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).
The standardization and testing of 28 slot armatures for 20 HP and 40/50 HP dynamos to resolve noise issues.
| Identifier | ExFiles\Box 165\6\ img109 | |
| Date | 1st November 1927 | |
| X.5661 EFC5/T3.11.27. To R.{Sir Henry Royce} from EFC. c. PJ. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} Wor.{Arthur Wormald - General Works Manager} c. Ev.{Ivan Evernden - coachwork} 20 HP. & 40/50 HP. CHASSIS. -DYNAMOS- X. 5661 X.8672 You will remember that about five months ago we standardised the 28 slot armature for the 20 HP. car. We are pleased to be able to report that about eighty of these armatures have now passed through the Test Dept., on production and that they appear to be quite satisfied that the armature noise trouble of these machines has been cured. It may also be of interest to remark that we arranged the relation of the armature slots to the commutator on this armature so that it is exactly interchangeable with the old standard 29 slot armature, without any change of brush position, and gives almost identically the same output curve. Further to this, there is a similarly good margin on the heating, e.g. what we call the maximum permissible output curve is some 2 amperes higher than the representative output curve as the dynamo is set for production. As previously reported, we have also experimented with 28 slot armatures for the 40/50 dynamos. In machines previous to those of the N.B. type recently standardised, cases of noise have invariably been experimentally cured by trying one of these armatures in the same carcase. In our latest arrangement of the old standard 40/50 dynamo, we have not very much trouble with the question of noise. A number of the newly standardised N.B. machines are in the course of production (these having 29 slot armatures) and there is every prospect, when these come properly on production, of the Contd. | ||