Wheel

(hwēl.) [A.S. hweol.] (Mech.) A simple machine, consisting of a round piece of wood, or metal, which revolves on an axis. The W. has an important place in most engines; it is of an a emblage of wheels that most engines are composed. The centre of a W. is like the fulcrum of a lever, and a simple action merely transfers the force on one side to the other side; but if wheels are so connected as to diminish velocity, then power is gained.- [s. 958]