• RA12008 cross roller bearing
  • THK RA12008 bearing
  • RA12008 slewing ring bearing structure
  • Part NO.

    Open type:RA12008

  • Dimension




  • Mounting

  • Basic Load Ratings



  • Equivalent Model


  • Features
  • Mounting
  • RA12008 cross roller bearing specifications:

    Type of guide Roller
    Space retainer Yes
    Material GCr15
    Standard lubrication method Grease lubrication
    Oil hole Yes
    Sealing Oil seal at both sides
    Radial clearance CC0, C0
    Rotation accuracy Radial/axial runout below 20μm
    Working temperature -20℃ ~ 80℃

    * RA12008UU is two sides sealed type.

    More RA cross roller bearing models


    RA12008 crossed roller bearing features:

    1. Integrated inner ring with separable outer ring.

    2. Sustain radial, axial and moment loads at the same time.

    3. High rigidity & running accuracy.

    4. Ultra-thin section, space saving and reduce the overall weight of the device.


    Regarding the benefits of preload of RA crossed roller bearings

    1. Improve the rotation accuracy
    After the bearing is pre-loaded, the internal clearance is eliminated, and each rolling element is subjected to a certain preload, so that the cross roller ring is supported from all directions. Therefore the running accuracy is improved.

    2. Increase stiffness
    The contact between the rolling element and the raceway is elastic contact. The rolling element can be regarded as a spring. Bearings with clearance are supported by only a few springs in the direction of force. But the pre-loaded cross roller bearings are spring-loaded in all directions and have a certain amount of preload. The number of rolling elements under load is greater than that when there is a clearance, so the stiffness can be improved.

    3. Extend bearings service life
    After pre-load, the number of cylindrical rollers under load is increased, so the load on each roller is reduced. At the same time, the load can be evenly distributed on each rolling element, so the life of the bearing can be extended.

    4. Improve the bearing’s damping and reduce noise
    Pre-load makes a stable oil film between the rollers and the raceways of crossed roller bearings. This will improve the damping between the rolling elements and the raceways, and can improve the dynamic characteristics of the support structure and reduce noise.

    5. Compensate for wear during operation.
    The bearing will increase the clearance due to wear during operation. This situation can be compensated by pre-load of crossed roller bearings.

  • RA12008 cross roller bearing installation instructions

    Cautions: For crossed roller bearings with split outer ring, when the rigidity of the mounting parts is not sufficient, stress concentration will occur at the contact area between the rollers and raceways, and the bearing performance will be deteriorated significantly.

    Therefore, it is necessary to carefully examine the rigidity of housing and the strength of fixing bolts when a large moment will be applied.


    1. Before installation, please clean bearing bracket, shaft, or other components, make sure there is no burrs or rough edge.
    2. Fix the inner and outer rings in the axial direction by using fixing plates, etc.
    3. Slightly loosen the fixing bolts of bearings outer ring during mounting.


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