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 from General Electric Company regarding the use of tungsten in automobile ignition apparatus.
| Identifier | ExFiles\Box 35\5\ scan 080 | |
| Date | 18th November 1919 | |
| (copy) X 2694 GENERAL ELECTRIC COMPANY General Office SCHENECTADY, N. Y. Nov. 18, 1919 Dict. Nov. 17. Mr. M.{Mr Moon / Mr Moore} Olley, Rolls-Royce of America, 701 City Realty Bldg., Springfield, Mass. Dear Sir:- In reply to your letter of November 10th, regarding tungsten. Tungsten is being used in this country upon all types of automobile ignition apparatus in place of platinum with the exception of the magneto. It is used in the form of a tungsten disc welded by a special process to an iron tack or screw. For this purpose, it is more satisfactory than platinum because of its high melting point and because it will not stick or weld together under ordinary conditions. The melting point is approximately 3000°C. We are attaching herewith some sketches of the ordinary tack and you will note that upon one of them, we have given the range of dimensions which are used at the present time. Practically all of the dimensions used for automobile purposes in this country come within these dimensions. The contacts are supplied in their finished form mounted upon the iron tack or screw, the price depending upon the diameter and thickness of the tungsten, there being no charge for the iron tack or screw. Tungsten is very difficult to work and cannot be handled except by special processes and therefore, we do not believe you would have any success in experimenting with tungsten wire and would suggest that you fill out one of the attached sketches with the dimensions which you would require and we would be glad to supply you with some finished contacts, no charge, for experimental purposes. Tungsten wire or rod has been used for spark plug purposes with considerable success, but it is very difficult to hold and is rather expensive for this purposes, because of the necessity of using a long piece of rod or wire. We would be glad to send you a sample piece of tungsten under separate cover for experimental purposes. It is well to bear in mind that the tungsten is extremely hard and therefore somewhat brittle and also that it cannot be welded, soldered, machined or brazed by ordinary methods. Very truly yours, SUPPLY DEPARTMENT. (signed) R.D.Thomsen. RDT:ES | ||