31322X-DF bearing: complete specifications & equivalents
The 31322X-DF is a ISO 355 radial bearing sized 110 x 240 x 126 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 110 mm |
| Outer diameter D | 240 mm |
| Width B | 126 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 841 kN |
| Basic static load rating C0 | 1160 kN |
| Fatigue load limit Pu | 122 kN |
| Reference speed (thermal) | 1500 rpm |
| Limiting speed (mechanical) | 2800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 26000 g |
| Manufacturer designation | SKF 31322 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 | 4.331 in |
|---|---|
| Outer diameter D | 9.449 in |
| Width B | 4.961 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 65 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) | 18 of 35 |
| Bore above smallest matched-df-series size | 85 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31322X | 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 31322X-DF model number is decoded
The code breaks down as base bearing 31322 X plus matched-set suffix /DF: two bearings of the 110 mm bore size, paired face-to-face (X) matched pair, with the 126 mm overall width spanning the whole arrangement. 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 126 mm overall width of 31322X-DF is the axial space the pair occupies. Selection arithmetic: the catalogue C 841 kN and C0 1160 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 122 kN as the fatigue floor. Journal and housing interface: the 110 mm bore takes a m6 shaft seat and the 240 mm outside diameter pairs with an H7 housing bore; the 126 mm width defines shoulder depth and the 26000 g mass is the dead load in thermal-growth calculations. Mounting order matters for 31322X-DF: seat the first bearing, fit the ground spacer, then the second bearing, and clamp axially as a unit — the 126 mm catalogue width is the assembled result and the gauge for correct assembly. The rotating cones of 31322X-DF take a m6 seat on the 110 mm shaft; the cups are a transition-to-loose fit so the pair can be clamped to its factory setting during assembly.31322X-DF is a matched pair of single-row tapered roller bearings arranged face-to-face (X) matched pair, supplied by SKF in SKF catalogue PUB BU/P1 17000 as one factory-set unit: the two bearings, spacers and setting are matched together and must not be mixed with other sets.
Typical equipment & failure modes
Common applications
- construction machinery drives
- marine deck machinery shafts
- heavy industrial gearboxes and speed reducers
- heavy industrial gearboxes and speed reducers
Known failure patterns
- preload loss as the mounted pair relaxes, letting rollers skid and smear the raceways
- roller large-end smearing against the cone rib after EP lubricant film failure
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- electrical pitting on VFD-driven shafts without grounding protection
- brinelling from pressing the cone or cup home through the rollers
Selection pitfalls — read before you substitute
- O and X arrangements are not interchangeable by turning the set around: 31322X-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 31322X-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.
- Clamp the 31322X-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 841/1160 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 31322 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 31322X-DF?
The SKF 31322 X/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 110 mm bore, 240 mm outer diameter and 126 mm overall width (4.331 × 9.449 × 4.961 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 841 kN, C0 1160 kN, fatigue load limit Pu 122 kN, reference speed 1,500 r/min, limiting speed 2,800 r/min, mass about 26.00 kg.
What does the /DF suffix on 31322X-DF mean?
The base 31322 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 31322X-DF for one bearing or the pair?
They are for the complete matched pair: C 841 kN dynamic and C0 1160 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 31322 X table values.
Can 31322X-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 110 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 110 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.