Leonardo da Vinci studied an early form of the ball bearing to reduce friction between moving surfaces.
His notebooks from the late fifteenth century include sketches of balls placed between rings or surfaces. The balls were intended to roll rather than slide, reducing friction and helping a mechanism rotate more easily. This principle is the foundation of modern rolling-element bearings.
Leonardo’s studies were connected with broader mechanical work, including machines, gears, and rotating components. He did not create the standardized, sealed, mass-produced ball bearings used in modern machinery, and the historical evidence does not show that his designs became an industrial product.
Modern ball bearings use carefully manufactured balls, races, cages, lubrication, and precise materials. They appear in vehicles, electric motors, tools, and countless other machines. Leonardo’s sketches are important because they clearly explore the rolling-contact principle well before industrial bearing manufacture.