Wheel

A wheel is a disc or circle-shaped mechanical device. Its main purpose is to allow things to roll; in other words, the wheel spins, and object on the wheels moves more easily along the ground. It is a simple machine.^[1] The principle behind the wheel is that of mechanical advantage.^[2]

Most land vehicles roll on wheels. Wheels are often used in pairs, connected by a rod of wood or metal known as an axle. The wheel and axle turn together. The part of the wheel that attaches to the axle is called the hub.

The wheel with an axle is the basis of many machines, not just vehicles. The potter's wheel, the lathe and the windlass are examples.^[2] Many machines have wheels with teeth, known as gears.

1. ↑ Prater, Edward L. 1994. Basic Machines, Naval Education and Training Professional Development and Technology Center, NAVEDTRA 14037
2. ↑ ^{2.0 2.1} Bowser, Edward Albert, 1890, An elementary treatise on analytic mechanics: with numerous examples. (Originally from the University of Michigan) D. Van Nostrand Company, pp. 190