NU3168-ECMA bearing: complete specifications & equivalents
The NU3168-ECMA is a ISO 15 radial bearing sized 340 x 580 x 190 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 340 mm |
| Outer diameter D | 580 mm |
| Width B | 190 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 3470 kN |
| Basic static load rating C0 | 5850 kN |
| Fatigue load limit Pu | 490 kN |
| Reference speed (thermal) | 950 rpm |
| Limiting speed (mechanical) | 1600 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 217000 g |
| Manufacturer designation | SKF NU 3168 ECMA |
| Standard | ISO 15 |
| Catalog version | SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings |
| Last verified | 2026-09-26 |
Source: catalog reference (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings) · extracted 2026-09-26
Parameters extracted from the official SKF Rolling Bearings catalogue (SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings); 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 & NU3100-series range
| Bore d | 13.386 in |
|---|---|
| Outer diameter D | 22.835 in |
| Width B | 7.48 in |
| ISO bore code | 68 |
| Radial section height (D−d)/2 | 120 mm |
| Smallest bore in NU3100-series | 280 mm |
| Largest outer diameter in NU3100-series | 870 mm |
| Width range across NU3100-series | 146–272 mm |
| Bore position in NU3100-series (smallest first) | 2 of 9 |
| Bore above smallest NU3100-series size | 60 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NU3168-ECMA model number is decoded
Ordering number SKF NU 3168 ECMA resolves to a 340×580×190 mm single-row caged cylindrical roller bearing (dimension series 31 (compact OD, wide)); two integral flanges on the outer ring and no flanges on the inner ring, so the inner ring together with the roller set is separable. Reading the NU prefix: two integral flanges on the outer ring and no flanges on the inner ring, so the inner ring together with the roller set is separable. This makes the execution non-locating: the inner ring assembly can float axially in both directions and the bearing cannot support axial load. The ECMA suffix denotes the E-design execution with a one-piece machined brass cage for higher-temperature and higher-speed continuous duty. Selection arithmetic: C0/C ≈ 1.69 (5850 against 3470 kN), and the Pu figure 490 kN is the fatigue load-limit floor for the SKF life equation; the catalogue lists 950 r/min thermal reference speed and 1,600 r/min mechanical limiting speed. Assembly note: fit the inner ring and roller assembly onto the shaft and the outer ring into the housing independently; thermal expansion is absorbed by axial float, so do not trap the inner ring between shaft shoulders. Heat steel rings inductively to max 120 °C.
Typical equipment & failure modes
Common applications
- large rolling-mill drive trains
- marine propulsion line shafts
- heavy turbogenerator rotor supports
- mining hoist and winder shafts
Known failure patterns
- inner-ring raceway spalling from overload or contamination in the line-contact hertz zone
- outer-ring raceway fatigue after extended service at loads above the catalogue L10 rating
- cage pocket wear from roller skew at light load
- polymer cage cracking or softening after sustained running above 120 °C or with incompatible lubricant
- roller-end scoring from inadequate oil flow in the roller-raceway contact
- edge-loading fatigue after shaft deflection beyond the 3–4 minute alignment limit
- hard-particle indentation of the raceway in unfiltered oil systems
Selection pitfalls — read before you substitute
- Do not use a NU bearing where axial load must be carried — the design carries radial load only
- The dimension series 31 (compact OD, wide) envelope is shared with the N/NU/NJ/NUP executions of 3168, but flange configuration and axial-locating behaviour differ — quote the full SKF NU 3168 ECMA and do not substitute rib styles without checking the shaft locating scheme.
- Shaft and housing fillets must clear the bearing chamfers; an oversized radius tilts the 190 mm-wide ring and concentrates load.
- Catalogue reference and limiting speeds are different criteria: observe the mechanical ceiling even when thermal calculations allow more.
- The 3470/5850 kN ratings are SKF catalogue 17000 (2018) values for the ECMA execution; re-verify against the current catalogue for critical drives and keep the catalogue version with the specification.
Frequently asked questions
What are the dimensions and catalogue data of NU3168-ECMA?
SKF NU 3168 ECMA is a single-row caged cylindrical roller bearing with 340 mm bore, 580 mm OD and 190 mm width per ISO 15. SKF lists C 3470 kN, C0 5850 kN, Pu 490 kN, reference speed 950 r/min and limiting speed 1,600 r/min, mass about 217000 g.
What does the NU designation and ECMA suffix mean?
The ECMA suffix denotes the E-design execution with a one-piece machined brass cage for higher-temperature and higher-speed continuous duty. Structurally this execution has two integral flanges on the outer ring and no flanges on the inner ring, so the inner ring together with the roller set is separable.
Can NU3168-ECMA take axial load and locate the shaft?
No — the inner ring has no flanges, so the NU bearing is non-locating and carries radial load only; use NJ (one direction), NUP (both directions) or a paired thrust bearing for axial duty.
How does NU3168-ECMA compare with the other executions in the same envelope?
The N/NU/NJ/NUP executions share the ISO 15 envelope and load ratings but differ in flange arrangement and axial-locating behaviour; quote the exact order number.
What limits the service life of this bearing most often?
Line-contact fatigue above the L10 rating, cage wear at light loads and high temperatures, and edge loading from misalignment beyond about 3–4 minutes of arc are the typical failure drivers.
Reviewed & verified by the MPN Base engineering desk against source catalog SKF PUB BU/P1 17000/1 EN (Oct 2018), ch. 6.1 single-row cylindrical roller bearings on 2026-09-26. Read our editorial & correction policy.