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Needle roller bearings

Needle roller bearings are rolling bearings that use small-diameter rollers whose length is much greater than their diameter as rolling elements. Because the roller and raceway contact is a line contact, they can carry large radial loads despite their small cross-sectional height, which suits space-saving bearing arrangements. Main types include shell types with a thin pressed steel outer ring, open at both ends (HK) or closed at one end (BK), solid types with a machined outer ring with or without flange and with or without inner ring, and caged needle rollers (cage and roller assemblies). Other types include self-aligning types, combined types with thrust bearings, and cam followers. They are used for rotational support in transmissions, automotive parts, pumps, and industrial machinery.

How to choose Needle roller bearings

  1. 1. Select dimensions by shaft diameter and presence of inner ring

    Types without an inner ring use the shaft directly as the raceway, so the roller pitch circle diameter Fw corresponds to the applicable shaft diameter. In this case the shaft requires sufficient hardness and surface finish. If the shaft cannot serve as the raceway, select a type with an inner ring and match the shaft diameter using the bore diameter d.

  2. 2. Check housing dimensions by outside diameter and width

    The outside diameter D determines the housing bore diameter, and the width C determines the axial installation space. Shell types have thin walls and allow a smaller outside diameter, but they are retained by press fit, so the housing bore tolerance and rigidity must be verified.

  3. 3. Verify life and static strength with rated loads

    The basic dynamic load rating Cr is used for calculating rolling fatigue life, and the basic static load rating C0r is used for examining permanent deformation under shock loads or stationary loads. The listed Cr values range widely from 1.23 to 13200 kN, and are larger for double-row types and larger diameters.

  4. 4. Choose the type suited to the application

    Select shell types for space savings and solid types for high load and high rigidity. Select self-aligning types where shaft tilt is present, combined types with thrust bearings for fixed-side positions that also carry axial load, and cam followers for applications rolling along cams or rails.

  5. 5. Match rotational speed with lubrication method

    The limiting speed varies with the lubrication method, and generally oil lubrication allows higher speeds than grease lubrication. Confirm that the operating speed is below the limiting speed for each lubrication condition.

  6. 6. Consider sealing and operating environment

    In environments where foreign matter or moisture may enter, selecting contact-seal types such as RS or 2RS, or grease-packed types, helps retain lubricant and reduces relubrication effort. However, the seal increases rotational resistance and imposes limits on operating temperature, so these points should be considered.

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