Leonardo da Vinci designed a screw jack to help lift heavy loads.
Leonardo’s notebooks contain studies of threaded mechanisms and lifting devices. A screw jack converts rotational motion into a slower, powerful linear movement, allowing a person to raise a heavy object with comparatively modest effort. The mechanical advantage comes from the screw’s pitch and the turning force applied to it.
Screw-based lifting devices were not invented by Leonardo; the screw was already an ancient mechanical principle associated with devices such as the Archimedes screw. Leonardo’s contribution was to analyze and refine mechanisms for engineering, construction, and machinery.
The term screw jack can refer to several historical and modern designs. Leonardo’s sketches are therefore best understood as studies of a screw-operated lifting mechanism, not as proof that he invented every later form of jack.