Definition
The bearings inside the wheel hubs of an aircraft's landing gear that allow the wheels to spin smoothly on their axles under the load of the aircraft during taxi, takeoff, and landing.
Plain English
The small metal parts inside each landing gear wheel that let the wheel turn freely on its axle. They sit between the wheel and the axle and carry the aircraft's weight while still allowing the wheel to roll.
Context Anchor
Seen in preventive maintenance, wheel removal, tire replacement, and inspections of the landing gear wheels.
Derivation
A bearing is a part that 'bears' (carries) a load while allowing motion. The word comes from the Old English beran, meaning to carry. In a wheel, the bearing carries the weight of the aircraft while letting the wheel rotate.
Why Pilots Care
Worn or dry bearings create drag, heat, and possible wheel lockup that can affect directional control on takeoff or landing.
Analogy
Like the bearings in a bicycle wheel hub. If they are clean and greased, the wheel spins freely. If they are dry or full of grit, the wheel drags and eventually fails.
Intuition Check
Gear does not mean loose equipment here; it means the aircraft’s landing gear. Bearings does not mean compass directions here; it means parts that support a rotating wheel.
Example Sentence 1
Repacking the gear wheel bearings with fresh grease is one of the preventive maintenance tasks a pilot is permitted to perform on their own aircraft.
Example Sentence 2
As preventive maintenance the pilot repacked the gear wheel bearings with the approved grease specified in the aircraft manual.