Leonardo da Vinci designed screw-jack mechanisms to lift heavy loads using threaded components and mechanical advantage.
His notebooks contain studies of screws, gears, and lifting devices. A screw jack converts rotational motion into a slower, powerful linear movement, allowing an operator to raise a heavy object with less force than direct lifting would require. Leonardo’s versions were part of his wider investigations into construction machinery and mechanical transmission.
This device is different from Leonardo’s famous aerial screw. The aerial screw was a proposed flight machine, while a screw jack is a lifting mechanism that works against a load. Confusing the two can produce an incorrect answer because both use a screw-shaped element.
Leonardo did not invent the screw principle itself; ancient and medieval engineers had already used screws in presses and lifting equipment. His contribution was to study and combine mechanical elements systematically in designs intended for practical work.