Leonardo da Vinci designed a ball bearing to reduce the effects of friction on moving parts.
In the late fifteenth century, Leonardo drew mechanisms in which balls moved between rings or races. The rolling balls were intended to reduce sliding friction, allowing one component to rotate more freely against another. His studies connected bearing design with clockwork and other machines that needed controlled, efficient motion.
Leonardo did not create the modern precision ball bearing used in bicycles, engines, and industrial machinery. Renaissance manufacturing could not reliably produce the uniform hardened balls and accurate races required for low-friction mass production. His sketches nevertheless show an early and clear understanding of the rolling-bearing principle.
A ball bearing is different from an escapement, which regulates the release of energy in a mechanical clock. It is also different from a pendulum, which provides a timing reference, and from a mainspring, which stores energy. Leonardo’s bearing concept addressed mechanical resistance rather than timekeeping regulation itself.