3308-A-2Z bearing: complete specifications & equivalents
The 3308-A-2Z is a ISO 15 radial bearing sized 40 x 90 x 36.5 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 | 40 mm |
| Outer diameter D | 90 mm |
| Width B | 36.5 mm |
| Material | GCr15 |
| Seal / shield | ZZ |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 64 kN |
| Basic static load rating C0 | 44 kN |
| Fatigue load limit Pu | 1.86 kN |
| Limiting speed (mechanical) | 7500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 930 g |
| Manufacturer designation | 3308 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 | 1.575 in |
|---|---|
| Outer diameter D | 3.543 in |
| Width B | 1.437 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 25 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) | 7 of 20 |
| Bore above smallest 3300-series size | 25 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3308-DNRCBM | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×36.5 mm envelope, but catalogue C/C0 differ between executions (64/44 kN vs 49.4/41.5 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3308-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 40×90×36.5 mm envelope with catalogue ratings within 10 %; 3308 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3308-ATN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 40×90×36.5 mm envelope with catalogue ratings within 10 %; 3308 ATN9 is the glass-fibre PA66 cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3308-DMA | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×36.5 mm envelope, but catalogue C/C0 differ between executions (64/44 kN vs 68.9/57 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3308-DTN9 | SKF | partial Main dimensions match; tolerances, seals or internal clearance differ. | Same 40×90×36.5 mm envelope, but catalogue C/C0 differ between executions (64/44 kN vs 68.9/57 kN) — boundary dimensions match, not a load-rating equivalent. |
| 3308-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 40×90×36.5 mm envelope with catalogue ratings within 10 %; 3308 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 3308-A-2Z model number is decoded
3308 A-2Z is the capped double-row angular-contact ball bearing for a 40 mm shaft, 40×90×36.5 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 40×90×36.5 mm (1.575×3.543×1.437 in), 25.0 mm radial section height, C 64 kN, C0 44 kN, Pu 1.86 kN.SKF publishes only the 7,500 r/min limiting speed for this execution, catalogue mass 930 g. At the printed limiting speed of 7,500 r/min the mean pitch diameter dm ≈ 65.0 mm implies a dn value around 488k mm·r/min; only the limiting speed is published for this execution. Selection figures for 3308 A-2Z: the static-to-dynamic ratio C0/C is 0.69, Pu 1.86 kN is about 3 % of C, and catalogue mass works out to roughly 23 g per millimetre of bore. Speed-ratio note for this exact unit: no thermal reference speed is listed (seal/grease life governs), so the 7,500 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
- 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
- loss of controlled axial clearance (CB) after thermal growth removes residual play
- edge loading from shaft deflection or housing misalignment
- brinelling from pressing the ring home through the balls or from static overload
Selection pitfalls — read before you substitute
- 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.
- The capped speed ceiling is 7,500 r/min — seal drag and grease life govern, which is why SKF publishes no thermal reference speed for A-2Z.
- The capped speed ceiling is 7,500 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.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3308 A-2Z as the double shielded execution; the other order numbers of the 3308 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 3308-A-2Z?
3308 A-2Z measures 40 mm bore × 90 mm OD × 36.5 mm width (1.575 × 3.543 × 1.437 in), mass about 930 g. SKF 17000 ratings: C 64 kN, C0 44 kN, Pu 1.86 kN, SKF publishes only the 7,500 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 is the difference between 3308 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 3308?
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.