The outer ring raceway of self-aligning ball bearings forms a spherical surface whose centre is common to the bearing centre. The inner ring of the bearing has two raceways. The balls, cage, and inner ring of these bearings are capable of shifting in order to compensate for a certain degree of misalignment with the outer rings. As a result, the bearing is able to align itself and compensate for shaft/housing finishing unevenness, bearing fitting error, and other sources of misalignment. Since axial load capacity is limited, self-aligning ball bearings are not suitable for applications with heavy axial loads.
In addition to spherical roller bearings with cylindrical bores, spherical roller bearings with tapered bores are also available. Bearings with tapered bores are specified by the suffix “K” at the end of the spherical roller bearing part number. The standard taper ratio is 1:12 for bearings with a “K” suffix.