What Leonardo da Vinci invention was a screw-operated machine designed to lift heavy loads?

Leonardo da Vinci’s screw jack was a screw-operated machine designed to lift heavy loads.

A screw jack converts rotational motion into a slower, powerful vertical movement. Turning the handle advances a threaded screw through a fixed or moving support, raising the load. Leonardo studied this principle in mechanical drawings concerned with lifting, construction, and military engineering.

The screw jack illustrates Leonardo’s interest in mechanical advantage: a person can apply a relatively modest force over a long turning motion to raise a much heavier object through a shorter distance. Thread shape, friction, and the strength of the supporting frame determine how safely the device works.

The design should not be confused with Leonardo’s water screw. Both use a helical form, but the screw jack lifts solid loads while the water screw transports liquid. Jacks and screw-based lifting mechanisms were not unique to Leonardo; ancient and medieval engineers had used related principles. His notebooks preserve detailed Renaissance studies of how such mechanisms could be arranged and improved.