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).
Letter discussing car lighting systems, specifically dynamo output speeds and bulb specifications.
| Identifier | ExFiles\Box 61\2\ scan0103 | |
| Date | 22th November 1918 | |
| 22.11.18 ml/H221118 750 500 15 22/11/18 4 Re our Car Lighting System. X.3374 EFC7/CT141118 - We do not consider that a dynamo giving the full output at 15 miles per hour is likely to be perfectly satisfactory, as cars used at night, especially in Town, are rarely able to run at an average speed of anything like 15 m.p.h. Moreover, we believe that the majority of the large number of Rolls-Royce ambulance cars now on the road are fitted with a C.A.V. dynamo, which gives the maximum output at a speed between about 8 and 10 m.p.h., and you will of course realise the undesirability of our supplying a dynamo which does not give full output until a speed of 15 m.p.h. is reached while cars are on the road with dynamos giving full output at a much lower speed. On these ambulance cars we understand the dynamo is driven from the front of the engine. The usual candle-power of the bulbs fitted in headlamps is 100 c.p. This is a half Watt bulb and can only be used satisfactorily with a special type of lens. Messrs. Lucas largely fit this size bulb, and name their special lens a "Difusa." The candle-power of the sidelamp bulb is usually 6 c.p., and of the tail lamp bulb, which usually has a carbon filament, 2 c.p. We send you herewith a copy of the large R.R. catalogue, and also copies of C.A.V. and Lucas lighting catalogues. All these are out of date, but are the latest that can be supplied. We also attach a print showing output curve of C.A.V. N.G.R.R. dynamo, which is C.A.V's latest production, and the machine they propose fitting to R.R. cars after the War. If there is any further information we can obtain for you, kindly let us know. C. [STAMP: S.D. RECEIVED 22 NOV 1918] | ||