Leonardo da Vinci designed a screw jack using a threaded shaft and a large handle to lift heavy loads. Turning the handle would advance a nut or platform along the screw, converting rotation into controlled vertical movement.
His notebooks contain several lifting machines based on screws, gears and cranks. A screw jack is valuable because it provides mechanical advantage: a worker can raise a substantial weight gradually with relatively modest force. Such devices could serve in construction, workshops or military engineering.
Screw lifting technology predates Leonardo, with ancient and medieval examples known from presses and hoists. Leonardo’s importance lies in his careful drawings and integration of the screw with other mechanisms. Modern vehicle jacks still use the same fundamental principle, although they are built with standardized steel parts and safety features.