Cylinder Force Calculation
The force a hydraulic cylinder produces is pressure multiplied by the effective piston area. In the extend direction the full piston area works, while in the retract direction the area is the piston area minus the rod cross-section; that is why, at the same pressure, retract force is always lower than extend force.
There is an easy rule for practical calculation: if you multiply pressure in bar by area in cm², you get a result directly in the kilogram-force range. This is because 1 bar applies about 1 kgf to 1 cm². If you want the result in newtons, multiply the same product by 10.
- Example: a piston 80 mm in diameter has an area of about 50 cm². At 200 bar the extend force is roughly 10,000 kgf, that is on the order of 10 tons.
- If the rod of the same cylinder is 45 mm, the area on the retract side drops to about 34 cm² and the force decreases by one third.
- Actual force stays somewhat below the calculated value because of friction and back pressure on the opposite side.
This calculation is used in machine selection and in setting the relief valve. The force produced by AXI's retrofit kits is not cylinder force, so do not confuse the two: HCT400 applies about 15 kgf to the manual lever, and HCT402 about 20 kgf. This force is for moving the valve lever; the working force is produced by the vehicle's own hydraulics.
Where this term is used: What Does the HCT402 Achieve, How, and How Much? A Technical Review