NU 303 ECP bearing
17 × 47 mm · dynamic rating 28.5 kN · static rating 20.4 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
NU 303 ECP specification
| Designation | NU 303 ECP |
| Type | Cylindrical roller bearing |
| Series | NU3 medium |
| Bore diameter d | 17 mm |
| Outside diameter D | 47 mm |
| Basic dynamic load rating C | 28.5 kN (28,500 N) |
| Basic static load rating C0 | 20.4 kN (20,400 N) |
| Ratio C0/C | 0.72 |
| Speed guide, grease lubrication | 20,000 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 303 ECP means
| Code | Meaning |
|---|---|
| NU | No flange on the inner ring, two flanges on the outer ring — inner ring can float axially |
| 303 | medium dimension series — bore code "03" = 17 mm (one of the four fixed small-bore codes, not the ×5 rule) |
| EC | Optimized internal design with more and/or larger rollers |
| P | Glass-fibre-reinforced PA66 cage, roller-centred |
Basic rating life of the NU 303 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 303 ECP with C = 28.5 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 5.7 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the NU 303 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 303 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 303 ECP belongs to the “NU3 medium” series. The next size up, the NU 304 ECP, has a bore of 20 mm and a rating of 35.5 kN (+25%).
Common problems on bearings like the NU 303 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 303 ECP
What are the dimensions of a NU 303 ECP bearing?
The NU 303 ECP has a bore of 17 mm and an outside diameter of 47 mm. It is a cylindrical roller bearing. Series: NU3 medium.
What is the load rating of a NU 303 ECP bearing?
In the Rotec AI catalogue the NU 303 ECP has a basic dynamic load rating C of 28.5 kN and a basic static load rating C0 of 20.4 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a NU 303 ECP bearing?
Use the Cross-Reference tool in Rotec AI to check brand equivalents for the NU 303 ECP.