Spherical roller bearings are designed to be robust in carrying heavy loads, and intrinsically self-aligning, with barrel rollers that roll and align themselves freely at the sphere outer ring raceway. However, they must not subject to any axial loads. These bearings are double row, consisting of solid outer ring with a concave or sphere raceway, solid inner rings, and two rows of barrel rollers in the cage. Spherical roller bearings are available in both cylindrical and tapered bores. Main advantage over the self-aligning ball bearings is their greater load carrying capacity.