Leonardo da Vinci designed a crankshaft mechanism to convert reciprocating motion into continuous rotary motion.
A crankshaft links a rotating shaft with connecting elements so that movement in one direction can become repeated turning. Leonardo’s sketches show crank mechanisms related to machines such as presses and other devices requiring regular rotary action. This mechanical conversion was important because many practical machines need a steady turn rather than a simple back-and-forth movement.
A crankshaft is not the same as a flywheel. A flywheel stores rotational energy and smooths motion, while a crankshaft changes the geometry of motion through cranks and connecting rods. A camshaft instead uses shaped cams to produce timed follower movements.
Leonardo’s machine drawings often isolate a single useful principle rather than present a complete working factory system. His crankshaft studies belong to the broader history of mechanical power transmission, which later became central to engines, pumps, presses, and vehicles.