C30-900-MB bearing: complete specifications & equivalents
The C30-900-MB is a ISO 15 radial bearing sized 900 x 1280 x 280 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 900 mm |
| Outer diameter D | 1280 mm |
| Width B | 280 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 12700 kN |
| Basic static load rating C0 | 26500 kN |
| Fatigue load limit Pu | 1530 kN |
| Reference speed (thermal) | 300 rpm |
| Limiting speed (mechanical) | 400 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 1200000 g |
| Manufacturer designation | C 30/900 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 & C3000-series range
| Bore d | 35.433 in |
|---|---|
| Outer diameter D | 50.394 in |
| Width B | 11.024 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 190 mm |
| Smallest bore in C3000-series | 120 mm |
| Largest outer diameter in C3000-series | 1420 mm |
| Width range across C3000-series | 46–308 mm |
| Bore position in C3000-series (smallest first) | 31 of 33 |
| Bore above smallest C3000-series size | 780 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C30-900-KMB | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 900×1280×280 mm ISO 15 envelope and equivalent catalogue C/C0; C 30/900 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 C30-900-MB model number is decoded
C 30/900 MB belongs to the CARB family — compact aligning roller bearings: envelope 900×1280×280 mm, radial rating 12700/26500 kN C/C0, and no axial-locating function by design. The designation C 30/900 MB separates into C (CARB), 30 (dimension series), 900 mm (slash-size) (900 mm bore — bore 900 mm is written directly after the slash) and MB (cylindrical bore for direct shaft fitting, machined inner-ring-guided brass cage (MB)); envelope 900×1280×280 mm follows the ISO 15 plan. The MB suffix is a machined two-piece brass cage guided on the inner ring, the standard choice for wide, large-bore CARB sizes where a polymer cage would run beyond its temperature or load limit. Selection arithmetic: C 12700 kN against C0 26500 kN gives a C0/C ratio of 2.09, and the 1530 kN fatigue load limit Pu sets the contamination-adjusted life floor. 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
- At 900 mm bore the 1200 kg mass and 280 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 300 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 12700/26500 kN ratings belong to this exact execution (C 30/900 MB); VE240 vibrating-screen variants and sealed 2CS/2NS variants have their own figures even at the same envelope.
- Never use C 30/900 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.
- Tapered-bore K executions mount on adapter sleeves (1:12) and K30 on withdrawal sleeves (1:30) — the 900 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- The 12700/26500 kN ratings and 1200000 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
Can a CARB bearing like C 30/900 MB locate the shaft axially?
No — that is the defining feature. C 30/900 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.
How is the C 30/900 MB designation read?
C = CARB toroidal family; 30 = dimension series; 900 mm (slash-size) = 900 mm bore (the bore is written directly after the slash (no bore code)); suffix MB selects cylindrical bore for direct shaft fitting, machined inner-ring-guided brass cage (MB). 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 (12700 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 30/900 MB is the cylindrical bore for direct shaft fitting, machined inner-ring-guided brass cage (MB).
How is C 30/900 MB mounted?
Slide or heat (max 120 °C) the bearing onto the 900 mm seat, give the outer ring a loose housing fit, leave the float travel unobstructed, and never press through the 280 mm roller set.
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.