6308 bearing
40 × 90 mm · dynamic rating 42.3 kN · static rating 24 kN. Dimensions, load ratings, designation meaning, life estimates and equivalent parts.
6308 specification
| Designation | 6308 |
| Type | Deep groove ball bearing |
| Series | 63 medium |
| Bore diameter d | 40 mm |
| Outside diameter D | 90 mm |
| Basic dynamic load rating C | 42.3 kN (42,300 N) |
| Basic static load rating C0 | 24 kN (24,000 N) |
| Ratio C0/C | 0.57 |
| Speed guide, grease lubrication | 11,000 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.
What the designation 6308 means
| Code | Meaning |
|---|---|
| 63 | Deep groove ball bearing, medium dimension series |
| 08 | bore code "08" = 8 × 5 = 40 mm |
Basic rating life of the 6308
Basic rating life is L10 = (C / P)p million revolutions, where P is the equivalent dynamic load and p = 3 (ball bearing). For a 6308 with C = 42.3 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 8.46 kN on this bearing. Use the Load Calculator to work out P for your actual radial and axial loads.
Equivalents of the 6308 from other brands
Deep groove ball bearings follow the ISO basic designation system, so the base number 6308 means the same bore (40 mm) and outside diameter (90 mm) at the major makers. Only the suffixes differ. For sealed versions, common suffixes are -2RS1 or -2Z at SKF, -2RSR or -2ZR at FAG, DDU or ZZ at NSK, and LLU or ZZ at NTN. Check clearance class, grease and seal type before substituting. Rotec AI has no brand-specific part numbers catalogued for the 6308 yet; the Cross-Reference tool shows what is catalogued for other sizes.
Where the 6308 is used
Deep-groove ball bearings are chosen for: Radial load with moderate axial load; high-speed compact equipment. Typical equipment: Motors, fans, pumps, gearboxes, auxiliaries. Single/multi-row; insulated or stainless variants available.
Other sizes in the same series
The 6308 is size 9 of 21 in the Rotec AI catalogue for the “63 medium” series. The next size down, the 6307, has a bore of 35 mm and a dynamic rating of 35.1 kN. The next size up, the 6309, has a bore of 45 mm and a rating of 55.3 kN (+31%).
Common problems on bearings like the 6308
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 6308
What are the dimensions of a 6308 bearing?
The 6308 has a bore of 40 mm and an outside diameter of 90 mm. It is a deep groove ball bearing. Series: 63 medium.
What is the load rating of a 6308 bearing?
In the Rotec AI catalogue the 6308 has a basic dynamic load rating C of 42.3 kN and a basic static load rating C0 of 24 kN. Always confirm against the manufacturer's current catalogue.
What is the equivalent of a 6308 bearing?
Brand equivalents for the 6308 are not yet in the Rotec AI tables. Use the Cross-Reference tool to check other designations.