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).
Modifications to improve the function of a trembler on a coil for 7-CA.
| Identifier | Morton\M3.3\ img011 | |
| Date | 2nd May 1918 | |
| R.R. 235 A (400 T) (S C. 536. 15-2-16) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1546 7 CA To' EFC. from R.{Sir Henry Royce} C. to CJ. X.682 X.562 Re - Tremblers on 7-CA. 682 The trembler on the coil sent with 7-CA was not a success, because the platinum blade made contact so quickly, that the armature had not returned to its stop. I have lately come to the conclusion that this is necessary for the good and regular working of any trembler. I altered this as follows:- The return of the iron armature was given greater accelleration by removing the brass rivets and the leather disc, and by filing away all unnecessary iron far removed from the centre of motion, and by slightly increasing the pressure of the spring which might in future be made of coarser gauge wire, probably in steel. Secondly, the blade carrying the platinum has been reduced in speed of return by reducing the set of the spring to about one quarter of the amount it had. This too, could in future be improved by making it/or thicker metal. (the blade) This pattern of trembler is by far the best I have seen or tried, and it is only the proportions that were bad. I have no means of measuring the current, but I feel sure it is not excessive because at each stroke of the trembler the circuit is clearly broken for a longer period. The ignition is much more regular, especially at low speeds, and I have reason to believe from experience with 49-CB, that the platinums will last for a much longer time. This matter is important only from a repair point of view. Send me as soon as convenient another 6 volt R.{Sir Henry Royce} Coil or at the moment a 4 volt one would do. R | ||