C31-670-MB bearing: complete specifications & equivalents

Specification table

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.

Cross references & equivalents

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 C31-670-MB model number is decoded

C 31/670 MB belongs to the CARB family — compact aligning roller bearings: envelope 670×1090×336 mm, radial rating 11800/21200 kN C/C0, and no axial-locating function by design. The designation C 31/670 MB separates into C (CARB), 31 (dimension series), 670 mm (slash-size) (670 mm bore — bore 670 mm is written directly after the slash) and MB (cylindrical bore for direct shaft fitting, machined inner-ring-guided brass cage (MB)); envelope 670×1090×336 mm follows the ISO 15 plan. 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 670 mm seat. Float capacity is a selection criterion: the catalogue lists the permissible axial displacement (s) for the 336 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 1090 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

Selection pitfalls — read before you substitute

• At 670 mm bore the 1300 kg mass and 336 mm width make seating geometry dominant: sphered-washer seats and oil flow must be verified in place, not just on the drawing.
• Reference and limiting speeds are different limits: the 380 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 quoted 11800/21200 kN ratings belong to this exact execution (C 31/670 MB); VE240 vibrating-screen variants and sealed 2CS/2NS variants have their own figures even at the same envelope.
• Envelope-identical spherical roller bearings (same ISO 15 d×D×B) are not drop-in equivalents — they locate the shaft axially, while C 31/670 MB must float; the two are designed to be used as a pair.
• Never use C 31/670 MB 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.
• The 11800/21200 kN ratings and 1300000 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.