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).
Repeated failure of a dynamo on chassis 99-MC and the results of its examination.
| Identifier | ExFiles\Box 70\3\ scan0310 | |
| Date | 16th September 1927 | |
| To BY.{R.W. Bailey - Chief Engineer} from EFC. c. Mr. Brock. X.8787dc EFC4/T16.9.27. 40/50 HP. DYNAMO CN.{Mr Chamberain}35. EX CHASSIS 99-MC. We have duly examined this machine referred to in your note (from Mr.Brock) of 14.9.27. It is therein stated that this is the third dynamo returned from this chassis in less than 8 weeks. This naturally suggests that there is something wrong with the electrical system outside of the dynamo, a suggestion which is supported almost to the point of certainty by examination of the machine in question. It may be remembered that in the case of the two previous machines there were other reasons suggested as likely to account for the trouble, in the absence of an exterior fault, but the present evidence suggests that the main cause of the two previous failures may have been other than that referred in in our reports. In the words of my assistant's report :- "The evidence resulting from an examination of this machine points to the fault being elsewhere on the electrical system of the chassis. Overheating of the whole armature appears to have occurred, as solder has been thrown from the commutator connections and also from the banding wires on the pulley end of the armature. The control and negative brushes were found the wrong way round in the holders, but the bedding was such as to suggest that the machine had been running with them in their correct positions, and that they were not moved until after trouble of some sort had occurred. It was found, further, that the machine has a control brush angle of about 124°, which means that the normal output was probably lower than that of the late standard machine; the C angle of which was 122°. The insulation of the machine is O.K. Judging from these facts, it appears most unlikely that this dynamo was originally at fault." It becomes necessary, therefore to indicate what other parts of the electrical system should be inspected in order to discover the reason of this failure. The following points should be carefully examined :- Contd. | ||