Leonardo da Vinci’s threaded lifting machine was a screw jack.
A screw jack raises or lowers a load by turning a threaded screw. Leonardo designed versions of this mechanism for lifting heavy objects, using the mechanical advantage created by a screw’s inclined plane wrapped around a cylinder. Turning the screw a relatively small distance could produce a much larger lifting force.
The screw principle was ancient, so Leonardo did not invent the screw jack from nothing. His contribution was to study, refine, and depict mechanical arrangements that could be useful in engineering and construction. A screw jack differs from a pulley, which changes force and direction through a rope and wheel, and from a winch, which winds a cable around a drum. Leonardo’s notebooks frequently examine how combinations of simple machines could multiply human effort.