C31-1000-MB bearing: complete specifications & equivalents
The C31-1000-MB 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 MB |
| 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-KMB | 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 KMB is the 1:12 tapered-bore K 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-MB model number is decoded
The CARB bearing C 31/1000 MB combines the self-aligning behaviour of a spherical roller bearing with the axial freedom of a cylindrical bearing in one 1000 mm bore, 1580 mm outside diameter, 462 mm wide unit rated 20400 kN dynamic. In C 31/1000 MB 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 MB then selects the cylindrical bore for direct shaft fitting, machined inner-ring-guided brass cage (MB). The cylindrical 1000 mm bore mounts directly on a machined seat; the outer ring takes a loose housing fit so the bearing can float axially. The same size is listed in both bore executions, and the boundary dimensions 1000×1580×462 mm are identical — only the mounting method changes. Speed planning separates the 220 r/min thermal reference from the 300 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. Seat tolerances follow the ISO 15 recommendation for the heavy-loaded position — the 1580 mm outer ring typically takes a loose housing fit to preserve float, and the rings must be supported across their full faces.
Typical equipment & failure modes
Common applications
- 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
- continuous-caster guide rolls and slab-caster segments under heat growth
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
- electrical erosion of raceways on VFD-driven shafts without grounding or insulation
- grease churning and overheating when a high-speed thrust position is over-packed
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.
- 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 MB); VE240 vibrating-screen variants and sealed 2CS/2NS variants have their own figures even at the same envelope.
- 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 MB must float; the two are designed to be used as a pair.
- Never use C 31/1000 MB 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.
- 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 MB is the cylindrical bore for direct shaft fitting, machined inner-ring-guided brass cage (MB).
How is C 31/1000 MB mounted?
Slide or heat (max 120 °C) the bearing onto the 1000 mm seat, give the outer ring a loose housing fit, leave the float travel unobstructed, and never press through the 462 mm roller set.
What are the dimensions and ratings of the C 31/1000 MB?
A C 31/1000 MB 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 MB locate the shaft axially?
No — that is the defining feature. C 31/1000 MB 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.