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).
Technical memorandum discussing the features, materials, and cost of American Bosch ignition coils and distributors.
| Identifier | ExFiles\Box 61b\4\ scan0023 | |
| Date | 7th March 1921 | |
| Oyl - G 7321 March 7, 1921 Mr. Claude Johnson - Sheet 2. ignition to meet our requirements. X.918 X.2494 X.3513 X 800. [All numbers are struck through] (3) Coil: The American Bosch coil is claimed by the makers to be waterproof in the sense that it will operate perfectly under a shower of water representing a heavy rain. With regard to its cost, this is $5.00, but of course this low price is entirely due to the enormous numbers which are produced. The makers claim a high efficiency for the coil, due to the close packing of the wires, which are not silk covered but have a very thin insulation of enamel. [Faint watermark 'COPY' overlaid on text] The brown moldings to which Mr. Royce refers are "High-Tensite", corresponding closely, we are told, to the German Bosch distributor material. This is only used by the American Bosch Company for rubbing tracks of distributors, etc. where Bakelite gives trouble with "spark tracking". (The Delco Company use hard rubber tracks for this condition.) The American Bosch Company use this material, however, for moldings in new designs and experimental work, but will change these moldings to which Mr. Royce refers to Bakelite, now that the coil is fully standardized. (4) Distributor: Reference was made in my letter of March 4 to the little ventilation holes in the distributor base. Referring to the cost ($14.00) of the Bosch battery ignition, we think this is entirely due to the quantity produced and the complete tooling of the job. X.3916 X.3917 X.3513 [All numbers are struck through] The American Bosch Company produces in normal times several thousand sets of magnetos and battery ignitions every week. There is no fitting or filing work in the whole factory, even burrs from machine operations being removed by special tools without hand work. The assembly work is done largely by girls, and is mechanical as far as possible. Armature coils are wound on small revolving spindles with a mechanical traverse-like winding the shuttle of a sewing machine, the insulating enamel-silk sheets being applied by hand after winding each layer. Everything possible is pressed or molded. The magnetos are tested on long benches, several hundred at a time. On quantities of two or three hundred magnetos which differ from standard, the Bosch Company put them through a special department called the "special contract" department, considering such quantities too small to put through their regular production. We would suggest that on quantities such as ours, the molding dies for Bakelite would be prohibitive in price. | ||