RNA4909 bearing: complete specifications & equivalents
The RNA4909 is a ISO 1206 radial bearing sized 52 x 68 x 22 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 | 22 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | none |
| Basic dynamic load rating C | 45.7 kN |
| Basic static load rating C0 | 78 kN |
| Fatigue load limit Pu | 9.65 kN |
| Reference speed (thermal) | 7500 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 180 g |
| Manufacturer designation | RNA 4909 |
| 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-49-series range
| Bore d | 2.047 in |
|---|---|
| Outer diameter D | 2.677 in |
| Width B | 0.866 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 8 mm |
| Smallest bore in RNA-49-series | 14 mm |
| Largest outer diameter in RNA-49-series | 190 mm |
| Width range across RNA-49-series | 13–50 mm |
| Bore position in RNA-49-series (smallest first) | 13 of 28 |
| Bore above smallest RNA-49-series size | 38 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| RNA4909-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 52×68×22 mm envelope, but catalogue C/C0 differ between the executions (45.7/78 vs 39.1/64 kN) — boundary dimensions match, not a load-rating equivalent. |
Interchange levels: full standard interchange · partial verify parameters · verify manual confirmation required. Links resolve to the equivalent model's specification page where available.
How the RNA4909 model number is decoded
RNA 4909 belongs to the machined-ring needle roller family: an outer ring turned and ground to 68 mm with two retaining flanges, a roller-and-cage set inside, and envelope 52×68×22 mm on a hardened 52 mm shaft. In SKF nomenclature RNA families drop the inner ring: the numbers after the letters give the 52 mm under-roller diameter and the 22 mm width, with the 68 mm outside diameter set by the dimension series 49 needle roller bearings without inner ring plan. The machined ring is through-hardened and ground on OD, bore-side raceway and faces; the flanged lip design means the housing shoulder can be omitted — the ring clamps axially between housing wall and cover washer. Catalogue mass 180 g at 52×68×22 mm makes this one of the highest capacity-per-gram choices in the dimension series 49 needle roller bearings without inner ring; the limit is usually the shaft's ability to serve as a raceway, not the rolling contact itself. 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
- cam followers built up from separate components
- crank pins and eccentrics where the hardened journal is the raceway
- gearbox planetary and idler gears on hardened pins
- piston-pin style pivots in hydraulic pumps
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
- abrasive paste formation from dust ingressing past open ends without effective housing seals
- rolling-contact fatigue spalling after the rated L10 life
- 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.
- Contamination, not fatigue, kills most small needle bearings: with raceways this narrow, one hard particle dents a full-width line — seal the housing even when the bearing execution itself is open.
- Do not interchange envelope-identical needle families blindly: RNA 4909 shares its 52×68×22 mm outline with inner-ring and sealed siblings whose ratings differ — the family letters are part of the specification, not decoration.
- The 45.7/78 kN ratings and 180 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 4909 have?
A RNA 4909 measures 52 mm bore/Fw × 68 mm outside diameter × 22 mm width (2.047 × 2.677 × 0.866 in). From SKF catalogue PUB BU/P1 17000: radial dynamic rating C 45.7 kN, static C0 78 kN, fatigue limit Pu 9.65 kN, limiting speed 8,500 r/min, reference speed 7,500 r/min, mass about 180 g.
What does RNA 4909 mean in SKF part numbering?
RNA names a machined-ring needle roller bearing without inner ring: the figures give Fw 52 mm and width 22 mm, OD 68 mm comes from the dimension series, and the flanged outer ring retains the caged rollers.
Does the RNA 4909 need a hardened and ground 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.
What mounting mistakes ruin a RNA 4909?
Press on the ring faces only with a fitting sleeve, keep everything square to the 52 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.