Leonardo da Vinci designed a screw jack that lifted heavy loads by converting rotary motion into vertical movement.
A screw jack uses a threaded screw and a supporting frame. Turning the screw advances it through a fixed or moving part, producing a controlled lifting force. Leonardo’s notebooks contain detailed studies of screws, gears, and lifting mechanisms, reflecting his work on construction and military engineering.
The screw principle was ancient, and earlier engineers had used threaded mechanisms. Leonardo’s importance was his systematic analysis and refinement of mechanical arrangements, including ways to multiply force and control movement.
A screw jack differs from a pulley block, which lifts through rope tension and wheel arrangements. It also differs from a hydraulic jack, which uses pressurized fluid. Leonardo’s proposed mechanism was mechanical and screw-driven.