3308-DMA 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-DMA model number is decoded

3308 DMA 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. DMA pairs the split inner ring with a machined brass outer-ring-centred MA cage. Envelope 40×90×36.5 mm (1.575×3.543×1.437 in), 25.0 mm radial section height, C 68.9 kN, C0 57 kN, Pu 2.45 kN.reference speed 8,000 r/min (thermal) and limiting speed 7,000 r/min (mechanical), catalogue mass 1050 g. Mass and section check: 1050 g inside the 40×90×36.5 mm outline leaves a 25.0 mm radial section, and the 57 kN static rating is 0.83× the dynamic rating — plan static safety and minimum load against those numbers rather than against sister executions. At the printed limiting speed of 7,000 r/min the mean pitch diameter dm ≈ 65.0 mm implies a dn value around 455k mm·r/min; the 8,000 r/min reference speed is the thermal-planning figure under catalogue load. 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. Split-ring execution note: DMA combines the two-piece inner ring (used to simplify mounting of the wide 33-series section) with a machined brass cage guided on the outer ring (MA rather than ball-centred M); outer-ring guidance steadies the cage in the heavy section at the cost of a different lubrication requirement at the guide land.

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.
• Compared with a single-row pair of the same bore, the double-row 3308 occupies less axial space but offers less freedom to adjust preload — do not substitute without re-checking the arrangement.
• 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.
• 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.
• 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 DMA as the double d ma execution; the other order numbers of the 3308 size are different products and may carry different ratings — always quote the full designation when purchasing.