C31-500-M bearing: complete specifications & equivalents
The C31-500-M 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 M |
| 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-KM | 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 KM is the 1:12 tapered-bore K 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-M model number is decoded
The CARB bearing C 31/500 M combines the self-aligning behaviour of a spherical roller bearing with the axial freedom of a cylindrical bearing in one 500 mm bore, 830 mm outside diameter, 264 mm wide unit rated 7500 kN dynamic. The designation C 31/500 M separates into C (CARB), 31 (dimension series), 500 mm (slash-size) (500 mm bore — bore 500 mm is written directly after the slash) and M (cylindrical bore for direct shaft fitting, machined brass M cage); envelope 500×830×264 mm follows the ISO 15 plan. The M 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. The 560000 g mass over the 500×830×264 mm envelope yields about 15.00 kN dynamic per millimetre of bore — the long toroidal rollers give this family its radial capacity density. 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 M); VE240 vibrating-screen variants and sealed 2CS/2NS variants have their own figures even at the same envelope.
- Never use C 31/500 M 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
What are the dimensions and ratings of the C 31/500 M?
A C 31/500 M measures 500 mm bore × 830 mm outside diameter × 264 mm width (19.685 × 32.677 × 10.394 in). From SKF catalogue PUB BU/P1 17000: dynamic C 7500 kN, static C0 12700 kN, fatigue limit Pu 850 kN, reference speed 530 r/min, limiting speed 750 r/min, mass about 560000 g.
Can a CARB bearing like C 31/500 M locate the shaft axially?
No — that is the defining feature. C 31/500 M 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 M 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 M selects cylindrical bore for direct shaft fitting, 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 M is the cylindrical bore for direct shaft fitting, machined brass M cage.
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.