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).
Tests and modifications to ignition system components, including the coil, condenser, and contact breaker.
| Identifier | ExFiles\Box 61b\1\ scan0032 | |
| Date | 1st April 1927 | |
| Contd. -2- EFCl/T1.4.27. (4) Umbrella type rotor to shield to some extent the contact points from the gasses produced in the jump distributor. (5) A still finer primary coil has been instructed experimentally though we doubt whether we can satis-factorily go any further in this direction. (6) It transpires that it is possible to get more condenser capacity in the present case, and we have therefore asked experimentally for a condenser of maximum capacity which can be got in the space, as this is a comparatively simple job. It will be remembered that we reported that no appreciable advantage was gained on a recent test with double condenser. It is agreed, however, that a second test should be made both with platinum and tungsten points. Since our last report we have received standard shape contact breaker lever springs giving approximately 50% bigger pressure on contact points. This single variation will be tried out experimentally on the bench for comparing with other results. In regard to the mechanical characteristics of the cam and contact breaker we have made up-to-date observations of this feature with both the standard spring and the spring of 50% increased pressure, and the results for these taken with the use of a non-inductive resistance are shown on the accompanying curves, one curve being given for each of the three platinum point gaps .010", .018", .026", corresponding approximately to make ratios of about .67, .555, and .46, the maximum distributor speed being taken to about 1800 r.p.m. The relatively small falling away of make ratio at high speeds will be noted, together with the slight improvement realised by the use of the stronger spring. These are curves of the current fed at a given voltage through the contact breaker with a purely non-inductive resistance in series, and the fact that one of the curves is nearly level up to a high speed indicates that the resistance, for the purpose in hand, is practically non-inductive. Any reduction in the current therefore from the slow speed make ratio value (the current when the points are closed having been adjusted to precisely 1.00 ampere) indicates a loss of time of closure of the points. The curves indicate that there must be practically no bouncing, because it is certain that the points cannot be closed at high speed during the periods when they would not be closed at low speeds. Contd. | ||