Leonardo da Vinci designed a screw jack to lift heavy loads using the mechanical advantage of a threaded shaft.
A screw jack converts rotational motion into slow, powerful linear motion. Turning the screw causes a load-bearing part to rise or fall, allowing a relatively small force applied over many turns to move a much heavier object. Leonardo’s engineering studies included screw-based lifting mechanisms for construction and machinery.
The screw jack was valuable because it offered controlled movement as well as lifting power. Unlike a sudden impact device, it could raise a load gradually and hold it in position while work continued.
Leonardo did not invent the screw principle itself; threaded mechanisms were known in the ancient world. His importance lies in developing and documenting sophisticated mechanical applications during the Renaissance. A screw jack is different from a pulley system, which lifts through ropes and wheels rather than a threaded shaft.