Leonardo da Vinci sketched a ball bearing using freely rolling balls to reduce friction.
In a ball bearing, hard balls sit between moving rings or surfaces. Instead of one surface sliding directly over another, the balls roll between them, reducing resistance and allowing smoother rotation. Leonardo’s studies included arrangements of balls that could keep them separated while supporting rotational movement.
His sketches date from the late fifteenth century and are among the early recorded designs for this principle. However, Leonardo did not create the modern standardized bearing industry. Practical bearings require careful materials, accurate manufacturing, lubrication, and methods for keeping the balls correctly spaced.
The idea is also different from a roller bearing, which uses cylindrical rollers rather than spherical balls. Leonardo’s drawing is historically important because it shows a clear understanding of how rolling contact can reduce friction in machinery, even though the complete modern bearing system developed much later.