Self-aligning ball bearings have two rows of balls, a common sphered raceway in the outer ring and two deep uninterrupted raceway grooves in the inner ring. The bearings are insensitive to angular misalignment of the shaft relative to the housing. They can accommodate static and dynamic misalignment. Self-aligning ball bearings generate less friction than any other type of rolling bearing, which enables them to run cooler even at high speeds. Because of low heat generation, the bearing temperature is lower, leading to extended bearing life and maintenance intervals. Self-aligning ball bearings can reduce noise and vibration levels, for example, in fans.