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).
Electrical tests of a dynamo and battery ignition system on a Phantom chassis.
| Identifier | ExFiles\Box 70\3\ scan0150 | |
| Date | 27th May 1926 guessed | |
| -2- Contd. Test on terminals of off side wing lamp with lamps on shewed 17 volts current available. Further tests with Weston ampere meter across the battery ignition points revealed that there was a rise of amperage from 2 to 2.75 amps. as soon as dynamo charging switch was put on. Voltage across coil gave the following readings. With dynamo off 7.5 volts; with dynamo on 10.5 volts, i.e. a rise of 3 volts. All these tests clearly reveal that an excessive current is being broken across the points of battery ignition when running with charging switch on, and this seems to me to be more than enough to account for excessive pitting of points. Dynamo is in perfect condition and the only cure is a new dynamo or adjustment to the present dynamo which will cut down excessive voltage now generated but leave amperage as at present. There seems to be no means of adjusting 3rd brush, perhaps Derby are rise on their generator about this. I think that you will agree that I have at last found out something which at any rate on this particular Phantom will go a long way to solving the problem. Apologising for bothering you with all this but I know that you are interested in finding out any fault on R.R. Phantom chassis. Yours very sincerely, (Sgd) P.S. Sidney. (Contd). | ||