THK RA12008UUC0 Cross Roller Ring
RA12008UUC0 is an ultra‑thin, high‑rigidity crossed roller bearing from THK’s RA series (separable outer ring, for inner‑ring rotation). It features cylindrical rollers alternately crossed at 90° between a one‑piece inner ring and a two‑piece outer ring, guided by a precision spacer retainer.
RA12008UUC0 is an ultra‑thin, high‑rigidity crossed roller bearing from THK’s RA series (separable outer ring, for inner‑ring rotation). It features cylindrical rollers alternately crossed at 90° between a one‑piece inner ring and a two‑piece outer ring, guided by a precision spacer retainer. This design enables the bearing to support radial, axial, and moment loads simultaneously in an extremely compact form factor. The unit is factory‑equipped with double non‑contact rubber seals (UU) and C0 radial internal clearance, delivering stable rotational accuracy, rigidity, and contamination resistance for space‑constrained precision applications.
Official Technical Specifications
| Parameter | Value | Unit |
|---|---|---|
| Model | RA12008UUC0 | — |
| Inner Diameter (d) | 120 | mm |
| Outer Diameter (D) | 136 | mm |
| Width (B) | 8 | mm |
| Roller Pitch Circle Diameter (dp) | 127 | mm |
| Minimum Chamfer (rₘᵢₙ) | 0.5 | mm |
| Grease Hole Diameter (d₀) | 1.5 | mm |
| Inner Ring Shoulder (ds, max) | 123.5 | mm |
| Outer Ring Shoulder (Dh, min) | 130.5 | mm |
| Basic Dynamic Load Rating (C) | 7.84 | kN |
| Basic Static Load Rating (C₀) | 16.5 | kN |
| Mass | 0.17 | kg |
| Seal Type | UU | Double non‑contact rubber seals (both sides) |
| Internal Clearance | C0 | Standard radial internal clearance |
| Retainer | Spacer separator | Precision roller guidance |
| Material | High‑carbon chromium bearing steel (SUJ2) | — |
| Operating Temperature | -30°C to +80°C | Standard service range |
| Accuracy Class | JIS Class 0 (P0) | ISO 492 / ABEC 1 |
| Lubrication | Factory‑filled lithium‑base grease | Non‑relubricatable |
| Structure | One‑piece inner ring, two‑piece outer ring | For inner‑ring rotationTHK |
Key Design Features
- Ultra‑Thin Profile: Compact dimensions (120×136×8 mm) ideal for space‑limited installationsTHK.
- High Rigidity: Crossed roller arrangement provides exceptional rigidity and minimal elastic deformation under combined loadsTHK.
- Multi‑Directional Load Capacity: Single bearing supports radial, axial, and moment loads, reducing system complexityTHK.
- Sealed Construction: UU double non‑contact seals prevent contamination ingress and retain lubricationTHK.
- Precision Spacer Retainer: Maintains roller alignment, reduces friction, and ensures stable rotational torqueTHK.
- C0 Clearance: Factory‑set standard radial clearance guarantees smooth rotation and consistent performance.
- Separable Outer Ring: Two‑piece outer ring allows for easy installation and preload adjustmentTHK.
Typical Applications
- Industrial robot joints and manipulator arms
- Precision rotary tables for machine tools
- Semiconductor manufacturing and inspection equipment
- Medical diagnostic and imaging devices
- Optical positioning systems and measuring instruments
- High‑precision automation modules and rotary stages
Model Code Explanation (THK Standard)
| Code | Meaning |
|---|---|
| RA | Separable outer ring type cross‑roller ring (for inner‑ring rotation) |
| 120 | Inner diameter = 120 mm |
| 08 | Width = 8 mm |
| UU | Double non‑contact rubber seals (both sides) |
| C0 | Standard radial internal clearance |
