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).
Analysis of dynamo performance and failures, focusing on the effects of brush bedding variation and the design of the 20 HP brush gear.
| Identifier | WestWitteringFiles\K\October1923\ Scan8 | |
| Date | 1st October 1923 | |
| Contd. -3- EFC1/T1.10.23. has not actually been tried as to whether this next worst condition would cause the commutator solder to run. The point brought home by this experiment is the large variation of output which is possible, due to an extreme variation of brush bedding, and also the fact that in the worst condition it is possible for the dynamo to damage itself, even when on the battery load and with the brush gear correct in other respects, though it must be remembered that this artificial condition is a very extreme one and it is considered rather improbable that any of the failures that have actually occurred have been due to this cause. It seems more probable that they have been due to other cause, or causes, mentioned in our previous reports, i.e. where no other simple explanation exists, such as removal of battery or the breakage of the negative dynamo connection. It is known from experience that our present design of 20 H.P. brush gear permits of variations of brush bedding of undesirable magnitude, irrespective of any faults which may exist in manufacture. For instance, it is not possible to realise dimensions of brushes and brush holders to such fine limits that the brushes can be safe from sticking and at the same time have the purely parallel motions in their brush holders which are desirable. | ||