Leonardo da Vinci designed screw-jack mechanisms for raising heavy materials. A screw jack converts rotary motion into a slower, powerful vertical lift, allowing a person to raise a substantial load with mechanical advantage.
Leonardo’s engineering notebooks contain studies of screws, gears, winches, and lifting systems. These mechanisms were useful in construction and military engineering, where heavy objects needed controlled movement rather than rapid motion.
A screw jack is different from a simple pulley. A pulley changes the direction of a rope force or, in systems with several pulleys, provides mechanical advantage. A screw jack uses the inclined-plane principle wrapped around a cylinder; turning the screw moves the load along its axis.
Leonardo did not originate the general principle of the screw jack, which had ancient mechanical precedents. His contribution was the detailed analysis and integration of lifting devices into sophisticated Renaissance machines.