NU324-ECP bearing: complete specifications & equivalents
The NU324-ECP is a ISO 15 radial bearing sized 120 x 260 x 55 mm (bore x OD x width). Verify dimensions against the official catalog before ordering.
Specification table
| Parameter | Value |
|---|---|
| Brand | SKF |
| Bore diameter d | 120 mm |
| Outer diameter D | 260 mm |
| Width B | 55 mm |
| Material | GCr15 |
| Seal / shield | open |
| Internal clearance | CN |
| Tolerance class | P0 |
| Cage | polymer (PA66 glass-fibre reinforced) |
| Basic dynamic load rating C | 610 kN |
| Basic static load rating C0 | 620 kN |
| Fatigue load limit Pu | 69.5 kN |
| Reference speed (thermal) | 2800 rpm |
| Limiting speed (mechanical) | 3200 rpm |
| Operating temperature | -40 to +120 °C |
| Mass | 13000 g |
| Manufacturer designation | SKF NU 324 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 & NU300-series range
| Bore d | 4.724 in |
|---|---|
| Outer diameter D | 10.236 in |
| Width B | 2.165 in |
| ISO bore code | 24 |
| Radial section height (D−d)/2 | 70 mm |
| Smallest bore in NU300-series | 17 mm |
| Largest outer diameter in NU300-series | 620 mm |
| Width range across NU300-series | 14–109 mm |
| Bore position in NU300-series (smallest first) | 21 of 33 |
| Bore above smallest NU300-series size | 103 mm |
Cross references & equivalents
| Equivalent model | Brand | Match level | Note |
|---|---|---|---|
| N324-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 120×260×55 mm and equivalent catalogue ratings; the N execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NJ324-ECJ | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 120×260×55 mm and equivalent catalogue ratings; the NJ execution differs in flange/retaining-ring configuration — boundary-dimension interchangeable, but axial-locating behaviour is not identical. |
| NUP324-ECP | SKF | full Dimensions and internal design equivalent — standard interchange. | Same ISO 15 envelope 120×260×55 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 NU324-ECP model number is decoded
In SKF catalogue PUB BU/P1 17000, SKF NU 324 ECP denotes a single-row caged cylindrical roller bearing on the ISO 15 120×260×55 mm envelope, dimension series 3 (medium-section ISO 15 envelope), with catalogue mass 13000 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 ECP suffix marks the E-design execution with a glass-fibre reinforced polyamide (PA66) cage, limited to 120 °C continuous. Selection arithmetic: C0/C ≈ 1.02 (620 against 610 kN), and the Pu figure 69.5 kN is the fatigue load-limit floor for the SKF life equation; the catalogue lists 2,800 r/min thermal reference speed and 3,200 r/min mechanical limiting speed. Fit practice for NU324-ECP: 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
- 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
- polymer cage softening above 120 °C
- 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
- 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 NU 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 324, but flange configuration and axial-locating behaviour differ — quote the full SKF NU 324 ECP 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 260 mm raceway.
- Shaft and housing fillets must clear the bearing chamfers; an oversized radius tilts the 55 mm-wide ring and concentrates load.
- The 610/620 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 NU324-ECP?
SKF NU 324 ECP is a single-row caged cylindrical roller bearing with 120 mm bore, 260 mm OD and 55 mm width per ISO 15. SKF lists C 610 kN, C0 620 kN, Pu 69.5 kN, reference speed 2,800 r/min and limiting speed 3,200 r/min, mass about 13000 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 NU324-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 NU324-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.