Leonardo da Vinci designed a screw jack that used a spiral thread to lift heavy loads with mechanical advantage.
Turning a threaded screw converts rotary motion into a slower linear movement. The operator must apply force over a longer distance, but the load rises with much greater lifting force. Leonardo’s notebooks contain detailed studies of screws, gears, and lifting mechanisms for construction and engineering work.
A screw jack could raise heavy materials gradually and hold them in position, making it useful for building or machinery. The concept was not an entirely new principle: ancient engineers already used screws, and Archimedes is traditionally associated with important screw mechanisms. Leonardo’s designs show how Renaissance engineers refined such mechanisms and combined them with gearing.
This device is different from the water-lifting machines in Leonardo’s notebooks. A screw jack lifts a solid load, while a pump or water screw moves liquid. The distinction matters because both rely on spiral geometry but serve different mechanical purposes.