2308-ETN9 bearing: complete specifications & equivalents
The 2308-ETN9 is a ISO 15 radial bearing sized 40 x 90 x 33 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 90 mm |
| Width B | 33 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 54 kN |
| Basic static load rating C0 | 16 kN |
| Fatigue load limit Pu | 0.82 kN |
| Reference speed (thermal) | 14000 rpm |
| Limiting speed (mechanical) | 10000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 930 g |
| Manufacturer designation | 2308 ETN9 |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018) |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); 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 & 2300-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 1.299 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in 2300-series | 10 mm |
| Largest outer diameter in 2300-series | 215 mm |
| Width range across 2300-series | 17–73 mm |
| Bore position in 2300-series (smallest first) | 9 of 21 |
| Bore above smallest 2300-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 2308 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×33 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 2308-E-2RS1TN9 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×33 mm envelope, but catalogue C/C0 differ between executions (54/16 kN vs 33.8/11.2 kN) — boundary dimensions match, not a load-rating equivalent. |
| 2308-E-2RS1KTN9 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×33 mm envelope, but catalogue C/C0 differ between executions (54/16 kN vs 33.8/11.2 kN) — boundary dimensions match, not a load-rating equivalent. |
| 2308-EKTN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 40×90×33 mm envelope with catalogue ratings within 10 %; 2308 EKTN9 is the glass-fibre PA66 cage, open arrangement, tapered bore execution of this size — boundary dimensions interchangeable, only the seal/cage/bore execution differs. |
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 2308-ETN9 model number is decoded
The 23xx series is the wide medium-section self-aligning ball bearing (ISO dimension series 23). the last two digits encode the bore: 2308 carries code 08 = 40 mm (code × 5). Envelope 40×90×33 mm (1.575×3.543×1.299 in) with a 25.0 mm radial section height, C 54 kN, C0 16 kN and Pu 0.82 kN. The open 2308 ETN9 carries no shields or seals and relies on application lubrication and external sealing. The ETN9 suffix identifies the glass-fibre-reinforced polyamide 66 cage execution. The bore is cylindrical (straight), for a press-fit on a 40 mm shaft. Reference (thermal) speed 14000 r/min, limiting speed 10000 r/min, catalogue mass 930 g.
Typical equipment & failure modes
Common applications
- industrial fans and blowers
- woodworking machinery
- pump shafts with mild misalignment
- material-handling equipment
Known failure patterns
- lubricant starvation where no regreasing interval is maintained
- contamination wear when the open arrangement is used without adequate external sealing
- false brinelling from vibration while the shaft stands idle
- fretting corrosion on a creeping shaft or housing seat
Selection pitfalls — read before you substitute
- Fillet radii must clear the 2308-ETN9 chamfer so the 33 mm-wide ring seats square; an oversized shaft radius creates point contact on the ring face.
- Fillet radii must clear the 2308-ETN9 chamfer so the 33 mm-wide ring seats square; an oversized shaft radius creates point contact on the ring face.
- The ETN9 suffix on 2308-ETN9 denotes a glass-fibre-reinforced polyamide 66 cage: quiet and light at the 10000 r/min limiting speed, but it softens above roughly 120 °C — check the oil temperature in hot drives.
- The spherical outer raceway lets 2308-ETN9 tolerate shaft deflection, but it does not increase thrust capacity — combined loads still need an angular-contact or deep-groove bearing.
- Fillet radii must clear the 2308-ETN9 chamfer so the 33 mm-wide ring seats square; an oversized shaft radius creates point contact on the ring face.
- Self-aligning ball bearings tolerate up to roughly 2–3° of static misalignment, but the sealed 2308-ETN9 (2RS1) allows less — the lip seal binds before the spherical raceway does.
Frequently asked questions
What are the dimensions of 2308-ETN9?
SKF 2308 ETN9 measures 40 mm bore × 90 mm OD × 33 mm width (1.575 × 3.543 × 1.299 in), mass about 930 g. It is open, with no shields or seals.
How does the bore code in 2308 work?
The final two digits of 2308 are bore code 08, multiplied by 5 to give 40 mm.
What load can 2308-ETN9 take?
Catalogue values for 2308 ETN9: dynamic C 54 kN, static C0 16 kN, fatigue limit Pu 0.82 kN. Use C in life calculation and C0 for static checks at 40 mm bore.
What is the speed rating of 2308-ETN9?
SKF lists a 14000 r/min thermal reference speed and a 10000 r/min mechanical limiting speed for 2308 ETN9; real limits also depend on lubrication and fits.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018) on 2026-09-27. Read our editorial & correction policy.