C3084-KM bearing: complete specifications & equivalents
The C3084-KM is a ISO 15 radial bearing sized 420 x 620 x 150 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 420 mm |
| Outer diameter D | 620 mm |
| Width B | 150 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 3800 kN |
| Basic static load rating C0 | 6400 kN |
| Fatigue load limit Pu | 455 kN |
| Reference speed (thermal) | 800 rpm |
| Limiting speed (mechanical) | 1100 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 150000 g |
| Manufacturer designation | C 3084 KM |
| 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 | 16.535 in |
|---|---|
| Outer diameter D | 24.409 in |
| Width B | 5.906 in |
| ISO bore code | 84 |
| Radial section height (D−d)/2 | 100 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) | 17 of 33 |
| Bore above smallest C3000-series size | 300 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C3084-M | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 420×620×150 mm ISO 15 envelope and equivalent catalogue C/C0; C 3084 M is the cylindrical-bore M 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 C3084-KM model number is decoded
C 3084 KM is a CARB toroidal roller bearing to ISO 15: a single row of long, symmetrical barrel-shaped rollers between guide flanges, sized 420×620×150 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 (84) encode the 420 mm bore; suffixes describe bore and execution. 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 420 mm shaft deflects; the 800 r/min reference and 1,100 r/min limiting speed are both catalogue values. Float capacity is a selection criterion: the catalogue lists the permissible axial displacement (s) for the 150 mm wide set; size the free-end housing so thermal growth stays within it, not just inside the overall width. Seat tolerances follow the ISO 15 recommendation for the heavy-loaded position — the 620 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
- long fan and kiln main shafts where the free end must float without thrust load
- heavy industrial gearbox layshafts used as the non-locating position
- winder and reel drums in paper and steel strip plants
- paper machine drying cylinders and calender rolls with long, thermally expanding shafts
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
- false brinelling and rust-red witness marks on standby machines under external vibration
- 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 (150 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 3084 KM must float; the two are designed to be used as a pair.
- Never use C 3084 KM 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 420 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- Reference and limiting speeds are different limits: the 800 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 3800/6400 kN ratings and 150000 g mass are SKF catalogue values transcribed from ch. 10.1 of PUB BU/P1 17000 (PDF table page 866); 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 3084 KM have?
A C 3084 KM measures 420 mm bore × 620 mm outside diameter × 150 mm width (16.535 × 24.409 × 5.906 in). From SKF catalogue PUB BU/P1 17000: dynamic C 3800 kN, static C0 6400 kN, fatigue limit Pu 455 kN, reference speed 800 r/min, limiting speed 1,100 r/min, mass about 150000 g.
What does C 3084 KM mean in SKF part numbering?
C marks CARB; 30 the dimension series; the size code gives 420 mm bore; KM is the execution (tapered 1:12 bore for adapter (H) sleeve mounting, machined brass M cage). The envelope follows ISO 15 and matches spherical roller bearing outlines, but the functions differ.
Why is C 3084 KM 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 3084 KM 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.