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).
Technical discussion on standardizing starter motors, focusing on armature construction with and without mica plate insulation.
| Identifier | ExFiles\Box 38\5\ Scan226 | |
| Date | 22th June 1922 | |
| Contd. -3- EFC3/T22.6.22. the larger battery is standardised. It is, of course, intended that existing stock shall be used and the alteration to be effected on future chassis, to come in when the Production Department see fit. X.4132. R.R.Std.Starter Motor with Field Coils two series two parallel, built up with solid poles (field) and no insulation other than oxide (or varnish if bright plates are used) between armature plates. This item has been signed "Agreed" by Ry, Rg{Mr Rowledge}, EP{G. Eric Platford - Chief Quality Engineer} and FH, and by Da{Bernard Day - Chassis Design}, purely as regards this method of building up the armature. By R.{Sir Henry Royce} ? EJ. remarks "Has Da{Bernard Day - Chassis Design}'s objection been considered CJ. remarks "Why scrap £780. Is the advantage sufficient ?" This figure is given as cost of parts in Works which will be scrapped if commenced on 5.4.22. R.{Sir Henry Royce} remarks "Agreed - to omit insulation materials between plates and trust to oxide or varnish. This is quite correct for punched plates, but if grooves are milled with cutter, then mica is necessary. Go slowly with parallel connections." With regard to the technical point raised, the actual bench tests, the report of which, viz. EFC6/T29.3.22, was given under cover of the standardisation sheet, were made upon armatures with milled slots in spite of the absence of mica separators and proved that the amount of short circuiting due to dragging of the metal by the tool is not appreciable. The armatures of both the 40/50 and the Goshawk machines are being built up with milled slots, as it is considered to cost no more than the use of punched plates owing to the time taken for filling up the armature core built up with punched plates, and because the teeth are so narrow that punched plates would not be successful in the case of the 40/50 starter motor, the (particularly as use of mica plates is standard and the object of our standardisation sheet is to effect a saving in the cost of production of these armatures. (these are skewed. It would appear that the results of our tests on 40/50 type motors should also be applicable to the Goshawk type motor, and that therefore it should be in order to build up Goshawk motors without the mica plates. As regards the dynamo, however, the circumstances being quite different, an additional special comparative test should be necessary in this case. We propose, therefore, with R's acquiescence, to make special comparative tests of a Goshawk dynamo with and without mica plates for separating the armature plates, but in each case with milled slots. | ||