Self-aligning ball bearings have two rows of ball on inner race with a common spherical surface on outer race with centre coinciding with bearings centre.
This design gives bearing self-aligning feature, permitting misalignments of about 0.07 radian (4 degree) with ordinary loads.
For heavier loads, spherical roller bearings, also having self-aligning feature are used.
These bearings are available with normal clearance & if desired with lower or higher clearance.
Self-aligning ball bearings are available with cylindrical & taper bore. Self-aligning ball bearings with bore taper 1:2 (suffix K) can be mounted either directly on a tapered shaft or on a cylindrical shaft using adapter sleeves.