1308-ETN9 bearing: complete specifications & equivalents
The 1308-ETN9 is a ISO 15 radial bearing sized 40 x 90 x 23 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 | 23 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 33.8 kN |
| Basic static load rating C0 | 11.2 kN |
| Fatigue load limit Pu | 0.57 kN |
| Reference speed (thermal) | 14000 rpm |
| Limiting speed (mechanical) | 9500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 680 g |
| Manufacturer designation | 1308 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 & 1300-series range
| Bore d | 1.575 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 0.906 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 25 mm |
| Smallest bore in 1300-series | 5 mm |
| Largest outer diameter in 1300-series | 320 mm |
| Width range across 1300-series | 6–74 mm |
| Bore position in 1300-series (smallest first) | 10 of 29 |
| Bore above smallest 1300-series size | 35 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 1308 | NTN | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×23 mm envelope per ISO 15; catalogue load ratings differ by >10% — re-rate the application before substituting. |
| 1308-EKTN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 40×90×23 mm envelope with catalogue ratings within 10 %; 1308 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 1308-ETN9 model number is decoded
The 13xx series is the medium/normal-section self-aligning ball bearing (ISO dimension series 03). the last two digits encode the bore: 1308 carries code 08 = 40 mm (code × 5). Envelope 40×90×23 mm (1.575×3.543×0.906 in) with a 25.0 mm radial section height, C 33.8 kN, C0 11.2 kN and Pu 0.57 kN. The open 1308 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 9500 r/min, catalogue mass 680 g.
Typical equipment & failure modes
Common applications
- woodworking machinery
- pump shafts with mild misalignment
- material-handling equipment
- industrial electric motors
Known failure patterns
- contamination wear when the open arrangement is used without adequate external sealing
- lubricant starvation where no regreasing interval is maintained
- raceway smearing under marginal lubrication at start-up
- electrical pitting in VFD-driven motors without shaft grounding
Selection pitfalls — read before you substitute
- Catalogue ratings for 1308-ETN9 (C 33.8 kN, C0 11.2 kN) are SKF figures from PUB BU/P1 17000; geometry revisions can change ratings without changing the designation, so keep the catalogue edition with the specification.
- Self-aligning ball bearings tolerate up to roughly 2–3° of static misalignment, but the sealed 1308-ETN9 (2RS1) allows less — the lip seal binds before the spherical raceway does.
- The ETN9 suffix on 1308-ETN9 denotes a glass-fibre-reinforced polyamide 66 cage: quiet and light at the 9500 r/min limiting speed, but it softens above roughly 120 °C — check the oil temperature in hot drives.
- Mount 1308-ETN9 by heating the inner ring (max 120 °C) on a cylindrical bore — driving it home through the outer ring or balls brinells the raceways.
- The fatigue load limit is 0.57 kN; it feeds the equivalent-mean-load check, not the basic life calculation — do not substitute one for the other.
- At 40 mm bore, C3 clearance is the safe choice when interference fits plus temperature rise consume the CN clearance; a hot tight bearing with no residual clearance fails fast.
Frequently asked questions
What are the dimensions of 1308-ETN9?
SKF 1308 ETN9 measures 40 mm bore × 90 mm OD × 23 mm width (1.575 × 3.543 × 0.906 in), mass about 680 g. It is open, with no shields or seals.
How does the bore code in 1308 work?
The final two digits of 1308 are bore code 08, multiplied by 5 to give 40 mm.
Can 1308-ETN9 take axial load?
A self-aligning ball bearing can carry some axial load in addition to radial load, but its axial capacity is lower than an angular-contact bearing of the same envelope. Use it where misalignment, not thrust, is the main requirement.
Which fits should I use for 1308-ETN9?
With a rotating inner ring use roughly k5 on the shaft and H7 in the 90 mm housing; reverse the interference if the outer ring rotates.
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.