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).
Comparison of American ZR 6, German Bosch, and Watford magnetos regarding construction, noise, and reliability.
| Identifier | ExFiles\Box 4\5\ 05-page063 | |
| Date | 20th July 1920 | |
| Contd. -2- Hs{Lord Ernest Hives - Chair}5/LG20.7.20. carbon brush on the high tension distributor. The American ZR 6 magneto is not as well made and finished as the German Bosch but it compares very favourably with the Watford in this respect. The contact breaker is the usual Bosch pattern but they use very short cams. We have the impression that the short cams make the magneto more noisy and also makes the contact breaker less reliable. The Watford magneto use the short cam at present but they propose to change to the longer cam shortly. One of the most serious complaints we have against all magnetos is the noise. We had this trouble on the German Bosch machines. We have it quite seriously on the Watofrd machines. The two American ZR 6 machines which we have tested are reasonable as regards silence but they are not as quiet as some magnetos we have had. The American Bosch Magneto has a similar arrangement to the German i.e. there is an eccentric bearing carrying the large gear wheel so that the me-shing of the teeth on the gear wheels can be adjusted. This is a hlep in obtaining silent magnetos. Below are some comparative tests which we have made with an American Bosch Magneto compared with the latest Watford Magneto. The Watford magneto is a later type than we are using at present on production engines but it is a type which we expect we shall be using before very long. The feature on this magneto is that there is a sleeve interposed between the pole pieces and the armature which moves with the advance and retard of the contat Contd. | ||