C39-750-KM bearing: complete specifications & equivalents
The C39-750-KM is a ISO 15 radial bearing sized 750 x 1000 x 185 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 750 mm |
| Outer diameter D | 1000 mm |
| Width B | 185 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 6100 kN |
| Basic static load rating C0 | 13400 kN |
| Fatigue load limit Pu | 815 kN |
| Reference speed (thermal) | 430 rpm |
| Limiting speed (mechanical) | 560 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 410000 g |
| Manufacturer designation | C 39/750 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 & C3900-series range
| Bore d | 29.528 in |
|---|---|
| Outer diameter D | 39.37 in |
| Width B | 7.283 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 125 mm |
| Smallest bore in C3900-series | 360 mm |
| Largest outer diameter in C3900-series | 2180 mm |
| Width range across C3900-series | 90–355 mm |
| Bore position in C3900-series (smallest first) | 9 of 15 |
| Bore above smallest C3900-series size | 390 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C39-750-M | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 750×1000×185 mm ISO 15 envelope and equivalent catalogue C/C0; C 39/750 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 C39-750-KM model number is decoded
C 39/750 KM is the dimension series 39 CARB toroidal roller bearings member of the CARB range: 750 mm bore, 1000 mm OD, 185 mm width, with the asymmetrical-looking toroidal roller set that defines the CARB principle. Reading the code: C marks the CARB toroidal family, the first two digits (39) identify the ISO dimension series and the last two (750 mm (slash-size)) encode the 750 mm bore; suffixes describe bore and execution. The K suffix gives a 1:12 tapered 750 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 750×1000×185 mm are identical — only the mounting method changes. Speed planning separates the 430 r/min thermal reference from the 560 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. Open executions accept relubrication — route it through the outer-ring groove on sizes that have one and purge stale grease at service intervals. Grease through the annular groove features where provided; on open executions feed lubricant past the long roller set at assembly, since the 185 mm wide cavity does not fill itself.
Typical equipment & failure modes
Common applications
- vibrating screen exciters fitted with the VE240 tolerance execution
- 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
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
- brinelling of washer raceways from impact or mounting force applied through the rolling elements
- abrasive paste forming as dust bypasses the housing seals into the open washer set
Selection pitfalls — read before you substitute
- At 750 mm bore the 410 kg mass and 185 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 39/750 KM must float; the two are designed to be used as a pair.
- Never use C 39/750 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 750 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- Reference and limiting speeds are different limits: the 430 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 6100/13400 kN ratings and 410000 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
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 39/750 KM have?
A C 39/750 KM measures 750 mm bore × 1000 mm outside diameter × 185 mm width (29.528 × 39.37 × 7.283 in). From SKF catalogue PUB BU/P1 17000: dynamic C 6100 kN, static C0 13400 kN, fatigue limit Pu 815 kN, reference speed 430 r/min, limiting speed 560 r/min, mass about 410000 g.
What does C 39/750 KM mean in SKF part numbering?
C marks CARB; 39 the dimension series; the size code gives 750 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 39/750 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.
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.