331981 bearing: complete specifications & equivalents
The 331981 is a ANSI ABMA 19.2 radial bearing sized 346.075 x 488.95 x 200.025 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 346.075 mm |
| Outer diameter D | 488.95 mm |
| Width B | 200.025 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 2835 kN |
| Basic static load rating C0 | 6300 kN |
| Fatigue load limit Pu | 510 kN |
| Operating temperature | -40 to +120 °C |
| Mass | 110000 g |
| Manufacturer designation | SKF 331981 |
| Standard | ANSI ABMA 19.2 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants |
| Last verified | 2026-09-29 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants) · extracted 2026-09-29
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants); 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 & tdo-series range
| Bore d | 13.625 in |
|---|---|
| Outer diameter D | 19.25 in |
| Width B | 7.875 in |
| ISO bore code | 81 |
| Radial section height (D−d)/2 | 71.4 mm |
| Smallest bore in tdo-series | 101.6 mm |
| Largest outer diameter in tdo-series | 596.9 mm |
| Width range across tdo-series | 49.212–284 mm |
| Bore position in tdo-series (smallest first) | 13 of 23 |
| Bore above smallest tdo-series size | 244.475 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 331981 | ISO 15 | full Dimensions and internal design equivalent — standard interchange. | ISO 15 boundary-dimension envelope; brand-specific OEM equivalents (NSK/FAG/NTN) pending multi-source data. |
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 331981 model number is decoded
Assembly datum check: verify the 200.025 mm width against the drawing before clamping — the width is the assembled result and the quickest field check that the correct execution of 331981 is on the shaft. The TDO/D execution of 331981 differs from sibling variants in internal detail — spacer style, rib execution or clearance class — while sharing the 346.075×488.95×200.025 mm boundary; the full designation including the variant is the only safe order reference. In the TDO X-arrangement the two cones of 331981 locate the shaft in both axial directions; the housing seat for the 488.95 mm double cup is a loose-to-transition fit so thermal growth does not preload the rows.The SKF 331981 is a 346.075×488.95×200.025 mm TDO double-row tapered roller bearing — two roller rows on a common double cup, delivered clearance-set as one assembly weighing 110.0 kg.The code SKF 331981 is not an ISO 355 number: double-row tapered bearings of this size follow SKF works numbering, where 331981 fixes the 346.075×488.95×200.025 mm envelope and the variant suffix (TDO/D) fixes the internal execution. Wear pattern reading at overhaul: the two rows of 331981 should show symmetric raceway contact; one-sided wear points to housing misalignment or a cocked seat rather than to a material defect. Static check: with C0 6300 kN the unit carries shock and standstill load up to the static safety factor of the application; the 510 kN Pu governs the fatigue side of the same calculation.
Typical equipment & failure modes
Common applications
- large crusher and mineral-processing drives
- wind-turbine main shafts
- marine propulsion gearboxes
- wind-turbine main shafts
Known failure patterns
- axial clamping ring bolt relaxation that lets the clearance-set rows walk apart under reversing thrust
- axial clamping ring bolt relaxation that lets the clearance-set rows walk apart under reversing thrust
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- mounting score marks when the cone is cocked over the shaft keyway or a burr
- electrical pitting on VFD-driven shafts without grounding protection
Selection pitfalls — read before you substitute
- Catalogue tables for this size class list no reference speed: derive permissible speed from the application heat balance, and instrument the first run of a 331981 installation with temperature logging.
- The 346.075 mm bore seat must be checked for ovality before mounting — at this size a worn seat lets the cone creep, and fretting debris then works between the rows of 331981.
- Never adjust the clearance of 331981 in the field: the two rows are set by ground spacers at the factory, and shim experiments on a 110.0 kg assembly usually end in overheated rows.
- The 2835/6300 kN ratings are SKF catalogue 17000 values for this execution; SKF can revise internal geometry without changing the order number, so keep the catalogue version (PUB BU/P1 17000/1 EN, 2018) with the specification.
- Quote the full SKF 331981 designation when purchasing — base-number-only orders are ambiguous across executions and variants.
Frequently asked questions
What are the dimensions and catalogue data of 331981?
The SKF 331981 is a double-row tapered roller bearing of TDO design with 346.075 mm bore, 488.95 mm outer diameter and 200.025 mm overall width (13.625 × 19.25 × 7.875 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 2835 kN, C0 6300 kN, fatigue load limit Pu 510 kN, mass about 110.00 kg.
What does the TDO/D variant code on 331981 mean?
Double-row tapered bearings of this size follow SKF works numbering: the base number 331981 fixes the 346.075×488.95×200.025 mm envelope, and the TDO/D code identifies the internal design variant — spacer execution, rib detail and clearance class. Same-envelope units under a different variant are not interchangeable without checking the variant meaning.
Why does the catalogue list no speed rating for 331981?
Bearings of this size class run in slow, heavily loaded machinery where the permissible speed is set by the application heat balance rather than a universal table value. Plan lubrication and cooling against the 110.0 kg assembly mass and instrument the first run with temperature logging.
Can components of 331981 be interchanged with another unit of the same base number?
No — cones, cups and spacers of a double-row set are matched per serial and the clearance is set by selective grinding at the factory. Replace 331981 as a complete assembly in the same TDO/D variant.
How does 331981 react axial load?
The TDO design works as a fixed X arrangement: one double cup with two cones locates the shaft in both axial directions, with load shared between the two rows according to the factory-set clearance.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 8.3-8.8 TRB variants on 2026-09-29. Read our editorial & correction policy.