Hydraulics & Pneumatics
Liquid and air pressure systems
Hydraulics and Pneumatics
Hydraulic systems use liquid (oil/water) under pressure to transfer force. Pneumatic systems use compressed air/gas. Hydraulics are powerful and precise (used in heavy machinery). Pneumatics are lighter and faster (used in factories and brakes). Both convert small input force to large output force.
Example
How They Work
Hydraulic system (syringes connected by tube):
Push small syringe → liquid travels through tube → pushes large syringe
Small piston area → large force on big piston (force multiplied!)
Pneumatic system:
Compressor pressurises air → air stored in tank → released through valves → pushes pistons
Examples: Hydraulic — excavator, car brakes, car jack
Pneumatic — dentist's drill, air brakes on trucks, nail gun
Note
Remember
Key difference: liquids CANNOT be compressed (hydraulic = precise control). Gases CAN be compressed (pneumatic = springy, stores energy). Pascal's principle: pressure is transmitted equally in all directions in a fluid. Hydraulic advantage = large piston area ÷ small piston area.
Key Vocabulary
HydraulicsUsing pressurised liquid to transfer force and motion
PneumaticsUsing compressed air to transfer force and motion
PressureForce applied per unit area (measured in Pa or kPa)
PistonA cylinder that moves inside a tube under fluid pressure
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Hydraulics
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