The self-aligning ball bearing was invented by SKF. It has two rows of balls and a common sphered raceway in the outer ring. The bearing is consequently self-aligning and insensitive to angular misalignments of the shaft relative to the housing.
The basic design self-aligning ball bearing is available with a cylindrical bore or, in certain size ranges, with a tapered bore
Self-aligning ball bearings are also available in a sealed version with contact seals on both sides. These sheet steel reinforced seals are made of oil and wear-resistant acrylonitrile-butadiene rubber (NBR). The permissible operating temperature range for these seals is –40 to +100 °C and up to +120 °C for brief periods. The seal lip contacts a smooth chamfer on the inner ring with light pressure. Sealed bearings are lubricated for life and require no maintenance. They should not be heated above 80 °C before mounting and should not be washed.
The design of self-aligning ball bearings is such that angular misalignment between the outer and the inner rings can be accommodated without any negative effect on bearing performance.