Leonardo da Vinci developed screw-jack designs using a spiral screw mechanism to lift heavy loads.
A screw jack converts rotational movement into controlled vertical movement. Turning the screw advances a threaded component, raising or lowering a load with mechanical advantage. Leonardo studied versions of this principle in his engineering notebooks, applying careful attention to threads, gears and supporting frames.
The screw principle itself was ancient; Archimedes and other earlier engineers used screws for machines and water movement. Leonardo’s contribution was not the invention of the screw as a concept, but the detailed development and application of mechanical lifting arrangements during the Renaissance.
A screw jack differs from a pulley crane, which lifts through ropes, wheels and tension. It also differs from a hydraulic jack, which uses pressurized fluid. Leonardo’s designs belong to the mechanical screw-jack tradition that later became important in vehicle lifting, machinery and workshop equipment.