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).
Letter from North & Sons Ltd regarding experiments on cam shapes and their effect on noise in contact breakers.
| Identifier | ExFiles\Box 65\3\ scan0128 | |
| Date | 8th November 1927 guessed | |
| NORTH & SONS LTD AH 2. Continuation Sheet No. 1. With regard to the last paragraph of your letter we beg to say that we have made numerous experiments over a long period in our 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 we 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. This opinion will not in any way affect our efforts to produce cams in accordance with your views at the earliest possible moment as we are most anxious to ensure that everything possible is done to produce a magneto as nearly noiseless as possible and we shall be very pleased to receive your report as soon as you have been able to test the machines. Yours faithfully, FOR AND ON BEHALF OF NORTH & SONS, LTD. DIRECTOR | ||