Leonardo da Vinci designed a screw jack, a lifting machine that raises heavy loads by turning a threaded screw.
A screw jack converts rotational motion into vertical movement. Turning the handle moves a load-bearing section upward or downward along the screw, while the thread’s mechanical advantage allows a relatively small force to lift a much heavier object. Leonardo’s engineering notebooks contain designs for lifting and construction mechanisms based on this principle.
The device belongs to a long history of screw-based lifting tools. Ancient Greek engineers, including Archimedes, are associated with screw mechanisms, while later builders adapted threaded jacks for machinery and construction. Leonardo’s contribution was his detailed study and application of mechanical systems rather than the invention of the screw itself.
A screw jack is not the same as a crane or a hydraulic jack. A crane uses a boom and lifting line, while a hydraulic jack uses pressurized fluid; the screw jack depends on threads and turning force.