3309-A-2Z bearing: complete specifications & equivalents
The 3309-A-2Z is a ISO 15 radial bearing sized 45 x 100 x 39.7 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 | 45 mm |
| Outer diameter D | 100 mm |
| Width B | 39.7 mm |
| Material | GCr15 |
| Seal / shield | ZZ |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 75 kN |
| Basic static load rating C0 | 53 kN |
| Fatigue load limit Pu | 2.24 kN |
| Limiting speed (mechanical) | 6700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1250 g |
| Manufacturer designation | 3309 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 | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 1.563 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 27.5 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) | 8 of 20 |
| Bore above smallest 3300-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3309-DNRCBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×39.7 mm envelope, but catalogue C/C0 differ between executions (75/53 kN vs 61.8/52 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3309-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×39.7 mm envelope with catalogue ratings within 10 %; 3309 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3309-ATN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×39.7 mm envelope with catalogue ratings within 10 %; 3309 ATN9 is the glass-fibre PA66 cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3309-DMA | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 45×100×39.7 mm envelope, but catalogue C/C0 differ between executions (75/53 kN vs 79.3/69.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3309-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 45×100×39.7 mm envelope with catalogue ratings within 10 %; 3309 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 3309-A-2Z model number is decoded
3309 A-2Z is the capped double-row angular-contact ball bearing for a 45 mm shaft, 45×100×39.7 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 45×100×39.7 mm (1.772×3.937×1.563 in), 27.5 mm radial section height, C 75 kN, C0 53 kN, Pu 2.24 kN.SKF publishes only the 6,700 r/min limiting speed for this execution, catalogue mass 1250 g. Load balance: C0 53 kN against C 75 kN gives a 0.71 ratio, typical of a steep-angle axial-oriented design; Pu 2.24 kN enters the SKF adjusted-life equation rather than the basic rating life. The 2.24 kN fatigue load limit is the equivalent-load floor for long-life adjustment; with 75/53 kN ratings and 1250 g mass this execution carries about 1.67 kN of C per millimetre of bore. Speed-ratio note for this exact unit: no thermal reference speed is listed (seal/grease life governs), so the 6,700 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
- agricultural machinery drives
- conveyor drum shafts
- fan and blower positions
Known failure patterns
- fine dust or moisture bypassing a worn 2RS1 lip in dirty or wet duty
- shield rubbing after misalignment or overheating of a 2Z execution
- grease escape past the non-contact shields in an overfilled or vertically mounted position
- loss of controlled axial clearance (CB) after thermal growth removes residual play
- electrical pitting on VFD-driven shafts without grounding protection
- rolling-contact fatigue spalling after the rated L10 life is exceeded
Selection pitfalls — read before you substitute
- The capped speed ceiling is 6,700 r/min — seal drag and grease life govern, which is why SKF publishes no thermal reference speed for A-2Z.
- The non-contact shields cap the speed with negligible drag: no relubrication is provided for, so mounting cleanliness decides much of the real grease life.
- Never wash 3309-A-2Z in solvent: the lifetime grease fill cannot be replaced once flushed out.
- The non-contact shields cap the speed with negligible drag: 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 3309 A-2Z as the double shielded execution; the other order numbers of the 3309 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 3309-A-2Z?
3309 A-2Z measures 45 mm bore × 100 mm OD × 39.7 mm width (1.772 × 3.937 × 1.563 in), mass about 1250 g. SKF 17000 ratings: C 75 kN, C0 53 kN, Pu 2.24 kN, SKF publishes only the 6,700 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.
Is 3309-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.
What is the difference between 3309 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).
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.