NU3188-ECMA-HB1 bearing: complete specifications & equivalents
The NU3188-ECMA-HB1 is a ISO 15 radial bearing sized 440 x 720 x 226 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 440 mm |
| Outer diameter D | 720 mm |
| Width B | 226 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | brass |
| Basic dynamic load rating C | 5120 kN |
| Basic static load rating C0 | 10000 kN |
| Fatigue load limit Pu | 765 kN |
| Reference speed (thermal) | 700 rpm |
| Limiting speed (mechanical) | 1200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 388000 g |
| Manufacturer designation | SKF NU 3188 ECMA/HB1 |
| 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 | 17.323 in |
|---|---|
| Outer diameter D | 28.346 in |
| Width B | 8.898 in |
| ISO bore code | 88 |
| Radial section height (D−d)/2 | 140 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) | 5 of 9 |
| Bore above smallest NU3100-series size | 160 mm |
Cross references & equivalents
No verified interchange data yet. Send an inquiry and our team will confirm equivalents manually.
How the NU3188-ECMA-HB1 model number is decoded
In SKF catalogue PUB BU/P1 17000, SKF NU 3188 ECMA/HB1 denotes a single-row caged cylindrical roller bearing on the ISO 15 440×720×226 mm envelope, dimension series 31 (compact OD, wide), with catalogue mass 388000 g. 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 plain designation (no cage suffix) identifies the basic execution supplied with a standard pressed-steel cage. Selection arithmetic: C0/C ≈ 1.95 (10000 against 5120 kN), and the Pu figure 765 kN is the fatigue load-limit floor for the SKF life equation; the catalogue lists 700 r/min thermal reference speed and 1,200 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
- cage pocket wear from roller skidding at insufficient radial load or during start-up before oil film build-up
- 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
- brinelling from static overload or impact during handling and mounting
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 3188, but flange configuration and axial-locating behaviour differ — quote the full SKF NU 3188 ECMA/HB1 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 226 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 5120/10000 kN ratings are SKF catalogue 17000 (2018) values for the ECMA/HB1 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 NU3188-ECMA-HB1?
SKF NU 3188 ECMA/HB1 is a single-row caged cylindrical roller bearing with 440 mm bore, 720 mm OD and 226 mm width per ISO 15. SKF lists C 5120 kN, C0 10000 kN, Pu 765 kN, reference speed 700 r/min and limiting speed 1,200 r/min, mass about 388000 g.
What does the NU designation and ECMA/HB1 suffix mean?
The plain designation (no cage suffix) identifies the basic execution supplied with a standard pressed-steel cage. 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 NU3188-ECMA-HB1 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 NU3188-ECMA-HB1 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.