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).
Internal memorandum discussing the design and operation of a double battery ignition system.
| Identifier | ExFiles\Box 61b\4\ scan0183 | |
| Date | 7th February 1931 | |
| X6105. To E.{Mr Elliott - Chief Engineer} from EFC. c. Wor.{Arthur Wormald - General Works Manager} c. Sg.{Arthur F. Sidgreaves - MD} Hs.{Lord Ernest Hives - Chair} EFC4/AM/7.2.31. X. 6105. DOUBLE BATTERY IGNITION. In thinking over the scheme suggested in E1/M2.2.31 and again referred to in E7/M7.2.31, it appeared to us that the idea therein contained is the utilisation of two contact breakers 180° apart operated by the same hexagonal cam together with two independent coils supplying their high tensions to a 12 point distributor as in sketch. As you state, one arrangement appears to be that adopted in the Stutz 8 cylinder concerning which we reported in our EFC2/T16.12.27 as follows :- "IGNITION. This is dual battery ignition by two coils and single 16 point distributor. There are two H.T. rotor pick-up carbon brushes each leading to a jump spark blade. One brush is carried in the centre of the distributor head and bears on the centre of the rotor which is in communication with the other blade. The other brush communicating with the other blade is carried eccentrically on the other rotor and bears on a brass ring in the head. A single 8 point cam operates two contact breakers in synchronism (placed 180° apart) each working one coil. Thus the distributor is only a mechanical superposition of two independent 8 cylinder distributors in a single unit, there being really no electrical relation between the two alternate sets of points, each set of which is suitably connected to its corresponding set of spark plugs." Beyond the above we have given a little thought to the matter and in particular as to whether it would not be possible to make each ignition fire all 12 plugs in turn i.e. first one side of the engine and then the other so that at one moment (A) ignition would be firing (a) sparking plug and (B) ignition (b) sparking plug | ||