C31-1000-KMB bearing: complete specifications & equivalents
The C31-1000-KMB is a ISO 15 radial bearing sized 1000 x 1580 x 462 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 1000 mm |
| Outer diameter D | 1580 mm |
| Width B | 462 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 20400 kN |
| Basic static load rating C0 | 45500 kN |
| Fatigue load limit Pu | 2500 kN |
| Reference speed (thermal) | 220 rpm |
| Limiting speed (mechanical) | 300 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 3800000 g |
| Manufacturer designation | C 31/1000 KMB |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 10.1 CARB toroidal roller bearings |
| Last verified | 2026-09-27 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 10.1 CARB toroidal roller bearings) · extracted 2026-09-27
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 10.1 CARB toroidal roller bearings); 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 & C3100-series range
| Bore d | 39.37 in |
|---|---|
| Outer diameter D | 62.205 in |
| Width B | 18.189 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 290 mm |
| Smallest bore in C3100-series | 100 mm |
| Largest outer diameter in C3100-series | 1580 mm |
| Width range across C3100-series | 52–462 mm |
| Bore position in C3100-series (smallest first) | 28 of 28 |
| Bore above smallest C3100-series size | 900 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C31-1000-MB | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 1000×1580×462 mm ISO 15 envelope and equivalent catalogue C/C0; C 31/1000 MB is the cylindrical-bore MB inner-ring-guided brass-caged execution of this size — boundary dimensions interchangeable, only mounting and cage execution differ. |
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 C31-1000-KMB model number is decoded
In SKF catalogue PUB BU/P1 17000, C 31/1000 KMB denotes a toroidal roller bearing whose 462 mm long rollers crown at both ends: the contact accepts angular misalignment while the ring positions float, which is why CARB bearings are specified at the free shaft end. In C 31/1000 KMB the 31 dimension series fixes the 1580 mm OD and 462 mm width around the 1000 mm bore (the bore is written directly after the slash (no bore code)); the suffix KMB then selects the tapered 1:12 bore for adapter (H) sleeve mounting, machined inner-ring-guided brass cage (MB). The open execution relies on the housing seals and lubrication system, fed through groove/hole features on the large sizes. Explorer-class heat treatment and the crowned roller profile keep edge stress down when the 1000 mm shaft deflects; the 220 r/min reference and 300 r/min limiting speed are both catalogue values. Selection arithmetic: C 20400 kN against C0 45500 kN gives a C0/C ratio of 2.23, and the 2500 kN fatigue load limit Pu sets the contamination-adjusted life floor. Open executions accept relubrication — route it through the outer-ring groove on sizes that have one and purge stale grease at service intervals. Grease through the annular groove features where provided; on open executions feed lubricant past the long roller set at assembly, since the 462 mm wide cavity does not fill itself.
Typical equipment & failure modes
Common applications
- long fan and kiln main shafts where the free end must float without thrust load
- heavy industrial gearbox layshafts used as the non-locating position
- winder and reel drums in paper and steel strip plants
- paper machine drying cylinders and calender rolls with long, thermally expanding shafts
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after sustained overload
- roller skew and cage damage after the bearing is clamped solid between shaft and housing shoulders
- brass cage pocket wear under marginal lubrication in the large-bore M/MB executions
- condensation pitting in machines that run intermittently in humid environments
- oil starvation at the sliding contact zones of large spherical roller thrust bearings on forced-feed trips
Selection pitfalls — read before you substitute
- At 1000 mm bore the 3800 kg mass and 462 mm width make seating geometry dominant: sphered-washer seats and oil flow must be verified in place, not just on the drawing.
- Do not block the axial displacement in the drawing: housing covers, labyrinth rings and snap rings must leave the catalogue float (s) free, or the bearing silently becomes a poorly located fixed bearing.
- Envelope-identical spherical roller bearings (same ISO 15 d×D×B) are not drop-in equivalents — they locate the shaft axially, while C 31/1000 KMB must float; the two are designed to be used as a pair.
- Reference and limiting speeds are different limits: the 220 r/min reference speed is the thermal criterion under load, the limiting value is the mechanical ceiling; observe the reference under load unless the arrangement calculation says otherwise.
- The quoted 20400/45500 kN ratings belong to this exact execution (C 31/1000 KMB); VE240 vibrating-screen variants and sealed 2CS/2NS variants have their own figures even at the same envelope.
- The 20400/45500 kN ratings and 3800000 g mass are SKF catalogue values transcribed from ch. 10.1 of PUB BU/P1 17000 (PDF table page 868); mounting data — axial displacement (s) and seating details — appears in the running text because the structured record carries the boundary envelope only.
Frequently asked questions
What is the difference between V and TN9 CARB executions?
V is the full-complement execution with no cage — more rollers, higher C (20400 kN here) but a lower speed ceiling and no thermal reference speed. TN9 is the glass-fibre PA66 caged execution, faster and quieter at somewhat lower load. C 31/1000 KMB is the tapered 1:12 bore for adapter (H) sleeve mounting, machined inner-ring-guided brass cage (MB).
How is C 31/1000 KMB mounted?
The tapered 1:12 bore mounts on an adapter (H) sleeve with a defined drive-up; heat the bearing to max 120 °C when fitting, support full ring faces, and verify axial float afterwards.
What are the dimensions and ratings of the C 31/1000 KMB?
A C 31/1000 KMB measures 1000 mm bore × 1580 mm outside diameter × 462 mm width (39.37 × 62.205 × 18.189 in). From SKF catalogue PUB BU/P1 17000: dynamic C 20400 kN, static C0 45500 kN, fatigue limit Pu 2500 kN, reference speed 220 r/min, limiting speed 300 r/min, mass about 3800000 g.
Can a CARB bearing like C 31/1000 KMB locate the shaft axially?
No — that is the defining feature. C 31/1000 KMB deliberately allows the inner ring to float axially inside the outer ring while the toroidal rollers self-align. It must be paired with a separate locating bearing (spherical, tapered or angular contact) that takes 100 % of the thrust.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 10.1 CARB toroidal roller bearings on 2026-09-27. Read our editorial & correction policy.