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).
Summary of test results for Goshawk dynamo brushes made from various materials.
| Identifier | ExFiles\Box 50\5\ Scan242 | |
| Date | 20th October 1923 | |
| X4333 To R.{Sir Henry Royce} from EFC. c. CJ. EFC4/T20.10.23. X.4333 - GOSHAWK DYNAMO BRUSHES. IN VARIOUS MATERIALS. Answering your R1/M18.10.23, this series of tests is now being completed and a complete report will be issued on Monday. In the meanwhile a short summary of results may be of interest. There appears to be no material which has shown definitely and consistently better results than the standard 'Z' Le Carbone brushes, though we consider from the tests that the EGO and EG2 Morganite give results which may be considered to be practically as good. The other grades we have tried, taking all things into consideration, appear to be not so suitable. The above comparative tests were run without the tops of the brushes being bevelled in accordance with our EFC1/T1.10.23, but our cumulative experience since that time is to the effect that the bevelling is a distinct improvement, particularly on the positive brush. MADE AT.CRO EFC. | ||