71904 CD bearing
20 × 37 mm · dynamic rating 6.05 kN · static rating 3.2 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
71904 CD specification
| Designation | 71904 CD |
| Type | Super-precision angular contact ball bearing |
| Series | CD — high capacity (light) |
| Bore diameter d | 20 mm |
| Outside diameter D | 37 mm |
| Basic dynamic load rating C | 6.05 kN (6,050 N) |
| Basic static load rating C0 | 3.2 kN (3,200 N) |
| Ratio C0/C | 0.53 |
| Speed guide, grease lubrication | 43,000 rpm |
| Speed guide, oil-air lubrication | 63,000 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.
Basic rating life of the 71904 CD
Basic rating life is L10 = (C / P)p million revolutions, where P is the equivalent dynamic load and p = 3 (ball bearing). For a 71904 CD with C = 6.05 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 1.21 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the 71904 CD
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 71904 CD is used
Super-precision angular contact bearings are used where rotational accuracy, stiffness and high speed matter, typically in machine-tool spindles. In this catalogue the CD — high capacity variant is listed with both grease and oil-air speed guides.
Other sizes in the same series
The 71904 CD belongs to the “CD — high capacity (light)” series. The next size down, the 71903 CD, has a bore of 17 mm and a dynamic rating of 4.16 kN. The next size up, the 71905 CD, has a bore of 25 mm and a rating of 6.76 kN (+12%).
Common problems on bearings like the 71904 CD
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 71904 CD
What are the dimensions of a 71904 CD bearing?
The 71904 CD has a bore of 20 mm and an outside diameter of 37 mm. It is a super-precision angular contact ball bearing. Series: CD — high capacity (light).
What is the load rating of a 71904 CD bearing?
In the Rotec AI catalogue the 71904 CD has a basic dynamic load rating C of 6.05 kN and a basic static load rating C0 of 3.2 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a 71904 CD bearing?
Use the Cross-Reference tool in Rotec AI to check brand equivalents for the 71904 CD.