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).
The use of long cams to reduce the noise of the contact breaker in magnetos.
| Identifier | ExFiles\Box 48\2\ Scan353 | |
| Date | 27th January 1926 | |
| Contd. -4- EFC {E. Fowler Clarke - Electrical Engineer} 3/T27.1.26. There would appear to be a further advantage in the use of long cams in reducing the noise of the contact breaker, and particularly if a continuous cam ring is used as in the B.T.H. and Lucas machines, but the objection to this is that the instant of break is not so definite, and not so independent of the platinum point gap, as when separate cams are used. It is not, however, necessary to have the instant of make so exact and therefore it would appear a reasonable thing to do to use cams which, though acting fairly sharply to cause the break at a fairly definite instant of time, irrespective of platinum point gap, could be so shaped that the fibre block in coming off the cam could let the contact points together more gently than is usually the case and possibly reduce the noise. If it is a fact that the contact breaker noise is caused by the hammering of the contact breaker points, a good deal of noise might be eliminated in this way. If, however, the noise is produced by the hammering of the fibre block against the cam, it would not, of course, have this effect. We suggest you put these points up for consideration to Messrs. Norths, as it seems more than likely that the contact breaker functioning of the Watford magneto can be improved at some extra expense, and it may probably Contd. | ||