3307-ATN9 bearing: complete specifications & equivalents
The 3307-ATN9 is a ISO 15 radial bearing sized 35 x 80 x 34.9 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 35 mm |
| Outer diameter D | 80 mm |
| Width B | 34.9 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 52 kN |
| Basic static load rating C0 | 35.5 kN |
| Fatigue load limit Pu | 1.5 kN |
| Reference speed (thermal) | 9500 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 740 g |
| Manufacturer designation | 3307 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 | 1.378 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 1.374 in |
| ISO bore code | 07 |
| Radial section height (D−d)/2 | 22.5 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) | 6 of 20 |
| Bore above smallest 3300-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3307-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 35×80×34.9 mm envelope with catalogue ratings within 10 %; 3307 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3307-DJ1 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 35×80×34.9 mm envelope, but catalogue C/C0 differ between executions (52/35.5 kN vs 52.7/41.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3307-A-2Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 35×80×34.9 mm envelope with catalogue ratings within 10 %; 3307 A-2Z is the stamped steel cage, shields (-2Z) execution of this size — boundary dimensions interchangeable, execution differs. |
| 3307-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 35×80×34.9 mm envelope with catalogue ratings within 10 %; 3307 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 3307-ATN9 model number is decoded
3307 ATN9 is SKF's 35 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, 35×80×34.9 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 35×80×34.9 mm (1.378×3.15×1.374 in), 22.5 mm radial section height, C 52 kN, C0 35.5 kN, Pu 1.5 kN.reference speed 9,500 r/min (thermal) and limiting speed 8,500 r/min (mechanical), catalogue mass 740 g. Mass and section check: 740 g inside the 35×80×34.9 mm outline leaves a 22.5 mm radial section, and the 35.5 kN static rating is 0.68× the dynamic rating — plan static safety and minimum load against those numbers rather than against sister executions. The 1.5 kN fatigue load limit is the equivalent-load floor for long-life adjustment; with 52/35.5 kN ratings and 740 g mass this execution carries about 1.49 kN of C per millimetre of bore. Speed-ratio note for this exact unit: the reference speed is 9,500 r/min against a 8,500 r/min limiting speed, i.e. a reference-to-limit ratio of 1.12.
Typical equipment & failure modes
Common applications
- elevator and hoist machinery
- printing and converting machinery
- gearbox input and output shafts with bidirectional thrust
Known failure patterns
- snap-ring groove or two-piece-ring damage when the D execution is pressed home through the wrong ring
- two-direction thrust overload concentrating load on one row and spalling its raceway
- TN9 cage embrittlement in a hot gearbox position beyond the 120 °C polymer ceiling
- rolling-contact fatigue spalling after the rated L10 life is exceeded
- rolling-contact fatigue spalling after the rated L10 life is exceeded
Selection pitfalls — read before you substitute
- The double-row 3307 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 3307-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
- Controlled axial clearance is the heart of the design: the A execution is produced to the standard double-row axial clearance; check residual clearance after mounting and at operating temperature.
- 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.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3307 ATN9 as the double atn9 execution; the other order numbers of the 3307 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 3307-ATN9?
3307 ATN9 measures 35 mm bore × 80 mm OD × 34.9 mm width (1.378 × 3.15 × 1.374 in), mass about 740 g. SKF 17000 ratings: C 52 kN, C0 35.5 kN, Pu 1.5 kN, reference speed 9,500 r/min (thermal) and limiting speed 8,500 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.
Why choose the double-row 3307 instead of two single-row bearings?
The double-row bearing locates the shaft in both axial directions in one unit, in one housing bore and with factory-controlled axial clearance — a more compact arrangement than a pair, with no field matching of ground faces. A single-row pair offers adjustable preload instead.
What does the D mean in ATN9?
D marks a two-piece inner ring, used on the heavy 33-series executions to simplify mounting; the rest of the suffix identifies the cage (MA brass outer-ring-centred, M brass ball-centred, J1 stamped steel, TN9 PA66) and snap-ring/clearance options (NR, CB).
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.