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).
Technical report on the examination and failure analysis of dynamo No. 293.
| Identifier | ExFiles\Box 47\4\ Scan185 | |
| Date | 14th May 1924 | |
| To EY. from EFC. EFC1/T14.5.24. X 4383 X.4383 - DYNAMO No.293 EX CHASSIS 72-A-7-. -SHUFFLEBOTHAM- Examination of the dynamo shows that the fault in this instance is practically as described in our EFC1/T10.5.24 in connection with dynamo No.101 ex chassis 48-G-4 - Field. As in that other case, there is no evidence of mica projecting between the commutator segments being the cause of the trouble. On the other hand, there is evidence that trouble has been due to excessive output, caused by an erroneous position of the control brush, it being again obvious from inspection that the control brush is distinctly more retarded than on the average machine. Our test shows that with the control brush bedding properly, the output is high. It would certainly seem to indicate that the machine was incorrectly set to the production test. Again we were able to demonstrate that the melting of the solder was caused by heating, due to excessive output, because by running the machine on a slightly exaggerated terminal volt-ampere characteristic, it was readily possible to melt the temporary solder from the commutator connections, the carcase temperature at the time being 86ºC as against the corresponding reading of 71.5ºC of a normally correct machine, but set for slightly higher output than on the production test. There was no evidence that the failure of the machine was due to a broken battery circuit. We return the dynamo herewith in a condition of commutator solder thrown. EFC. | ||