Leonardo da Vinci studied a ball bearing as a way to reduce friction between moving surfaces.
Among Leonardo’s mechanical studies are designs using balls placed between rings or surfaces. The balls were intended to roll rather than allow one surface to slide directly against another. This principle reduces friction and is fundamental to many modern bearings.
Leonardo’s work is often described as an early ball-bearing concept, not the invention of every form of ball bearing used today. Ancient and medieval engineers had used rolling elements in various ways, and later designers developed standardized bearings, cages, materials, and manufacturing methods. Leonardo’s importance lies in clearly studying the mechanical principle and its possible applications.
A bearing supports motion and load; a gear, by contrast, transfers motion and torque through toothed wheels. A pulley changes the direction or mechanical advantage of a force. These parts can appear together in machines, but they perform different jobs. Leonardo’s bearing studies show his interest in making machines operate more efficiently.