Kullager

Kullager is the Swedish term for a ball bearing, a mechanical element that allows one shaft or housing to rotate relative to another with minimal friction. A typical kullager comprises an inner race, an outer race, rolling elements (balls) and a cage that spaces the balls. The races are hardened steel, and lubrication reduces wear and heat generated during operation.

Common configurations include radial ball bearings, which mainly support radial loads; angular contact ball bearings, capable of higher axial loads in one direction; deep groove ball bearings, a versatile general-purpose type; self-aligning ball bearings that accommodate shaft misalignment; and thrust ball bearings designed for axial loads. Ball bearings come in many sizes and accuracy grades to suit different speeds and environments.

Construction materials typically use bearing steel such as chromium steel for races and balls; cages may be steel or polymer. Bearings are lubricated with grease or oil, and may be sealed or shielded to retain lubricant and keep contaminants out. Important design choices include material, clearance, and fit to ensure reliable operation at expected speeds and loads.

Operation and life depend on loads, speed, lubrication, and temperature. Each bearing type is given a dynamic load rating (C) and a static rating (Co). With proper lubrication and maintenance, the expected service life follows established life calculations, commonly expressed as the L10 life, roughly proportional to (C/P)^3, where P is the applied load.

Applications span automotive transmissions, engines, electric motors, industrial machinery, and consumer appliances. Installation requires correct mounting and seating to avoid preloads; cleanliness and correct lubrication are essential. Regular inspection for noise, play, or overheating helps detect wear or contamination and extend bearing life.