Self aligning roller bearings have double row rollers, with one shared spherical raceway on the outer ring and two raceways on the inner ring that are tilted at an angle relative to the bearing axis. This ingenious structure enables it to have automatic centering performance, making it less susceptible to errors or shaft bending caused by the angle between the shaft and the bearing housing. It is suitable for situations where installation errors or shaft bending cause angle errors. This bearing can not only withstand radial loads, but also axial loads acting in both directions. There are two types of inner holes for self-aligning roller bearings: cylindrical and conical. The taper of the conical hole is 1:30 and 1:12. This type of conical inner hole bearing is equipped with a locking sleeve or a detachable sleeve, which can easily and quickly assemble the conical inner hole self-aligning ball bearing on the optical shaft or stepped machine shaft.