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).
The use of materials like Bakelite, Ebonite, Stabilite, and Tensite for electrical components, comparing American and German practices.
| Identifier | ExFiles\Box 39\3\ Scan075 | |
| Date | 10th December 1920 | |
| -2- Contd. conductor for subsequent sparks. For these positions it is necessary to use hard rubber without any lamp-black or other carbonaceous filling material or else to use the German stabilite or the hightensite of the American Bosch Company which is claimed to be a similar material. The American Bosch claim to have discovered a method of molding high tensite for magneto distributors which they claim was not molded in the German Bosch magnetos at the time they took over the business. Beyond the uses specified above, Ebonite, (or "hard rubber" as it is called here) is not used except for experimental work. Rubbing Contacts. As already written, Bakelite impregnated linen is used extensively by a great number of makers for the rubbing contacts of contact breaker rockers. The American Bosch use it on the battery ignition and are about to adopt it for the magneto rubbing contact and bush instead of "bone fiber", and the Eisemann uses it for rubbing contact and bush. Use of Bakelite sheet materials etc. in coils. Mr. Royce will notice in our letter Cy6/G24.3.21 that we make suggestions for using Bakelite materials in sheet, rod or tube form to replace practically every piece of insulation at present made from paper, fiber, ebonite or other similar materials. This would be strictly in line with American electrical practice, which is undoubtedly very much advanced because of the extensive use of these materials. In connection with the winding of the coils, we have suggested in letter Cy6/G24.3.21 that these should be wound with enamelled wire and not impregnated. This practice is confirmed by the two letters attached from the Westinghouse and Bosch Companies in reply to my letter Cy3/G21.3.21, of which copies are also enclosed. Even the ignition coil would be treated in this way in American practice, as witness the American Bosch battery ignition coil. Impregnation is not generally recommended on coils wound with enamelled wire because of the impregnating varnish softening the enamel covering of the wire. Bakelite varnish impregnation cannot be used except | ||