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).
Tests comparing machine brushes for wear and noise, and experiments with armatures to improve commutation and reduce dynamo noise.
| Identifier | ExFiles\Box 51\1\ Scan297 | |
| Date | 11th November 1923 | |
| Contd. -3- EFC {E. Fowler Clarke - Electrical Engineer} 1/T1.11.23. Lucas E.575 machines, comprising in the one case over 10,000 miles, and the results were particularly satisfactory, the wear being slightly less than our present standard CM.9 Morganite brushes on the Lucas machines. The reason for retaining the CM.9 was merely that they are slightly quieter, the EGO brushes being composed largely of graphitized carbon are inclined to be a little noisy, but this would not carry so much weight on the GoshawkAero EngineCodename for 20HP Car / Aero Engine after KestrelAero Engine machines, and it is at any rate doubtful if they are any more noisy than the present standard Z brushes. One of the most promising experiments has been the armature with two coils per slot. The output characteristics in this instance were not materially affected, but the excellent commutation experienced appears to be quite a good improvement. The machine fitted with this special armature has been put on 5GII which we understand is to come to you shortly. Further armatures of this type are being prepared and it is thought that this feature may at the same time be a cure for noisiness in the dynamos which phenomenon seems to be always with us more or less and is very elusive to track down. None of the experiments definitely designed to overcome noise have succeeded. We still have the noise with the cast iron end bracket in the one case anddwith the trailing edges of the poles eased off in the other. Contd. | ||