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).
Report discussing the probable causes of dynamo overheating related to brush contact and bedding.
| Identifier | ExFiles\Box 50\5\ Scan221 | |
| Date | 27th September 1923 | |
| Contd. -2- EFC4/T27.9.23. Partial contact at the positive and or control (or field) brushes could only reduce the output and would be very much less serious. It seems probable that cases of overheating which have occurred may have been due to this cause, it being considered very unlikely from experience on bench experimental work, that the dynamo could, with satisfactory brush contact, attain a high enough temperature to melt the solder from the commutator connections. This we feel could not happen, even with the worst condition of brush bedding, so long as no brush was actually sticking and we are experimenting to prove that this is the case. The great difference as compared with a shunt machine, or a machine controlled by Smith or Lucas methods is of course that in this case, the removal of this particular main brush does not interfere with the exciting circuit. Thus, from a reliability point of view, the condition of the negative brush and brush holder appears to be of major importance. EFC. | ||