Leonardo da Vinci designed a screw jack to raise heavy loads using a threaded screw and a rotating mechanism. A screw jack converts turning motion into a slower, powerful lifting motion.
The design reflects Leonardo’s interest in machines that could multiply human force. By turning a handle or crank, an operator could advance the screw and lift an object gradually. This principle is especially useful when controlled movement matters more than speed.
A screw jack is different from a simple pulley or a winch. A pulley changes the direction or mechanical advantage of a rope, while a winch winds rope around a drum. A screw jack relies primarily on the inclined plane represented by the screw thread.
Leonardo did not invent every underlying mechanical principle in isolation, but his notebooks contain detailed studies of lifting devices, screws, gears, and force transmission. Later jacks became common in engineering and vehicle maintenance.