31313-DF bearing: complete specifications & equivalents
The 31313-DF is a ISO 355 radial bearing sized 65 x 140 x 72 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 65 mm |
| Outer diameter D | 140 mm |
| Width B | 72 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 348 kN |
| Basic static load rating C0 | 380 kN |
| Fatigue load limit Pu | 47.5 kN |
| Reference speed (thermal) | 2800 rpm |
| Limiting speed (mechanical) | 4800 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 5000 g |
| Manufacturer designation | SKF 31313/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 | 2.559 in |
|---|---|
| Outer diameter D | 5.512 in |
| Width B | 2.835 in |
| ISO bore code | 13 |
| Radial section height (D−d)/2 | 37.5 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) | 9 of 35 |
| Bore above smallest matched-df-series size | 40 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31313 | 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 31313-DF model number is decoded
Face-to-face matching puts the small rib ends outward, so the pressure cones cross inside the pair; 31313-DF therefore runs cooler where the shaft expands axially, at the price of lower moment stiffness than an O-arrangement of the same 65 mm bore. Dividing the pair C 348 kN by the 65 mm bore gives 5.35 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. Journal and housing interface: the 65 mm bore takes a k5 shaft seat and the 140 mm outside diameter pairs with an H7 housing bore; the 72 mm width defines shoulder depth and the 5000 g mass is the dead load in thermal-growth calculations. Thermal behaviour of the pair: heat generated in the 65 mm bore cones flows along the shaft and changes the setting; the /DF clearance class is chosen for the catalogue speed range 2,800–4,800 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 72 mm overall width against the catalogue value before final torquing of the shaft nut.Ordering number SKF 31313/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 65 mm shaft — one order number, one factory setting.Numbering ties the set to its envelope: base 31313 fixes the 65 mm bore and 140 mm OD of each bearing, the /DF suffix fixes the arrangement and setting, and the catalogue 72 mm width is the combined pair dimension.
Typical equipment & failure modes
Common applications
- marine deck machinery shafts
- heavy industrial gearboxes and speed reducers
- large process pump and compressor shafts
- crane sheave and hoist gearboxes
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
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- edge loading from shaft deflection or housing misalignment
- grease degradation after long shelf storage without rotation or re-greasing
Selection pitfalls — read before you substitute
- Replace 31313-DF as a complete set: pairing a new bearing with a worn partner leaves the clearance undefined even when the designation matches.
- Setting is built into 31313-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.
- Replace 31313-DF as a complete set: pairing a new bearing with a worn partner leaves the clearance undefined even when the designation matches.
- The 348/380 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 31313/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 31313-DF?
The SKF 31313/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 65 mm bore, 140 mm outer diameter and 72 mm overall width (2.559 × 5.512 × 2.835 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 348 kN, C0 380 kN, fatigue load limit Pu 47.5 kN, reference speed 2,800 r/min, limiting speed 4,800 r/min, mass about 5.00 kg.
What does the /DF suffix on 31313-DF mean?
The base 31313 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 31313-DF for one bearing or the pair?
They are for the complete matched pair: C 348 kN dynamic and C0 380 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 31313 table values.
Can 31313-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 (k5 on a rotating 65 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 65 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.