C30-800-KMB bearing: complete specifications & equivalents
The C30-800-KMB is a ISO 15 radial bearing sized 800 x 1150 x 258 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 800 mm |
| Outer diameter D | 1150 mm |
| Width B | 258 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 9300 kN |
| Basic static load rating C0 | 19300 kN |
| Fatigue load limit Pu | 1140 kN |
| Reference speed (thermal) | 360 rpm |
| Limiting speed (mechanical) | 480 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 941000 g |
| Manufacturer designation | C 30/800 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 & C3000-series range
| Bore d | 31.496 in |
|---|---|
| Outer diameter D | 45.276 in |
| Width B | 10.157 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 175 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) | 29 of 33 |
| Bore above smallest C3000-series size | 680 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C30-800-MB | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 800×1150×258 mm ISO 15 envelope and equivalent catalogue C/C0; C 30/800 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 C30-800-KMB model number is decoded
For long shafts that grow thermally, SKF supplies C 30/800 KMB: the toroidal rollers allow the 800 mm inner ring to displace axially without induced thrust, while still accommodating shaft deflection like a spherical bearing. The designation C 30/800 KMB separates into C (CARB), 30 (dimension series), 800 mm (slash-size) (800 mm bore — bore 800 mm is written directly after the slash) and KMB (tapered 1:12 bore for adapter (H) sleeve mounting, machined inner-ring-guided brass cage (MB)); envelope 800×1150×258 mm follows the ISO 15 plan. The KMB 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. Pairing rule: use the CARB bearing opposite one locating spherical or tapered bearing — never at both shaft ends — and check the locating bearing takes 100 % of the thrust, since C 30/800 KMB deliberately carries none. Seat tolerances follow the ISO 15 recommendation for the heavy-loaded position — the 1150 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
- 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
- long fan and kiln main shafts where the free end must float without thrust load
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
- rolling-contact fatigue spalling after the catalogue L10 life is exhausted
- oil starvation at the sliding contact zones of large spherical roller thrust bearings on forced-feed trips
Selection pitfalls — read before you substitute
- At 800 mm bore the 941 kg mass and 258 mm width make seating geometry dominant: sphered-washer seats and oil flow must be verified in place, not just on the drawing.
- Never use C 30/800 KMB 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 800 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- The quoted 9300/19300 kN ratings belong to this exact execution (C 30/800 KMB); VE240 vibrating-screen variants and sealed 2CS/2NS variants have their own figures even at the same envelope.
- 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.
- The 9300/19300 kN ratings and 941000 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
How is C 30/800 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 30/800 KMB?
A C 30/800 KMB measures 800 mm bore × 1150 mm outside diameter × 258 mm width (31.496 × 45.276 × 10.157 in). From SKF catalogue PUB BU/P1 17000: dynamic C 9300 kN, static C0 19300 kN, fatigue limit Pu 1140 kN, reference speed 360 r/min, limiting speed 480 r/min, mass about 941000 g.
Can a CARB bearing like C 30/800 KMB locate the shaft axially?
No — that is the defining feature. C 30/800 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.
How is the C 30/800 KMB designation read?
C = CARB toroidal family; 30 = dimension series; 800 mm (slash-size) = 800 mm bore (the bore is written directly after the slash (no bore code)); suffix KMB selects tapered 1:12 bore for adapter (H) sleeve mounting, 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.
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.