Meaning and mechanism
The change in pressure applied to a sealed fluid is transmitted throughout the entire fluid as a static deviation. The force acting on the piston is pressure multiplied by area.
Because the large piston receives the same pressure over a larger area, it can generate a greater force. The volume displaced by the small piston must be equal to the volume moved by the large piston.
Relationships and conditions
The value is F₂/F₁=A₂/A₁, and in non-compressed fluids, it is A₁s₁=A₂s₂. If there is no loss and the height difference is ignored, the result is preserved as F₁s₁=F₂s₂.
The actual device exhibits fluid compressibility, leakage, and friction. If the piston height differs, the difference in hydraulic pressure must also be considered.
What to observe in the simulation
Equal pressure gives the large piston more force over less travel.
Incompressible fluid and frictionless pistons move quasistatically. Hydrostatic head and losses are omitted. Do not build or imitate high-pressure hydraulic equipment.
Key relationships and symbols
F₂/F₁ = A₂/A₁ · s₂/s₁ = A₁/A₂ · F₁s₁ = F₂s₂
| Symbol | Meaning | Unit |
|---|---|---|
| A₁, A₂ | Input and output piston areas | m² |
| s₁, s₂ | Displacement of each piston | m |
Worked example
If force is amplified tenfold, what is output travel?
One tenth of input travel · Equal pressure gives the large piston more force over less travel.
Common misconceptions
- In a hydraulic system, the reported force is not greater than the actual energy produced.