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).
Inconclusive investigation into a failed chassis dynamo, model JS.95M.
| Identifier | ExFiles\Box 70\3\ scan0338 | |
| Date | 16th December 1927 | |
| X 8982do To SFT.{Mr Swift} from EFC. c. Mr. Brock. c. Mx.{John H Maddocks - Chief Proving Officer} EFC1/T16.12.27. CHASSIS DYNAMO JS.{Mr Johnson's Secretary}95M. We have duly examined this dynamo, but we cannot arrive at a definite conclusion with the evidence of the dynamo only; though we are assured by Mr. Brock that the only thing wrong with the distribution box was the fusing and burning of the contact points, the residual magnetism of the core, if found to have been incorrect, would have offered some evidence. We understand that the whole system was O.K. on the dynamometer and the car was run round to the Test Dept. on the battery used on the dynamometer. Then this battery was removed and another one put in its place. We cannot say with any degree of certainty that this was the case; but the nature of the failure is such as would probably have been explained by the polarity of the dynamo having been reversed between the dynamo running and subsequent excitation on a car. We are assured that the Test Dept. battery was put on and connected the right way round, and that when the ammeter read the discharge current with the points in contact it was reading on the correct discharge side of the scale, so that it would not appear that the battery was finally put on the wrong way round. Supposing, however, the machine had for some reason been touched with a battery with the wrong polarity so as to get excited the wrong way round, although we do not say that such a thing must have happened, this would have been an explanation of the observed effect. Apart from that, and the incompleteness of the evidence from our point of view, I am afraid we cannot offer any exact explanation of the failure, and can only suggest that it be treated as a pure accident of a type of which the exact explanation must remain a mystery. We have no doubt whatever that we could explain the whole things if we had exact particulars of everything that was done. We are returning the machine to Mr. Brock. EFC. | ||