30238-DF bearing: complete specifications & equivalents
The 30238-DF is a ISO 355 radial bearing sized 190 x 340 x 120 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 190 mm |
| Outer diameter D | 340 mm |
| Width B | 120 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 1308 kN |
| Basic static load rating C0 | 2000 kN |
| Fatigue load limit Pu | 190 kN |
| Reference speed (thermal) | 1100 rpm |
| Limiting speed (mechanical) | 1800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 42500 g |
| Manufacturer designation | SKF 30238/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 | 7.48 in |
|---|---|
| Outer diameter D | 13.386 in |
| Width B | 4.724 in |
| ISO bore code | 38 |
| Radial section height (D−d)/2 | 75 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) | 26 of 35 |
| Bore above smallest matched-df-series size | 165 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 30238 | 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. |
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 30238-DF model number is decoded
Material and manufacturing detail: the 42500 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. Thermal behaviour of the pair: heat generated in the 190 mm bore cones flows along the shaft and changes the setting; the /DF clearance class is chosen for the catalogue speed range 1,100–1,800 r/min, so re-select the clearance class if the application runs hotter. Clamp the assembled pair axially through the cones — never through the rollers — and verify the 120 mm overall width against the catalogue value before final torquing of the shaft nut.Ordering number SKF 30238/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 190 mm shaft — one order number, one factory setting.Digit by digit, 30238-DF reads as the ISO 355 base bearing 30238 supplied as a face-to-face (X) matched pair matched pair (/DF); the 190 mm bore and 340 mm OD are per-bearing, the 120 mm width is for the set. 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 120 mm overall width of 30238-DF is the axial space the pair occupies. Selection arithmetic: the catalogue C 1308 kN and C0 2000 kN are ratings of the complete pair, not of one bearing — never halve them back to a single-row figure when checking L10 life, and use the pair Pu 190 kN as the fatigue floor.
Typical equipment & failure modes
Common applications
- heavy-duty rolling-mill gearboxes
- large crusher and mineral-processing drives
- wind-turbine main shafts
- large crusher and mineral-processing drives
Known failure patterns
- uneven load sharing in a pair when spacer faces are not parallel to the bore
- 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
- edge loading from shaft deflection or housing misalignment
- hard-particle indentation of the tapered raceway in unfiltered oil
Selection pitfalls — read before you substitute
- A matched /DF set is ground as one system: never separate the two bearings of 30238-DF or swap the spacer — the factory clearance is lost the moment the set is broken.
- Setting is built into 30238-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.
- Spacer faces must stay parallel within the set's own tolerance; a tilted spacer in 30238-DF concentrates reversing thrust on one bearing and shows up as one-sided raceway wear.
- The 1308/2000 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 30238/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 30238-DF?
The SKF 30238/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 190 mm bore, 340 mm outer diameter and 120 mm overall width (7.48 × 13.386 × 4.724 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 1308 kN, C0 2000 kN, fatigue load limit Pu 190 kN, reference speed 1,100 r/min, limiting speed 1,800 r/min, mass about 42.50 kg.
What does the /DF suffix on 30238-DF mean?
The base 30238 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 30238-DF for one bearing or the pair?
They are for the complete matched pair: C 1308 kN dynamic and C0 2000 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 30238 table values.
Can 30238-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 (m6 on a rotating 190 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 190 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.