C31-500-KM bearing: complete specifications & equivalents
The C31-500-KM is a ISO 15 radial bearing sized 500 x 830 x 264 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 500 mm |
| Outer diameter D | 830 mm |
| Width B | 264 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 7500 kN |
| Basic static load rating C0 | 12700 kN |
| Fatigue load limit Pu | 850 kN |
| Reference speed (thermal) | 530 rpm |
| Limiting speed (mechanical) | 750 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 560000 g |
| Manufacturer designation | C 31/500 KM |
| 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 | 19.685 in |
|---|---|
| Outer diameter D | 32.677 in |
| Width B | 10.394 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 165 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) | 21 of 28 |
| Bore above smallest C3100-series size | 400 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C31-500-M | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 500×830×264 mm ISO 15 envelope and equivalent catalogue C/C0; C 31/500 M is the cylindrical-bore M 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 C31-500-KM model number is decoded
In SKF catalogue PUB BU/P1 17000, C 31/500 KM denotes a toroidal roller bearing whose 264 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 31/500 KM the 31 dimension series fixes the 830 mm OD and 264 mm width around the 500 mm bore (the bore is written directly after the slash (no bore code)); the suffix KM then selects the tapered 1:12 bore for adapter (H) sleeve mounting, machined brass M cage. The KM suffix is a one-piece machined brass cage centred on the rollers, supplied for the 500 mm and larger sizes needing robust guidance under heavy load. Speed planning separates the 530 r/min thermal reference from the 750 r/min mechanical limiting speed. The full-complement V executions carry more load but list no thermal reference speed; the brass-caged executions run faster and cooler at light load. After fitting, confirm the inner ring can be pushed axially by hand through the catalogue displacement range; a ring that will not slide means the position is locked and will preload in service.
Typical equipment & failure modes
Common applications
- winder and reel drums in paper and steel strip plants
- paper machine drying cylinders and calender rolls with long, thermally expanding shafts
- continuous-caster guide rolls and slab-caster segments under heat growth
- vibrating screen exciters fitted with the VE240 tolerance execution
Known failure patterns
- raceway spalling once the catalogue L10 life is exceeded or after sustained overload
- edge loading and premature spalling when the CARB position is blocked from its designed axial float
- PA66 cage (TN9) softening when the sustained temperature passes the polymer limit
- condensation pitting in machines that run intermittently in humid environments
- grease churning and overheating when a high-speed thrust position is over-packed
Selection pitfalls — read before you substitute
- Above 200 mm bore these bearings weigh tens of kilograms (560 kg here) — lifting gear and induction heating are mandatory, and a cocked ring scores the toroidal raceway before start-up.
- Reference and limiting speeds are different limits: the 530 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 7500/12700 kN ratings belong to this exact execution (C 31/500 KM); VE240 vibrating-screen variants and sealed 2CS/2NS variants have their own figures even at the same envelope.
- Never use C 31/500 KM as the locating bearing: it carries no axial load by design — the arrangement needs a separate locating spherical, tapered or angular bearing facing the thrust.
- Tapered-bore K executions mount on adapter sleeves (1:12) and K30 on withdrawal sleeves (1:30) — the 500 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- The 7500/12700 kN ratings and 560000 g mass are SKF catalogue values transcribed from ch. 10.1 of PUB BU/P1 17000 (PDF table page 866); 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
Can a CARB bearing like C 31/500 KM locate the shaft axially?
No — that is the defining feature. C 31/500 KM 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.
How is the C 31/500 KM designation read?
C = CARB toroidal family; 31 = dimension series; 500 mm (slash-size) = 500 mm bore (the bore is written directly after the slash (no bore code)); suffix KM selects tapered 1:12 bore for adapter (H) sleeve mounting, machined brass M cage. K is a 1:12 tapered bore for an adapter sleeve, K30 a 1:30 bore for a withdrawal sleeve.
What is the difference between V and TN9 CARB executions?
V is the full-complement execution with no cage — more rollers, higher C (7500 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 31/500 KM is the tapered 1:12 bore for adapter (H) sleeve mounting, machined brass M cage.
How is C 31/500 KM 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.
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.