Leonardo da Vinci designed a screw jack using a spiral screw to raise heavy loads.
The device belongs to Leonardo’s studies of mechanical engineering and appears among his designs for lifting and construction equipment. Turning a handle rotated a threaded screw, converting a relatively small input force into a larger upward force. A load could therefore be raised gradually and held securely at a chosen height.
Screw-based lifting devices were not wholly new in Leonardo’s time. The important point is that Leonardo carefully explored their geometry, materials and practical applications. His drawings show how mechanical advantage could be used in workshops, building projects and military engineering.
A screw jack differs from a pulley or crane because its lifting action comes from the screw thread rather than a hanging rope system. Modern mechanical and automotive jacks still use the same basic principle, although many contemporary jacks use hydraulic pressure instead.