wheel and axle

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A simple machine consisting of an axle to which a wheel is fastened so that torque applied to the wheel winds a rope or chain onto the axle, yielding a mechanical advantage equal to the ratio of the diameter of the wheel to that of the axle.

Wiktionary

1. n. a simple machine consisting of a wheel (or similar lever) that turns an axle around which a cord is wound; its mechanical advantage is the ratio of the diameters of the wheel and axle

GNU Webster's 1913

1. n. (Mech.) one of the elementary machines or mechanical powers, consisting of a wheel fixed to an axle, and used for raising great weights, by applying the power to the circumference of the wheel, and attaching the weight, by a rope or chain, to that of the axle. Called also axis in peritrochio, and perpetual lever, -- the principle of equilibrium involved being the same as in the lever, while its action is continuous. See Mechanical powers, under Mechanical.

WordNet 3.0

1. n. hoist so arranged that a rope unwinding from a wheel is wound onto a cylindrical drum or shaft coaxial with the wheel