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).
Continued report on testing 'B' coil and ballast lamp configurations for a vehicle's electrical system.
| Identifier | ExFiles\Box 34\1\ Scan044 | |
| Date | 4th February 1919 | |
| R.R. 235a (500T) (S.D. 408. 26-4-17.) Bm. 2/156/13. -4- EFC6/T4.2.19. 2 Contd. tions, even with the 'B' coil, is very reasonable; we wish to try this out on the bench as a life test under exactly the same conditions that we are standardising, after which, we have in mind putting on some tungsten points which we have received from the Delco Company, and which we wish to try out in comparison. We are now rigging up on 49-GB as part of a ballast, a 12-volt 4 ampere metallic filament lamp. We shall, in future, always work with a .5 make ratio as suggested, and therefore we shall require a considerable additional ballast to this lamp. We have determined that 25" of ballast is suitable in series with this lamp, the two together making up such a resistance that signs of missing only begin to occur at 2000 R.P.M. of the contact breaker. We think this will be safe on the car; if it is not, we can easily reduce the ballast a little. We have added to the photostat copy of consumption curves a curve showing the consumption at different speeds with this new condition of .5 make ratio and resistance as above. It will be noticed that this curve has been considerably flattened out as compared with that for the A.1 type coil. We think this condition represents what we should standardise. We shall try this on the car and notice the amount of light given by the lamp at slow speed and high speed as we have done on the bench. If we wish to use a lamp as the only ballast, what it appears to require is not a 12 volt lamp of higher resistance (because this would be lit up too brilliantly), but rather a 18 volt or 24 volt lamp of the same gauge of filament as the present lamp. We might try and obtain such a lamp. E.F.C. | ||