31307-DF bearing: complete specifications & equivalents
The 31307-DF is a ISO 355 radial bearing sized 35 x 80 x 45.5 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 35 mm |
| Outer diameter D | 80 mm |
| Width B | 45.5 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 129 kN |
| Basic static load rating C0 | 134 kN |
| Fatigue load limit Pu | 15.6 kN |
| Reference speed (thermal) | 5000 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1100 g |
| Manufacturer designation | SKF 31307/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 | 1.378 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 1.791 in |
| ISO bore code | 07 |
| Radial section height (D−d)/2 | 22.5 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) | 3 of 35 |
| Bore above smallest matched-df-series size | 10 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31307 | 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 31307-DF model number is decoded
31307-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.Digit by digit, 31307-DF reads as the ISO 355 base bearing 31307 supplied as a face-to-face (X) matched pair matched pair (/DF); the 35 mm bore and 80 mm OD are per-bearing, the 45.5 mm width is for the set. Face-to-face matching puts the small rib ends outward, so the pressure cones cross inside the pair; 31307-DF therefore runs cooler where the shaft expands axially, at the price of lower moment stiffness than an O-arrangement of the same 35 mm bore. Catalogue mass 1100 g covers both bearings and the ground spacer of 31307-DF; keep the set complete — substituting one bearing or a non-ground spacer destroys the factory clearance. Cross-section geometry: the 22.5 mm half-section ((80−35)/2) places the roller pitch diameter near 57 mm, and the 45.5 mm axial width sets the abutment depth — geometry that fixes the contact angle behaviour of 31307-DF. When a matched /DF set like 31307-DF is replaced, replace the whole set: mixing a new bearing with a worn partner from the old set leaves the clearance and load sharing of the pair undefined. Do not separate 31307-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.
Typical equipment & failure modes
Common applications
- automotive and light-truck wheel hubs
- industrial gearbox shafts and reducers
- differential and pinion drives
- automotive and light-truck wheel hubs
Known failure patterns
- thermal preload runaway in an O-arrangement pair when inner-ring heat expands the setting
- roller large-end smearing against the cone rib after EP lubricant film failure
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- electrical pitting on VFD-driven shafts without grounding protection
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- Setting is built into 31307-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.
- Spacer faces must stay parallel within the set's own tolerance; a tilted spacer in 31307-DF concentrates reversing thrust on one bearing and shows up as one-sided raceway wear.
- O and X arrangements are not interchangeable by turning the set around: 31307-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.
- The 129/134 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 31307/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 31307-DF?
The SKF 31307/DF is a matched pair of single-row tapered roller bearings in face-to-face (X) matched pair arrangement with 35 mm bore, 80 mm outer diameter and 45.5 mm overall width (1.378 × 3.15 × 1.791 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 129 kN, C0 134 kN, fatigue load limit Pu 15.6 kN, reference speed 5,000 r/min, limiting speed 8,500 r/min, mass about 1.10 kg.
What does the /DF suffix on 31307-DF mean?
The base 31307 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 31307-DF for one bearing or the pair?
They are for the complete matched pair: C 129 kN dynamic and C0 134 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 31307 table values.
Can 31307-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 35 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 35 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.