Leonardo da Vinci designed a screw jack to create a spiral lifting motion for raising materials. A screw jack converts rotational movement into controlled vertical movement through the action of a threaded screw.
Leonardo's notebooks contain studies of screws, gears, and lifting machines. A screw-based lifting device could raise heavy loads gradually and hold them in position, making it useful in construction and mechanical work. The design reflects his effort to understand how simple machines could multiply force.
A screw jack is different from Leonardo's aerial screw. The aerial screw was a proposed flying machine based on a rotating helical surface, while a screw jack is a ground-based lifting mechanism. Leonardo's drawings often explore related screw principles in different contexts, so the names can be confused when modern summaries group his inventions together.