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).
Comparative performance of different battery ignition systems, focusing on the mechanics and longevity of their contact points.
| Identifier | ExFiles\Box 35\6\ scan 334 | |
| Date | 6th October 1927 | |
| X2894 To OY. from EFC. c. EY. EP.{G. Eric Platford - Chief Quality Engineer} EFCA/T6.10.27. RE BATTERY IGNITION. X2894 X4281 XU581 We have received your note of Sept. 12th concerning ignition. We have also received copies of your OY16-E91327 with attached report on the running of the De Jon ignition on the bench and on chassis MX.{John H Maddocks - Chief Proving Officer}2 and attached prints A.10862/3. We note from your OY16-E91327 that you are sending over a pair of De Jon ignition sets comprising ignition heads and coils, also that you are proposing this change from the U.S.A. Bosch as a temporary step. We shall put one of these sets through a 10,000 mile test on the bench and let you know the result. According to our own experimental results, as I think I told you before, Delco-Remy ignition is a much more satisfactory proposal. We gave you a number of reasons for it being better than the U.S.A. Bosch, to which may be added the fact that in our experiments the rubbing block wears away more quickly. From your bench tests of the De Jon this also appears to be the case on that equipment. We have since had a certain amount of further evidence that the working of the U.S.A. Bosch contact points is nowhere near as good as the Delco-Remy. This brings us to the question of contact points. We are carrying out a number of experiments with varying conditions of the mechanics of the contact points, so that we can ultimately obtain equally good results with tungsten contacts on our own ignition as we do on the Delco-Remy. All these experiments have gone to show that the performance of the points is not a question of the electrical characteristics of the circuit, within reason, but is purely and simply a question of the mechanics of the contact breaker. Perhaps it is unnecessary to give you these experiments in detail, but we would very definitely emphasize that that is the conclusion to which the experiments have forced us, and if you saw all the results I am sure you would agree that all the evidence goes to show that it is this, and this alone, that determines the correct functioning and long life of the contact points. There is a particular kind of small scrubbing action which is necessary, i.e. the points must meet and part in some definite way and then they will go very nicely and there will be no blue oxidation of the point. This condition we can get every time on the Delco-Remy, even when we vary the electrical conditions of the circuit. We are approximating to it with various arrangements for mounting the fixed point which gives it a smaller amount of flexibility and allows movement in a Contd. | ||