31307 bearing: complete specifications & equivalents
The 31307 is a ISO 355 radial bearing sized 35 x 80 x 22.75 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 | 22.75 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 75.4 kN |
| Basic static load rating C0 | 67 kN |
| Fatigue load limit Pu | 7.8 kN |
| Reference speed (thermal) | 6300 rpm |
| Limiting speed (mechanical) | 8500 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 520 g |
| Manufacturer designation | SKF 31307 |
| Standard | ISO 355 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB); 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 & 31300-series range
| Bore d | 1.378 in |
|---|---|
| Outer diameter D | 3.15 in |
| Width B | 0.896 in |
| ISO bore code | 07 |
| Radial section height (D−d)/2 | 22.5 mm |
| Smallest bore in 31300-series | 25 mm |
| Largest outer diameter in 31300-series | 320 mm |
| Width range across 31300-series | 18.25–82 mm |
| Bore position in 31300-series (smallest first) | 3 of 22 |
| Bore above smallest 31300-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 355 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 model number is decoded
31307 is a single-row tapered roller bearing in the ISO 31300 dimension series: a separable cone-and-cup design for combined radial and one-direction axial load, listed by SKF in SKF catalogue PUB BU/P1 17000.On the SKF nameplate, 31307 follows the ISO 355 convention: 3 for the tapered-roller type, 13 for the steep-angle heavy section, final digits 07 for the 35 mm bore. SKF lists the plain number as the basic execution; letter suffixes such as B denote a steeper contact angle and are different order numbers. With C 75.4 kN and C0 67 kN, the 31307 pair-sizing check is dominated by the axial share: keep the equivalent load P below the rating at the required L10, remembering one bearing alone cannot cover reversing thrust at 8,500 r/min. Mounting practice for 31307: the rotating cone takes the interference fit (k5 on a 35 mm shaft), the cup slides for axial location, and reversing-thrust duty demands a paired O/X set rather than one bearing.
Typical equipment & failure modes
Common applications
- pump and compressor shafts
- machine-tool spindles
- belt-driven fan and blower shafts
- axle-boxes in material-handling equipment
Known failure patterns
- cup or cone misalignment when the separable rings are not seated square during mounting
- loose cup rotation in the housing when the specified press fit is not achieved
- thermal preload runaway in an O-arrangement pair when inner-ring heat expands the setting
- 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
- fretting corrosion on a loose rotating shaft seat
Selection pitfalls — read before you substitute
- On this 35 mm bore, interference and temperature rise consume clearance inside a preloaded pair; calculate the residual clearance after mounting and at operating temperature — an over-tight 31307 pair heats, loses setting control and smears the roller-rib contact.
- The 313 series at 35 mm bore (80×22.75 mm) has a steeper contact angle than the 302/303 families — higher axial capacity per radial load but more induced thrust and heat; do not interchange with a 30307 without re-running the pair calculation.
- At the 75.4 kN rating of 31307, preload class changes stiffness by tens of percent but also heat generation; select light preload for the 8,500 r/min speed end and heavier preload only where moment stiffness dominates.
- The tapered contact angle creates an induced axial load under pure radial force; include it in the 31307 rating calculation (and account for it in both bearings of a pair) or the unloaded bearing skids its rollers.
- Catalogue reference speed and limiting speed are different limits: the 6,300 r/min reference is a thermal criterion under load, while the 8,500 r/min limiting value is the mechanical ceiling — observe both.
- The 75.4/67 kN ratings are SKF catalogue 17000 values for the basic 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 and re-verify for critical drives.
- SKF lists several executions of 31307 (basic, B steeper angle, Q/J2 clearance variants); they are not interchangeable order numbers — quote the full SKF 31307 designation when purchasing and match the execution to the mounting arrangement.
Frequently asked questions
What are the dimensions and catalogue data of 31307?
The SKF 31307 is a single-row tapered roller bearing with 35 mm bore, 80 mm outer diameter and 22.75 mm width (1.378 × 3.15 × 0.896 in) per ISO 355. From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 75.4 kN, C0 67 kN, fatigue load limit Pu 7.8 kN, reference speed 6,300 r/min, limiting speed 8,500 r/min, mass about 520 g. It is an open, separable bearing with a pressed-steel cage.
How does the 31307 bore code work?
The last two digits of 31307 are bore code 07, so 07 × 5 = 35 mm bore. The 80 mm OD and 22.75 mm width come from the ISO 355 dimension-series plan, shared with other tapered bearings of the same code.
What do the 31307 series and basic execution designations mean?
The leading 3 marks a single-row tapered roller bearing; the second digit 13 is the ISO 355 series (steep-angle heavy section). The SKF catalogue lists the ISO 355 dimension-series code after the bare number. A steeper-contact-angle variant (B suffix) is a different order number and is not interchangeable with the basic execution.
Can a single 31307 take axial load in both directions?
No — one single-row tapered roller bearing reacts thrust in one direction only, and under radial load its contact angle induces an axial force. Use two bearings as a matched pair: O (back-to-back) for a rigid, moment-resisting arrangement, X (face-to-face) where thermal expansion must be tolerated, or tandem where one-direction thrust is shared.
How does 31307 compare with a ball bearing of the same bore?
A tapered roller bearing has line contact and a steep contact angle: much higher combined axial-plus-radial capacity and shock resistance than a ball bearing of the same bore, at the cost of speed, one-direction thrust, mandatory pairing for reversing loads and a minimum axial load requirement. A ball bearing cannot be dropped into a combined-load 31307 position and vice versa — verify load direction, Fa/Fr ratio and speed before substituting.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.1 metric single-row TRB on 2026-09-26. Read our editorial & correction policy.