NU228-ECM bearing: complete specifications & equivalents
The NU228-ECM is a ISO 15 radial bearing sized 140 x 250 x 42 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 | 250 mm |
| Width B | 42 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 450 kN |
| Basic static load rating C0 | 510 kN |
| Fatigue load limit Pu | 57 kN |
| Reference speed (thermal) | 2800 rpm |
| Limiting speed (mechanical) | 3200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 9400 g |
| Manufacturer designation | SKF NU 228 ECM |
| 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 & NU200-series range
| Bore d | 5.512 in |
|---|---|
| Outer diameter D | 9.843 in |
| Width B | 1.654 in |
| ISO bore code | 28 |
| Radial section height (D−d)/2 | 55 mm |
| Smallest bore in NU200-series | 15 mm |
| Largest outer diameter in NU200-series | 580 mm |
| Width range across NU200-series | 11–92 mm |
| Bore position in NU200-series (smallest first) | 23 of 35 |
| Bore above smallest NU200-series size | 125 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ228-ECJ | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 140×250×42 mm and equivalent catalogue ratings; the NJ execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NUP228-ECJ | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 140×250×42 mm and equivalent catalogue ratings; the NUP execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
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 NU228-ECM model number is decoded
In SKF catalogue PUB BU/P1 17000, SKF NU 228 ECM denotes a single-row caged cylindrical roller bearing on the ISO 15 140×250×42 mm envelope, dimension series 2 (light-section ISO 15 envelope), with catalogue mass 9400 g. Structurally, the NU design 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. In arrangement terms it is non-locating: the inner ring assembly can float axially in both directions and the bearing cannot support axial load. The ECM suffix denotes the E-design execution with a one-piece machined brass cage for higher-temperature and higher-speed continuous duty. The one-piece machined brass cage is reflected in the published speeds and temperature limits. Speed planning for NU228-ECM: the catalogue lists 2,800 r/min thermal reference speed and 3,200 r/min mechanical limiting speed. The mass entry 9400 g covers the complete catalogue execution. 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
- mining hoist and winder shafts
- offshore drawworks shafts
- large rolling-mill drive trains
- marine propulsion line 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
- surface distress (micro-pitting) when the EHL film falls below the composite roughness at high specific load
- edge-loading fatigue after shaft deflection beyond the 3–4 minute alignment limit
- rolling-contact fatigue spalling after the rated L10 life is exceeded
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 2 (light-section ISO 15 envelope) envelope is shared with the N/NU/NJ/NUP executions of 228, but flange configuration and axial-locating behaviour differ — quote the full SKF NU 228 ECM and do not substitute rib styles without checking the shaft locating scheme.
- Catalogue reference and limiting speeds are different criteria: observe the mechanical ceiling even when thermal calculations allow more.
- Press-fit force goes through ring faces only; driving a ring home through the rollers brinells the 250 mm raceway.
- The 450/510 kN ratings are SKF catalogue 17000 (2018) values for the ECM 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 NU228-ECM?
SKF NU 228 ECM is a single-row caged cylindrical roller bearing with 140 mm bore, 250 mm OD and 42 mm width per ISO 15. SKF lists C 450 kN, C0 510 kN, Pu 57 kN, reference speed 2,800 r/min and limiting speed 3,200 r/min, mass about 9400 g.
What does the NU designation and ECM suffix mean?
The ECM 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 NU228-ECM 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 NU228-ECM 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.