3211-ATN9 bearing: complete specifications & equivalents
The 3211-ATN9 is a ISO 15 radial bearing sized 55 x 100 x 33.3 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 55 mm |
| Outer diameter D | 100 mm |
| Width B | 33.3 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 60 kN |
| Basic static load rating C0 | 47.5 kN |
| Fatigue load limit Pu | 2 kN |
| Reference speed (thermal) | 6300 rpm |
| Limiting speed (mechanical) | 6300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 910 g |
| Manufacturer designation | 3211 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 | 2.165 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 1.311 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 22.5 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) | 12 of 22 |
| Bore above smallest 3200-series size | 45 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3211-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 55×100×33.3 mm envelope with catalogue ratings within 10 %; 3211 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3211-A-2Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 55×100×33.3 mm envelope with catalogue ratings within 10 %; 3211 A-2Z is the stamped steel cage, shields (-2Z) execution of this size — boundary dimensions interchangeable, execution differs. |
| 3211-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 55×100×33.3 mm envelope with catalogue ratings within 10 %; 3211 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 3211-ATN9 model number is decoded
3211 ATN9 is SKF's 55 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, 55×100×33.3 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 55×100×33.3 mm (2.165×3.937×1.311 in), 22.5 mm radial section height, C 60 kN, C0 47.5 kN, Pu 2 kN.reference speed 6,300 r/min (thermal) and limiting speed 6,300 r/min (mechanical), which coincide for this size, catalogue mass 910 g. Mass and section check: 910 g inside the 55×100×33.3 mm outline leaves a 22.5 mm radial section, and the 47.5 kN static rating is 0.79× the dynamic rating — plan static safety and minimum load against those numbers rather than against sister executions. The 2 kN fatigue load limit is the equivalent-load floor for long-life adjustment; with 60/47.5 kN ratings and 910 g mass this execution carries about 1.09 kN of C per millimetre of bore. Bore-to-OD planning: OD 100 over bore 55 is a 1.82× step for this size, and the 33.3 mm width gives a bore/width ratio of 1.65; use these ratios when housing space around the 55 mm shaft is the first constraint.
Typical equipment & failure modes
Common applications
- two-direction thrust positions without room for a paired single-row set
- centrifugal pump shafts
- elevator and hoist machinery
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
- electrical pitting on VFD-driven shafts without grounding protection
Selection pitfalls — read before you substitute
- The double-row 3211 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.
- Compared with a single-row pair of the same bore, the double-row 3211 occupies less axial space but offers less freedom to adjust preload — do not substitute without re-checking the arrangement.
- Compared with a single-row pair of the same bore, the double-row 3211 occupies less axial space but offers less freedom to adjust preload — do not substitute without re-checking the arrangement.
- A capped 3211-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3211 ATN9 as the double atn9 execution; the other order numbers of the 3211 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 3211-ATN9?
3211 ATN9 measures 55 mm bore × 100 mm OD × 33.3 mm width (2.165 × 3.937 × 1.311 in), mass about 910 g. SKF 17000 ratings: C 60 kN, C0 47.5 kN, Pu 2 kN, reference speed 6,300 r/min (thermal) and limiting speed 6,300 r/min (mechanical), which coincide for this size.
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 3211 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.