3311-A-2RS1 bearing: complete specifications & equivalents
The 3311-A-2RS1 is a ISO 15 radial bearing sized 55 x 120 x 49.2 mm (bore x OD x width) with 2RS sealing. Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 55 mm |
| Outer diameter D | 120 mm |
| Width B | 49.2 mm |
| Material | GCr15 |
| Seal / shield | 2RS |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 112 kN |
| Basic static load rating C0 | 81.5 kN |
| Fatigue load limit Pu | 3.45 kN |
| Limiting speed (mechanical) | 3800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2650 g |
| Manufacturer designation | 3311 A-2RS1 |
| 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 | 2.165 in |
|---|---|
| Outer diameter D | 4.724 in |
| Width B | 1.937 in |
| ISO bore code | 11 |
| Radial section height (D−d)/2 | 32.5 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) | 10 of 20 |
| Bore above smallest 3300-series size | 40 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3311-DNRCBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 55×120×49.2 mm envelope, but catalogue C/C0 differ between executions (112/81.5 kN vs 95.6/83 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3311-DMA | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 55×120×49.2 mm envelope, but catalogue C/C0 differ between executions (112/81.5 kN vs 111/100 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3311-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 55×120×49.2 mm envelope with catalogue ratings within 10 %; 3311 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3311-ATN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 55×120×49.2 mm envelope with catalogue ratings within 10 %; 3311 ATN9 is the glass-fibre PA66 cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3311-A-2Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 55×120×49.2 mm envelope with catalogue ratings within 10 %; 3311 A-2Z is the stamped steel cage, shields (-2Z) 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 3311-A-2RS1 model number is decoded
3311 A-2RS1 is the capped double-row angular-contact ball bearing for a 55 mm shaft, 55×120×49.2 mm, greased and sealed (or shielded) for life at the SKF works. A on this double-row bearing means no filling slots, so both ball rows retain their full complement. -2RS1 marks a contact NBR elastomer seal on each side, riding the inner ring: better fine-dust and moisture protection than a shield at the cost of seal drag and a lower speed ceiling. Envelope 55×120×49.2 mm (2.165×4.724×1.937 in), 32.5 mm radial section height, C 112 kN, C0 81.5 kN, Pu 3.45 kN.SKF publishes only the 3,800 r/min limiting speed for this execution, catalogue mass 2650 g. Selection figures for 3311 A-2RS1: the static-to-dynamic ratio C0/C is 0.73, Pu 3.45 kN is about 3 % of C, and catalogue mass works out to roughly 48 g per millimetre of bore. Envelope economics: the 49.2 mm width over a 32.5 mm section yields 1.51 mm of ring width per section millimetre, and the bearing weighs 2650 g for 112 kN of dynamic capacity — about 24 g per rated kN. Speed-ratio note for this exact unit: no thermal reference speed is listed (seal/grease life governs), so the 3,800 r/min limiting value is the single published ceiling. Contact-seal execution note: the two NBR -2RS1 lips ride the inner-ring lands, sealing the factory grease against moisture and fine dust; the lips add running torque and set the lower limiting speed printed for this size, and the sealed cavity is maintenance-free by design (no relubrication path). The A-2Z shielded order number is the low-drag alternative for cleaner positions.
Typical equipment & failure modes
Common applications
- conveyor drum shafts
- fan and blower positions
- material-handling equipment
Known failure patterns
- contamination trapped for life when a capped bearing is mounted with dirty hands or tools
- contact-seal lip hardening and grease-life expiry after long high-temperature service
- seal-lip wear and grease loss after fine abrasive dust reaches the lip contact
- tilted mounting that loads one double row more heavily than the other
- brinelling from pressing the ring home through the balls or from static overload
- hard-particle indentation of the asymmetric raceway in unfiltered oil
Selection pitfalls — read before you substitute
- Fit and fillet rules are unchanged from the open double-row 3311: k5 on a 55 mm rotating shaft, radii clearing the chamfer.
- The shields/seals do not make the bearing waterproof under immersion or pressure washing; select external sealing for wet or wash-down duty.
- Open 3311 and capped 3311-A-2RS1 share the 55×120×49.2 mm envelope and 112/81.5 kN ratings — the choice is maintenance access and contamination, not capacity.
- The contact NBR seals add drag and a lower speed ceiling: no relubrication is provided for, so mounting cleanliness decides much of the real grease life.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3311 A-2RS1 as the double contactsealed execution; the other order numbers of the 3311 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 3311-A-2RS1?
3311 A-2RS1 measures 55 mm bore × 120 mm OD × 49.2 mm width (2.165 × 4.724 × 1.937 in), mass about 2650 g. SKF 17000 ratings: C 112 kN, C0 81.5 kN, Pu 3.45 kN, SKF publishes only the 3,800 r/min limiting speed for this execution.
What does the A-2RS1 suffix mean?
A on this double-row bearing means no filling slots, so both ball rows retain their full complement. -2RS1 marks a contact NBR elastomer seal on each side, riding the inner ring: better fine-dust and moisture protection than a shield at the cost of seal drag and a lower speed ceiling.
What is the difference between 3311 A-2Z and A-2RS1?
Both share the double-row A geometry, dimensions and ratings; A-2Z uses non-contact metal shields (lower drag, higher speed, dust protection), A-2RS1 uses contact NBR rubber seals (better moisture and fine-dust protection, lower speed ceiling and more drag).
Can I wash or repack a capped 3311?
No — solvent flushes the factory grease with no way to replace it fully; keep the original protection in place and mount the bearing with clean tools.
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.