30309-DF bearing: complete specifications & equivalents
The 30309-DF is a ISO 355 radial bearing sized 45 x 100 x 54.5 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 | 54.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 227 kN |
| Basic static load rating C0 | 240 kN |
| Fatigue load limit Pu | 28.5 kN |
| Reference speed (thermal) | 4500 rpm |
| Limiting speed (mechanical) | 7000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 2000 g |
| Manufacturer designation | SKF 30309/DF |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants |
| Last verified | 2026-09-29 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants) · extracted 2026-09-29
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants); 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 & matched-df-series range
| Bore d | 1.772 in |
|---|---|
| Outer diameter D | 3.937 in |
| Width B | 2.146 in |
| ISO bore code | 09 |
| Radial section height (D−d)/2 | 27.5 mm |
| Smallest bore in matched-df-series | 25 mm |
| Largest outer diameter in matched-df-series | 540 mm |
| Width range across matched-df-series | 34.5–280 mm |
| Bore position in matched-df-series (smallest first) | 5 of 35 |
| Bore above smallest matched-df-series size | 20 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30309 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
| 30309-NTN | NTN | verify Commonly quoted cross reference; confirm against the target catalog before ordering. | Model-number interchange per ISO 15; confirm dimensions, sealing and ratings in the supplier catalogue. |
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-DF model number is decoded
In SKF catalogue PUB BU/P1 17000, 30309-DF appears as SKF 30309/DF: a matched face-to-face (X) matched pair pair for a 45 mm shaft, rated as a set at C 227 kN and C0 240 kN.Numbering ties the set to its envelope: base 30309 fixes the 45 mm bore and 100 mm OD of each bearing, the /DF suffix fixes the arrangement and setting, and the catalogue 54.5 mm width is the combined pair dimension. In the face-to-face (X) arrangement the load lines of the two bearings converge toward the shaft axis: the set tolerates shaft deflection and thermal growth better than a back-to-back pair, but is less stiff against overturning moments. The 54.5 mm overall width of 30309-DF is the axial space the pair occupies. The C0/C balance of the pair is about 1.06; combined with the 28.5 kN fatigue limit this frames a set sized for reversing combined load on a 45 mm shaft rather than for pure radial duty. Material and manufacturing detail: the 2000 g catalogue mass reflects through-hardened bearing steel machined to the listed envelope; ring roundness and width tolerance keep the mounted-setting scatter inside the catalogue class. Mounting order matters for 30309-DF: seat the first bearing, fit the ground spacer, then the second bearing, and clamp axially as a unit — the 54.5 mm catalogue width is the assembled result and the gauge for correct assembly. Lubrication for the pair should be sized against the combined 54.5 mm width and 2000 g mass: two roller sets sweep twice the contact area of a single bearing of the same bore.
Typical equipment & failure modes
Common applications
- axle-boxes in material-handling equipment
- automotive and light-truck wheel hubs
- industrial gearbox shafts and reducers
- axle-boxes in material-handling equipment
Known failure patterns
- false brinelling on idle paired sets exposed to machine vibration
- thermal preload runaway in an O-arrangement pair when inner-ring heat expands the setting
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- brinelling from pressing the cone or cup home through the rollers
- brinelling from pressing the cone or cup home through the rollers
Selection pitfalls — read before you substitute
- O and X arrangements are not interchangeable by turning the set around: 30309-DF in face-to-face (X) matched pair arrangement has its load-line geometry fixed — specify the arrangement from the shaft thermal and stiffness analysis.
- Setting is built into 30309-DF; the classic field error is re-adjusting a matched pair as if it were two loose single bearings, which destroys the /DF clearance class.
- O and X arrangements are not interchangeable by turning the set around: 30309-DF in face-to-face (X) matched pair arrangement has its load-line geometry fixed — specify the arrangement from the shaft thermal and stiffness analysis.
- The 227/240 kN ratings are SKF catalogue 17000 values for this 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.
- Quote the full SKF 30309/DF designation when purchasing — base-number-only orders are ambiguous across executions and variants.
Frequently asked questions
What are the dimensions and catalogue data of 30309-DF?
The SKF 30309/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 45 mm bore, 100 mm outer diameter and 54.5 mm overall width (1.772 × 3.937 × 2.146 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 227 kN, C0 240 kN, fatigue load limit Pu 28.5 kN, reference speed 4,500 r/min, limiting speed 7,000 r/min, mass about 2.00 kg.
What does the /DF suffix on 30309-DF mean?
The base 30309 is the ISO 355 single-row bearing; the /DF suffix marks the matched-set execution — the arrangement (face-to-face (X)), the ground spacer and the factory-set axial clearance class. A matched set cannot be assembled from loose single bearings; quote the full designation when ordering.
Are the C and C0 ratings of 30309-DF for one bearing or the pair?
They are for the complete matched pair: C 227 kN dynamic and C0 240 kN static already include load sharing between the two bearings. Do not halve them for single-bearing checks, and do not compare them directly with the single-row 30309 table values.
Can 30309-DF be adjusted like two loose tapered bearings?
No — the axial clearance is set at the factory by selective spacer grinding. Mounting work is limited to clean seats, correct fits (k5 on a rotating 45 mm shaft) and axial clamping through the cones; re-setting in the field destroys the matched clearance class.
When should a face-to-face (X) matched set be chosen?
Choose the face-to-face (X) set where the shaft grows thermally or alignment is imperfect — the converging load lines tolerate deflection. It is the default choice for wheel hubs and general gearbox shafts at the 45 mm bore.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants on 2026-09-29. Read our editorial & correction policy.