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).
Modifying third brush control machines and dynamos to increase their output.
| Identifier | WestWitteringFiles\U\May1930-July1930\ Scan028 | |
| Date | 6th May 1930 | |
| -3- FCL/AML.6.5.30 contd. Any modification which serves to increase the output of the ordinary third brush control,machine at moderate and higher speeds — and this appears to apply universally whatever form the modification may take — has its effect in putting up the cutting in speed, so such modifications must not be overdone. We can get an almost exactly similar curve from a higher output machine without polar modification as we can from a medium output machine with polar modification, so that so long as the simple form of three brush machine is used the problem reduces technically only to the question of a suitable compromise, and commercially to the least costly method. The advantage of the 48 coil armature is that medium and high outputs are both available with but a change in the pole pieces and cutting in speed in the medium output is reasonably maintained. The advantage of the particular form of pole piece modification sponsored by Mr.Brock is that the resulting main brush position in relation to the neutral axis of commutation remains correct for the best alround result. That is to say, although the angular displacement of the main brushes from the no load commutating axis is different, the position of the main brushes in relation to the pole piece centre lines requires no change when thereby modifying the dynamo from medium to high output. It will be seen from what we have said that we are in agreement that the same effect may possibly be brought | ||