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).
Diagnosing a faulty Goshawk Dynamo, identifying worn and incorrectly positioned brushes as the cause of overheating.
| Identifier | ExFiles\Box 47\4\ Scan171 | |
| Date | 25th February 1924 | |
| X 4383 To BY.{R.W. Bailey - Chief Engineer} from EFC. c. EP.{G. Eric Platford - Chief Quality Engineer} c. SFT.{Mr Swift} for Mr. Brock. EFC1/T25.2.24. X.4383 - FAULTY GOSHAWK DYNAMO No.208. FROM Chassis 59-S-6. Reference memos EP{G. Eric Platford - Chief Quality Engineer}/CEP1/H18.2.24 and BY7/P19.2.24, please find attached copy of my assistant's report on examination of this machine. It will be seen from this that the original fault is perhaps a little obscure because it appears that the spare set of brushes provided for this machine have been put on, and in doing so have been put on in inter-changed positions. Contrary to the statements in the two memos referred to, the brush that has worn away is the negative brush on the machine (though the positive brush as handed). The real final fault on the machine is that the brush has worn down to the limit of springing and arcing and overheating has thus occurred. As previously pointed out, it does not seem possible, and we know of no case where a positive brush would cause, or has caused, overheating. Bad contact at this point is not so serious, because excitation is immediately reduced. Bad contact at the negative brush leaves the machine fully, and more than fully, excited. EFC. | ||