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).
Preliminary report on the Scintilla Magneto Type AM6-A.
| Identifier | WestWitteringFiles\L\2April1924-June1924\ Scan52 | |
| Date | 28th May 1923 | |
| To EPC. PB.95. PRELIMINARY REPORT ON SCINTILLA MAGNETO TYPE AM6-A.{Mr Adams} Although very different in design, the principles (apart from the automatic advance fitted) involved in this magneto, which is of the revolving magnet type, are the same as in the revolving armature type magneto. The difference is due to the fact that an attempt has been made to make all moving parts as strong as possible. With that end in view, the armature, contact breaker, and distributor brush, which are amongst the most delicate parts of a magneto and which usually rotate, are in this machine made stationary while their relative and more robust parts rotate. Therefore, although perhaps more complicated in design, on the whole it should be a more durable machine. The magneto which is roughly a horse shoe, is carried on a stout shaft, similar to that of the R.{Sir Henry Royce} Bosch ZR.6 magneto. This shaft also carries the cam at one end, and apparently the auto advance mechanism as well; housed between the limbs of the magnet. The armature core, pole pieces, and it is believed the ends of the magnet as well, are laminated. A point in favour of the stationary armature is that the core can more easily be laminated with safety, also that the windings for a given size of machine can be better insulated. The latter is revealed on this magneto by the long safety gap provided. Instead of the usual revolving H.T. brush carried by the distributor gear wheel, there are two drums, each carrying a segment; six stationary brushes, three working on each drum taking the place of the usual six segments. With this arrangement of distribution troubles due to tracking should be reduced. Ample lubrication of the cam is obtained by means of a thick wick one end of which rests in a supply of oil, while the other rubs on the lobes of the cam as they pass. Distributor terminals are similar to those on the Watford magneto, but with uninsulated securing screws countersunk on the inside. A material like stabalite or bakelite is used for the distributor cover and drums, and what appears to be a light brown fibre for the contact breaker rubbing block. The contact points are set well out of the reach of oil and are easily accessible for adjustment without removal, although, by means a flange locking arrangement the whole contact breaker can be quickly removed. CAP. | ||