NU 311 ECP bearing
55 × 120 mm · dynamic rating 156 kN · static rating 143 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
NU 311 ECP specification
| Designation | NU 311 ECP |
| Type | Cylindrical roller bearing |
| Series | NU3 medium |
| Bore diameter d | 55 mm |
| Outside diameter D | 120 mm |
| Basic dynamic load rating C | 156 kN (156,000 N) |
| Basic static load rating C0 | 143 kN (143,000 N) |
| Ratio C0/C | 0.92 |
| Speed guide, grease lubrication | 7,000 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 311 ECP means
| Code | Meaning |
|---|---|
| NU | No flange on the inner ring, two flanges on the outer ring — inner ring can float axially |
| 311 | medium dimension series — bore code "11" = 11 × 5 = 55 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 311 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 311 ECP with C = 156 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 31.2 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the NU 311 ECP
Brand-by-brand equivalents for this exact designation are not yet in the Rotec AI cross-reference tables. The Cross-Reference tool accepts SKF, FAG, NSK, NTN, Timken, Koyo and NRB designations, and shows what is catalogued.
Where the NU 311 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 311 ECP is size 9 of 18 in the Rotec AI catalogue for the “NU3 medium” series. The next size down, the NU 310 ECP, has a bore of 50 mm and a dynamic rating of 127 kN. The next size up, the NU 312 ECP, has a bore of 60 mm and a rating of 173 kN (+11%).
Common problems on bearings like the NU 311 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 311 ECP
What are the dimensions of a NU 311 ECP bearing?
The NU 311 ECP has a bore of 55 mm and an outside diameter of 120 mm. It is a cylindrical roller bearing. Series: NU3 medium.
What is the load rating of a NU 311 ECP bearing?
In the Rotec AI catalogue the NU 311 ECP has a basic dynamic load rating C of 156 kN and a basic static load rating C0 of 143 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a NU 311 ECP bearing?
Brand equivalents for the NU 311 ECP are not yet in the Rotec AI tables. Use the Cross-Reference tool to check other designations.