Leonardo da Vinci sketched a screw jack, a lifting machine that raises heavy loads through a threaded screw mechanism.
A screw jack converts rotary motion into slow, powerful vertical movement. Turning a handle rotates the screw, and the threads force a supporting component upward or downward. Leonardo’s mechanical notebooks include studies of screws, gears, and lifting devices that apply this principle to practical engineering.
The screw jack was not a completely new concept in Leonardo’s era. Earlier civilizations and engineers had used screw-based lifting devices, and the ancient Greek mathematician Archimedes is traditionally associated with screw mechanisms. Leonardo’s contribution was his detailed analysis and adaptation of mechanical systems for construction and military applications.
This device should not be confused with a pulley or a crane. Pulleys mainly redirect force or provide mechanical advantage through rope, while a screw jack uses a threaded shaft to produce controlled lifting. Its slow movement is a limitation for speed but an advantage when precision and load-holding ability matter.