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).
Comparison of Lucas type ERS and Watford magneto modifications and specifications.
| Identifier | WestWitteringFiles\Q\2April1927-June1927\ 169 | |
| Date | 1st April 1927 guessed | |
| -2- Contd. (3) Longer contact breaker cams like those of the new ROI magneto. (4) Considerably easier moving cam ring - a distinct improvement. Lucas type ERS magneto. From a preliminary examination, the only two apparent modifications as compared with previously observed details are :- (1) Provision of alternative bakelite moulded jump spark distributor and rotor which is interchangeable with the previous type carbon brush wipe distributor, which is also returned to us so that we can compare the two distributors. (2) Contact points which are undoubtedly of tungsten have been provided with a somewhat increased spring pressure on contact. Note. These modifications appear to be just those which would overcome the troubles we have experienced with the carbon brush distributor and contact breaker points respectively. (3) H.T. safety gap. Watford 9.2 mm. Lucas 9.0 mm. (4) Primary point gaps. As received, these were :- Watford .012" Lucas .010" Contact breaker timing. Referring to the position of maximum flux of the armature (dead slow) i.e. the position in which the armature is naturally held by the magnet, as the datum position, we find that in the advanced position of the contact breaker, the makes occur 27° before and 7½° before this datum position respectively for the Watford and Lucas magnetos. Contd. | ||