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 concerning the materials and performance of American Bosch battery ignition systems.
| Identifier | ExFiles\Box 61b\4\ scan0018 | |
| Date | 4th March 1921 | |
| CC Mr. Belnap Mr. Beaver Mr. Nadin Mr. Bagnall Mr. Hulley Mr. Southern Oy4 - G 4321 March 4, 1921 Mr. Claude Johnson, Managing Director, Rolls-Royce Ltd., London, England. Attention: Messrs. Royce & Hives. Dear Sir:- X.4275 Re: American Bosch Battery Ignition In reference to Mr. Royce's letter on the above subject (R11/G16/2/21), we wish to draw Mr. Royce's attention to the following points: Contact Breaker: X 1818. X 1819. X 2894. The points are Tungsten, which is used here universally on battery ignition and gives absolute satisfaction so long as the current is not excessive. The running current on the 6 volt ignition in this case is about 1 amp (on the 12 volt I suppose it would be about the same). From what I can gather, there is some doubt in the minds of American ignition manufacturers whether Tungsten is as satisfactory in the moister climate of England as it is here. Platinum is always used in the better grade magnetos because of the greater current, though Tungsten is apparently found satisfactory for trigger-operated magnetos on farm machinery and the like. The rubbing contact is a special Bakelite/composition and silk with the grain normal to the rubbing surface. This is said to wear very little. The Westinghouse battery ignition makes the entire cam of this material and claims on test a wear of only one thousandth in a bench run equivalent to fifty thousand miles at sixty miles an hour. Distributor: X.800 X.3917 X.3309 The distributor has a central electrode on the rotor of pure nickel, while the six terminal points are of brass. When | ||