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).
Design evolution and issues of the Phantom II switchbox and distribution board.
| Identifier | WestWitteringFiles\T\2July1929-December1929\ Scan172 | |
| Date | 30th November 1929 | |
| To R.{Sir Henry Royce} from EFC. c. Sg.{Arthur F. Sidgreaves - MD} E.{Mr Elliott - Chief Engineer} c. By.{R.W. Bailey - Chief Engineer} Wor.{Arthur Wormald - General Works Manager} ORIGINAL EPCL/AD30.11.29. X7730 PHANTOM II SWITCHBOX, DISTRIBUTION BOARD AND FUSES. The first switchboxes made for experimental S.S. chassis were of the type with what we call the "extended armature contact", i.e. though the field circuit of the dynamo was broken, the armature circuit was not broken in the first or M & B position of the switch. This was done to produce a bigger delay between the breaking of the field circuit first and the subsequent breaking of the armature circuit. At the same time, the first S.S. distribution boxes were of the long type incorporating the green lamp switch unit. Owing to certain connection troubles associated with the use of the green lamp switch unit, it became necessary to adopt a type of switchbox in which the armature contact was not extended to the first "on" position of the switch, but only relatively to the field contact in the second "on" position in such a way as to give the maximum delay between the breaking of the field and the armature circuit in passing from the second to the first "on" position. A switchbox of this type recently removed from experimental chassis 12-EX after having done 27,700 miles, has been examined by us, and my assistant's report A.D.40. on the condition of the contact is as follows :- | ||