From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Lamp failure tests, detailing bulb types, hours run, and the nature of the failures.
| Identifier | WestWitteringFiles\F\January1921\ Scan41 | |
| Date | 25th January 1921 | |
| -4- Contd. | Failure No. | Lamp falling. | No. of hrs. run. | Nature of failure. | Remarks. | |-------------|---------------|------------------|------------------------------------------------------|------------------------------------------------------------------------------------------------------| | 1 | Mazda head. | 5 | Bulb loosened in cap. | | | 2. | Mazda head. | 8.5 | " | From this failure onwards, vibration was once again decreased and remained so until the end of the test. | | 3. | R.{Sir Henry Royce} Ediswan head. | 108 | Filament fell off one side. | Bulb started to discolour after 70 hours. | | @. | Mazda head. | 117 | Filament broke whilst lamp was under vibration, but not lighted. | The only case of failure whilst the lamps were not alight. | | 5. | Mazda head. | 201 | Filament broken. | | | 6. | Mazda head. | 277 | Filament broken. | | After two head lamp failures had occurred, two Mazda side lamps, 12 volt, 12 watt, were put in the holders and these two ran for 124 1/2 and 182 hours respectively under vibration before failing, the failure in each case being a looseness of the bulb in the cap. Regarding half watt lamps, it appears that those which have been latterly received have been considerably improved over the earlier ones. Many of the failures appear to have been due to inefficient connections to the filaments. Contd. | ||