Japanese housing bearings
NTN Housing Bearings
Application & rating life
Typical rating life (Ln, in operating hours) used when selecting a bearing for a given service classification. Use it as a starting reference — actual life depends on load, speed, lubrication and environment.
| Service classification | Machine application | Life time Ln (h) |
|---|---|---|
| Machines used occasionally | Door mechanisms, garage shutter | 500 |
| Short-period or intermittent service, interruption permissible | Household appliances, electric hand tools, agricultural machines, lifting tackles in shops | 4 000 – 8 000 |
| Intermittent service — high reliability | Power-station auxiliary equipment, elevators, conveyors, deck cranes | 8 000 – 14 000 |
| Machines used 8 h/day, not always full operation | Ore wagon axles, important gear units | 14 000 – 20 000 |
| Machines fully used for 8 hours | Blowers, general machinery in shops, continuous-operation cranes | 20 000 – 30 000 |
| Machines continuously used 24 h/day | Compressors, pumps | 50 000 – 60 000 |
| 24 h/day with maximum reliability | Power-station equipment, urban water-supply equipment, mine ventilators | 100 000 – 200 000 |
Source: NTN engineering data — rating life by application.