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 the complications of a relay for a tail lamp indicator and an overcharge prevention switch.
| Identifier | ExFiles\Box 60\3\ Scan013 | |
| Date | 13th April 1927 | |
| X4040 EFC {E. Fowler Clarke - Electrical Engineer} 2/T. 13th April, 1927. Mr. G.R.N.Minchin, Messrs. Peto & Radford, 50, Grosvenor Gardens, London, S.W.1. Dear Mr. Minchin, Answering yours M {Mr Moon / Mr Moore} /5. of the 7th inst, with reference to the tail lamp indicator, the objection was not so much to the complication of an extra lamp as to the relay which was necessary to operate it, and this piece of apparatus would still be necessary if the same lamp is used for both purposes. Moreover the relay itself would have to be more complicated, as it would need a shunt and a series coil (in opposition to one another) in order satisfactorily to use the lamp for both purposes, otherwise when the water reached the pre-determined temperature in the day time, the ordinary 'regarde' relay would buzz. The rough diagrams attached may make this clear. In fig.1 the normal position of the relay contacts is "on", and the lamp current pulls them off. In fig.2 the normal position of the relay contacts would have to be "off", so that the lamp lighting current from the thermometer contacts can pass through the relay. Then when the tail lamp is switched on, they would still have to remain "off" until the current through the series coil on its way to the tail lamp failed when the shunt coil would close the contacts and light the lamp. Therefore we should still have quite a good deal of complication. Concerning the overcharge prevention auto switch, I am sending you a copy of our report EFC {E. Fowler Clarke - Electrical Engineer} 2/T15.3.27, with which I think you will be interested. These switches are still working quite satisfactorily on the two cars to which they are fitted and we have a further switch to fit to the next car which goes to Mr. Royce upon his return. Yours faithfully, FOR ROLLS ROYCE LIMITED | ||