hydraulics

Everyday

1. Hydraulics is the science and use of liquids, usually oil or water, pushed through pipes to move or lift things. tree →
2. The hydraulics of a machine are its parts that work by liquid pressure. tree →

In the lessons

In science and design-and-technology lessons hydraulics explains how a small push on a liquid in one syringe can lift a heavy load at the other end, because liquids cannot be squashed. Diggers, car brakes, lifts, dentist chairs and aeroplane flaps use hydraulics. Phrases: «hydraulic lift», «hydraulic brakes», «the hydraulics failed».

Examples

• Hydraulics lets a small digger lift huge rocks. tree →
• We built a hydraulic arm from syringes, tubes and water. tree →
• The pilot said there was a problem with the hydraulics. tree →
• Car brakes use hydraulics to press the pads on the wheels. tree →
• The engineer studied hydraulics at university. tree →
• When the hydraulics failed, the drawbridge would not rise. tree →
• A hydraulic jack can lift a car with one person pumping the handle. tree →

Note

Looks plural but takes a singular verb: «Hydraulics is useful». The adjective is «hydraulic» (no «s»). From Greek «hydro» (water). Related: «pneumatics» works the same way but with air. In maths and science problems, liquid pressure is the same everywhere in a closed system, so a piston with a bigger area pushes with a bigger force.