Which Leonardo da Vinci machine used screw threads to lift heavy loads?

Leonardo da Vinci designed a screw jack to lift heavy loads through the mechanical advantage of a threaded screw.

A screw jack converts rotary motion into slow, powerful vertical motion. Turning a handle advances the screw through a threaded support, raising a platform or load. The arrangement is useful because a relatively small force applied over many turns can lift something much heavier.

Leonardo studied screw mechanisms in the context of machines for workshops, construction, and military engineering. His notebooks contain careful diagrams of screws, gears, frames, and lifting arrangements, although the drawings do not prove that he manufactured every device.

The screw jack should not be confused with a hydraulic jack, which uses pressurized fluid, or a block and tackle, which uses ropes and pulleys. Leonardo’s design belongs to the long history of screw-based lifting tools.