Leonardo da Vinci is often credited with designing an early ball bearing to reduce friction between moving parts.
His notebooks contain sketches of balls arranged between rings, allowing one component to rotate more freely against another. The principle is simple: rolling contact generally produces less friction than sliding contact. Leonardo studied the arrangement while investigating machines, gears, and other mechanical systems.
The design is important historically, but it should not be confused with the modern industrial ball bearing. Precision manufacturing, standardized steel, and sealed bearing assemblies developed much later. Leonardo's drawing represents an early conceptual application of rolling elements rather than a complete modern product.
Leonardo also explored related mechanical ideas, including rollers and low-friction supports. These studies demonstrate his habit of examining basic physical problems before applying them to larger machines.