Backing bearing is a special cylindrical roller bearing. Multiple backing bearings are mounted on one roll. The external surface of each backing bearing is used as part of the rolling surface. So, it is required that the backing bearings shall have uniform cross sections. The precision requirements for their parts are very strict.
The double-row cylindrical roller bearing has two optional structures: cylindrical bore and tapered bore(suffix K),and two optional designs: NNU and NN. The NN design has an inner ring with two ribs and an outer ring without ribs. The NNU design has an inner ring without ribs and an outer ring with two ribs.