cylinder force calculated?

The force a cylinder produces is pressure times the area it acts on: F = p × A. On the extend stroke oil acts on the full piston, so A = π × D² / 4. On the retract stroke the rod takes away part of the area, leaving the annulus A_h = π × (D² − d²) / 4. That is why pull force is lower than push force at the same pressure.

A handy conversion is 1 bar = 0.1 N/mm²: 160 bar is 16 N/mm², and with area in mm² the force comes out in newtons.

Speed and stroke time

Piston speed is flow divided by area: v = Q / A. Because the annulus is smaller, the cylinder retracts faster than it extends for the same flow. Stroke time is t = L / v.

Example

A cylinder with a 63 mm bore and a 36 mm rod runs at 160 bar. The piston area is 3117 mm² and the annulus area 2099 mm². The theoretical push force is 49.9 kN and the pull force 33.6 kN. With 20 L/min the extend speed is 0.107 m/s and the retract speed 0.159 m/s. A 500 mm stroke takes 4.7 seconds out and 3.1 seconds back.

Limits

The calculator gives force and speed in steady motion. Seal friction is covered by the efficiency you enter, and return line pressure is taken as zero. Rod buckling, barrel strength and mountings need separate checks. For lifting and pressing duties, select the cylinder from manufacturer data and the applicable standard.