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Cylindrical Roller Bearings

Cylindrical roller bearings are rolling bearings in which cylindrical rollers contact the inner and outer raceways in line contact to support rotation. Compared with ball bearings, which make point contact, they have a higher capacity for radial loads (loads perpendicular to the shaft) and suit heavy and shock loads. Depending on the flange arrangement, they are classified into NU and N types (allow axial movement and are used on the free side), NJ and NF types (support axial load in one direction), and NUP types (support axial load in both directions). Single-row, double-row and multi-row designs are available, as are full-complement types without cage and tapered bore types. They are used in electric motors and generators, rolling mills, railway vehicle axle boxes, crane sheaves, and machine tool spindles.

How to choose Cylindrical Roller Bearings

  1. 1. Boundary dimensions that fit the shaft and housing

    Select the bore diameter d to match the shaft diameter and the outside diameter D to match the housing bore, and determine the width B from the available installation space. Even with the same bore, there are dimension series with different outside diameters and widths, and wide-section types and types with thicker outer ring walls also exist. Confirm the boundary dimensions d×D×B combination against the bearing number.

  2. 2. Select a rated load that suits the load conditions

    The basic dynamic load rating Cr is the basis for life calculation; calculate whether the required life is met from the actual load and rotational speed. For large loads at standstill or low speed, or for shock loads, also check the basic static load rating C0r. Wide-section, double-row and full-complement types are options when greater load capacity is needed.

  3. 3. Determine the type for fixed and free positions

    NU and N types allow relative axial movement between the inner and outer rings, making them suitable for the free side that absorbs thermal expansion of the shaft. If axial load is applied, choose NJ or NF types for one direction, or NUP types for both directions. First determine which bearing in the overall bearing arrangement locates the shaft axially.

  4. 4. Select a clearance that suits fit and temperature

    Internal clearance is available in classes such as C2, CN and C3. Consider a larger clearance class where an interference fit or a temperature difference between inner and outer rings reduces the clearance during operation. Tapered bore double-row types allow clearance adjustment by the amount of push-in and are used in applications with strict clearance control, such as machine tool spindles.

  5. 5. Match rotational speed with cage and accuracy grade

    For high-speed rotation, check the permissible rotational speed as well as the cage material (brass, steel sheet or resin) and the accuracy class. Full-complement types without cage have high load capacity but are unsuitable for high speed. Hybrid types with silicon nitride rollers offer low friction and support high-speed rotation.

  6. 6. Check electrical erosion countermeasures and maintainability

    In inverter-driven motors and generators, current can flow through the bearing causing electrical erosion, so consider insulated-coated or ceramic-roller types. For outdoor use or locations that are difficult to lubricate, also check for sealed, grease-packed designs, rust-preventive treatment, and ease of disassembly and inspection.

This guide was written by AI based on the listed products' documents and specification items. Check each manufacturer's documents before adopting.