The inner ring of this type of bearing has two raceways and the outer ring has a single spherical raceway with its center of curvature coincident with the bearing axis. Therefore, the axis of the inner ring, balls, and cage can deflect to some extent around the bearing center. Consequently, minor angular misalignment of the shaft and housing caused by machining or mounting errors are automatically corrected. Generally, self-aligning ball bearings feature a tapered bore for mounting using adapter sleeves.
These are particularly suitable for applications where considerable shaft deflection or misalignment is to be expected. Self-aligning ball bearings have the lowest friction of all rolling bearings, enabling them to run cooler even at high speeds.