31328X-DF bearing: complete specifications & equivalents
The 31328X-DF is a ISO 355 radial bearing sized 140 x 300 x 154 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 140 mm |
| Outer diameter D | 300 mm |
| Width B | 154 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 1264 kN |
| Basic static load rating C0 | 1800 kN |
| Fatigue load limit Pu | 180 kN |
| Reference speed (thermal) | 1200 rpm |
| Limiting speed (mechanical) | 2200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 49000 g |
| Manufacturer designation | SKF 31328 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 | 5.512 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 6.063 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 80 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) | 21 of 35 |
| Bore above smallest matched-df-series size | 115 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31328X | 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 31328X-DF model number is decoded
Mounting order matters for 31328X-DF: seat the first bearing, fit the ground spacer, then the second bearing, and clamp axially as a unit — the 154 mm catalogue width is the assembled result and the gauge for correct assembly. Do not separate 31328X-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.Ordering number SKF 31328 X/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 140 mm shaft — one order number, one factory setting.Reading the designation: 31328 X is the ISO 355 single-row base bearing (140 mm bore), and the suffix /DF marks the matched-set execution — arrangement, spacer grinding and factory clearance class. The pair envelope is 140×300×154 mm; the width covers both bearings of the set. Face-to-face matching puts the small rib ends outward, so the pressure cones cross inside the pair; 31328X-DF therefore runs cooler where the shaft expands axially, at the price of lower moment stiffness than an O-arrangement of the same 140 mm bore. With a pair mass of 49000 g across the 140×300×154 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. Dimensional interchange map: within its boundary plan the 140×300×154 mm envelope of 31328X-DF is fixed, so shoulder, spacer and seal drawings can be dimensioned straight from the catalogue table.
Typical equipment & failure modes
Common applications
- large crusher and mineral-processing drives
- wind-turbine main shafts
- marine propulsion gearboxes
- large industrial mixer shafts
Known failure patterns
- uneven load sharing in a pair when spacer faces are not parallel to the bore
- uneven load sharing in a pair when spacer faces are not parallel to the bore
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- mounting score marks when the cone is cocked over the shaft keyway or a burr
- rolling-contact fatigue spalling after the rated L10 life is exceeded
Selection pitfalls — read before you substitute
- Replace 31328X-DF as a complete set: pairing a new bearing with a worn partner leaves the clearance undefined even when the designation matches.
- Clamp the 31328X-DF pair axially through the cones, never through the rollers; pressing force across the roller complement brinells the raceways of both bearings at once.
- Clamp the 31328X-DF pair axially through the cones, never through the rollers; pressing force across the roller complement brinells the raceways of both bearings at once.
- The 1264/1800 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 31328 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 31328X-DF?
The SKF 31328 X/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 140 mm bore, 300 mm outer diameter and 154 mm overall width (5.512 × 11.811 × 6.063 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 1264 kN, C0 1800 kN, fatigue load limit Pu 180 kN, reference speed 1,200 r/min, limiting speed 2,200 r/min, mass about 49.00 kg.
What does the /DF suffix on 31328X-DF mean?
The base 31328 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 31328X-DF for one bearing or the pair?
They are for the complete matched pair: C 1264 kN dynamic and C0 1800 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 31328 X table values.
Can 31328X-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 140 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 140 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.