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).
Comparison of 48 and 56 coil armatures, discussing modifications for 'intermediate' output machines.
| Identifier | ExFiles\Box 62\3\ scan0024 | |
| Date | 1st February 1930 guessed | |
| EFCl/AMO.2.30 contd. -2- The 48 coil armature of the "intermediate" output type offers certain advantages over the standard and "higher" output type 56 coil armatures from a manufacturing point of view. We have now had confirmation on one machine at least, that magnetic moan or hum is equally absent as in the 56 coil armature. There is a possibility of brush noise difficulty but we hope to overcome this by the use of suitable brush material. The outcome of our work to,date is that we are now working to the following end viz. - Firstly, the provision of 48 coil armature machines in standard carcases to provide outputs a moderate amount greater than present standard, but output still falling somewhat at speed though not so much proportionally. These machines are intended for more immediate standardisation previous to the provision of reduced charge switching. Secondly, the provision of 48 coil armature machines in carcases with modified magnetic circuits to provide outputs a relatively large amount greater than present standard, these machines being intended for use only with the simultaneous provision of reduced charge switching. The exact nature of the modification to the magnetic circuit will be decided on the result of tests to be of such nature as to introduce as little extra manufacturing cost as possible. A 20 HP. machine of the second type i.e. "intermediate" output type with a modification of the magnetic | ||