31330T179X-DB bearing: complete specifications & equivalents
The 31330T179X-DB is a ISO 355 radial bearing sized 150 x 320 x 179 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 150 mm |
| Outer diameter D | 320 mm |
| Width B | 179 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 1427 kN |
| Basic static load rating C0 | 2040 kN |
| Fatigue load limit Pu | 200 kN |
| Reference speed (thermal) | 1100 rpm |
| Limiting speed (mechanical) | 2000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 58500 g |
| Manufacturer designation | SKF 31330T179 X/DB |
| Standard | ISO 355 |
| 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 & matched-db-series range
| Bore d | 5.906 in |
|---|---|
| Outer diameter D | 12.598 in |
| Width B | 7.047 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 85 mm |
| Smallest bore in matched-db-series | 35 mm |
| Largest outer diameter in matched-db-series | 480 mm |
| Width range across matched-db-series | 41.5–288 mm |
| Bore position in matched-db-series (smallest first) | 20 of 30 |
| Bore above smallest matched-db-series size | 115 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31330T179X | 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 31330T179X-DB model number is decoded
Load system: C 1427 kN against C0 2040 kN gives a 1.43 balance, and 9.51 kN of dynamic capacity per millimetre of the 150 mm bore is the density figure to compare against neighbouring sizes. Setting note for 31330T179X-DB: the axial clearance is set at the factory by selective spacer grinding for the /DB execution; in service, re-checking end play after the first thermal cycle catches seating relaxation before it becomes roller skid. Do not separate 31330T179X-DB into single-bearing service stock — as individual bearings the components are not interchangeable with catalogue single-row executions because the rings are ground for the set.SKF 31330T179 X/DB belongs to the SKF matched tapered-roller range — the 150 mm bore entry in back-to-back (O) matched pair arrangement, dimensioned 320 mm OD and 179 mm overall width for the pair.The code breaks down as base bearing 31330T179 X plus matched-set suffix /DB: two bearings of the 150 mm bore size, paired back-to-back (O) matched pair, with the 179 mm overall width spanning the whole arrangement. In the back-to-back (O) arrangement the load lines diverge toward the shaft axis, giving the pair a wide effective spread: 31330T179X-DB resists overturning moments and tilting loads stiffly, which is why O-sets are preferred for gearbox output shafts and pinion supports. Speed planning for the set uses the catalogue pair values: 1,100 r/min thermal reference and 2,000 r/min mechanical limiting speed — a matched pair runs warmer than one bearing because two roller sets share the 179 mm space.
Typical equipment & failure modes
Common applications
- offshore winch and drawworks drums
- rolling-mill roll-neck bearings
- heavy-duty rolling-mill gearboxes
- rolling-mill roll-neck bearings
Known failure patterns
- preload loss as the mounted pair relaxes, letting rollers skid and smear the raceways
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- pressed-steel cage wear or fracture after prolonged running above the limiting speed
- grease degradation after long shelf storage without rotation or re-greasing
- mounting score marks when the cone is cocked over the shaft keyway or a burr
Selection pitfalls — read before you substitute
- O and X arrangements are not interchangeable by turning the set around: 31330T179X-DB in back-to-back (O) matched pair arrangement has its load-line geometry fixed — specify the arrangement from the shaft thermal and stiffness analysis.
- Spacer faces must stay parallel within the set's own tolerance; a tilted spacer in 31330T179X-DB concentrates reversing thrust on one bearing and shows up as one-sided raceway wear.
- A matched /DB set is ground as one system: never separate the two bearings of 31330T179X-DB or swap the spacer — the factory clearance is lost the moment the set is broken.
- The 1427/2040 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 31330T179 X/DB designation when purchasing — base-number-only orders are ambiguous across executions and variants.
Frequently asked questions
What are the dimensions and catalogue data of 31330T179X-DB?
The SKF 31330T179 X/DB is a matched pair of single-row tapered roller bearings in back-to-back (O) matched pair arrangement with 150 mm bore, 320 mm outer diameter and 179 mm overall width (5.906 × 12.598 × 7.047 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 1427 kN, C0 2040 kN, fatigue load limit Pu 200 kN, reference speed 1,100 r/min, limiting speed 2,000 r/min, mass about 58.50 kg.
What does the /DB suffix on 31330T179X-DB mean?
The base 31330T179 X is the ISO 355 single-row bearing; the /DB suffix marks the matched-set execution — the arrangement (back-to-back (O)), the ground spacer and the factory-set axial clearance class. A matched set cannot be assembled from loose single bearings; quote the full designation when ordering.
Are the C and C0 ratings of 31330T179X-DB for one bearing or the pair?
They are for the complete matched pair: C 1427 kN dynamic and C0 2040 kN static already include load sharing between the two bearings. Do not halve them for single-bearing checks, and do not compare them directly with the single-row 31330T179 X table values.
Can 31330T179X-DB be adjusted like two loose tapered bearings?
No — the axial clearance is set at the factory by selective spacer grinding. Mounting work is limited to clean seats, correct fits (m6 on a rotating 150 mm shaft) and axial clamping through the cones; re-setting in the field destroys the matched clearance class.
When should a back-to-back (O) matched set be chosen?
Choose the back-to-back (O) set where moment stiffness dominates — pinion supports, gearbox output shafts, crane sheaves. The diverging load lines give the widest effective spread at the 150 mm bore.
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.