RNA6909 bearing: complete specifications & equivalents
The RNA6909 is a ISO 1206 radial bearing sized 52 x 68 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 | 52 mm |
| Outer diameter D | 68 mm |
| Width B | 40 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 70.4 kN |
| Basic static load rating C0 | 137 kN |
| Fatigue load limit Pu | 17 kN |
| Reference speed (thermal) | 7500 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 340 g |
| Manufacturer designation | RNA 6909 |
| 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 | 2.047 in |
|---|---|
| Outer diameter D | 2.677 in |
| Width B | 1.575 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 8 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) | 12 of 22 |
| Bore above smallest RNA-69-series size | 36 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the RNA6909 model number is decoded
SKF's dimension series 69 needle roller bearings without inner ring include RNA 6909: 52 mm Fw, 68 mm outside diameter, 40 mm width — a machined and ground outer ring whose rolled flanges retain the needle rollers, running on the shaft as the inner raceway. The letters identify a flanged machined outer ring without inner ring; the figures give 52 mm Fw and 40 mm B — dimensionally identical envelopes exist with an inner ring under the NA/NKI names, which changes the shaft seat entirely. 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 70.4/137 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
- raceway spalling once the catalogue L10 life is exceeded or after overload events
- polymer cage deformation when the local temperature exceeds the 120 °C sustained limit
- grease starvation at the roller ends when relubrication intervals are stretched in dirty duty
- corrosion pitting from condensation in intermittently operated machinery
- smearing of rollers and journal during idle periods because the radial section holds too little lubricant
Selection pitfalls — read before you substitute
- Above 50 mm bore, thermal growth matters: the 52 mm inner ring or journal grows with temperature faster than the housing, and the small clearance of a needle roller contact leaves little reserve — check running clearance hot, not just at assembly.
- Hardness is load capacity: in families without an inner ring the 52 mm journal must hold 58–64 HRC with a ground finish; a surface that looks fine but sits at 45 HRC will rib the raceway within weeks.
- The quoted 70.4/137 kN ratings are SKF catalogue values for this exact execution (RNA 6909); ratings can be revised without the order number changing, so keep the catalogue version (SKF catalogue PUB BU/P1 17000) with the drawing.
- The 70.4/137 kN ratings and 340 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
What limits the service life of a RNA 6909?
Beyond the L10 rating, the practical limits are journal/raceway hardness for the 52 mm seat, lubricant condition at the roller ends, and contamination through open ends — the 8.0 mm radial section leaves no reserve once a raceway is dented or ribboned.
What are the dimensions and ratings of the RNA 6909?
A RNA 6909 measures 52 mm bore/Fw × 68 mm outside diameter × 40 mm width (2.047 × 2.677 × 1.575 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 70.4 kN, static C0 137 kN, fatigue limit Pu 17 kN, limiting speed 8,500 r/min, reference speed 7,500 r/min, mass about 340 g.
How is the RNA 6909 designation read?
RNA names a machined-ring needle roller bearing without inner ring: the figures give Fw 52 mm and width 40 mm, OD 68 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Can the RNA 6909 run on an unhardened shaft?
No. In this execution the 52 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.
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.