31326X-DF bearing: complete specifications & equivalents
The 31326X-DF is a ISO 355 radial bearing sized 130 x 280 x 144 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 130 mm |
| Outer diameter D | 280 mm |
| Width B | 144 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 1110 kN |
| Basic static load rating C0 | 1560 kN |
| Fatigue load limit Pu | 160 kN |
| Reference speed (thermal) | 1300 rpm |
| Limiting speed (mechanical) | 2400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 39500 g |
| Manufacturer designation | SKF 31326 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 | 5.118 in |
|---|---|
| Outer diameter D | 11.024 in |
| Width B | 5.669 in |
| ISO bore code | — |
| 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) | 20 of 35 |
| Bore above smallest matched-df-series size | 105 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31326X | 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 31326X-DF model number is decoded
Dividing the pair C 1110 kN by the 130 mm bore gives 8.54 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. Dimensional interchange map: within its boundary plan the 130×280×144 mm envelope of 31326X-DF is fixed, so shoulder, spacer and seal drawings can be dimensioned straight from the catalogue table. Spacer discipline: the spacer between the two bearings of 31326X-DF is ground to the individual set — it carries a serial link to the pair, so never swap spacers between sets of the same designation. The rotating cones of 31326X-DF take a m6 seat on the 130 mm shaft; the cups are a transition-to-loose fit so the pair can be clamped to its factory setting during assembly.In SKF catalogue PUB BU/P1 17000, 31326X-DF appears as SKF 31326 X/DF: a matched face-to-face (X) matched pair pair for a 130 mm shaft, rated as a set at C 1110 kN and C0 1560 kN.Digit by digit, 31326X-DF reads as the ISO 355 base bearing 31326 X supplied as a face-to-face (X) matched pair matched pair (/DF); the 130 mm bore and 280 mm OD are per-bearing, the 144 mm width is for the set. Face-to-face matching puts the small rib ends outward, so the pressure cones cross inside the pair; 31326X-DF therefore runs cooler where the shaft expands axially, at the price of lower moment stiffness than an O-arrangement of the same 130 mm bore.
Typical equipment & failure modes
Common applications
- wind-turbine main shafts
- marine propulsion gearboxes
- large industrial mixer shafts
- large crusher and mineral-processing drives
Known failure patterns
- roller large-end smearing against the cone rib after EP lubricant film failure
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- 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
- 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 31326X-DF or swap the spacer — the factory clearance is lost the moment the set is broken.
- Spacer faces must stay parallel within the set's own tolerance; a tilted spacer in 31326X-DF concentrates reversing thrust on one bearing and shows up as one-sided raceway wear.
- A matched /DF set is ground as one system: never separate the two bearings of 31326X-DF or swap the spacer — the factory clearance is lost the moment the set is broken.
- The 1110/1560 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 31326 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 31326X-DF?
The SKF 31326 X/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 130 mm bore, 280 mm outer diameter and 144 mm overall width (5.118 × 11.024 × 5.669 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 1110 kN, C0 1560 kN, fatigue load limit Pu 160 kN, reference speed 1,300 r/min, limiting speed 2,400 r/min, mass about 39.50 kg.
What does the /DF suffix on 31326X-DF mean?
The base 31326 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 31326X-DF for one bearing or the pair?
They are for the complete matched pair: C 1110 kN dynamic and C0 1560 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 31326 X table values.
Can 31326X-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 130 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 130 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.