Wheel and Axle 

You would probably be quick to agree that moving a heavy item is easier with a wheelbarrow than if you had to carry the item yourself. A skateboard probably can get you around easier than walking (at least, if you are skilled with a skateboard!). Maybe you prefer to ride a bike or take a train? All of these machines use the same simple machine, the wheel and the axle, to make your work easier. Wheels and axles have a mechanical advantage just as ramps, wedges and levers do.

Wheels work the same way that a lever does in that a wheel is like the outer end of the lever. The axle, which is the inner part of the wheel near the center, is the fulcrum.  In fact, a wheel and axle is nothing more than a rotating lever that moves around a fixed point, or axle.

Wheel and Axle