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).
Cause and solutions for an electric shock from the auxiliary magneto switch on a Phantom II.
| Identifier | ExFiles\Box 65\2\ scan0045 | |
| Date | 9th December 1929 | |
| X7730 To Ry. from EFC. {E. Fowler Clarke - Electrical Engineer} To EP. {G. Eric Platford - Chief Quality Engineer} c. Wor. {Arthur Wormald - General Works Manager} c. Hs. {Lord Ernest Hives - Chair} c. C. EFC {E. Fowler Clarke - Electrical Engineer} 2/AD9.12.29. X8791. X.7730. PHANTOM II. SHOCK FROM AUXILIARY MAGNETO SWITCH. Referring to EP {G. Eric Platford - Chief Quality Engineer} 2/H6.12.29, the circumstances of the occurrence of this shock are known to us. The design of the magneto switches i.e. this auxiliary switch together with the magneto portion of the switchbox switch were originally such that it would be possible for this shock to be received in all "on" positions of the switchbox switch. It was possible, without any alteration to the latter, to re-arrange the auxiliary magneto switch so that, as is at present the case, the shock can only occur when the switchbox switch is in the M & C position. This has been done. It may appear at first sight, and may actually be the case, that the simplest way to avoid the remaining shock in the M & C position is to insulate the auxiliary magneto switch. To make a proper job of this it is not merely necessary to insulate the knob, but it would be much better to insulate the bridge piece which makes connection between the terminals of the switch as is done in an ordinary tumbler switch with metal knob. At present, not only is the knob alive from the magneto but the whole casing of the switch, and it is not inconceivable that this switch might be mounted in such a way as to be earthed, in which case, the magneto would be put out of operation when the switch is "on" even in the M & C position, which is not intended to be the case. However it would seem possible that it may be the case on some cars due to the earthing of the auxiliary switch casing, and would probably not be noticed as anything out of the ordinary because it would make the "on" and "off" of the auxiliary magneto switch be the truth instead of the "off" position not giving off, at the same time there would be, with the auxiliary switch as/re-arranged, no shock. already So the more correct way electrically of overcoming the shock difficulty and the way which does not need any alteration to the auxiliary switch, is to alter the magneto switch in the switchbox by insulating the revolving sector and connecting this by means of an insulated brush to the magneto. What this amounts to is putting the auxiliary | ||