Hydraulic cylinders are used to convert hydraulic power into linear motion. The amount of force a hydraulic cylinder can exert is a function of the piston area and the hydraulic pressure. This is represented by the formula:
Hydraulic Cylinder Basic CircuitF = P x A where
F = force in Newtons (N)
P = pressure in Pascals (Pa)
A = area in square meters (m2)
A basic circuit to drive a hydraulic cylinder is shown in figure 1.
When a double acting hydraulic cylinder is extending the oil pressure acts on the total piston area, however when the cylinder is retracting the area available is the piston less the rod. Therefore for the same pressure the hydraulic cylinder extending force will always be greater than the retracting force.