The outside diameter of the bearing is spherical to matchthe correspondinginner concavee spherical surface of thehousing providing self-aligning between these two parts. they are widely used on support shafts with poor rigidity and large deflection such as agricultural machinery, conveying systems and construction equipment. normally there is a dilated inne ring inside this bearing, and it can be fixed on the shaft by bolts or eccentric sleeves or adapter sleeves. there are two kinds of bearing bores: Cylindrical bore and tapered bore. the tolerance for the inside diameter of inner ring should be upper tolerance for easy assembling. the seals of these kinds of bearing are normally double seals or tripe-lips seals, and the radial clearance adopt C3 group clearance of the deep groove ball bearings. the inner ring of the bearing is heated-treated, the part that the set screw is fixed on the elongated end of the inner ring is tempered by high temperature to keep tenacity. this special heat-treatmentprevents the set screws from loosening during operation pr causing inner ring broken. the bearings cover two series: metric system series and inch system.