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).
Experimental 20 HP Dynamo armature with 28 slots for noise reduction.
| Identifier | ExFiles\Box 165\6\ img075 | |
| Date | 26th April 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Ds. EY. c. EP.{G. Eric Platford - Chief Quality Engineer} Wor.{Arthur Wormald - General Works Manager} c. Mx.{John H Maddocks - Chief Proving Officer} X5661 EFC1/T26.4.27. 20 HP. DYNAMO. Sometime back, as an experiment on dynamo noise reduction, an armature with 28 slots in place of 29, with two coils per slot as in the standard 29 slot armature, in which the coil which would otherwise become a dummy is included in the winding lapwise in the manner sometime ago described in connection with the Rotax machine (ref. our report EFC2/T12.7.21) was experimentally made. With this arrangement we have a 56 segment commutator and the number of armature teeth per pole is a whole number, so that there is the same configuration of teeth under each pole at the same instant. The first of these armatures shewed up very favourably for noise reduction, and a machine with this armature is at present on the 20 HP. 10,000 mile test car in France, with a view to standardisation. The output characteristics and the appearance of the armature as compared with the standard are scarcely discernably different. Subsequently three further armatures were produced and each of these has been tested and very favourably reported upon from the noise point of view by the Test Dept. There therefore appears little doubt but that this modification is really definitely effective in reducing the noise, and subject to satisfactory operation on the 10,000 mile test, we propose issuing a standardisation sheet for this item. Three experimental armatures on the same lines are also now being produced for the 40/50 HP. machines. EFC. | ||