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).
Summary of test results for a special 20 HP dynamo armature with a two-coil-per-slot design.
| Identifier | WestWitteringFiles\L\2Jan1924-March1924\ Scan81 | |
| Date | 14th March 1924 | |
| To R.{Sir Henry Royce} from EFC. c. CJ. & FN. c. RY. EP.{G. Eric Platford - Chief Quality Engineer} c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} ORIGINAL EFC3/T14.3.24. X.4610 - SPECIAL 20 HP. DYNAMO ARMATURE WITH TWO COILS PER SLOT (ONE DUMMY COIL) AND 57 COMMUTATOR SEGMENTS. Please find attached copies of my assistant's reports AB.100 of 24.1.24, AB.103 of 15.2.24 and AC.7 of 1.3.24, being particularly with reference to tests of special 20 HP. dynamo armatures having two coils per slot and 57 commutator segments. Summarizing the results covered by these reports, and other results to date, it appears that there is a definite improvement in the general running in the direction of improved commutation and reduced brush wear, resulting from the use of such an armature. It will be noted that a certain amount of investigation has been carried out with narrower main and control brushes. This particular experiment as compared with the general experiment shows certain disadvantages but has the disadvantage of increased wear, the amount of wear being greater than when using the standard brushes, but seems less than when using the standard brushes with the standard armature. The experiment of the narrower brushes was made by actually filing away standard brushes. It is suggested in the report that the experiment of making all the brushes the same thickness as the present control brush might be tried, but in view of the experiments that are going through with the new type of brush gear (E.A.C. type), on the 20 HP dynamo it is not considered that this special experiment, involving | ||