C3056-K bearing: complete specifications & equivalents
The C3056-K is a ISO 15 radial bearing sized 280 x 420 x 106 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 280 mm |
| Outer diameter D | 420 mm |
| Width B | 106 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel |
| Basic dynamic load rating C | 1860 kN |
| Basic static load rating C0 | 3100 kN |
| Fatigue load limit Pu | 250 kN |
| Reference speed (thermal) | 1200 rpm |
| Limiting speed (mechanical) | 1600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 50500 g |
| Manufacturer designation | C 3056 K |
| 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 | 11.024 in |
|---|---|
| Outer diameter D | 16.535 in |
| Width B | 4.173 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 70 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) | 10 of 33 |
| Bore above smallest C3000-series size | 160 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C3056 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 280×420×106 mm ISO 15 envelope and equivalent catalogue C/C0; C 3056 is the cylindrical-bore steel-caged execution of this size — boundary dimensions interchangeable, only mounting and cage execution differ. |
| 23056 | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (280×420×106 mm) SKF spherical roller bearing SKF 23056 CC/W33 with ratings within 10 % — not a drop-in substitute: SKF 23056 CC/W33 locates the shaft axially while the CARB bearing must float; the two are designed to run as a locating/non-locating pair. |
| 23056-CCK-W33 | SKF | full Dimensions and internal design equivalent — standard interchange. | Envelope-identical (280×420×106 mm) SKF spherical roller bearing SKF 23056 CCK/W33 with ratings within 10 % — not a drop-in substitute: SKF 23056 CCK/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 C3056-K model number is decoded
C 3056 K is the dimension series 30 CARB toroidal roller bearings member of the CARB range: 280 mm bore, 420 mm OD, 106 mm width, with the asymmetrical-looking toroidal roller set that defines the CARB principle. In C 3056 K the 30 dimension series fixes the 420 mm OD and 106 mm width around the 280 mm bore (code 56 × 5); the suffix K then selects the tapered 1:12 bore for adapter (H) sleeve mounting, pressed steel cage. The K suffix gives a 1:12 tapered 280 mm bore, mounted on an adapter (H) sleeve so the bearing can be driven up to the specified clearance. The same size is listed in both bore executions, and the boundary dimensions 280×420×106 mm are identical — only the mounting method changes. Speed planning separates the 1,200 r/min thermal reference from the 1,600 r/min mechanical limiting speed. The full-complement V executions carry more load but list no thermal reference speed; the steel-caged executions run faster and cooler at light load. Mounting: mount on the adapter (H) sleeve matched to the 1:12 tapered bore, drive up to the catalogue reduction and lock the nut; never press through the 106 mm roller set, and leave the free-end housing shoulder clear so axial float is unrestricted.
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
- brass cage pocket wear under marginal lubrication in the large-bore M/MB executions
- 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
- Above 200 mm bore these bearings weigh tens of kilograms (50.5 kg here) — lifting gear and induction heating are mandatory, and a cocked ring scores the toroidal raceway before start-up.
- Never use C 3056 K 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 280 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- The quoted 1860/3100 kN ratings belong to this exact execution (C 3056 K); 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 1860/3100 kN ratings and 50500 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
How is C 3056 K 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 3056 K?
A C 3056 K measures 280 mm bore × 420 mm outside diameter × 106 mm width (11.024 × 16.535 × 4.173 in). From SKF catalogue PUB BU/P1 17000: dynamic C 1860 kN, static C0 3100 kN, fatigue limit Pu 250 kN, reference speed 1,200 r/min, limiting speed 1,600 r/min, mass about 50500 g.
Can a CARB bearing like C 3056 K locate the shaft axially?
No — that is the defining feature. C 3056 K 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 3056 K designation read?
C = CARB toroidal family; 30 = dimension series; 56 = 280 mm bore (code 56 × 5); suffix K selects tapered 1:12 bore for adapter (H) sleeve mounting, pressed steel cage. 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.