31328T170X-DB bearing: complete specifications & equivalents
The 31328T170X-DB is a ISO 355 radial bearing sized 140 x 300 x 170 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 140 mm |
| Outer diameter D | 300 mm |
| Width B | 170 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | steel, stamped ribbon (J-type) |
| Basic dynamic load rating C | 1264 kN |
| Basic static load rating C0 | 1800 kN |
| Fatigue load limit Pu | 180 kN |
| Reference speed (thermal) | 1200 rpm |
| Limiting speed (mechanical) | 2200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 49000 g |
| Manufacturer designation | SKF 31328T170 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 | 5.512 in |
|---|---|
| Outer diameter D | 11.811 in |
| Width B | 6.693 in |
| ISO bore code | — |
| Radial section height (D−d)/2 | 80 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) | 19 of 30 |
| Bore above smallest matched-db-series size | 105 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| 31328T170X | 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 31328T170X-DB model number is decoded
Ordering number SKF 31328T170 X/DB in SKF catalogue PUB BU/P1 17000 denotes two single-row tapered roller bearings supplied as a matched back-to-back (O) matched pair set for a 140 mm shaft — one order number, one factory setting.Reading the designation: 31328T170 X is the ISO 355 single-row base bearing (140 mm bore), and the suffix /DB marks the matched-set execution — arrangement, spacer grinding and factory clearance class. The pair envelope is 140×300×170 mm; the width covers both bearings of the set. Back-to-back matching puts the large rib ends outward — the stiffest arrangement for moment load, but one that converts shaft thermal growth into preload change; the factory setting of 31328T170X-DB already accounts for the expected temperature gradient across the 170 mm pair width. The C0/C balance of the pair is about 1.42; combined with the 180 kN fatigue limit this frames a set sized for reversing combined load on a 140 mm shaft rather than for pure radial duty. Journal and housing interface: the 140 mm bore takes a m6 shaft seat and the 300 mm outside diameter pairs with an H7 housing bore; the 170 mm width defines shoulder depth and the 49000 g mass is the dead load in thermal-growth calculations. Load sharing in 31328T170X-DB depends on spacer face parallelism; a cocked spacer concentrates the reversing thrust on one bearing of the pair and shows up as asymmetric raceway wear at overhaul. Clamp the assembled pair axially through the cones — never through the rollers — and verify the 170 mm overall width against the catalogue value before final torquing of the shaft nut.
Typical equipment & failure modes
Common applications
- large industrial mixer shafts
- offshore winch and drawworks drums
- rolling-mill roll-neck bearings
- large industrial mixer shafts
Known failure patterns
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- axial overload spalling at the roller-rib contact beyond the single-row thrust rating
- cage pocket scoring when the bearing starts cold with grease of too-high base-oil viscosity
- electrical pitting on VFD-driven shafts without grounding protection
- rolling-contact fatigue spalling after the rated L10 life is exceeded
Selection pitfalls — read before you substitute
- Spacer faces must stay parallel within the set's own tolerance; a tilted spacer in 31328T170X-DB concentrates reversing thrust on one bearing and shows up as one-sided raceway wear.
- Clamp the 31328T170X-DB pair axially through the cones, never through the rollers; pressing force across the roller complement brinells the raceways of both bearings at once.
- O and X arrangements are not interchangeable by turning the set around: 31328T170X-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.
- The 1264/1800 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 31328T170 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 31328T170X-DB?
The SKF 31328T170 X/DB is a matched pair of single-row tapered roller bearings in back-to-back (O) matched pair arrangement with 140 mm bore, 300 mm outer diameter and 170 mm overall width (5.512 × 11.811 × 6.693 in). From SKF catalogue PUB BU/P1 17000: basic dynamic load rating C 1264 kN, C0 1800 kN, fatigue load limit Pu 180 kN, reference speed 1,200 r/min, limiting speed 2,200 r/min, mass about 49.00 kg.
What does the /DB suffix on 31328T170X-DB mean?
The base 31328T170 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 31328T170X-DB for one bearing or the pair?
They are for the complete matched pair: C 1264 kN dynamic and C0 1800 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 31328T170 X table values.
Can 31328T170X-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 140 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 140 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.