Self Aligning Ball Bearing (Dia.10-100mm) These bearings come in internal and external types. Internal bearings have an outer-ring ball groove ground to a spherical surface. This surface makes these bearings insensitive to misalignment, but increases raceway contact stresses, which cuts load capacity. Externally self-aligning bearings have a spherical surface on the outside of the outer ring, which matches a concave spherical housing.