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).
Redesign and material specifications for a ballast resistance unit on a 40/50 HP chassis.
| Identifier | WestWitteringFiles\C\May1919\ Scan20 | |
| Date | 24th May 1919 | |
| To DA.{Bernard Day - Chassis Design} from E.{Mr Elliott - Chief Engineer} Copy to CJ. " " BN.{W.O. Bentley / Mr Barrington} " " BY.{R.W. Bailey - Chief Engineer} " " EH. " " EFC. ORIGINAL. E1/26/24/5/19. 1919 RE BALLAST RESISTANCE ON IGNITION COIL X.3445 40/50 H.P. CHASSIS. X.3129 RECEIVED We send you herewith drawing No. Lec.1094 shewing the above redesigned in accordance with Mr. Royce's wishes. The resistance unit is protected by a little aluminium casing, the two halves of which should be made if required, in quantity, as die castings. If the undercut which forms the heat insulating feature on the top half between the flange and the body cannot be conveniently formed in the die casting, then it should be machined out. The base which carries the resistance should be made in slate or marble for immediate requirements, but for production purposes, as soon as such can be got going, the material should be ignition plug earthenware. The terminal bolt on the lower half of the casing has a square stem to prevent rotation, surrounded by a square bakelite bush. Bakelite was chosen as it was not thought convenient to make this square bush out of micanite. As this is probably the coolest spot on the casing, it is thought that the bakelite will not suffer owing to excessive temperature. All other insulation on the job should be micanite. The top and bottom plates of the resistance unit should be made from stainless steel, in accordance with Mr. Royce's instructions, as a strong material is required which, at the same time will not tarnish, and spoil its ability to make a good contact. If it is found necessary, the screwed collar which forms the means of clamping on the upper half of the casing, shoul (Contd.) | ||