Leonardo da Vinci sketched a screw jack for raising heavy loads with a threaded mechanism.
A screw jack converts rotational motion into slow vertical lifting. When a handle turns the screw, the threaded parts advance and raise a platform or load. The mechanical advantage makes it possible to lift substantial weight with less force than direct lifting, although the movement is gradual.
Leonardo studied screw-based lifting machines in the context of construction and mechanical engineering. His notebooks contain detailed investigations of screws, gears, winches, and other devices that could multiply force or control motion. These studies show his interest in practical mechanisms as well as spectacular inventions.
Leonardo was not the inventor of the screw principle itself; ancient engineers had used screws and screw presses earlier. His importance lies in analyzing and refining mechanisms, recording their geometry, and combining them with other machine elements. A screw jack should also not be confused with his aerial screw, which was a flight concept rather than a lifting tool for loads.