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).
To Claude Johnson discussing issues and comparisons of various magneto and battery ignition distributor systems.
| Identifier | ExFiles\Box 61b\4\ scan0019 | |
| Date | 4th March 1921 | |
| Oy4 - G 4321 Mar. 4.21 Mr. Claude Johnson - Sheet 2. questioned as to the use of brass, they pointed to the B-6 magneto (which has a jump-spark distributor) and stated that this distributor had given them no trouble though using brass points of small section and passing a far hotter spark than would occur in the battery distributor. On the battery ignition for 4-EX, however, they are using platinum points throughout, so as to insure success in whatever climate they are used. This was after I had told them that the B-6 distributor had given us trouble on test. The Bosch battery ignition distributor and contact breaker are ventilated through the two hollow rivets holding the hinges of the spring clips. We think these holes must have escaped Mr. Royce's inspection. The spring clips serve as shields, to prevent mud and dirt from being flung into the distributor. (Incidentally the B-6 magneto distributor is now ventilated by holes in the base, and all except the first few magnetos were so ventilated. Mr. Clarke states that the B-6 at Derby is not ventilated, so that I imagine this must be one of the very early machines. These gave trouble, as Mr. Clarke found on test, by corrosion of the points.) X.1819 The American Bosch 6 cylinder battery ignition has been tested for long periods at 24,000 sparks a minute, without giving trouble or failing to spark regularly. The form of contact breaker, with a simple arm, similar to the Delco, is not adopted simply with the idea of cheapness. The makers stated they had tried out our form of ignition withthe evenly moving rocker and contacts on a light blade, and had met trouble at high speeds with the springing and vibration of the blade, and had therefore abandoned it. Probably in the small sizes at which they are aiming, this vibration of the blade would be serious. Mr. Royce will recall that we met with a similar trouble on the small magneto contact breaker which we made during the war. Yours truly, ROLLS-ROYCE OF AMERICA, Inc. Per M.{Mr Moon / Mr Moore} Olley MO/G | ||