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).
Recommending a new, higher voltage bulb for the radiator thermometer indicating lamp to prevent it from burning out.
| Identifier | ExFiles\Box 175\4\ img098 | |
| Date | 27th October 1927 | |
| To HY.{Tom Haldenby - Plant Engineer} from EFC. X3875 EFC4/T27.10.27 BULB FOR RADIATOR THERMOMETER INDICATING LAMP. Owing to the tendency of these small 12 volt bulbs to burn out and also to take a larger current than is necessary through the delicate contacts of the thermometer, we obtained two 16/18 Volt 2.4 watt lamps from the G.E.C. Attached please find copy of Mr. Lidsey's report on the running of these on two of the experimental cars. We recommend that this type of bulb be adopted for this purpose, and I think you will agree that being only an electric bulb, i.e. an item always liable to failure, a standardisation sheet is quite unnecessary. The full particulars of the bulb in question are :- 16/18 Volts, 3 watts, .2 amp. type S.7954 with Edison screwed caps. Personally we doubt whether the fusing of the contacts mentioned in the report was due to the lamp current. | ||