C39-630-M bearing: complete specifications & equivalents
The C39-630-M is a ISO 15 radial bearing sized 630 x 850 x 165 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 630 mm |
| Outer diameter D | 850 mm |
| Width B | 165 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 4650 kN |
| Basic static load rating C0 | 10000 kN |
| Fatigue load limit Pu | 640 kN |
| Reference speed (thermal) | 530 rpm |
| Limiting speed (mechanical) | 700 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 275000 g |
| Manufacturer designation | C 39/630 M |
| 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 | 24.803 in |
|---|---|
| Outer diameter D | 33.465 in |
| Width B | 6.496 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 110 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) | 7 of 15 |
| Bore above smallest C3900-series size | 270 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C39-630-KM | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 630×850×165 mm ISO 15 envelope and equivalent catalogue C/C0; C 39/630 KM is the 1:12 tapered-bore K 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 C39-630-M model number is decoded
SKF lists C 39/630 M in the dimension series 39 CARB toroidal roller bearings: the toroidal roller profile both follows tolerates angular misalignment and lets the inner ring slide axially inside the outer ring, giving free axial displacement at the non-locating position. SKF builds the CARB order number from size plus execution: the bare number C 39/630 is the brass-caged cylindrical-bore bearing, K (or K30) makes the bore tapered for sleeve mounting, and the cage/seal letters follow — here M. CARB bearings locate neither radially nor axially: the inner ring can walk axially inside the outer ring over the catalogue-listed axial-displacement range (s), so shaft thermal growth disappears as thrust rather than preloading the 630 mm seat. The 275000 g mass over the 630×850×165 mm envelope yields about 7.38 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 850 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
- PA66 cage (TN9) softening when the sustained temperature passes the polymer limit
- rolling-contact fatigue spalling after the catalogue L10 life is exhausted
- grease churning and overheating when a high-speed thrust position is over-packed
Selection pitfalls — read before you substitute
- At 630 mm bore the 275 kg mass and 165 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 39/630 M must float; the two are designed to be used as a pair.
- Never use C 39/630 M 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 630 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- Reference and limiting speeds are different limits: the 530 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 4650/10000 kN ratings and 275000 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
What does C 39/630 M mean in SKF part numbering?
C marks CARB; 39 the dimension series; the size code gives 630 mm bore; M is the execution (cylindrical bore for direct shaft fitting, machined brass M cage). The envelope follows ISO 15 and matches spherical roller bearing outlines, but the functions differ.
Why is C 39/630 M 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 39/630 M 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.
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.