The wheel and axle, a form of simple machine, applies effort and resistance to lift or move objects and people. The lifting and moving is performed by multiplying speed or force.
This simple machine consists of a large rounded part (the wheel) and a smaller rounded rod (the axle). The wheel spins around the axle.
One type of wheel and axle moves people around via bicycles, cars and Ferris wheels. The type that moves objects can be seen on screwdrivers and drills as well as cranes.
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How the Wheel and Axle Works
Wheels and axles work either by draping rope around a grooved wheel to lift objects (pulleys) or by rotating the wheel around a fulcrum (axle) to move objects horizontally. Effort force can be applied to the wheel (e.g., door knob) or the axle (e.g., car tires).
Large forces applied to the axle cause the wheel to travel rapidly, triggering an automobile to drive faster, for example. In this case the wheel and axle perform as a speed multiplier.
Applying minor forces to the wheel so it travels a longer distance generates a greater force in the axle so it turns a smaller distance. The wheel and axle (e.g., windmill, spindle) is a force multiplier.