MEPX
Chapter 4 of 10All chapters
  1. 1The simple machines
  2. 2Levers and gears
  3. 3Engines
  4. 4Hydraulics and pneumatics
  5. 5Getting power where it is needed
  6. 6Household machines
  7. 7Electric motors and generators
  8. 8Efficiency and losses
  9. 9Why machines fail
  10. 10Working out an unfamiliar machine

Chapter 4 of 10

Hydraulics and pneumatics

Force through a fluid.

Pressure everywhere

Pressure applied to a confined liquid acts equally in all directions. A small piston pushing a large one multiplies force by the ratio of their areas.

  • A car jack and a digger arm are the same principle at different scales.
  • Liquids barely compress, which is what makes hydraulics precise.

Air instead

Pneumatics use compressed air: springy, fast and forgiving, which suits tools and grippers. Hydraulics carry far larger forces and need seals and cleanliness.