What are ball bearings used for?

--Reduce Friction in Rotating Parts
Ball bearings replace sliding friction with rolling friction, allowing shafts, wheels, and gears to spin freely with minimal energy loss. This is critical for efficiency in machinery.

--Support Radial Loads in Vehicles
Wheels (Cars/Motorcycles/Bicycles): Carry vehicle weight while enabling smooth wheel rotation.
Drive Shafts: Support rotating axles transmitting power from engines to wheels.

--Enable Precision Movement
Industrial Robots: Provide accurate joint positioning in articulated arms.
CNC Machines: Ensure high-precision linear motion in cutting tools.

--Handle High-Speed Applications
Electric Motors: Reduce friction in spinning rotors (e.g., power tools, fans, EV motors).
Turbines: Support shafts in jet engines or wind turbines at extreme RPMs.

--Everyday Consumer Goods
Skateboards/Inline Skates: Allow wheels to spin smoothly under rider weight.
Fishing Reels: Ensure fluid line retrieval without jerking.
Household Appliances: Found in washing machine drums, blender blades, and ceiling fans.

--Motorcycle-Specific Functions
Wheel Hubs: Bear radial loads from bike weight and road impact.
Steering Stem: Facilitate smooth handlebar turns (though tapered rollers better handle axial forces).
Clutch/Throttle Cables: Miniature bearings reduce cable friction for responsive control.

--Compromise for Light Axial Loads
Where space is limited and axial forces are modest:
Bicycle Pedals: Support rider push-force while rotating.
Conveyor Rollers: Guide belts with minor side loads.

--Failures Dictate Replacement Needs
Ball bearings are used until:
Grinding/vibration indicates race or ball damage.
Seal leaks or contamination cause roughness.
Fatigue cracks (spalling) release metal flakes into lubricant.