7228 BM /DB bearing
140 × 250 mm · dynamic rating 322.38 kN · static rating 424 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
7228 BM /DB specification
| Designation | 7228 BM /DB |
| Type | Matched pair of angular contact ball bearings (back-to-back) |
| Series | 72 light (pair) |
| Bore diameter d | 140 mm |
| Outside diameter D | 250 mm |
| Basic dynamic load rating C | 322.38 kN (322,380 N) |
| Basic static load rating C0 | 424 kN (424,000 N) |
| Ratio C0/C | 1.32 |
| Speed guide, grease lubrication | 3,240 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 7228 BM /DB means
| Code | Meaning |
|---|---|
| 72 | Angular contact ball bearing, light dimension series |
| 28 | bore code "28" = 28 × 5 = 140 mm |
| B | 40° contact angle |
| /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 7228 BM /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 7228 BM /DB with C = 322.38 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 64.48 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the 7228 BM /DB
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 7228 BM /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 7228 BM /DB is size 25 of 31 in the Rotec AI catalogue for the “72 light (pair)” series. The next size down, the 7226 BM /DB, has a bore of 130 mm and a dynamic rating of 301.32 kN. The next size up, the 7230 BCBM /DB, has a bore of 150 mm and a rating of 349.92 kN (+9%).
Common problems on bearings like the 7228 BM /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 7228 BM /DB
What are the dimensions of a 7228 BM /DB bearing?
The 7228 BM /DB has a bore of 140 mm and an outside diameter of 250 mm. It is a matched pair of angular contact ball bearings (back-to-back). Series: 72 light (pair).
What is the load rating of a 7228 BM /DB bearing?
In the Rotec AI catalogue the 7228 BM /DB has a basic dynamic load rating C of 322.38 kN and a basic static load rating C0 of 424 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a 7228 BM /DB bearing?
Brand equivalents for the 7228 BM /DB are not yet in the Rotec AI tables. Use the Cross-Reference tool to check other designations.