RAU5008 Cross Roller Bearing | 50 × 66 × 8 mm

RAU5008 Cross Roller Bearing Overview

The RAU5008 cross roller bearing combines a 50 mm bore, 66 mm outside diameter and 8 mm width. THK identifies its RA-compatible RAU design as integrated inner and outer rings, suitable for either ring to rotate. The separate 5 mm-wide RAU family should not be confused with this model. [1] Crossed cylindrical rollers can support radial, bidirectional axial and moment loading in one bearing position. RAU5008 leaves an 8 mm radial section, calculated as (66 − 50) ÷ 2. The shaft, retaining parts and routed services must fit the complete assembly. Compare ring construction using the cross roller bearing selection guide.

RAU5008 Dimensions and Reference Ratings

These figures identify the THK reference model; the approved LYDL drawing defines the item supplied. C and C₀ are radial rating inputs, not allowable payloads or moment limits. Combined loads, acceleration and required life need a separate assessment. [2, 3]

RAU5008 Structure and Mounting Diagram

The diagram below represents the RA-compatible RAU family, including RAU5008. Read d = 50 mm as the bore, D = 66 mm as the outside diameter and B / B₁ = 8 mm as the width. ds and Dh describe mounting shoulders, not bearing diameters. The open and double-sealed sections illustrate configuration choices; use the approved drawing for manufacture. [1, 2]

RAU5008 vs RA5008: What Changes?

THK lists RAU5008 and RA5008 with the same nominal 50 × 66 × 8 mm envelope. Their construction differs: RAU has integrated rings, while RA has a separable outer ring. THK identifies RAU as an RA-interchangeable type, but a replacement review must still include the full designation, mounting arrangement and required performance. [1, 2] Review the existing RA5008 product page when the original assembly uses a split outer ring. A shared envelope helps preserve shaft and housing space; it does not resolve seal orientation, rotating-ring accuracy or the lubrication interface. For a different 50 mm-bore envelope, CRBH5013A / CRBHV5013A measures 50 × 80 × 13 mm. Compared with RAU5008, it needs 14 mm more outside diameter and 5 mm more width. Treat it as a layout alternative, with its own load and mounting review.

Specify Seals, Clearance and Rotating-Ring Accuracy

RAU5008 bearing orders should identify the configuration alongside the base model. THK’s example RAU5008 UU CC0 P4 B illustrates several independent choices. The following meanings are THK references; record the agreed LYDL configuration on the quotation and drawing. [4] P4 specifies an accuracy grade; R or B identifies the ring covered by that requirement. State the rotating ring and inspection datum separately. For a one-sided seal, show the marked face in the order drawing.

Compact Axis Applications

A 50x66x8 cross roller bearing can be evaluated for these four layouts. Selection depends on the complete axis design and operating conditions.

• Compact robotics: wrist and gripper axes can route services through a hollow shaft. Check tool offset, emergency-stop loads and ring support.
• Optical and precision stages: the 8 mm width suits compact rotary layouts. Define axis tilt, encoder position and repeatability at the optical element.
• Semiconductor equipment: inspection and handling modules may need compact rotation. Confirm contamination limits and any cleanroom lubricant or seal requirements separately.
• Laboratory automation: sample-handling axes often combine short movements with dwell periods. Specify the motion sequence, cleaning conditions and lubricant.

Browse RAU series cross roller bearings if the passage needs to increase. Changing bore size also changes the surrounding geometry and reference ratings; select the new model from its own dimensional row.

Housing Support and Lubrication Access

The shaft shoulder reference is a maximum diameter of 53.5 mm; the housing shoulder reference is a minimum diameter of 60.5 mm. Their directions matter. Check the bearing chamfer against the mating corner, and review the retaining faces and ring height relationship before releasing machined parts. [2, 5] The RAU reference drawing identifies four ø1.5 mm lubrication holes. Provide an accessible lubricant path in the assembly. Do not use these holes to fasten the bearing, or treat their diameter as a fixing-bolt specification. [2] Keep the supporting surfaces clean and free of burrs. Apply fitting force to the ring being installed, and avoid tilting the thin assembly. THK’s RAU assembly guidance places the roller insertion plug outside the maximum-load zone and the presser flange on the rotating-axis side. Retaining-fastener size and torque need the actual housing design. [5, 6] For commissioning, record rotation resistance before and after retention. A change after clamping helps isolate mounting effects. Check runout using the agreed datum before connecting the axis to its drive. Choose lubricant for the operating temperature, motion pattern and cleanliness requirement. Small oscillations need attention to lubricant film formation; special environments need their own lubricant selection. A sealed reference does not establish vacuum suitability or a maintenance-free lifetime. [7]

Inspection and Export Packing

Make acceptance requirements part of the purchase specification: measured dimensions, rotating-ring runout, clearance or preload, and rotation resistance where required. Define the inspection method and acceptance limits so the supplier and incoming inspector evaluate the same characteristics. Keep the full configuration identifiable on the bearing label and accompanying records. For export packing, agree corrosion protection, individual support, moisture protection and carton identification. Specify which inspection records are needed with the shipment. Packaging photographs should show the actual process used for the order.

RAU5008 FAQ

1. Does RAU5008 belong to the 5 mm-wide RAU range?

No. RAU5008 is the 8 mm-wide RA-dimensional reference. THK distinguishes this family from its small-diameter, 5 mm thin type. Do not transfer the latter’s catalogue restrictions to RAU5008. [1, 4]

2. Can I bolt RAU5008 through the four small outer-ring holes?

No. The drawing labels them as lubrication holes, each ø1.5 mm. Retain the rings using the approved assembly design; these openings are not a mounting-bolt pattern. [2]

3. Is RAU5008UU enough information for a precision replacement?

No. UU identifies seals at both ends. Clearance or preload, accuracy grade and the ring covered by that accuracy requirement must also be defined. Include them when matching a replacement specification. [4]

4. Which way should the roller insertion plug face?

THK advises keeping the plug away from the area carrying the maximum load. Locate that zone from the actual load direction and mounting arrangement, then mark the required orientation on the assembly drawing. [6]

5. How should I read ds and Dh in the structure diagram?

They are shoulder-diameter limits: ds is a maximum of 53.5 mm and Dh is a minimum of 60.5 mm for the RAU5008 reference. They are not fit tolerances. Check the mating corners and retaining faces against the approved drawing. [2, 5]

Request an RAU5008 Drawing and Quote

Send the existing full bearing designation, order quantity and assembly section to request an RAU5008 quotation from LYDL. Include the rotating ring, forces and moments, motion cycle, operating temperature, sealing and accuracy requirements. For replacements, identify compatibility requirements. Confirm configuration, acceptance criteria and delivery terms before ordering.

Technical References

1. THK RAU, RA-interchangeable type — family and ring construction.
2. THK catalogue 515-1E, A18-32–33 — RAU5008 and RA5008 dimensions and radial ratings.
3. THK Static Safety Factor — combined-load assessment.
4. THK Model Number Coding — RAU suffixes and reference faces.
5. THK Housing and Presser Flange Design — ring support.
6. THK Procedure for Assembly — plug orientation and retention.
7. THK Handling Precautions — lubrication and operating conditions.

References checked on 10 October 2026. THK is the reference manufacturer; LYDL supplies this product. Reference data do not certify LYDL performance or imply manufacturer affiliation.