Leonardo da Vinci designed a screw jack with a screw and a rotating arm for lifting heavy loads.
A screw jack converts rotary motion into slow, powerful vertical movement. Turning the handle advances the screw through a threaded component, raising or lowering the load with mechanical advantage. Leonardo’s mechanical studies included screw-based lifting devices that could be useful in construction, workshops, and military engineering.
The screw jack was not an entirely new principle invented by Leonardo. Screws and other lifting mechanisms had older precedents, and Renaissance engineers regularly adapted established ideas. Leonardo’s importance lies in the careful visualization and refinement of mechanisms in his notebooks. A screw jack also differs from a pulley crane: a crane may use ropes and wheels to lift loads, whereas the jack raises a load directly through threaded screw motion.