Leonardo da Vinci designed a screw jack to convert rotary motion into a screw’s upward movement.
A screw jack uses a threaded screw and a turning handle or gear system to lift a heavy load. Turning the mechanism advances the screw through a threaded support, producing a controlled vertical movement. The arrangement offers mechanical advantage: a relatively small force applied over a longer circular path can raise a much heavier object.
Leonardo’s notebooks include detailed studies of screws, gears, and lifting mechanisms. His design work helped explain how these elements could be combined in machines for construction, engineering, and military use. The screw jack was not an entirely new principle in Leonardo’s time; screw-based lifting devices had earlier precedents.
The device is sometimes confused with a simple lever or pulley. Those machines lift loads through different arrangements of force. A screw jack is identified by its threaded lifting element, and its chief advantage is precise, gradual control rather than rapid movement.