Leonardo da Vinci designed a screw jack that used a screw mechanism to lift heavy loads.
In Renaissance engineering, a screw jack could convert rotary motion into a slower, powerful linear lift. Leonardo’s mechanical studies include screw-based lifting devices intended to raise weights with less direct force. Turning the handle would rotate the threaded component, causing the lifting part to move upward in controlled increments.
This principle is mechanically different from a pulley crane. A pulley changes the direction or effective magnitude of a force through rope and wheels, while a screw jack uses the mechanical advantage of a thread. The slow movement is a disadvantage for speed but an advantage for control and load holding.
Leonardo did not invent the screw as a general machine; screw mechanisms were already known in antiquity. His contribution was to analyze and adapt familiar mechanical principles for practical machines. His notebooks repeatedly combine screws, gears, levers, and pulleys into systems for construction and military engineering.