Leonardo da Vinci sketched a ball bearing using balls to reduce friction.
Around 1498, Leonardo studied how rolling elements could allow one part of a machine to move more freely against another. His drawings show balls arranged so that surfaces could rotate with less sliding friction. This is the basic principle of a ball bearing.
The sketches are important because they show an early understanding of rolling support in mechanical design. Leonardo’s notes also explore cages or arrangements that keep the balls separated, a practical problem in bearing construction. However, his drawings did not create the complete industrial bearing technology used today.
Ball bearings became widespread much later, after improvements in manufacturing made accurately shaped balls and races possible. Leonardo’s work is therefore best regarded as an early design study. It should not be confused with the invention of the modern standardized bearing industry, which required precision production and later engineering developments.