As a rule, self-aligning ball bearings have two rows of balls with a sphered raceway in the outer ring. This construction feature allows them to withstand the misalignments of the shaft relative to the housing up to 2...3°. Acceptable misalignment angle appearing as a result of shaft deflection under the influence of external load or due to technical machining and mounting inaccuracies is limited by the condition of keeping contact of all the balls in both rows with the working surface of the outer ring raceway. The bearings are designed for the accommodation of radial loads, but can simultaneously accommodate axial loads in both directions too.
The bearings are usually installed in the following constructions: multi-supporting shafts of transmission type; double-supporting shafts subjected to large deflections; units with technologically unprovided strict coaxiality of seats (while boring holes in the housings with more than one pass, when installing bearings in separate housings, etc.).
Self-aligning ball bearings are produced with the cylindrical and tapered bore as well as with extended inner rings. The design with built-in contact seals is also possible.
In the majority of self-aligning ball bearings, the cages are pressed steel or cast glass fiber reinforced polyamide. Large size bearings can be manufactured with machined brass cages.