Rolling elements

Rolling elements transfer load between inner and outer ring by rolling on the raceways. Common forms are balls, cylindrical rollers, needle rollers, tapered rollers and spherical rollers. Balls make point contact, favouring high speeds at moderate loads; rollers make line contact, carrying much higher loads for the same size but tolerating less misalignment. They are made from through-hardened bearing steel (typically 100Cr6) to extremely tight tolerances; hybrid bearings use silicon nitride ceramic balls — lighter, harder and electrically insulating. Standstill vibration can cause false brinelling, and current passage causes fluting, both appearing as patterns at rolling-element spacing.