NU203-ECP bearing: complete specifications & equivalents
The NU203-ECP is a ISO 15 radial bearing sized 17 x 40 x 12 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 17 mm |
| Outer diameter D | 40 mm |
| Width B | 12 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 20 kN |
| Basic static load rating C0 | 14.3 kN |
| Fatigue load limit Pu | 1.73 kN |
| Reference speed (thermal) | 20000 rpm |
| Limiting speed (mechanical) | 22000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 68 g |
| Manufacturer designation | SKF NU 203 ECP |
| 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 | 0.669 in |
|---|---|
| Outer diameter D | 1.575 in |
| Width B | 0.472 in |
| ISO bore code | 03 |
| Radial section height (D−d)/2 | 11.5 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) | 2 of 35 |
| Bore above smallest NU200-series size | 2 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| N203-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 17×40×12 mm and equivalent catalogue ratings; the N execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NJ203-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 17×40×12 mm and equivalent catalogue ratings; the NJ execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NUP203-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 17×40×12 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 NU203-ECP model number is decoded
For a 17 mm shaft, SKF lists NU203-ECP as single-row caged cylindrical roller: 40 mm OD, 12 mm wide, Pu 1.73 kN, the catalogue lists 20,000 r/min thermal reference speed and 22,000 r/min mechanical limiting speed. 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 ECP suffix marks the E-design execution with a glass-fibre reinforced polyamide (PA66) cage, limited to 120 °C continuous. The glass-fibre reinforced polyamide (PA66) window-type cage is reflected in the published speeds and temperature limits. Selection arithmetic: C0/C ≈ 0.72 (14.3 against 20 kN), and the Pu figure 1.73 kN is the fatigue load-limit floor for the SKF life equation; the catalogue lists 20,000 r/min thermal reference speed and 22,000 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 — the PA66 cage sets the ceiling.
Typical equipment & failure modes
Common applications
- small industrial electric-motor shafts
- light gearbox layshafts
- motor-cycle and small-engine transmissions
- appliance and fan armature 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
- polymer cage softening above 120 °C
- 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
- 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 2 (light-section ISO 15 envelope) envelope is shared with the N/NU/NJ/NUP executions of 203, but flange configuration and axial-locating behaviour differ — quote the full SKF NU 203 ECP 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 12 mm-wide ring and concentrates load.
- Press-fit force goes through ring faces only; driving a ring home through the rollers brinells the 40 mm raceway.
- The 20/14.3 kN ratings are SKF catalogue 17000 (2018) values for the ECP 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 NU203-ECP?
SKF NU 203 ECP is a single-row caged cylindrical roller bearing with 17 mm bore, 40 mm OD and 12 mm width per ISO 15. SKF lists C 20 kN, C0 14.3 kN, Pu 1.73 kN, reference speed 20,000 r/min and limiting speed 22,000 r/min, mass about 68 g.
What does the NU designation and ECP suffix mean?
The ECP suffix marks the E-design execution with a glass-fibre reinforced polyamide (PA66) cage, limited to 120 °C continuous. 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 NU203-ECP 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 NU203-ECP 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.