This design allows the bearing to tolerate a small angular misalignment resulting from shaft or housing deflections or improper mounting. The bearing was used mainly in arrangements with very long shafts, such as transmission shafts in textile factories. One drawback of the self aligning ball bearings is a limited load rating, as the outer raceway has very low osculation (radius is much larger than ball radius). This led to the invention of the spherical roller bearing, which has a similar design, but use rollers instead of balls.