Leonardo da Vinci studied and sketched a ball bearing, using rolling balls to reduce friction between moving surfaces.
A ball bearing places balls between rings or races so that motion occurs mainly through rolling rather than sliding. Leonardo’s notes and drawings from the late 15th century show an attempt to keep the balls separated while allowing them to circulate. This was a practical mechanical problem because balls touching one another would increase friction and disrupt smooth motion.
Leonardo’s design is often cited as an early ball-bearing concept, but he did not create the standardized industrial bearings used today. The manufacture of accurately sized balls, smooth races, cages, and durable materials required later advances in precision engineering. Philip Vaughan patented an early modern ball-bearing design in Britain in 1794.
The invention is sometimes mistakenly described as entirely Leonardo’s. A more precise claim is that his notebooks contain an early recognizable design and an insightful study of friction reduction. Bearings became essential in clocks, machinery, vehicles, turbines, and many other systems.