C30-800-MB bearing: complete specifications & equivalents
The C30-800-MB 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 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 | 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-KMB | 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 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 C30-800-MB model number is decoded
C 30/800 MB is a CARB toroidal roller bearing to ISO 15: a single row of long, symmetrical barrel-shaped rollers between guide flanges, sized 800×1150×258 mm, as listed in SKF catalogue PUB BU/P1 17000 ch. 10.1. Reading the code: C marks the CARB toroidal family, the first two digits (30) identify the ISO dimension series and the last two (800 mm (slash-size)) encode the 800 mm bore; suffixes describe bore and execution. The cylindrical 800 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 800×1150×258 mm are identical — only the mounting method changes. Speed planning separates the 360 r/min thermal reference from the 480 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
- 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
- roller-end and flange smearing after lubricant starvation at the long roller contacts
- thermal preloading when a shaft is located at both ends and growth has nowhere to go
- brass cage pocket wear under marginal lubrication in the large-bore M/MB executions
- hard-particle indentation where oil or grease filtration is inadequate
- grease churning and overheating when a high-speed thrust position is over-packed
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.
- Envelope-identical spherical roller bearings (same ISO 15 d×D×B) are not drop-in equivalents — they locate the shaft axially, while C 30/800 MB must float; the two are designed to be used as a pair.
- Never use C 30/800 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.
- 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.
- 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 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
Is the C 30/800 MB sealed?
No, it is an open execution relying on the housing seals; relubrication follows the groove/hole features of the size.
What fails first on a misapplied CARB bearing?
Blocking the designed axial float — clamping the free end or locating both shaft ends — turns thermal growth into edge loading and spalls the toroidal raceways. Cage damage and ordinary fatigue follow overload or dry running.
Which dimensions does the C 30/800 MB have?
A C 30/800 MB 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.
What does C 30/800 MB mean in SKF part numbering?
C marks CARB; 30 the dimension series; the size code gives 800 mm bore; MB is the execution (cylindrical bore for direct shaft fitting, machined inner-ring-guided brass cage (MB)). The envelope follows ISO 15 and matches spherical roller bearing outlines, but the functions differ.
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.