eHow says in an article called The Types of Simple Machines Found in Your Home:
Wheels and Axles
Like a lever, a wheel works by rotating around a fulcrum; in this case, the axle. Cars, toys, fans and fishing reels all use wheels and axles. Door hinges are also an example of this device--the round part of the hinge is an elongated wheel. On interior doors, the side attached to the wall and the side attached to the door have multiple wheels that rotate around a common axle.