Leonardo da Vinci designed a screw jack to lift heavy loads through the mechanical advantage of a threaded screw.
A screw jack converts rotary motion into controlled vertical movement. Turning the screw advances a load-bearing component a small distance, allowing a relatively modest force to raise a much heavier object. Leonardo’s mechanical drawings explored this principle in detail, alongside gears, winches, and other lifting devices.
The screw jack was not a single famous machine with one confirmed construction date. It belongs to a wider tradition of screw-based lifting mechanisms used in engineering and construction. Leonardo’s contribution was his systematic analysis and refinement of mechanisms, including ways to transmit motion and increase force.
A screw jack differs from a simple pulley because it does not lift by redirecting a rope. It also differs from a hydraulic jack, which uses pressurized fluid. The threaded screw provides the lifting action and helps hold the load in position.