NU 304 ECP bearing
20 × 52 mm · dynamic rating 35.5 kN · static rating 26 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
NU 304 ECP specification
| Designation | NU 304 ECP |
| Type | Cylindrical roller bearing |
| Series | NU3 medium |
| Bore diameter d | 20 mm |
| Outside diameter D | 52 mm |
| Basic dynamic load rating C | 35.5 kN (35,500 N) |
| Basic static load rating C0 | 26 kN (26,000 N) |
| Ratio C0/C | 0.73 |
| Speed guide, grease lubrication | 18,000 rpm |
| Life exponent p | 10/3 (roller bearing) |
Values come from the Rotec AI bearing catalogue and are indicative. Confirm against the manufacturer's current catalogue before ordering. Not every dimension (such as width) is listed here.
What the designation NU 304 ECP means
| Code | Meaning |
|---|---|
| NU | No flange on the inner ring, two flanges on the outer ring — inner ring can float axially |
| 304 | medium dimension series — bore code "04" = 4 × 5 = 20 mm |
| EC | Optimized internal design with more and/or larger rollers |
| P | Glass-fibre-reinforced PA66 cage, roller-centred |
Basic rating life of the NU 304 ECP
Basic rating life is L10 = (C / P)p million revolutions, where P is the equivalent dynamic load and p = 10/3 (roller bearing). For a NU 304 ECP with C = 35.5 kN, the table shows what that gives at different load levels. It is the ISO 281 basic life only: it does not include lubrication, contamination, misalignment or reliability modifiers.
| C / P | P as share of C | L10 (million rev) | L10 at 1,500 rpm | L10 at 3,000 rpm |
|---|---|---|---|---|
| 3 | 33.3% | 39 | 430 | 220 |
| 5 | 20.0% | 214 | 2,400 | 1,200 |
| 8 | 12.5% | 1,024 | 11,400 | 5,700 |
| 12 | 8.3% | 3,956 | 44,000 | 22,000 |
For example, a C / P of 5 means the equivalent load is 7.1 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the NU 304 ECP
Brand-by-brand equivalents for this exact designation are not shown here. The Cross-Reference tool accepts SKF, FAG, NSK, NTN, Timken, Koyo and NRB designations, and shows what is catalogued.
Where the NU 304 ECP is used
Cylindrical roller bearings are chosen for: High radial load and high speed; separable arrangements. Typical equipment: Gearboxes, traction motors, rolling mills, generators. Some variants carry axial load; common in railway drive systems.
Other sizes in the same series
The NU 304 ECP belongs to the “NU3 medium” series. The next size down, the NU 303 ECP, has a bore of 17 mm and a dynamic rating of 28.5 kN. The next size up, the NU 305 ECP, has a bore of 25 mm and a rating of 46.5 kN (+31%).
Common problems on bearings like the NU 304 ECP
Most field failures trace back to lubrication, contamination, fits and alignment rather than the bearing itself. These guides explain how to recognise and prevent them:
Questions about the NU 304 ECP
What are the dimensions of a NU 304 ECP bearing?
The NU 304 ECP has a bore of 20 mm and an outside diameter of 52 mm. It is a cylindrical roller bearing. Series: NU3 medium.
What is the load rating of a NU 304 ECP bearing?
In the Rotec AI catalogue the NU 304 ECP has a basic dynamic load rating C of 35.5 kN and a basic static load rating C0 of 26 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a NU 304 ECP bearing?
Use the Cross-Reference tool in Rotec AI to check brand equivalents for the NU 304 ECP.