Leonardo da Vinci studied and designed screw jacks that use a threaded shaft to raise heavy loads.
Turning the screw converts rotary motion into a slower linear movement. That mechanical advantage allows a relatively small force applied over a longer distance to lift or support a much heavier object. Leonardo’s notebooks contain studies of screws, gears, and lifting mechanisms as part of his broader work in mechanical engineering.
A screw jack is not the same as a pulley block. A pulley changes the direction or mechanical advantage of a rope force, while a screw jack relies on the inclined-plane principle wrapped around a cylinder. Leonardo’s drawings often combine screw mechanisms with frames, handles, and gearing to make controlled lifting possible.
The screw jack belongs to a long history of lifting devices, but Leonardo’s careful drawings helped document how components could work together. Similar screw-based jacks later became common in workshops, presses, vehicles, and construction equipment.