30309 bearing: complete specifications & equivalents
The 30309 is a ISO 355 radial bearing sized 45 x 100 x 27.25 mm (bore x OD x width). 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 | 27.25 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 132 kN |
| Basic static load rating C0 | 120 kN |
| Fatigue load limit Pu | 14.3 kN |
| Reference speed (thermal) | 5600 rpm |
| Limiting speed (mechanical) | 7000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 970 g |
| Manufacturer designation | SKF 30309 |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB); 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 & 30300-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 1.073 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in 30300-series | 15 mm |
| Largest outer diameter in 30300-series | 500 mm |
| Width range across 30300-series | 14.25–105 mm |
| Bore position in 30300-series (smallest first) | 8 of 32 |
| Bore above smallest 30300-series size | 30 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30309 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 355 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
| 30309-NTN | NTN | full Dimensions and internal design equivalent — standard interchange. | Identical ISO 15 envelope, seal and ratings band — standard interchange; re-verify precision class and clearance per supplier. |
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 30309 model number is decoded
For a 45 mm shaft carrying combined load, SKF lists 30309 under catalogue execution SKF 30309: one open single-row tapered roller bearing in the heavy-OD section of the 30300 family.Numbering ties the bearing to its envelope: 30309 means tapered-roller type 3, heavy-OD section series 03, 45 mm bore — which is why the 100×27.25 mm outline swaps dimensionally with other ISO 355 bearings of the same code. The SKF catalogue adds the ISO 355 dimension-series code after the bare number (e.g. 2FB); it is the dimensional series, not a separate part number. Selection arithmetic: the C0/C ratio is about 0.91 (static 120 kN against dynamic 132 kN), typical of a tapered roller sized for axial capacity, and the 14.3 kN fatigue load limit Pu is the equivalent-load floor used in the life calculation. A single 30309 locates the shaft in one axial direction only; mount it against a second bearing in O (back-to-back) or X (face-to-face) arrangement, and set the running clearance by the mounting procedure — not by feel.
Typical equipment & failure modes
Common applications
- automotive and light-truck wheel hubs
- industrial gearbox shafts and reducers
- differential and pinion drives
- pump and compressor shafts
Known failure patterns
- cup or cone misalignment when the separable rings are not seated square during mounting
- loose cup rotation in the housing when the specified press fit is not achieved
- roller large-end smearing against the cone rib after EP lubricant film failure
- false brinelling on idle paired sets exposed to machine vibration
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- edge loading from shaft deflection or housing misalignment
Selection pitfalls — read before you substitute
- On this 45 mm bore, interference and temperature rise consume clearance inside a preloaded pair; calculate the residual clearance after mounting and at operating temperature — an over-tight 30309 pair heats, loses setting control and smears the roller-rib contact.
- The 303 series at 45 mm bore (100×27.25 mm) carries a larger OD and higher capacity than 30209 at the same bore; the bigger section runs hotter, so re-check the 7,000 r/min speed ceiling and shoulder diameters before substituting.
- Setting is a design value, not an assembly feel: excessive preload in the 30309 pair raises operating temperature and can trigger thermal runaway, while too little lets the rollers skid and smear the raceway under light load.
- At the 132 kN rating of 30309, preload class changes stiffness by tens of percent but also heat generation; select light preload for the 7,000 r/min speed end and heavier preload only where moment stiffness dominates.
- Open 30309 units need application-supplied sealing and a defined EP lubricant supply; the roller-rib contact is the first to fail when the additive film breaks down.
- The 132/120 kN ratings are SKF catalogue 17000 values for the basic execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification and re-verify for critical drives.
- SKF lists several executions of 30309 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 30309 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of 30309?
The SKF 30309 is a single-row tapered roller bearing with 45 mm bore, 100 mm outer diameter and 27.25 mm width (1.772 × 3.937 × 1.073 in) per ISO 355. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 132 kN, C0 120 kN, fatigue load limit Pu 14.3 kN, reference speed 5,600 r/min, limiting speed 7,000 r/min, mass about 970 g. It is an open, separable bearing with a pressed-steel cage.
How does the 30309 bore code work?
The last two digits of 30309 are bore code 09, so 09 × 5 = 45 mm bore. The 100 mm OD and 27.25 mm width come from the ISO 355 dimension-series plan, shared with other tapered bearings of the same code.
What do the 30309 series and basic execution designations mean?
The leading 3 marks a single-row tapered roller bearing; the second digit 03 is the ISO 355 series (heavy-OD section). The SKF catalogue lists the ISO 355 dimension-series code after the bare number. A steeper-contact-angle variant (B suffix) is a different order number and is not interchangeable with the basic execution.
Can a single 30309 take axial load in both directions?
No — one single-row tapered roller bearing reacts thrust in one direction only, and under radial load its contact angle induces an axial force. Use two bearings as a matched pair: O (back-to-back) for a rigid, moment-resisting arrangement, X (face-to-face) where thermal expansion must be tolerated, or tandem where one-direction thrust is shared.
How does 30309 compare with a ball bearing of the same bore?
A tapered roller bearing has line contact and a steep contact angle: much higher combined axial-plus-radial capacity and shock resistance than a ball bearing of the same bore, at the cost of speed, one-direction thrust, mandatory pairing for reversing loads and a minimum axial load requirement. A ball bearing cannot be dropped into a combined-load 30309 position and vice versa — verify load direction, Fa/Fr ratio and speed before substituting.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB on 2026-09-26. Read our editorial & correction policy.