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).
List of material specification changes for various electrical components and coils.
| Identifier | ExFiles\Box 34\3\ Scan079 | |
| Date | 24th March 1921 | |
| -2- Contd. Qy6-G24.3.21. (2) Contd. Washers in coils F-7054, F-6710 and G-4288 changed from Presspahn to Bakelite Dilecto, grade XX, or Bakelite Micarta (paper base). Insulating plate F-7269 changed from Ebonite to one of the above materials. Bolt F-7049 should be sweated to the terminals F.7045 and F.7084. Insulating tube G-4287 should be changed from paper to materials as above. Coils wire should be changed from silk covered wire to a good grade of enamelled wire. Outsides of coils bound with string dipped in varnish and baked without impregnating. (3) Main Switch: Insulating plate E-12965 changed from asbestos composition to Contintental Bakelite Sheet or Bakelite Micarta sheet (duck base). Insulating washer E-12955 changed from Micanite to Bakelite Micarta (paper base) or Bakelite Dilecto grade XX. Insulating washer E-12953 same as above Insulating washer E-12948 " " " Insulating tube E-12956 " " " Insulating tube E-12957 " " " Magnet coil. washer E-12961 same as above. tube E-12970 " " " washer F-6710 " " " washer F-6711 " " " Coils wound with enamelled wire wrapped with string dipped in varnish without impregnating. (4) Push Button Switch: Base G-5536 changed from Ebonite to Bakelite or Condensite. Plunger contact G-5534 changed from Fiber to Bakelite, linen rod. (See my letter of Mar.23 - Qy4/G23321). Tail lamp junction block plate, changed from Teak to Bakelite or Condensite. The changes recommended above are in line with the best American electrical practice, and we think that the fewer types of insulation used together with the fact that these materials can be bought in the molded condition or as pressings, and that impregnation of the coils would no longer be necessary because all the insulation would be of weatherproof material, would cheapen the production of the electrical instruments. Contd. | ||