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).
Continued report on vibration and life tests for various headlamp bulbs and holders.
| Identifier | WestWitteringFiles\F\January1921\ Scan40 | |
| Date | 25th January 1921 | |
| Contd. -3- Note:- After failure No.6, the voltage was increased to about 14.8. Discounting failures Nos. 2, 4, 5 and 11, which were really due to the holders, it would appear that the Royal Ediswan lamps are the best make, with the Mazda coming second. It must be remembered that the Mazda head lamps were of the half watt type. Subsequently we obtained some very much better Lucas lamp holders and fitted these up for further lamp tests, which holders have not failed in any way. With six of these holders rigged up on an angle iron attached to the plank, vibration and life tests of five 12-14 volt B.T.H. Mazda 24 watt, half watt type head lamp bulbs have been made, together with one Royal Ediswan No.11 12 volt, 36 watt, medium head lamp, it having been considered that the first Mazda half watt lamps made for 12 volts were not satisfactory. This further test has shown that these lamps as now made for 14 volts are very much more satisfactory. The voltage used for this last test was 14 volts from seven cells and the rig was gently vibrated, the vibration being rather less than formerly, as it was considered perhaps too severe. In this last test the lamps were not kept lighted for the whole of the period of vibration, but after being lighted for 5 hours approx., the lamps were turned off for 1 1/4 hours whilst under vibration, this procedure being repeated 44 times in all. The results of this test were as follows :- Contd. | ||