Definition
A type of anti-friction bearing in which hardened steel balls roll between an inner race and an outer race, allowing a shaft to rotate smoothly while supporting radial loads, thrust loads, or both.
Plain English
A ring of small steel balls that sits between two metal rings so that a spinning shaft can turn easily without rubbing.
Context Anchor
Seen in aircraft maintenance when discussing wheels, pulleys, control-system parts, engine accessories, electric motors, and other rotating parts.
Derivation
Called a 'bearing' because it bears (carries) the load of the rotating shaft. The 'ball' simply describes the rolling element. Older shaft supports used plain sleeves, where the shaft slid against a bushing; replacing that sliding contact with rolling balls dramatically reduced friction.
Why Pilots Care
Ball bearings are essential in aircraft engines, propellers, and instruments to maintain smooth rotation under high speeds and loads.
Analogy
It is like putting small rollers under a heavy object so it can move more easily instead of scraping along the floor.
Intuition Check
A ball bearing is not a navigation bearing or direction. Here, “bearing” means a part that supports another part while allowing it to turn.
Example Sentence 1
The mechanic replaced the wheel ball bearings during the annual inspection because the inner race showed signs of pitting.
Example Sentence 2
Worn ball bearings in the propeller hub can cause vibration during flight.