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 The Morgan Crucible Co. Ltd. regarding faulty brushes from an experimental dynamo.
| Identifier | ExFiles\Box 35\1\ scan 075 | |
| Date | 25th June 1920 | |
| X.2656. EFC5/T. 25th June, 1920. The Morgan Crucible Co.Ltd., Battersea Works, Church Road, London, S.W.11. Dear Sirs, X.2656 Re Brushes from Experimental Dynamo. X30149 We are sending to you under separate cover a set of three brushes taken from a Lucas A.400 dynamo, which is an experimental type of dynamo, one of which we have run on one of our experimental cars. We yesterday found that this dynamo was not working properly and on getting to the root of the matter, we discovered this to be due to one of the main brushes of C.M.4 quality having fritted right down to the extent you will see on examination of the brushes. This was one of the main brushes, the control brush having been of E.G. quality. We should very much like to have from you your opinion as to what this phenomenon can be due. The dynamo appeared to work satisfactorily up to the last moment, when, owing to the fact probably that the brush could not go down any further under spring load, the commutator and brush got very hot due to the imperfect contact, there being signs of this heat in the fact that some of the solder from the commutator connections is now missing. We should mention that all three brushes were set to spring tension at the first stage, the two brushes appear to have behaved quite normally. The condition of the commutator is not extremely bad, although it appears that copper has been taken off the commutator fairly uniformly all round to a depth of perhaps .020". After inspection, could you kindly return the two good brushes and if possible, would you be so good as to give us a replacement for the bad one? Yours faithfully, | ||