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).
Performance tests of the Goshawk dynamo, focusing on the benefits of using a narrow control brush.
| Identifier | ExFiles\Box 51\1\ Scan059 | |
| Date | 7th April 1922 | |
| X.4383. Hs.{Lord Ernest Hives - Chair} (at Le CanadelHenry Royce's French residence) c. E.{Mr Elliott - Chief Engineer} c. Hy.{Tom Haldenby - Plant Engineer} c. EP.{G. Eric Platford - Chief Quality Engineer} EFC1/T7.4.22. X.4383 - GOSHAWK DYNAMO. We have arrived at the conclusion from very careful tests that the performance of the R.R. Goshawk dynamo is better, cooler, and more consistent with a narrow control brush (about half the present circumferential width). The commutation is also very much improved by this modification and blackening of the commutator does not take place to anything like the same extent as it does with a full width control brush. This apparently has already been arrived at by Messrs. Lucas and C.A.V., both of whom fitted their dynamos for the Goshawk with narrow control brushes, also by U.S.A. Bosch. We think that the modification of the narrower brush holder should be entertained. In our tests we merely file the brush away to the desired width. We are also carrying out careful comparative tests of different grades of brushes for these machines. The grade recommended by R.{Sir Henry Royce} as having been recommended to him by Royce Ltd. viz., Le Carbone Grade 'O', although this is being fitted as standard at the moment, we do not find to be altogether satisfactory generally - they are somewhat noisy. So far we seem to be obtaining better results with brushes of H.M.6 and C.M.5 Morganite, which improve commutation 50%. We have not been able to effect good commutation with the hard 'O' brushes owing to blackening of the commutator. We have a dynamo at the moment running on the bench with C.M.5 brushes and narrow control brush, which appears to be a particularly good machine, maintaining the specified output satisfactorily without exceeding the temperature of 65°C, the ambient temperature being 16°C. and keeping its commutator nicely clean. EFC. | ||