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).
Tests on Lucas dynamos regarding the effect of retarding brushes on cutting-in speeds for post-war cars.
| Identifier | ExFiles\Box 48\3\ Scan137 | |
| Date | 13th December 1920 | |
| To EWT. for Oy. c. EP. {G. Eric Platford - Chief Quality Engineer} X.4211 EFCl/T13.12.20. X.30146 (struck through) X.3770 (struck through) X.4165 (struck through) RE ELECTRICAL EQUIPMENT ON POST-WAR CARS. X.3958 (struck through) X.4211 (struck through) Reference your note EWT/HJC10/G20.11.20 with attached copy of note Oy9/G12.11.20, our remarks on this are as follows. We attach for Mr. Olley's information curves we have taken on two different Lucas dynamos, showing the effect of retarding the brushes on the output curve and cutting in point, from which it will be seen in both cases that we obtained as near as figures could be taken the same cutting-in point in the normal and retarded positions, but in the advanced position of the control brush the cutting-in speed was just a little later. We have previously stated that moving the control brush did not materially affect the cutting-in speed and to this statement we still hold. The results shown on the curves were taken with the dynamo in a hot condition. We have since then taken some results with a similar dynamo in the cold condition. We attach copy of a sheet containing some results illustrating the actual change observed in the dynamo in this condition from which it will again be seen that from central position to full retarded position very little change is experienced, but that from central position to fully advanced a slight increase in cutting-in speed results. With regard to Mr. Olley's last paragraph, we have the impression that a number of Lucas switchboxes went out with the spring control of the cutout adjustable, but that latterly these have gone out with the adjustment soldered up | ||