Leonardo da Vinci designed a screw jack, a lifting machine that used a threaded screw to raise a movable platform.
A screw jack converts rotational motion into controlled vertical movement. Turning the screw forces a platform upward or downward, making it useful for lifting heavy loads gradually. Leonardo's notebooks contain detailed studies of screws, gears, and mechanisms that could be applied to lifting and construction.
The screw jack belongs to a long mechanical tradition rather than being an entirely new physical principle invented by Leonardo. Ancient and medieval engineers had already used screw mechanisms, but Leonardo analyzed and illustrated them with unusual precision. His drawings helped document how mechanical advantage could be produced through threaded parts.
This device is different from a crane or hoist. A crane usually raises loads with a rope, pulley, or boom, while a screw jack supports and moves a load directly through the screw's rotation.