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 memorandum replying to queries about the functionality of a vehicle's switchbox.
| Identifier | ExFiles\Box 166\3\ img020 | |
| Date | 7th March 1934 | |
| WST s l o d o q W/S. To Gx. from E/Lid.{A. J. Lidsey} E/Lid.{A. J. Lidsey}1/HP.7.3.34. c. Sg.{Arthur F. Sidgreaves - MD} Wr. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Switchbox. --------- Replying to your Cx.{Major Len W. Cox - Advertising Manager}2/KW.22.2.34 and Cx.{Major Len W. Cox - Advertising Manager}10/KW. 5.3.34, the answer to the query relative to the starter switch is that the relay circuit actuating the main starter switch is broken when the switch is in the 'off' position. By this means the starter is rendered inoperable although the starter motor main current circuit is not interrupted. Owing to the very large current passing through the starter main circuit (when the starter motor is in operation) a very massive switch would be needed to interrupt the circuit, it is far simpler therefore to interrupt the relay circuit which carries very little current. With regard to the switch for operating the instrument board lights, this is not included in the switchbox, the proposal being to incorporate this in the instrument patch itself. The fitting at the right hand corner of the switchbox is the lock and key. Referring to paragraph 5 of Cx.{Major Len W. Cox - Advertising Manager}2/KW22.2.34, the ignition switch is entirely separate from the lighting switching so that it is more correct to say that the ignition switch can be on with any position of the main switch except when the switch is at 'off' or at 'P.L'. The proposal of introducing a resistance into the side lamp circuit is not catered for in this switch box and we do not think that there is room to incorporate it in the space available. Actually the P.L. position on the switchbox gives side and tail lamp illumination exactly as in the S & T. position, the difference between the two switch positions being that everything else except the side and tail lamps are switched off and can be locked off in the P.L. position. We are not enthusiastic about the resistance proposal. Actually the illumination varies as the 6th power of the current so that the current saved by reducing the | ||