4308-ATN9 bearing: complete specifications & equivalents
The 4308-ATN9 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 | 55.9 kN |
| Basic static load rating C0 | 45 kN |
| Fatigue load limit Pu | 1.9 kN |
| Reference speed (thermal) | 12000 rpm |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 950 g |
| Manufacturer designation | 4308 ATN9 |
| 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 & 4300-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 4300-series | 12 mm |
| Largest outer diameter in 4300-series | 160 mm |
| Width range across 4300-series | 17–55 mm |
| Bore position in 4300-series (smallest first) | 8 of 14 |
| Bore above smallest 4300-series size | 28 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 62308-2RS | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×33 mm envelope as SKF 62308-2RS1, but catalogue C/C0 differ (55.9/45 kN vs 41/24 kN) — envelope match only after a load check. |
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 4308-ATN9 model number is decoded
4308 ATN9 is a double-row deep-groove ball bearing in the 4300-series: the last two digits encode the bore: 4308 carries code 08 = 40 mm (code × 5). Two complete ball sets share the 40×90×33 mm (1.575×3.543×1.299 in) envelope, giving C 55.9 kN, C0 45 kN and Pu 1.9 kN, with reversing axial capacity a single-row bearing cannot match. ATN9 is the glass-fibre PA66 cage. Limiting speed 6700 r/min, mass 950 g. The arrangement is open and requires external sealing.
Typical equipment & failure modes
Common applications
- agricultural gearboxes
- belt take-up and tensioner units
- machine tool feed drives
- lifting and hoisting gear
Known failure patterns
- uneven load sharing between the two raceways when one ring is tilted
- polyamide cage embrittlement after sustained high-temperature service
- raceway smearing under marginal lubrication at start-up
- electrical pitting in VFD-driven motors without shaft grounding
Selection pitfalls — read before you substitute
- Double-row 4308 is open and needs application sealing and lubrication; in dusty drives add external seals rather than expecting the bearing itself to stay clean.
- C 55.9 kN in a 33 mm width is the strength of the double-row design; use it for combined or reversing axial loads rather than pure radial duty where a slimmer single-row bearing would run cooler.
- Fit both rings square on the shoulders: the narrow internal land between the two raceways of 4308-ATN9 is sensitive to cocking during pressing.
- The ATN9 cage is glass-fibre-reinforced polyamide 66: it is light and quiet but caps continuous service around 100–120 °C in oil/grease — above that use the pressed-steel or machined-cage version of the 40 mm position.
- The ATN9 cage is glass-fibre-reinforced polyamide 66: it is light and quiet but caps continuous service around 100–120 °C in oil/grease — above that use the pressed-steel or machined-cage version of the 40 mm position.
- Clearance suffixes follow the seal code in the designation stack (e.g. 4308-2Z/C3 in SKF spelling); no suffix means normal CN internal clearance.
Frequently asked questions
What are the dimensions of 4308-ATN9?
Double-row 4308 ATN9 measures 40×90×33 mm (1.575×3.543×1.299 in), about 950 g.
What does ATN9 mean on 4308 ATN9?
A = double-row deep-groove arrangement, TN9 is a glass-fibre-reinforced polyamide 66 cage; it limits continuous temperature to roughly 100–120 °C.
Is 4308-ATN9 interchangeable with a 62-series single-row bearing?
No: although bore matches, OD and width differ and the seat shoulders must suit the wide double-row ring; 40×90×33 mm is its own envelope.
Does 4308-ATN9 run as fast as a single-row bearing?
Somewhat slower: SKF rates it to 6700 r/min; the two cages and wider grease volume generate more drag than a single-row 6208.
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.