Cylindrical Roller Bearings
Cylindrical roller bearings have rollers, which are cylindrical, are in linear contact with the raceways. They have a high radial load capacity and are suitable for high speeds. There are different types designated NU, NJ, NUP, N, NF for single row bearings, and NNU, NN for double row bearings depending on the design or absence of side ribs. The outer ring and inner rings of all types are separable. Some cylindrical roller bearings have no ribs on either the inner ring and outer ring, so the rings can move axially relative to each other. These can be used as free-end bearings. Cylindrical roller bearings, in which either the inner or outer rings has two ribs and the other ring has one, are capable of taking some axial load in one direction. Double-row cylindrical roller bearings have high radial rigidity and are used primarily for precision machine tools. Pressed steel or machined brass cages are generally used, but sometimes molded polyamide cages are also used.
Cylindrical roller bearings can accommodate heavy radial loads and permit high speed operations. Double row cylindrical roller bearings have low sectional height, high load carrying capacity and little resilience. They enable stiff bearing arrangements for the support of heavy loads to be made and are mainly employed in machine tools and rolling mills. Cylindrical roller bearings are manufactured to normal tolerances and have normal radial internal clearance as standard.