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).
Failure analysis of a Dynamo EB.35 from chassis 92-HC, which overheated and melted solder at the commutator connections.
| Identifier | ExFiles\Box 70\3\ scan0260 | |
| Date | 23th November 1926 | |
| To BY.{R.W. Bailey - Chief Engineer} from EFC. c. to Sft{Mr Swift}/Mr. Brock. c. Mr. Strong (Repair). X&J R3do EFC3/T23.11.26. DYNAMO EB.35 - EX CHASSIS 92-HC. Reference the latter half of your note EY11/H15.11.26. Although in the case of this machine the solder has melted and run, especially at the commutator connections, the armature as a whole does not appear to have been excessively hot. It does appear that some amount of sparking may have been taking place at the commutator and a certain amount of local heating produced there. This machine is one of those with 120° angle between the control brush and the main positive brush, and would therefore be giving a bigger output than our present standard. We consider that in this case the failure of the dynamo armature has occurred due to no external reason, but is one of those cases which, through an unfortunate combination of circumstances, has attained such a high temperature under normal running as to arrive at the point of running the solder from the connections. This dynamo happens to be one which passed through our hands on the monthly production test, 1.8.25, and according to observations taken on the machine at that time, it would have given a peak output of 13.5 amperes at 18.0 volts, on the road, in the normally hot condition. We return the machine herewith, but if convenient should like to have this armature returned to us with the commutator connections lifted, so that we may make a test on the condition of the armature EFC. coils | ||