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).
Results of bench tests on an auto switch's behavior without a series coil.
| Identifier | WestWitteringFiles\R\2October1927-November-1927\ 183 | |
| Date | 30th November 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} PN.{Mr Northey} c. CWB. EY. c. Wor.{Arthur Wormald - General Works Manager} ORIGINAL EFC3/T30.11.27. AUTO SWITCH. Further to our EFC1/T17.11.27 we have now completely tried out on the bench the results of using no series coil on the auto switch and these are precisely as anticipated. When the headlamp filaments are cold the auto switch, assumed to be off contact, invariably responds immediately to the switching on of the headlamps, going over to and staying over at the full charge position. We have arranged apparatus in our laboratory as nearly as possible representative of the chassis system, including the use of all similar units, wires, and lamp bulbs, except that the battery ignition load is omitted. The 20 HP. generator at present used for this is driven at a speed (1420 r.p.m.) which is nearly independent of the load and corresponding to about 20 m.p.h., i.e. just below the peak output of the dynamo. (For the 40/50 generator, the speed will correspond to about 26 m.p.h., i.e. just above the peak output of the dynamo). The system functions under the different circumstances of switching and of disconnecting the battery exactly in the manner which has been described. The system is quite O.K. when, as is frequently the case, the headlamps are switched off momentarily in passing another car. If all the lamps were switched off it would then be possible for the battery voltage to have time to rise and throw the auto switch over before the headlamp filaments had time to cool, and switching on all the lights | ||