Leonardo da Vinci drew a ball-bearing concept using balls between moving surfaces to reduce friction.
In a ball bearing, rolling balls separate two rings or surfaces, allowing one part to rotate while limiting sliding friction. Leonardo included a related design in his studies of friction and mechanical motion. The arrangement showed his recognition that rolling contact could make machines more efficient than direct rubbing contact.
Leonardo did not invent every principle behind rolling bearings, and his drawing was not the same as a complete modern standardized bearing. Early bearing concepts existed before him, while practical mass-produced bearings required later advances in materials, precision manufacturing, lubrication, and industrial production.
His design is nevertheless historically important because it demonstrates a clear understanding of how rolling elements can support motion. Modern bearings use carefully shaped races, cages, and hardened materials, features that developed long after Leonardo’s notebooks.