31330X-DF bearing: complete specifications & equivalents
The 31330X-DF is a ISO 355 radial bearing sized 150 x 320 x 164 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 150 mm |
| Outer diameter D | 320 mm |
| Width B | 164 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 1427 kN |
| Basic static load rating C0 | 2040 kN |
| Fatigue load limit Pu | 200 kN |
| Reference speed (thermal) | 1100 rpm |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 58500 g |
| Manufacturer designation | SKF 31330 X/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 | 5.906 in |
|---|---|
| Outer diameter D | 12.598 in |
| Width B | 6.457 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 85 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) | 22 of 35 |
| Bore above smallest matched-df-series size | 125 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31330X | 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 31330X-DF model number is decoded
Load system: C 1427 kN against C0 2040 kN gives a 1.43 balance, and 9.51 kN of dynamic capacity per millimetre of the 150 mm bore is the density figure to compare against neighbouring sizes. Load sharing in 31330X-DF depends on spacer face parallelism; a cocked spacer concentrates the reversing thrust on one bearing of the pair and shows up as asymmetric raceway wear at overhaul. Do not separate 31330X-DF into single-bearing service stock — as individual bearings the components are not interchangeable with catalogue single-row executions because the rings are ground for the set.The SKF 31330 X/DF is a 150×320×164 mm matched tapered-roller set — two single-row bearings in face-to-face (X) matched pair arrangement, ground and shipped together with the axial clearance fixed at the factory.The code breaks down as base bearing 31330 X plus matched-set suffix /DF: two bearings of the 150 mm bore size, paired face-to-face (X) matched pair, with the 164 mm overall width spanning the whole arrangement. Face-to-face matching puts the small rib ends outward, so the pressure cones cross inside the pair; 31330X-DF therefore runs cooler where the shaft expands axially, at the price of lower moment stiffness than an O-arrangement of the same 150 mm bore. Dividing the pair C 1427 kN by the 150 mm bore gives 9.51 kN per millimetre of journal for the complete arrangement — a density metric that compares matched sets across the face-to-face (X) matched pair family.
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
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- rolling-contact fatigue spalling after the rated L10 life is exceeded
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- Setting is built into 31330X-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.
- Setting is built into 31330X-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.
- Setting is built into 31330X-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.
- The 1427/2040 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 31330 X/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 31330X-DF?
The SKF 31330 X/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 150 mm bore, 320 mm outer diameter and 164 mm overall width (5.906 × 12.598 × 6.457 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 1427 kN, C0 2040 kN, fatigue load limit Pu 200 kN, reference speed 1,100 r/min, limiting speed 2,000 r/min, mass about 58.50 kg.
What does the /DF suffix on 31330X-DF mean?
The base 31330 X 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 31330X-DF for one bearing or the pair?
They are for the complete matched pair: C 1427 kN dynamic and C0 2040 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 31330 X table values.
Can 31330X-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 150 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 150 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.