Leonardo da Vinci studied a ball bearing as a rotating support intended to reduce friction between moving parts.
A ball bearing places balls between two rings or races so that rotation occurs mainly through rolling rather than sliding. Leonardo’s notes include a design with balls arranged to prevent them from touching one another, an important detail because freely rubbing balls would increase friction and interfere with smooth motion.
The sketch is often cited as an early bearing concept, but Leonardo did not invent the general idea of reducing friction with rolling elements. Ancient and medieval engineers used related methods, and later industrial manufacturing made bearings precise, durable, and practical at scale. Leonardo’s contribution was a thoughtful mechanical design recorded during the Renaissance.
Ball bearings are used in machinery, bicycles, electric motors, and many other devices. They should not be confused with roller bearings, which use cylindrical or tapered rollers instead of spherical balls.