RNA6908 bearing: complete specifications & equivalents
The RNA6908 is a ISO 1206 radial bearing sized 48 x 62 x 40 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 48 mm |
| Outer diameter D | 62 mm |
| Width B | 40 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 67.1 kN |
| Basic static load rating C0 | 125 kN |
| Fatigue load limit Pu | 15.3 kN |
| Reference speed (thermal) | 8000 rpm |
| Limiting speed (mechanical) | 9500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 260 g |
| Manufacturer designation | RNA 6908 |
| Standard | ISO 1206 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring); SKF® and SKF Explorer® are trademarks of AB SKF, used here for identification only — mpnbase is not an authorized SKF distributor. Boundary dimensions are ISO 15 interchangeable; current production values may differ, verify at skf.com.
Dimensions in inches & RNA-69-series range
| Bore d | 1.89 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 1.575 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 7 mm |
| Smallest bore in RNA-69-series | 16 mm |
| Largest outer diameter in RNA-69-series | 130 mm |
| Width range across RNA-69-series | 22–63 mm |
| Bore position in RNA-69-series (smallest first) | 11 of 22 |
| Bore above smallest RNA-69-series size | 32 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the RNA6908 model number is decoded
RNA 6908 is a machined-ring needle roller bearing without an inner ring: a solid outer ring with integral flanges guiding the caged rollers, riding directly on a 48 mm hardened shaft journal, as listed in SKF catalogue PUB BU/P1 17000. In SKF nomenclature RNA families drop the inner ring: the numbers after the letters give the 48 mm under-roller diameter and the 40 mm width, with the 62 mm outside diameter set by the dimension series 69 needle roller bearings without inner ring plan. SKF offers this family open as standard; a matching IR inner ring can be added separately when the shaft cannot be hardened, which converts the envelope into the NKI/NA equivalent. For life calculation, the 67.1/125 kN ratings assume raceway geometry supplied by the shaft and housing in families without an inner ring — journal hardness, roundness and finish are part of the bearing, not of the application. Mounting: the flanged outer ring presses into the H7 housing bore against its flange face; the shaft (hardened to 58–64 HRC, ground) enters afterwards, and axial retention is by the housing wall plus a cover washer.
Typical equipment & failure modes
Common applications
- guide rollers running on hardened tracks
- swing arms and lever pivots with oscillating duty
- cam followers built up from separate components
- crank pins and eccentrics where the hardened journal is the raceway
Known failure patterns
- needle edge loading and raceway denting when the shaft deflects beyond the compensation range
- cage pocket wear and roller skew after sustained operation with too little radial preload
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- rolling-contact fatigue spalling after the rated L10 life
- rapid raceway scoring when the shaft journal hardness drops below 58 HRC or the ground finish wears away
Selection pitfalls — read before you substitute
- At 48 mm bore, verify shaft deflection against the needle length: these rollers tolerate little edge loading, and a simply supported span between 48 mm seats can bend past the compensation range long before the load rating is exhausted.
- The quoted 67.1/125 kN ratings are SKF catalogue values for this exact execution (RNA 6908); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- Oscillating pivots fail differently: rocking through a small angle concentrates wear in the same roller positions — inspect those zones, and consider rotating the assembly's clock position at service intervals.
- The 67.1/125 kN ratings and 260 g mass are SKF catalogue values transcribed from ch. 7.3 of PUB BU/P1 17000 (PDF table page 632); combined-type axial ratings appear in the text above because the structured record carries radial values only.
Frequently asked questions
Which dimensions does the RNA 6908 have?
A RNA 6908 measures 48 mm bore/Fw × 62 mm outside diameter × 40 mm width (1.89 × 2.441 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 67.1 kN, static C0 125 kN, fatigue limit Pu 15.3 kN, limiting speed 9,500 r/min, reference speed 8,000 r/min, mass about 260 g.
What does RNA 6908 mean in SKF part numbering?
RNA names a machined-ring needle roller bearing without inner ring: the figures give Fw 48 mm and width 40 mm, OD 62 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Does the RNA 6908 need a hardened and ground shaft?
No. In this execution the 48 mm shaft journal is the inner raceway: it must be ground and hardened to 58–64 HRC (with matching housing bore quality on the outside). If the shaft cannot meet that, order the inner-ring sibling (NKI/NA execution) plus its ground inner ring instead.
What mounting mistakes ruin a RNA 6908?
Press on the ring faces only with a fitting sleeve, keep everything square to the 48 mm seat, and never transmit force through the rolling elements. Follow the catalogue's seat tolerances — the narrow needle contact forgives neither tilt nor burrs.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 7.3 machined rings with flanges, without an inner ring on 2026-09-26. Read our editorial & correction policy.