N304-ECP bearing: complete specifications & equivalents
The N304-ECP is a ISO 15 radial bearing sized 20 x 52 x 15 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 20 mm |
| Outer diameter D | 52 mm |
| Width B | 15 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 35.5 kN |
| Basic static load rating C0 | 26 kN |
| Fatigue load limit Pu | 3.25 kN |
| Reference speed (thermal) | 15000 rpm |
| Limiting speed (mechanical) | 18000 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 150 g |
| Manufacturer designation | SKF N 304 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 & N300-series range
| Bore d | 0.787 in |
|---|---|
| Outer diameter D | 2.047 in |
| Width B | 0.591 in |
| ISO bore code | 04 |
| Radial section height (D−d)/2 | 16 mm |
| Smallest bore in N300-series | 17 mm |
| Largest outer diameter in N300-series | 280 mm |
| Width range across N300-series | 14–58 mm |
| Bore position in N300-series (smallest first) | 2 of 22 |
| Bore above smallest N300-series size | 3 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| NJ304-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 20×52×15 mm and equivalent catalogue ratings; the NJ execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NUP304-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 20×52×15 mm and equivalent catalogue ratings; the NUP execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NU304 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 20×52×15 mm and equivalent catalogue ratings; the NU execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NU304 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 20×52×15 mm and equivalent catalogue ratings; the NU execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NU304 | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 20×52×15 mm and equivalent catalogue ratings; the NU 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 N304-ECP model number is decoded
N304-ECP is the 20 mm bore entry in the N300 range: a 20×52×15 mm single-row caged cylindrical roller bearing with a glass-fibre reinforced polyamide (PA66) window-type cage, rated C 35.5 kN / C0 26 kN. Structurally, the N design has two integral flanges on the inner ring and no flanges on the outer ring, so the plain outer ring is the separable part. In arrangement terms it is non-locating: the outer ring can displace axially in both directions and the bearing carries radial load only. Reading the order-string suffix ECP: the E-design execution with a glass-fibre reinforced polyamide (PA66) cage, limited to 120 °C continuous. Speed planning for N304-ECP: the catalogue lists 15,000 r/min thermal reference speed and 18,000 r/min mechanical limiting speed. The mass entry 150 g covers the complete catalogue execution. Assembly note: the outer ring slides in its housing seat; provide axial retention for the outer ring only if the application requires it, and let it float to absorb shaft expansion. Heat steel rings inductively to max 120 °C — the PA66 cage sets the ceiling.
Typical equipment & failure modes
Common applications
- appliance and fan armature shafts
- small pump rotor shafts
- small industrial electric-motor shafts
- light gearbox layshafts
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
- 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
- edge loading from shaft deflection beyond the bearing alignment limit (≈ 3-4 minutes of arc for single-row CRB)
Selection pitfalls — read before you substitute
- Do not use a N bearing where axial load must be carried — the design carries radial load only
- The dimension series 3 (medium-section ISO 15 envelope) envelope is shared with the N/NU/NJ/NUP executions of 304, but flange configuration and axial-locating behaviour differ — quote the full SKF N 304 ECP 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.
- Shaft and housing fillets must clear the bearing chamfers; an oversized radius tilts the 15 mm-wide ring and concentrates load.
- The 35.5/26 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 N304-ECP?
SKF N 304 ECP is a single-row caged cylindrical roller bearing with 20 mm bore, 52 mm OD and 15 mm width per ISO 15. SKF lists C 35.5 kN, C0 26 kN, Pu 3.25 kN, reference speed 15,000 r/min and limiting speed 18,000 r/min, mass about 150 g.
What does the N 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 inner ring and no flanges on the outer ring, so the plain outer ring is the separable part.
Can N304-ECP take axial load and locate the shaft?
No — the plain outer ring has no flanges, so the N bearing floats axially and is for radial load; locate the shaft with a separate bearing.
How does N304-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.