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).
Motor performance issues like gear scream and insufficient power, with proposals for a new armature design.
| Identifier | ExFiles\Box 64\2\ scan0198 | |
| Date | 27th July 1928 | |
| -3- Contd. (4) There is a rather high pitched gear scream of relatively short duration when the first engine explosion throws the motor out of gear. (N.B. Disengaging end thump occurs when running on teazer only, or when armature is thrown out by engine). (5) The power of the motor for turning the engine cold is, as anticipated in EFC/T27.7.28, insufficient for really satisfactory results. In the next motor, therefore, we are reverting to the 41 slot armature, but with the same number of main field turns per pole. There will also be a slight gain in efficiency by reducing the armature taper, thereby making the iron and copper difficulties in the armature somewhat easier. As previously explained, we consider we can arrive at the best alround power and efficiency results of the motor by bench experiment with main field windings of varying numbers of turns, and also with the arrangement of teazer winding on two poles only and main winding on two poles only. We are also proposing a 37 slot armature for which, we are of the opinion, after investigating the matter, that 5½ turns per main field pole will be superior to 6¼. The iron and copper proportions of the armature are so very much easier. The operating current it is true will be somewhat greater, but we have no doubt that the liveliness of the motor will not be impaired thereby as compared with the 41 slot armature, and may be improved. We hope to receive your recommendations in the matter. EFC. | ||