Leonardo da Vinci designed a screw jack to lift heavy loads with a screw and rotating drum.
A screw jack converts rotary motion into a slow, powerful vertical lift. Leonardo studied versions of this mechanism in his engineering notebooks, where he analyzed screws, gears, drums, and lifting systems. Turning the handle advances the screw and raises the load in controlled increments.
The device belongs to a long history of lifting technology. Screw mechanisms were known before Leonardo, so his work should be described as a design and refinement rather than the invention of the basic screw principle. His contribution was to examine how mechanical elements could be arranged for practical construction and force multiplication.
A screw jack is different from a crane. A crane uses a boom, cable, or hoisting arrangement to move loads, while a jack raises a load from below or through a compact lifting mechanism. Leonardo’s study illustrates his recurring interest in making heavy work manageable through mechanical advantage.