C39-850-M bearing: complete specifications & equivalents
The C39-850-M is a ISO 15 radial bearing sized 850 x 1120 x 200 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 850 mm |
| Outer diameter D | 1120 mm |
| Width B | 200 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 7350 kN |
| Basic static load rating C0 | 16300 kN |
| Fatigue load limit Pu | 960 kN |
| Reference speed (thermal) | 360 rpm |
| Limiting speed (mechanical) | 480 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 540000 g |
| Manufacturer designation | C 39/850 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 | 33.465 in |
|---|---|
| Outer diameter D | 44.094 in |
| Width B | 7.874 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 135 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) | 11 of 15 |
| Bore above smallest C3900-series size | 490 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| C39-850-KM | SKF | full Dimensions and internal design equivalent — standard interchange. | Same 850×1120×200 mm ISO 15 envelope and equivalent catalogue C/C0; C 39/850 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 C39-850-M model number is decoded
In SKF catalogue PUB BU/P1 17000, C 39/850 M denotes a toroidal roller bearing whose 200 mm long rollers crown at both ends: the contact accepts angular misalignment while the ring positions float, which is why CARB bearings are specified at the free shaft end. SKF builds the CARB order number from size plus execution: the bare number C 39/850 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 850 mm seat. Selection arithmetic: C 7350 kN against C0 16300 kN gives a C0/C ratio of 2.22, and the 960 kN fatigue load limit Pu sets the contamination-adjusted life floor. After fitting, confirm the inner ring can be pushed axially by hand through the catalogue displacement range; a ring that will not slide means the position is locked and will preload in service.
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
- PA66 cage (TN9) softening when the sustained temperature passes the polymer limit
- 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 850 mm bore the 540 kg mass and 200 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 39/850 M must float; the two are designed to be used as a pair.
- Never use C 39/850 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 850 mm bore changes the sleeve family, and the drive-up procedure differs accordingly.
- Reference and limiting speeds are different limits: the 360 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 7350/16300 kN ratings and 540000 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
Why is C 39/850 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 39/850 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.
Which dimensions does the C 39/850 M have?
A C 39/850 M measures 850 mm bore × 1120 mm outside diameter × 200 mm width (33.465 × 44.094 × 7.874 in). From SKF catalogue PUB BU/P1 17000: dynamic C 7350 kN, static C0 16300 kN, fatigue limit Pu 960 kN, reference speed 360 r/min, limiting speed 480 r/min, mass about 540000 g.
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.