3309-ATN9 bearing: complete specifications & equivalents
The 3309-ATN9 is a ISO 15 radial bearing sized 45 x 100 x 39.7 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 45 mm |
| Outer diameter D | 100 mm |
| Width B | 39.7 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 75 kN |
| Basic static load rating C0 | 53 kN |
| Fatigue load limit Pu | 2.24 kN |
| Reference speed (thermal) | 7500 rpm |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1250 g |
| Manufacturer designation | 3309 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 & 3300-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 1.563 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in 3300-series | 15 mm |
| Largest outer diameter in 3300-series | 240 mm |
| Width range across 3300-series | 19–92.1 mm |
| Bore position in 3300-series (smallest first) | 8 of 20 |
| Bore above smallest 3300-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3309-DNRCBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×39.7 mm envelope, but catalogue C/C0 differ between executions (75/53 kN vs 61.8/52 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3309-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×39.7 mm envelope with catalogue ratings within 10 %; 3309 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3309-DMA | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×39.7 mm envelope, but catalogue C/C0 differ between executions (75/53 kN vs 79.3/69.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3309-A-2Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×39.7 mm envelope with catalogue ratings within 10 %; 3309 A-2Z is the stamped steel cage, shields (-2Z) execution of this size — boundary dimensions interchangeable, execution differs. |
| 3309-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×39.7 mm envelope with catalogue ratings within 10 %; 3309 A-2RS1 is the stamped steel cage, contact NBR seals (-2RS1) execution of this size — boundary dimensions interchangeable, 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 3309-ATN9 model number is decoded
3309 ATN9 is SKF's 45 mm-bore double-row angular-contact ball bearing of the 3300 series — two ball rows back-to-back for two-direction axial location in one unit, 45×100×39.7 mm. A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. glass-fibre reinforced PA66 cage, ball-centred (suffix TN9), with a 120 °C continuous-temperature ceiling. Envelope 45×100×39.7 mm (1.772×3.937×1.563 in), 27.5 mm radial section height, C 75 kN, C0 53 kN, Pu 2.24 kN.reference speed 7,500 r/min (thermal) and limiting speed 6,700 r/min (mechanical), catalogue mass 1250 g. The 2.24 kN fatigue load limit is the equivalent-load floor for long-life adjustment; with 75/53 kN ratings and 1250 g mass this execution carries about 1.67 kN of C per millimetre of bore. Load balance: C0 53 kN against C 75 kN gives a 0.71 ratio, typical of a double-row bidirectional design; Pu 2.24 kN enters the SKF adjusted-life equation rather than the basic rating life. Bore-to-OD planning: OD 100 over bore 45 is a 2.22× step for this size, and the 39.7 mm width gives a bore/width ratio of 1.13; use these ratios when housing space around the 45 mm shaft is the first constraint.
Typical equipment & failure modes
Common applications
- printing and converting machinery
- gearbox input and output shafts with bidirectional thrust
- two-direction thrust positions without room for a paired single-row set
Known failure patterns
- false brinelling on the loaded row while the shaft stands idle under vibration
- snap-ring groove or two-piece-ring damage when the D execution is pressed home through the wrong ring
- TN9 cage embrittlement in a hot gearbox position beyond the 120 °C polymer ceiling
- raceway staining from water in the lubricant during idle periods
- raceway staining from water in the lubricant during idle periods
Selection pitfalls — read before you substitute
- The D executions have a two-piece inner ring: mount both halves square to each other, never press on the outer ring, and keep the split faces clean during fitting.
- The double-row 3309 takes thrust in both directions by itself — that is the reason to choose it over two single-row bearings: one housing bore, one fit, built-in set geometry.
- A capped 3309-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
- Interference goes on the rotating ring (about k5 at 45 mm bore); the wide 39.7 mm ring is sensitive to tilted seats, so check squareness before clamping.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3309 ATN9 as the double atn9 execution; the other order numbers of the 3309 size are different products and may carry different ratings — always quote the full designation when purchasing.
Frequently asked questions
What are the dimensions and catalogue data of 3309-ATN9?
3309 ATN9 measures 45 mm bore × 100 mm OD × 39.7 mm width (1.772 × 3.937 × 1.563 in), mass about 1250 g. SKF 17000 ratings: C 75 kN, C0 53 kN, Pu 2.24 kN, reference speed 7,500 r/min (thermal) and limiting speed 6,700 r/min (mechanical).
What does the ATN9 suffix mean?
A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. glass-fibre reinforced PA66 cage, ball-centred (suffix TN9), with a 120 °C continuous-temperature ceiling.
Does the 3309 double-row bearing need pairing?
No — both ball rows are built into one bearing, so bidirectional location does not require a second unit. Controlled axial clearance is part of the design rather than a field adjustment.
Which fits should I use?
With a rotating inner ring use roughly k5 on the 45 mm shaft and H7 in the 100 mm housing; check the wide ring seats square because the 39.7 mm width is sensitive to tilt.
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.