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).
Letter to S. Smith & Sons Ltd. detailing faults and feedback on a new dynamo.
| Identifier | ExFiles\Box 3\5\ 05-page156 | |
| Date | 26th February 1920 | |
| X.295 CK{Mr Clark}3/T. 26th February, 1920. Messrs. S. Smith & Sons Ltd., 179-185 Great Portland Street, London, W.1. Dear Sirs, X.295. HE DYNAMO. X 1402 In answer to your letter CM1/LLL of the 25th inst., we are sorry to say that we have had a little trouble with your new dynamo with superior finish, on our bench. We found that when the machine got hot, the armature fouled the pole pieces in one place. We also noticed that the brush gear and plate did not appear to be as well fitted as possible, or it may be that the carcase is somewhat distorted, because we noticed that the brush gear and plate did not sit down quite correctly in the spigot. Another fault which occurred was that when the machine got hot, one brush stuck in its holder, resulting in the disturbance of the control of the machine. The above faults made us wonder if you had given this a good load test before sending the machine along. The general finish of the machine is certainly an improvement over the previous one. Also the commutator and brush gear, when in proper order, are better and responsible for much less noise than occurred in the old machine. On the other hand, we find this machine to give an excessive magnetic hum at almost all speeds, which certainly does not occur on the old machine. Another point we would like to criticise is that there is insufficient surface length of insulation between the brushes and the carcase so that any accumulation of copper carbon dust might cause a leak. The possibility of this could be reduced we think, by making the insulation cover a larger portion of the surface of the end plate. | ||