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).
Modifications to dynamo brush gear, including slant angle adjustments and overheating issues.
| Identifier | WestWitteringFiles\K\October1923\ Scan11 | |
| Date | 1st October 1923 | |
| Contd. -6- EFC1/T1.10.23. Some time ago a set of brushes, from experimental car 3 GII, was altered in this manner, the slant angle given being 17° to 18° (an angle which we have confidence in recommending as suitable), since which the dynamo has run on this car at least 7000 miles. As regards bedding and general satisfactory condition of brushes and commutator, this system is the best in our recollection on 20 H.P. dynamos which we have observed, and we are all at the Works of the opinion that this is a desirable modification which might immediately be made to all brush gear and brushes possible. In making this modification, it is necessary to watch the suitability of the springs for producing the pressure on the slanting surface for the whole range of brush movement and not at any time on the corner. This is not likely to be wrong on the negative and control brushes, but should be carefully watched as regards the positive brush, owing to its different hand. Reverting to the case of overheated armatures by over-excitation due to (1). Jamming of negative brush (2). Breakage of negative wire. (3). Removal of battery, etc. would it not now perhaps be as well to provide in this Goshawk system a field fuse of sufficiently low current Contd | ||