Rolling bearing

Rolling bearings support parts that move relative to each other — typically a rotating shaft in a stationary housing — with minimal friction. Rolling elements (balls or rollers) run between hardened raceways on the inner and outer ring, separated by a cage; rolling contact replaces the sliding friction of plain bearings. Key standards are DIN 625 (deep groove ball bearings), ISO 492 (tolerances) and ISO 281 (rating life). Ball bearings suit high speeds, roller bearings carry heavier loads via line contact. Selection depends on load, speed, misalignment, lubrication and environment; correct fits and clean mounting often govern service life more than calculated fatigue life.