Leonardo da Vinci drew a ball bearing using rolling elements to reduce friction.
His notebooks include a design in which balls move between rings, allowing one surface to rotate against another with less sliding friction. The arrangement resembles the principle of modern ball bearings, which use hardened balls between races to support loads and permit smooth rotation.
The drawing is commonly dated to the late 15th century and is often cited as an early bearing concept. Leonardo’s purpose was to prevent the balls from touching one another, because contact between the rolling elements would increase friction and interfere with motion. That detail shows his interest in practical mechanical behavior rather than merely in abstract geometry.
Leonardo did not invent the complete modern bearing industry. Ancient and medieval devices used rollers and other low-friction arrangements, and later engineers developed precise materials, cages, seals, and manufacturing methods. His importance lies in clearly recording a sophisticated rolling-bearing idea centuries before modern mass production.