Pascal Hydraulic Press
Trade piston displacement for force in an ideal hydraulic press while checking equal pressure change and conserved work.
Free theory articleTrade piston displacement for force in an ideal hydraulic press while checking equal pressure change and conserved work.
Concept & interpretation
Pascal's principle states that a change in pressure applied to an enclosed incompressible fluid is transmitted undiminished to all portions of the fluid and to the walls of its container. A hydraulic press uses this principle by applying a small input force F1 over a small piston areaA1, creating a pressure incrementΔP = F1 / A1. This same pressure increment acts on a larger output piston A2, resulting in a proportionally larger output force F2 = ΔP × A2.
Experiment: Trading Force for Displacement
In the interactive visualization, you can alter the sizes of both pistons as well as the input force and stroke. Notice that while you can amplify the output force to lift heavier objects, you cannot amplify the total work done. Any mechanical advantage in force requires a proportional sacrifice in the displacement of the load.
- Set the Input piston area A1 to 1 cm2.
- Set the Output piston area A2 to 4 cm2.
- Set the Input force F1 to 20 N.
- Set the Input stroke s1 to 8 cm.
- Observe that the Force Ratio is 4.