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 findings on commutator and brush performance issues from various contributors.
| Identifier | ExFiles\Box 50\5\ Scan143 | |
| Date | 12th December 1922 guessed | |
| -3- Contd. Joel. S Le Carbone - mica abrasive copper unaffected. Use dissimilar metals in rings and brushes. Whitehorn. Spacing round commutator very important. Narrow brushes preferable, tend to cool in spite of higher current density. Perex. Chattering due drag and resonance of spring etc. Hunter-Brown. Berlin tram motors arranged [diagram of two angled brushes] to reduce flash-over. King. Negative temp. coefficient. One brush red-hot. Forrest. Buckling due temp. difference between leading and trailing edges - caüses sparking. Contact resistance +ve > -ve. Equal pressures important. [Watermark: DICKINSON BOND 1804] | ||