The self-aligning roller bearing has double row rollers, the outer ring has one common spherical raceway, and the inner ring has two raceways and is inclined to an angle with respect to the bearing axis. This ingenious structure makes it have the function of self-aligning, so it is not easy to be influenced by the angle between the shaft and the bearing housing on the error or the bending of the shaft. It is suitable for the occasion where the angle error is caused by the installation error or the bending of the shaft. The bearing can bear not only the radial load, but also the axial load of two-way action.

The inner hole of self-aligning roller bearing has two kinds: cylindrical and conical, and the taper of conical bore is 1:30 and 1:12. This kind of tapered inner hole bearing is equipped with a tight set sleeve or a withdrawal sleeve, so that the tapered inner hole self-aligning ball bearing can be conveniently and rapidly assembled on the optical shaft or the step machine shaft.