3311-A-2Z bearing: complete specifications & equivalents
The 3311-A-2Z is a ISO 15 radial bearing sized 55 x 120 x 49.2 mm (bore x OD x width) with ZZ 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 | ZZ |
| 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) | 5300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2650 g |
| Manufacturer designation | 3311 A-2Z |
| 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-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 55×120×49.2 mm envelope with catalogue ratings within 10 %; 3311 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 3311-A-2Z model number is decoded
3311 A-2Z 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. -2Z marks a sheet-metal shield on each side: non-contacting, grease-retention and dust protection with negligible drag, the bearing remaining open-style relubricatable only through the shield clearance. 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 5,300 r/min limiting speed for this execution, catalogue mass 2650 g. 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. At the printed limiting speed of 5,300 r/min the mean pitch diameter dm ≈ 87.5 mm implies a dn value around 464k mm·r/min; only the limiting speed is published for this execution. Speed-ratio note for this exact unit: no thermal reference speed is listed (seal/grease life governs), so the 5,300 r/min limiting value is the single published ceiling. Shielded execution note: the two sheet-metal -2Z covers clip into the outer ring without contacting the inner ring, giving grease retention and coarse-dust protection at virtually no friction; the cavity is factory-greased and the shield arrangement suits dry, moderately dusty positions rather than wash-down duty, where the A-2RS1 contact-seal order number is the alternative.
Typical equipment & failure modes
Common applications
- conveyor drum shafts
- fan and blower positions
- material-handling equipment
Known failure patterns
- shield rubbing after misalignment or overheating of a 2Z execution
- grease loss when the sealed-for-life cavity is overheated with no relubrication path
- grease escape past the non-contact shields in an overfilled or vertically mounted position
- tilted mounting that loads one double row more heavily than the other
- hard-particle indentation of the asymmetric raceway in unfiltered oil
- mounting score marks when the bearing is cocked over a burr or keyway
Selection pitfalls — read before you substitute
- Never wash 3311-A-2Z in solvent: the lifetime grease fill cannot be replaced once flushed out.
- The capped speed ceiling is 5,300 r/min — seal drag and grease life govern, which is why SKF publishes no thermal reference speed for A-2Z.
- Open 3311 and capped 3311-A-2Z share the 55×120×49.2 mm envelope and 112/81.5 kN ratings — the choice is maintenance access and contamination, not capacity.
- Never wash 3311-A-2Z in solvent: the lifetime grease fill cannot be replaced once flushed out.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3311 A-2Z as the double shielded 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-2Z?
3311 A-2Z 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 5,300 r/min limiting speed for this execution.
What does the A-2Z suffix mean?
A on this double-row bearing means no filling slots, so both ball rows retain their full complement. -2Z marks a sheet-metal shield on each side: non-contacting, grease-retention and dust protection with negligible drag, the bearing remaining open-style relubricatable only through the shield clearance.
What loads can 3311-A-2Z take?
The same bidirectional combined loads as the open double-row 3311: C 112 kN, C0 81.5 kN, Pu 3.45 kN. Capping changes sealing and speed, not the basic ratings.
Is 3311-A-2Z sealed for life?
It is shielded on both sides (-2Z) and delivered filled with the appropriate SKF grease; the non-contact shields give low-drag grease retention and dust protection, but the arrangement is not a contact-sealed cavity.
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.