3204-A bearing: complete specifications & equivalents
The 3204-A 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 | steel, stamped ribbon (J-type) |
| 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 A |
| 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-ATN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 20×47×20.6 mm envelope with catalogue ratings within 10 %; 3204 ATN9 is the glass-fibre PA66 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-A model number is decoded
3204 A 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. with no cage suffix the double-row A execution uses the standard stamped steel ball-centred cage. 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. Load balance: C0 12.9 kN against C 20.4 kN gives a 0.63 ratio, typical of a double-row bidirectional design; Pu 0.55 kN enters the SKF adjusted-life equation rather than the basic rating life. Speed-ratio note for this exact unit: the reference speed is 16,000 r/min against a 14,000 r/min limiting speed, i.e. a reference-to-limit ratio of 1.14.
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
- tilted mounting that loads one double row more heavily than the other
- false brinelling on the loaded row while the shaft stands idle under vibration
- stamped steel cage noise and pocket wear in marginal-lubrication starts, where a brass-cage execution would survive
- fretting corrosion on a loose rotating shaft seat
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- Catalogue ratings of 20.4/12.9 kN apply to the A execution; the D and DNRCBM two-piece-ring executions carry their own figures on their own pages.
- Interference goes on the rotating ring (about k5 at 20 mm bore); the wide 20.6 mm ring is sensitive to tilted seats, so check squareness before clamping.
- 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 double-row 3204 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.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3204 A as the double a steel 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-A?
3204 A 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 A suffix mean?
A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. with no cage suffix the double-row A execution uses the standard stamped steel ball-centred cage.
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.