Leonardo da Vinci designed a screw jack for lifting heavy loads with mechanical advantage.
His engineering notebooks contain lifting mechanisms based on a threaded screw, a nut, and a handle or gear arrangement. Turning the mechanism converts rotary motion into a slower upward movement, allowing a relatively small force to raise a much heavier object. Leonardo studied such devices in the context of construction, fortification, and machine design.
A screw jack is different from a pulley crane, which lifts through ropes and wheels, and from a hydraulic jack, which uses pressurized fluid. Leonardo did not invent the screw principle itself; ancient Greek engineers had already used screws in machines such as the water screw. His contribution was to develop and document practical mechanical arrangements with careful attention to force, motion, and construction. The designs show why Leonardo is often studied as both an artist and an engineer.