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).
Successful bench trial and construction of a new auto switch unit for reducing charging current.
| Identifier | ExFiles\Box 35\3\ scan 101 | |
| Date | 11th November 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} Wor.{Arthur Wormald - General Works Manager} c. By.{R.W. Bailey - Chief Engineer} CWB. X 4088 EFC3/T11.11.27. AUTO SWITCH. X.4098. X.4088 In our EFC7/T27.10.27 we stated that we had an idea that we were working on by which we hoped to obtain the very big reduction of charging current desired with the avoidance of vibrator regulator action. We have now tried out this idea on the bench with a 20 HP. chassis system, and find that it does everything that was expected of it. At the moment of writing the exact amount of resistance (at present 16.5 ohms) is not finally confirmed, but all other points we can think of have been carefully considered and tried and the general result is very satisfactory. We are arranging for three auto switch units of this type to be made up out of distribution board parts for putting on experimental cars. The unit consists of a cutout unit, but with an opening contact instead of a closing contact, on a base with six terminals. The shunt winding is identical and identically placed with the cutout shunt winding. On the bobbin which normally contains the cutout series winding there are two windings, the inner one for the head lamp current at present in three layers of No.16 SWG. and the outer composed of the resistance of 18-1/2 ft. of No.22 SWG. D.C.C. Eureka; these just comfortably fill the space. Thus no additional base space is required for the resistance. The normal heating of the resistance on the bobbin is quite O.K., the number of watts being less than 5. Contd. | ||