Leonardo da Vinci designed a screw jack using a threaded screw to lift heavy loads.
A screw jack converts rotational motion into a slower upward movement. Turning the screw advances a threaded component, creating mechanical advantage and allowing a person to raise a load that would be difficult to lift directly. Leonardo’s engineering notebooks contain designs for lifting and construction machinery based on this principle.
A screw jack differs from a pulley block, which uses ropes and wheels, and from a hydraulic jack, which uses fluid pressure. The screw principle is especially useful when controlled, stable lifting is more important than speed.
Leonardo frequently applied screws, gears, pulleys, and levers to practical problems. His lifting designs belong to the same broader engineering tradition used in building, military works, and workshop machinery.