Double-Row Cylindrical Roller Bearings

Specifications

How to choose Cylindrical Roller Bearings

Points to check when selecting, with the values for this product (Double-Row Cylindrical Roller Bearings).

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

   This product: Inner diameter d 100～670 mm

   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.

About Cylindrical Roller Bearings and all products

Description

Double-row cylindrical roller bearings with bore diameters of 100 to 670 mm. Available with cylindrical bore (NN type, NNU type) and tapered bore (designated by suffix K in the bearing number). Bearings with oil holes and oil grooves in the outer ring are indicated by the supplementary code W.

FAQ

Q. What are the bore diameter, outside diameter, and width ranges for double-row cylindrical roller bearings (NN type, NNU type)?

A. Bore diameter d is 100 to 670 mm, outside diameter D is 140 to 870 mm, and width B is 40 to 320 mm.

Q. What is the difference between the cylindrical bore and tapered bore in double-row cylindrical roller bearings (NN type, NNU type)?

A. They are available with a cylindrical bore (NN type, NNU type) and a tapered bore. Tapered bore bearings are designated by suffix K in the bearing number. Tapered bore bearings achieve the specified clearance through drive-up amount.

Q. How can clearance be adjusted when selecting tapered bore bearings for double-row cylindrical roller bearings?

A. Clearance of tapered bore bearings can be adjusted by drive-up amount.

Q. How can you identify double-row cylindrical roller bearings with oil holes and oil grooves in the outer ring from the model number?

A. Bearings with oil holes and oil grooves in the outer ring are indicated by the supplementary code W.

Written by AI based on the content of the source documents.

Source documents

• Catalog JTEKT 大形転がり軸受カタログ（技術解説・軸受寸法表） Open page 76
  Found on: https://koyo.jtekt.co.jp/support/catalog-download/