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).
Desired qualities of dynamo brushes, including resistance, wear, and issues with different makes.
| Identifier | ExFiles\Box 50\5\ Scan109 | |
| Date | 19th July 1922 | |
| X4333 To EFC. {E. Fowler Clarke - Electrical Engineer} from R. {Sir Henry Royce} R1/M19.7.22. X+4333. I have received your memo. re Le Carbone's references to GoshawkAero EngineCodename for 20HP Car / Aero Engine after KestrelAero Engine dynamo brushes. I do not know the peculiarities of the 2 grades mentioned but what we are particularly desirous of using is (1) a brush which has fairly high specific resistance so as to reduce the tendency to spark, and (2) it should also be exceedingly good from a wearing point of view, this being particularly necessary owing to the high speed of the dynamo. We are not desirous of using a very efficient brush as regards loss of voltage or current carrying capacity, these being in my impression distinctly against the first condition. We shall of course be pleased to hear the results of the test of the wearing and sparking qualities of the EG.30 suggested by Le Carbone's as an alternative for the ZO. I believe the ZO is the quality recommended by me from experienced with Royce Ltd., We are not anxious to venture into various other makes of brushes under the present conditions in which we are working. We are very anxious not to do pioneer work outside our own direct business, and only that which is absolutely necessary. The brushes on the dynamo at this house grow in thickness and jam in the holders, and have to be repeatedly and regularly filed to make them free - a most mysterious and troublesome fault should it occur on a car. R. {Sir Henry Royce} | ||