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).
Instructions on 48 coil armature dynamos for 20HP and 40/50HP cases, detailing changes to brush angles and pole pieces.
| Identifier | ExFiles\Box 60\1\ Scan182 | |
| Date | 10th February 1930 | |
| X6004 By.{R.W. Bailey - Chief Engineer} from EFC. EFC6/AD5.2.30. X6003 X6004 48 COIL ARMATURE DYNAMOS. This constitutes a further instruction to our report EFC1/AD5.2.30 shortly being issued, our ideas of the best steps to be taken have now slightly varied. Having weighed up all evidence, experimental and otherwise, so far as available, we are of the opinion that we should now proceed, in the first instance at any rate, and both in the 40/50 HP. and 20 HP. cases, with machines for two different outputs but all of these machines to be of the 48 coil armature type. The machines with outputs suitable for more immediate adoption in the absence of reduced charge switching, will be of the normal 48 coil output as already instructed by our EFC3/AD3.1.30. The control brush angles for the two cases can now be given as follows :- Angle between control brush and main positive brush :- 20 HP. case 123° 40/50 HP. " 132° Will you please arrange for the instruction of 10 such machines on the same lines as previously requested. The machines for outputs suitable for adoption with reduced charge switching are tentatively but with good reason, being specified as being precisely similar to the former class as above with the exception of (1) The provision of Mr.Brocks modification to the pole pieces. and (2) The resulting necessary change to the main brush angle. and possibly (3) The use of different (a) Control brush angle. (b) Brush grade. (c) Brush bevel and shape of spring. We are looking into the above details and the necessary information will very shortly be available. | ||