Leonardo da Vinci designed a screw jack, a lifting device that used a threaded screw and a platform.
The mechanism appears among his studies of machines for raising heavy loads. Turning a handle would rotate the screw, converting circular motion into slow vertical movement. That mechanical advantage allowed a relatively small force to lift or support a much heavier object.
Leonardo did not invent the general principle of the screw. Ancient engineers had already used screws in devices such as presses and water-lifting machines. His contribution was to study and combine familiar mechanical principles in carefully drawn machine designs, often improving their arrangement or explaining how they could be manufactured.
A screw jack differs from a crane. A crane normally lifts with a rope, pulley, or drum, while a screw jack directly raises a load through the movement of a threaded screw. Leonardo’s machine studies helped make such distinctions visible by treating mechanics as a subject that could be analyzed through diagrams and proportional reasoning.