NU2256-ECML bearing: complete specifications & equivalents
The NU2256-ECML is a ISO 15 radial bearing sized 280 x 500 x 130 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 280 mm |
| Outer diameter D | 500 mm |
| Width B | 130 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 2330 kN |
| Basic static load rating C0 | 3750 kN |
| Fatigue load limit Pu | 320 kN |
| Reference speed (thermal) | 1200 rpm |
| Limiting speed (mechanical) | 2200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 115000 g |
| Manufacturer designation | SKF NU 2256 ECML |
| 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 & NU2200-series range
| Bore d | 11.024 in |
|---|---|
| Outer diameter D | 19.685 in |
| Width B | 5.118 in |
| ISO bore code | 56 |
| Radial section height (D−d)/2 | 110 mm |
| Smallest bore in NU2200-series | 17 mm |
| Largest outer diameter in NU2200-series | 1030 mm |
| Width range across NU2200-series | 16–272 mm |
| Bore position in NU2200-series (smallest first) | 32 of 39 |
| Bore above smallest NU2200-series size | 263 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NU2256-ECML model number is decoded
In SKF catalogue PUB BU/P1 17000, SKF NU 2256 ECML denotes a single-row caged cylindrical roller bearing on the ISO 15 280×500×130 mm envelope, dimension series 22 (light-section, wide), with catalogue mass 115000 g. The NU configuration means 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; functionally the bearing is non-locating: the inner ring assembly can float axially in both directions and the bearing cannot support axial load. The ECML 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. Load-per-bore for the 280 mm seat is about 8.32 kN/mm, typical of dimension series 22 (light-section, wide); use C0 3750 kN for static checks such as crane hook blocks standing under load. Fit practice for NU2256-ECML: 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. Single-row cylindrical rollers tolerate only about 3–4 minutes of arc misalignment, so verify shaft and housing alignment.
Typical equipment & failure modes
Common applications
- offshore drawworks shafts
- large rolling-mill drive trains
- marine propulsion line shafts
- heavy turbogenerator rotor supports
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
- false brinelling on standby machines exposed to external vibration
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 22 (light-section, wide) envelope is shared with the N/NU/NJ/NUP executions of 2256, but flange configuration and axial-locating behaviour differ — quote the full SKF NU 2256 ECML and do not substitute rib styles without checking the shaft locating scheme.
- Press-fit force goes through ring faces only; driving a ring home through the rollers brinells the 500 mm raceway.
- Catalogue reference and limiting speeds are different criteria: observe the mechanical ceiling even when thermal calculations allow more.
- The 2330/3750 kN ratings are SKF catalogue 17000 (2018) values for the ECML 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 NU2256-ECML?
SKF NU 2256 ECML is a single-row caged cylindrical roller bearing with 280 mm bore, 500 mm OD and 130 mm width per ISO 15. SKF lists C 2330 kN, C0 3750 kN, Pu 320 kN, reference speed 1,200 r/min and limiting speed 2,200 r/min, mass about 115000 g.
What does the NU designation and ECML suffix mean?
The ECML 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 NU2256-ECML 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 NU2256-ECML 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.