3305-A bearing: complete specifications & equivalents
The 3305-A is a ISO 15 radial bearing sized 25 x 62 x 25.4 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 25 mm |
| Outer diameter D | 62 mm |
| Width B | 25.4 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 32 kN |
| Basic static load rating C0 | 20.4 kN |
| Fatigue load limit Pu | 0.865 kN |
| Reference speed (thermal) | 12000 rpm |
| Limiting speed (mechanical) | 11000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 350 g |
| Manufacturer designation | 3305 A |
| 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 | 0.984 in |
|---|---|
| Outer diameter D | 2.441 in |
| Width B | 1 in |
| ISO bore code | 05 |
| Radial section height (D−d)/2 | 18.5 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) | 4 of 20 |
| Bore above smallest 3300-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 3305-ATN9 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 25×62×25.4 mm envelope with catalogue ratings within 10 %; 3305 ATN9 is the glass-fibre PA66 cage, open arrangement execution of this size — boundary dimensions interchangeable, execution differs. |
| 3305-A-2Z | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 25×62×25.4 mm envelope with catalogue ratings within 10 %; 3305 A-2Z is the stamped steel cage, shields (-2Z) execution of this size — boundary dimensions interchangeable, execution differs. |
| 3305-A-2RS1 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 25×62×25.4 mm envelope with catalogue ratings within 10 %; 3305 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 3305-A model number is decoded
3305 A is SKF's 25 mm-bore double-row angular-contact ball bearing of the 3300 series — two ball rows back-to-back for two-direction axial location in one unit, 25×62×25.4 mm. A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. with no cage suffix the double-row A execution uses the standard stamped steel ball-centred cage. Envelope 25×62×25.4 mm (0.984×2.441×1 in), 18.5 mm radial section height, C 32 kN, C0 20.4 kN, Pu 0.865 kN.reference speed 12,000 r/min (thermal) and limiting speed 11,000 r/min (mechanical), catalogue mass 350 g. Sizing arithmetic on the 25 mm bore: 32 kN C divided by the 18.5 mm radial section height gives 1.7 kN per section millimetre; the 350 g mass and 3 % Pu/C share frame the light-load floor for the adjusted-life check. Load balance: C0 20.4 kN against C 32 kN gives a 0.64 ratio, typical of a double-row bidirectional design; Pu 0.865 kN enters the SKF adjusted-life equation rather than the basic rating life. Speed-ratio note for this exact unit: the reference speed is 12,000 r/min against a 11,000 r/min limiting speed, i.e. a reference-to-limit ratio of 1.09.
Typical equipment & failure modes
Common applications
- elevator and hoist machinery
- printing and converting machinery
- gearbox input and output shafts with bidirectional thrust
Known failure patterns
- tilted mounting that loads one double row more heavily than the other
- false brinelling on the loaded row while the shaft stands idle under vibration
- stamped steel cage noise and pocket wear in marginal-lubrication starts, where a brass-cage execution would survive
- fretting corrosion on a loose rotating shaft seat
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- Compared with a single-row pair of the same bore, the double-row 3305 occupies less axial space but offers less freedom to adjust preload — do not substitute without re-checking the arrangement.
- Compared with a single-row pair of the same bore, the double-row 3305 occupies less axial space but offers less freedom to adjust preload — do not substitute without re-checking the arrangement.
- Interference goes on the rotating ring (about k5 at 25 mm bore); the wide 25.4 mm ring is sensitive to tilted seats, so check squareness before clamping.
- Interference goes on the rotating ring (about k5 at 25 mm bore); the wide 25.4 mm ring is sensitive to tilted seats, so check squareness before clamping.
- Catalogue ratings are SKF PUB BU/P1 17000 figures for 3305 A as the double a steel execution; the other order numbers of the 3305 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 3305-A?
3305 A measures 25 mm bore × 62 mm OD × 25.4 mm width (0.984 × 2.441 × 1 in), mass about 350 g. SKF 17000 ratings: C 32 kN, C0 20.4 kN, Pu 0.865 kN, reference speed 12,000 r/min (thermal) and limiting speed 11,000 r/min (mechanical).
What does the A suffix mean?
A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. with no cage suffix the double-row A execution uses the standard stamped steel ball-centred cage.
Does the 3305 double-row bearing need pairing?
No — both ball rows are built into one bearing, so bidirectional location does not require a second unit. Controlled axial clearance is part of the design rather than a field adjustment.
Which fits should I use?
With a rotating inner ring use roughly k5 on the 25 mm shaft and H7 in the 62 mm housing; check the wide ring seats square because the 25.4 mm width is sensitive to tilt.
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.