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).
The investigation of a faulty Goshawk dynamo (No.48) from chassis 45-G.6, caused by an incorrectly assembled control brush.
| Identifier | ExFiles\Box 47\4\ Scan151 | |
| Date | 9th January 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. EFC7/T9.1.24. X.4383 - GOSHAWK DYNAMO FROM CHASSIS 45-G.6. PARKINSON. Herewith we return this dynamo (No.48) to you. The control brush of this machine has been removed and replaced with the ring insulating washers in the wrong position, as you will see. This would cause the control brush to be earthed to the carcase and this earthing of the brush is sufficient to account for all the trouble that is in evidence on the machine. It would mean that, were the charging switch put on with the engine standing, a strong current would be flowing from the battery through both the field winding and the armature to earth. It is assumed, however, that the charging switch would not have been put on, on account of its being also the ignition switch, until it was required to run the engine, and so that the discharge shown on the ammeter might not have been noticed. Then when the dynamo were run up to speed, the cutout would operate in the usual way, and a larger current than usual would be given to the battery, so overloading the machine. At the same time a larger current than usual would be passing through the series coil and the cutout and also a larger current through the shunt, due in this case to the fact that the negative brush would have been at a lower potential than the armature. Contd. | ||