Leonardo da Vinci studied a ball bearing as a low-friction support for rotating shafts.
Around 1498, Leonardo drew a bearing arrangement in which balls separated moving surfaces. The balls were intended to prevent the parts from rubbing directly against one another, reducing friction and helping a shaft rotate more freely. His design used channels or races to keep the rolling elements positioned.
The principle is the same basic principle used in many modern rolling-element bearings, although present-day bearings benefit from precise manufacturing, hardened materials, seals, and lubricants. Leonardo’s sketch is therefore an important early record of the idea, not evidence that he produced a standardized modern bearing industry.
Historians sometimes describe Leonardo as the inventor of the ball bearing, but that wording can oversimplify the history of rolling supports. Earlier cultures used rolling objects for transport, and the modern bearing developed through many later improvements. Leonardo’s contribution was a clear mechanical design for using balls to reduce rotational friction.