Pascal's Law — Hydraulic Press

Press the small piston and the pressure spreads equally through the fluid, pushing up on the large piston with far more force: F₂ = F₁·(A₂/A₁). You gain force but lose distance — the small piston travels much farther than the load rises.

Output force F₂ = F₁·(A₂/A₁)

2.50 kN

lifts up to 255 kg (m = F₂/g)

Input force F₁100 N

Small piston Ø d₁4.0 cm

Large piston Ø d₂20.0 cm

Fluid pressure P

79.6 kPa

Mech. advantage

25.0×

Small piston A₁12.6 cm²

Large piston A₂314 cm²

Distance trade-off25.0 cm : 1 cm

P is the same everywhere in the fluid (Pascal's principle). Areas A = π·(d/2)². g = 9.81 m/s² · ideal, incompressible fluid.

Tip: shrink d₁ or grow d₂ and watch the mechanical advantage — and the distance trade-off — climb.