7311 BEP /DB bearing
55 × 120 mm · dynamic rating 128.47 kN · static rating 110 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
7311 BEP /DB specification
| Designation | 7311 BEP /DB |
| Type | Matched pair of angular contact ball bearings (back-to-back) |
| Series | 73 medium (pair) |
| Bore diameter d | 55 mm |
| Outside diameter D | 120 mm |
| Basic dynamic load rating C | 128.47 kN (128,466 N) |
| Basic static load rating C0 | 110 kN (110,000 N) |
| Ratio C0/C | 0.86 |
| Speed guide, grease lubrication | 6,030 rpm |
| Life exponent p | 3 (ball 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 7311 BEP /DB means
| Code | Meaning |
|---|---|
| 73 | Angular contact ball bearing, medium dimension series |
| 11 | bore code "11" = 11 × 5 = 55 mm |
| B | 40° contact angle |
| E | Optimized internal design |
| P | Glass-fibre-reinforced PA66 cage, ball-centred |
| /DB | Two bearings mounted back-to-back as a matched pair — carries combined radial + axial load from both directions with high stiffness |
Basic rating life of the 7311 BEP /DB
Basic rating life is L10 = (C / P)p million revolutions, where P is the equivalent dynamic load and p = 3 (ball bearing). For a 7311 BEP /DB with C = 128.47 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% | 27 | 300 | 150 |
| 5 | 20.0% | 125 | 1,400 | 690 |
| 8 | 12.5% | 512 | 5,700 | 2,800 |
| 12 | 8.3% | 1,728 | 19,200 | 9,600 |
For example, a C / P of 5 means the equivalent load is 25.69 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the 7311 BEP /DB
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 7311 BEP /DB is used
Angular-contact ball bearings are chosen for: Combined radial and axial load; precision/high-speed arrangements. Typical equipment: Pumps, compressors, spindles, generators, aerospace accessories. Often paired/preloaded; contact angle and lubrication matter.
Other sizes in the same series
The 7311 BEP /DB belongs to the “73 medium (pair)” series. The next size down, the 7310 BECBP /DB, has a bore of 50 mm and a dynamic rating of 121.5 kN. The next size up, the 7312 BEP /DB, has a bore of 60 mm and a rating of 154.87 kN (+21%).
Common problems on bearings like the 7311 BEP /DB
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 7311 BEP /DB
What are the dimensions of a 7311 BEP /DB bearing?
The 7311 BEP /DB has a bore of 55 mm and an outside diameter of 120 mm. It is a matched pair of angular contact ball bearings (back-to-back). Series: 73 medium (pair).
What is the load rating of a 7311 BEP /DB bearing?
In the Rotec AI catalogue the 7311 BEP /DB has a basic dynamic load rating C of 128.47 kN and a basic static load rating C0 of 110 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a 7311 BEP /DB bearing?
Use the Cross-Reference tool in Rotec AI to check brand equivalents for the 7311 BEP /DB.