Leonardo da Vinci designed a screw jack to lift heavy loads using a threaded mechanism.
A screw jack converts rotary motion into a slower, stronger linear movement. Turning a handle rotates the screw, causing a platform or lifting piece to rise. Leonardo studied screw-based lifting devices as part of his broader work on machines, force, and mechanical advantage.
The concept was useful for construction and engineering because it could raise substantial weight with relatively modest effort. Its drawback is speed: a screw jack lifts slowly, especially when the screw has a fine thread.
Leonardo did not invent the general screw principle, which was known in the ancient world. His importance lies in analyzing and refining mechanical systems and recording designs that anticipated later engineering practice. Modern mechanical and hydraulic jacks apply the same goal—lifting loads—through different technologies.