Pulley

A pulley is a wheel mounted on an axle that allows a taut rope, cable or belt running over it to change direction or transmit power, and grooved pulleys are used to guide the rope and keep it from slipping off the wheel. The earliest evidence for pulleys comes from ancient Egypt during the Twelfth Dynasty, around 1991 to 1802 BC, and from Mesopotamia in the early second millennium BC; the device was later described by the Greek mathematician Archytas of Tarentum, and the Roman-era Greek engineer Hero of Alexandria classified the pulley as one of six fundamental simple machines, while ancient accounts describe Archimedes demonstrating the power of a compound pulley system by single-handedly hauling a fully laden ship.