30208-DF bearing: complete specifications & equivalents
The 30208-DF is a ISO 355 radial bearing sized 40 x 80 x 39.5 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 40 mm |
| Outer diameter D | 80 mm |
| Width B | 39.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 130 kN |
| Basic static load rating C0 | 137 kN |
| Fatigue load limit Pu | 15.3 kN |
| Reference speed (thermal) | 5600 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 870 g |
| Manufacturer designation | SKF 30208/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 | 1.575 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 1.555 in |
| ISO bore code | 08 |
| Radial section height (D−d)/2 | 20 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) | 4 of 35 |
| Bore above smallest matched-df-series size | 15 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30208 | 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. |
| 30208-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 30208-DF model number is decoded
Thermal behaviour of the pair: heat generated in the 40 mm bore cones flows along the shaft and changes the setting; the /DF clearance class is chosen for the catalogue speed range 5,600–8,500 r/min, so re-select the clearance class if the application runs hotter. Lubrication for the pair should be sized against the combined 39.5 mm width and 870 g mass: two roller sets sweep twice the contact area of a single bearing of the same bore.Ordering number SKF 30208/DF in SKF catalogue PUB BU/P1 17000 denotes two single-row tapered roller bearings supplied as a matched face-to-face (X) matched pair set for a 40 mm shaft — one order number, one factory setting.On the SKF nameplate, 30208-DF reads as base 30208 in a /DF matched execution — the suffix is part of the order number because a matched set is ground for a specific axial clearance and cannot be assembled from loose single bearings. 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 39.5 mm overall width of 30208-DF is the axial space the pair occupies. With a pair mass of 870 g across the 40×80×39.5 mm envelope, the set replaces what would otherwise be two separate bearings plus spacer grinding work — the factory setting is the engineering value being purchased. Cross-section geometry: the 20.0 mm half-section ((80−40)/2) places the roller pitch diameter near 60 mm, and the 39.5 mm axial width sets the abutment depth — geometry that fixes the contact angle behaviour of 30208-DF.
Typical equipment & failure modes
Common applications
- industrial gearbox shafts and reducers
- differential and pinion drives
- pump and compressor shafts
- machine-tool spindles
Known failure patterns
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- preload loss as the mounted pair relaxes, letting rollers skid and smear the raceways
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- edge loading from shaft deflection or housing misalignment
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- O and X arrangements are not interchangeable by turning the set around: 30208-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 30208-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.
- Replace 30208-DF as a complete set: pairing a new bearing with a worn partner leaves the clearance undefined even when the designation matches.
- The 130/137 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 30208/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 30208-DF?
The SKF 30208/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 40 mm bore, 80 mm outer diameter and 39.5 mm overall width (1.575 × 3.15 × 1.555 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 130 kN, C0 137 kN, fatigue load limit Pu 15.3 kN, reference speed 5,600 r/min, limiting speed 8,500 r/min, mass about 0.87 kg.
What does the /DF suffix on 30208-DF mean?
The base 30208 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 30208-DF for one bearing or the pair?
They are for the complete matched pair: C 130 kN dynamic and C0 137 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 30208 table values.
Can 30208-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 40 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 40 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.