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).
Specifications for the installation of insulated conductor bars and associated fixings, including a diagram of washer arrangements.
| Identifier | ExFiles\Box 180\M6\ img072 | |
| Date | 5th July 1927 guessed | |
| (3) say lower and less difficult to insulate, or for the object of the doubtful insulation avoiding the required high insulation of a public or large distribution plant. (1) The conductors should be bars 18 ft. long, if fixed every 6 ft. to allow of (2) central fixing and arranged to expand and slide past fixing each side, and extend 3 ft. beyond so as to have fishplates bolted tightly to one bar, and sliding tightness to the other; the joint could be near one fixing, or halfway. (3) At each fixing there is a plate so that one stud or set screw into the 12 X 6 I could fix all 3 bars. (4) A cast brass or malleable iron box is provided for each fixing and each bar, into which a bolt is placed so that bakelite or other insulation can entirely encase the bolt head and form an insulator, somewhat as shewn in the sketch, and might form a standard insulator for carrying such bars, or the collecting rod base. (5) It will be noticed that such an insulator does away with the tubes, and the difficulties and defects of the insulation at the ends. (6) This brings me to the glaring defect in the arrangement of your insulated tubes and washers; when these have to be used, either round or square, the tubes need only be thin, but the washers must be very thick, and the tube can be cemented into one washer. [Diagram Text Left] But thick insulating washers, and stiff metal washers. [Diagram Text Right] Thin metal plate only needed. Thin insulating tube only needed. (7) The upper metal washer and plate can form water petticoat for rain. It will be seen that thick washers give greater surface insulation outside and inside. This feature has been preached by me for thirty to forty years. Surface of insulation can dry outside but often moisture getting inside cannot dry out, and insulation breaks down. o | ||