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).
Experiments to determine the cause of noise in contact breakers and magnetos, focusing on cam shape and condenser discharge.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan054 | |
| Date | 13th December 1927 | |
| Contd. -2- EFC6/T13.12.27. noisiness Messrs. North in a letter to us remarked that they have made numerous experiments over a long period in their quiet room with cams of various shapes, running the contact breakers without generating current in order to test for mechanical noises only, and running them under normal conditions to detect noises arising from all causes. The opinions they have formed from these tests are that the form of the cam has no effect on the amount of noise and that there are two causes for the noise made by a contact breaker, one being the discharge of the condenser when contact is broken and the other being the meeting of the contact points as contact is made. It appears to us unlikely that the actual discharge with correctly made condenser could possibly make a noise - it would appear to necessitate some kind of mechanical movement for a noise to be produced, i.e. for the condenser itself to make a noise. We are still of the opinion that a considerable noise must occur at make with an unsatisfactory let-down of the moving point on the fixed, and that this must surely be affected by the form of the cam at make. However, Messrs. Norths say that they will not relax their efforts to produce a cam in accordance with our views, being most anxious to insure that they do everything possible to produce a magneto as nearly noiseless as possible. Contd. | ||