3204-ATN9 bearing: complete specifications & equivalents
The 3204-ATN9 is a ISO 15 radial bearing sized 20 x 47 x 20.6 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 47 mm |
| Width B | 20.6 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 20.4 kN |
| Basic static load rating C0 | 12.9 kN |
| Fatigue load limit Pu | 0.55 kN |
| Reference speed (thermal) | 16000 rpm |
| Limiting speed (mechanical) | 14000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 160 g |
| Manufacturer designation | 3204 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 & 3200-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 1.85 in |
| Width B | 0.811 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 13.5 mm |
| Smallest bore in 3200-series | 10 mm |
| Largest outer diameter in 3200-series | 200 mm |
| Width range across 3200-series | 14–69.8 mm |
| Bore position in 3200-series (smallest first) | 5 of 22 |
| Bore above smallest 3200-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3204-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×47×20.6 mm envelope with catalogue ratings within 10 %; 3204 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3204-A-2Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×47×20.6 mm envelope with catalogue ratings within 10 %; 3204 A-2Z is the stamped steel cage, shields (-2Z) execution of this size — boundary dimensions interchangeable, execution differs. |
| 3204-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×47×20.6 mm envelope with catalogue ratings within 10 %; 3204 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 3204-ATN9 model number is decoded
3204 ATN9 is SKF's 20 mm-bore double-row angular-contact ball bearing of the 3200 series — two ball rows back-to-back for two-direction axial location in one unit, 20×47×20.6 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 20×47×20.6 mm (0.787×1.85×0.811 in), 13.5 mm radial section height, C 20.4 kN, C0 12.9 kN, Pu 0.55 kN.reference speed 16,000 r/min (thermal) and limiting speed 14,000 r/min (mechanical), catalogue mass 160 g. Sizing arithmetic on the 20 mm bore: 20.4 kN C divided by the 13.5 mm radial section height gives 1.5 kN per section millimetre; the 160 g mass and 3 % Pu/C share frame the light-load floor for the adjusted-life check. Mass and section check: 160 g inside the 20×47×20.6 mm outline leaves a 13.5 mm radial section, and the 12.9 kN static rating is 0.63× the dynamic rating — plan static safety and minimum load against those numbers rather than against sister executions. Bore-to-OD planning: OD 47 over bore 20 is a 2.35× step for this size, and the 20.6 mm width gives a bore/width ratio of 0.97; use these ratios when housing space around the 20 mm shaft is the first constraint.
Typical equipment & failure modes
Common applications
- small double-supported gear shafts needing two-direction location in one bearing
- compact pump and compressor drives
- textile machinery roller drives
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
- fretting corrosion on a loose rotating shaft seat
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- A capped 3204-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
- 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 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 of 20.4/12.9 kN apply to the ATN9 execution; the D and DNRCBM two-piece-ring executions carry their own figures on their own pages.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3204 ATN9 as the double atn9 execution; the other order numbers of the 3204 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 3204-ATN9?
3204 ATN9 measures 20 mm bore × 47 mm OD × 20.6 mm width (0.787 × 1.85 × 0.811 in), mass about 160 g. SKF 17000 ratings: C 20.4 kN, C0 12.9 kN, Pu 0.55 kN, reference speed 16,000 r/min (thermal) and limiting speed 14,000 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 3204 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 20 mm shaft and H7 in the 47 mm housing; check the wide ring seats square because the 20.6 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.