C4168-K30MB bearing: complete specifications & equivalents
The C4168-K30MB is a ISO 15 radial bearing sized 340 x 580 x 243 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 340 mm |
| Outer diameter D | 580 mm |
| Width B | 243 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 5600 kN |
| Basic static load rating C0 | 9150 kN |
| Fatigue load limit Pu | 680 kN |
| Reference speed (thermal) | 670 rpm |
| Limiting speed (mechanical) | 900 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 271000 g |
| Manufacturer designation | C 4168 K30MB |
| 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 & C4100-series range
| Bore d | 13.386 in |
|---|---|
| Outer diameter D | 22.835 in |
| Width B | 9.567 in |
| ISO bore code | 68 |
| Radial section height (D−d)/2 | 120 mm |
| Smallest bore in C4100-series | 100 mm |
| Largest outer diameter in C4100-series | 1090 mm |
| Width range across C4100-series | 65–412 mm |
| Bore position in C4100-series (smallest first) | 8 of 14 |
| Bore above smallest C4100-series size | 240 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 24168 | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (340×580×243 mm) SKF spherical roller bearing SKF 24168 ECCJ/W33 with ratings within 10 % — not a drop-in substitute: SKF 24168 ECCJ/W33 locates the shaft axially while the CARB bearing must float; the two are designed to run as a locating/non-locating pair. |
| 24168-ECCK30J-W33 | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (340×580×243 mm) SKF spherical roller bearing SKF 24168 ECCK30J/W33 with ratings within 10 % — not a drop-in substitute: SKF 24168 ECCK30J/W33 locates the shaft axially while the CARB bearing must float; the two are designed to run as a locating/non-locating pair. |
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 C4168-K30MB model number is decoded
C 4168 K30MB is the dimension series 41 CARB toroidal roller bearings member of the CARB range: 340 mm bore, 580 mm OD, 243 mm width, with the asymmetrical-looking toroidal roller set that defines the CARB principle. SKF builds the CARB order number from size plus execution: the bare number C 4168 is the brass-caged cylindrical-bore bearing, K (or K30) makes the bore tapered for sleeve mounting, and the cage/seal letters follow — here K30MB. The open execution relies on the housing seals and lubrication system, fed through groove/hole features on the large sizes. Explorer-class heat treatment and the crowned roller profile keep edge stress down when the 340 mm shaft deflects; the 670 r/min reference and 900 r/min limiting speed are both catalogue values. The 271000 g mass over the 340×580×243 mm envelope yields about 16.47 kN dynamic per millimetre of bore — the long toroidal rollers give this family its radial capacity density. Seat tolerances follow the ISO 15 recommendation for the heavy-loaded position — the 580 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
- 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
- roller-end and flange smearing after lubricant starvation at the long roller contacts
- edge loading and premature spalling when the CARB position is blocked from its designed axial float
- 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
- abrasive paste forming as dust bypasses the housing seals into the open washer set
Selection pitfalls — read before you substitute
- Above 200 mm bore these bearings weigh tens of kilograms (271 kg here) — lifting gear and induction heating are mandatory, and a cocked ring scores the toroidal raceway before start-up.
- Envelope-identical spherical roller bearings (same ISO 15 d×D×B) are not drop-in equivalents — they locate the shaft axially, while C 4168 K30MB must float; the two are designed to be used as a pair.
- Never use C 4168 K30MB 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 quoted 5600/9150 kN ratings belong to this exact execution (C 4168 K30MB); 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 5600/9150 kN ratings and 271000 g mass are SKF catalogue values transcribed from ch. 10.1 of PUB BU/P1 17000 (PDF table page 864); 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
Which dimensions does the C 4168 K30MB have?
A C 4168 K30MB measures 340 mm bore × 580 mm outside diameter × 243 mm width (13.386 × 22.835 × 9.567 in). From SKF catalogue PUB BU/P1 17000: dynamic C 5600 kN, static C0 9150 kN, fatigue limit Pu 680 kN, reference speed 670 r/min, limiting speed 900 r/min, mass about 271000 g.
What does C 4168 K30MB mean in SKF part numbering?
C marks CARB; 41 the dimension series; the size code gives 340 mm bore; K30MB is the execution (tapered 1:30 bore for withdrawal (AH) sleeve mounting, machined inner-ring-guided brass cage (MB)). The envelope follows ISO 15 and matches spherical roller bearing outlines, but the functions differ.
Why is C 4168 K30MB used opposite a spherical roller bearing?
The spherical bearing locates the shaft and takes thrust; the CARB bearing at the other end self-aligns but floats, absorbing thermal expansion without inducing axial load. The pair is standard on paper machine drying cylinders and long caster rolls.
Is the C 4168 K30MB sealed?
No, it is an open execution relying on the housing seals; relubrication follows the groove/hole features of the size.
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.