Leonardo da Vinci sketched a ball bearing using low-friction rolling balls.
Around the late 15th century, Leonardo drew mechanisms in which balls moved between rings or surfaces. The purpose was to reduce friction by replacing sliding contact with rolling contact. This principle is the basis of modern ball bearings, which support rotating shafts and reduce energy loss.
Leonardo’s sketches show important thinking about friction, but they were not identical to standardized industrial bearings. Some of his designs did not fully constrain the balls, so the balls could bunch together and interfere with smooth operation. Later engineers added cages and improved manufacturing precision.
The idea is often attributed solely to Leonardo, but rolling-element bearings have a longer history, and practical bearing technology developed gradually. Leonardo’s importance is that his notebooks contain clear, systematic bearing concepts at a time when many machines still relied heavily on sliding surfaces.