Mechanical Systems

Gears, pulleys, levers and linkages

Gears, Pulleys and Levers

Mechanical systems use moving parts to transfer force and motion. Gears (toothed wheels) change speed, direction or force. Pulleys (wheels with ropes) lift heavy loads. Levers (bars on pivots) multiply force. Linkages connect parts and change the direction of movement.

Example

Mechanical Advantage

Gears: Small gear drives large gear = slower but more powerful (torque) Gear ratio: Driven gear teeth ÷ Driver gear teeth 48 teeth ÷ 12 teeth = 4:1 ratio (4× more force, ¼ speed) Pulleys: More pulleys = less force needed (but pull rope further) Single pulley: changes direction only Double pulley: halves the force needed Levers: Longer effort arm = less force needed

Note

Remember

Mechanical advantage means making work easier — but you never get something for nothing. If a machine reduces the force needed, you must move the effort further. Bicycles use gears: low gear = easy pedalling uphill (slow), high gear = harder pedalling on flat (fast).

Key Vocabulary

GearA toothed wheel that meshes with another to transfer motion

PulleyA wheel with a groove for a rope, used to lift loads

LeverA bar that turns on a fulcrum to multiply force

Mechanical advantageHow much a machine multiplies force

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