3306-A-2Z bearing: complete specifications & equivalents
The 3306-A-2Z is a ISO 15 radial bearing sized 30 x 72 x 30.2 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 | 30 mm |
| Outer diameter D | 72 mm |
| Width B | 30.2 mm |
| Material | GCr15 |
| Seal / shield | ZZ |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 42.5 kN |
| Basic static load rating C0 | 30 kN |
| Fatigue load limit Pu | 1.27 kN |
| Limiting speed (mechanical) | 9000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 520 g |
| Manufacturer designation | 3306 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 | 1.181 in |
|---|---|
| Outer diameter D | 2.835 in |
| Width B | 1.189 in |
| ISO bore code | 06 |
| Radial section height (D−d)/2 | 21 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) | 5 of 20 |
| Bore above smallest 3300-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3306-A | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 30×72×30.2 mm envelope with catalogue ratings within 10 %; 3306 A is the stamped steel cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3306-ATN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 30×72×30.2 mm envelope with catalogue ratings within 10 %; 3306 ATN9 is the glass-fibre PA66 cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3306-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 30×72×30.2 mm envelope with catalogue ratings within 10 %; 3306 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 3306-A-2Z model number is decoded
3306 A-2Z is the capped double-row angular-contact ball bearing for a 30 mm shaft, 30×72×30.2 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 30×72×30.2 mm (1.181×2.835×1.189 in), 21.0 mm radial section height, C 42.5 kN, C0 30 kN, Pu 1.27 kN.SKF publishes only the 9,000 r/min limiting speed for this execution, catalogue mass 520 g. Selection figures for 3306 A-2Z: the static-to-dynamic ratio C0/C is 0.71, Pu 1.27 kN is about 3 % of C, and catalogue mass works out to roughly 17 g per millimetre of bore. Speed planning distinguishes the two published ceilings mechanically: the cage and balls tolerate 9,000 r/min and no separate thermal reference is published; at dm ≈ 51.0 mm the corresponding dn is approximately 459k mm·r/min. Bore-to-OD planning: OD 72 over bore 30 is a 2.40× step for this size, and the 30.2 mm width gives a bore/width ratio of 0.99; use these ratios when housing space around the 30 mm shaft is the first constraint. 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
- lifetime-lubricated electric motor and gearbox positions
- agricultural machinery drives
- conveyor drum shafts
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
- grease escape past the non-contact shields in an overfilled or vertically mounted position
- two-direction thrust overload concentrating load on one row and spalling its raceway
- brinelling from pressing the ring home through the balls or from static overload
- mounting score marks when the bearing is cocked over a burr or keyway
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 shields/seals do not make the bearing waterproof under immersion or pressure washing; select external sealing for wet or wash-down duty.
- The shields/seals do not make the bearing waterproof under immersion or pressure washing; select external sealing for wet or wash-down duty.
- Never wash 3306-A-2Z in solvent: the lifetime grease fill cannot be replaced once flushed out.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3306 A-2Z as the double shielded execution; the other order numbers of the 3306 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 3306-A-2Z?
3306 A-2Z measures 30 mm bore × 72 mm OD × 30.2 mm width (1.181 × 2.835 × 1.189 in), mass about 520 g. SKF 17000 ratings: C 42.5 kN, C0 30 kN, Pu 1.27 kN, SKF publishes only the 9,000 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 3306-A-2Z take?
The same bidirectional combined loads as the open double-row 3306: C 42.5 kN, C0 30 kN, Pu 1.27 kN. Capping changes sealing and speed, not the basic ratings.
Is 3306-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.