What mechanical device did Leonardo da Vinci design to produce continuous motion from falling weights?

Leonardo da Vinci designed a perpetual-motion machine intended to produce continuous motion from falling weights.

His notebooks contain drawings of wheels and systems of weights that appear to seek an unending imbalance. In one arrangement, weights move along angled channels so that they seem to remain farther from the center on one side of a wheel than the other. That apparent imbalance was supposed to keep the wheel turning.

Leonardo eventually recognized that such mechanisms could not generate endless useful motion. Friction, air resistance and the changing positions of the weights prevent a closed system from supplying more energy than it receives. His notes are important because they show a transition from imaginative mechanism design toward critical mechanical analysis.

The phrase perpetual-motion machine does not mean a normal clock, water wheel or flywheel that can keep moving for a while. A genuine perpetual-motion machine would violate established principles of thermodynamics by producing work indefinitely without an energy input. Leonardo's drawings are historical studies of the idea, not successful power sources.