3308-DNRCBM bearing: complete specifications & equivalents

Specification table

Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018)) · extracted 2026-09-27

Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018)); 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 3308-DNRCBM model number is decoded

3308 DNRCBM is SKF's 40 mm-bore double-row angular-contact ball bearing of the 3300 series — two ball rows back-to-back for two-direction axial location in one unit, 40×90×36.5 mm. A on a double-row bearing means no filling slots, so both rows carry their full ball complement in both directions. D marks a two-piece (split) inner ring that simplifies mounting of the heavy 33-series section. NR adds a snap-ring groove in the outer ring supplied with the appropriate snap ring, and CB gives controlled axial clearance. DNRCBM combines the split inner ring, snap ring (NR), controlled CB clearance and a machined brass ball-centred M cage. CB means universally matchable with Normal axial internal clearance: the two side faces are ground so any two units form DB (back-to-back), DF (face-to-face) or DT (tandem) sets without regrinding. Envelope 40×90×36.5 mm (1.575×3.543×1.437 in), 25.0 mm radial section height, C 49.4 kN, C0 41.5 kN, Pu 1.76 kN.reference speed 8,000 r/min (thermal) and limiting speed 7,000 r/min (mechanical), catalogue mass 1200 g. Sizing arithmetic on the 40 mm bore: 49.4 kN C divided by the 25.0 mm radial section height gives 2.0 kN per section millimetre; the 1200 g mass and 4 % Pu/C share frame the light-load floor for the adjusted-life check. Envelope economics: the 36.5 mm width over a 25.0 mm section yields 1.46 mm of ring width per section millimetre, and the bearing weighs 1200 g for 49.4 kN of dynamic capacity — about 24 g per rated kN. Speed-ratio note for this exact unit: the reference speed is 8,000 r/min against a 7,000 r/min limiting speed, i.e. a reference-to-limit ratio of 1.14.

Typical equipment & failure modes

Selection pitfalls — read before you substitute

• The double-row 3308 takes thrust in both directions by itself — that is the reason to choose it over two single-row bearings: one housing bore, one fit, built-in set geometry.
• The double-row 3308 takes thrust in both directions by itself — that is the reason to choose it over two single-row bearings: one housing bore, one fit, built-in set geometry.
• A capped 3308-2Z/-2RS1 execution of this envelope exists for sealed-for-life duty; an open double-row bearing needs application sealing and a defined lubricant supply.
• Catalogue ratings of 49.4/41.5 kN apply to the DNRCBM execution; the D and DNRCBM two-piece-ring executions carry their own figures on their own pages.
• The D executions have a two-piece inner ring: mount both halves square to each other, never press on the outer ring, and keep the split faces clean during fitting.
• Catalogue ratings are SKF PUB BU/P1 17000 figures for 3308 DNRCBM as the double d nr cb m execution; the other order numbers of the 3308 size are different products and may carry different ratings — always quote the full designation when purchasing.