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 Midgley-Scholey chassis electrical equipment, including the dynamo and control units.
| Identifier | ExFiles\Box 35\3\ scan 071 | |
| Date | 18th March 1922 | |
| X4058 To CJ. from EFC. EFC2/T18.3.22. RE MIDGLEY-SCHOLEY CHASSIS ELECTRICAL EQUIPMENT. Re your CJ5/E7.3.22, the reason of the delay in sending you this report is that we have been getting together a little more information on the system. We think, as far as we can judge without seeing any of the actual apparatus, that the complete system would be reasonably satisfactory, if properly carried out, but there are one or two points of detail which we will criticise under the various units, and one or two claims which the producers of this equipment make which we do not consider justifiable. Dynamo Unit. The method fo control of the dynamo output appears to be quite new, and there seems very little doubt that dynamos constructed on these lines will run satisfactorily, without brush sparking and the consequent commutation troubles. We do not consider, however, that this system has any advantage in results over the original Trier & Martin system of control as used on the Smith dynamos. The running qualities and output characteristic of which we have always found to be excellent. As compared with the single field winding third brush controlled machine, i.e. the simplest possible type of controlled dynamo, no doubt there are advantages, as there certainly are difficulties and possibilities of bad commutation in this simple type of machine. The step from this simple type of machine to the Trier & Martin machine involves only one additional brush and no additional windings, and for the slight extra complication, important advantages are secured. In stepping over from the Smith type to the Midgley-Scholey type of control, the further complication of two different field coil windings is introduced without, we think, any advantage over the Trier & Martin system. It is, of course, difficult for us to judge the mechanical qualities and finish of one of these machines, without seeing the actual machine. Cutout and Overcharge Control Unit| It is not easy to judge this from the illustrations though it appears a reasonably well carried out job. Complication is, of course, introduced by having the twin unit in place of the single cutout unit, the other item of the twin unit being the overcharge control, which, if the voltage of the system rises at any time above a certain figure, causes resistance tobe inserted in the main field | ||