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).
Issues with a sticking magneto and failures of cup leathers.
| Identifier | WestWitteringFiles\M\2April1925-June1925\ Scan20 | |
| Date | 21th April 1925 | |
| R.R. 493A (50R) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -3- Expl. No. REF: HS{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}1/LG21.4.25. The magneto also had a tendency to stick partially advanced if the engine was suddenly stopped when running fast. Normally the vibration of the make and break is almost sufficient to ensure the magneto returning when the engine is running. We tried the W.W. scheme for a return spring on the magneto. We found that with this spring in position the tendency of the controls to pivot about the magneto advance arm was more pronounced than ever. In addition the linkage showed a pronounced tendency to buckle when fully advanced. We therefore removed this spring, and to obviate the difficulty increased the return spring strength in the relay by 50%. We also requested Messrs. North to reduce the stiffness of the magneto sleeve by 50% while still endeavouring to conform with the limits of silence and vibration required. We expect to receive one of these cup leathers tomorrow. Cup leathers. A number of cup leathers have failed on test and two on the 10,000 miles car. We originally attributed these failures to the quality of leather employed. We therefore obtained special chrome leathers. These failed in much the same way. A laboratory test showed that either of the two leathers should be able to sustain a temperature of 90°C for a considerable period without becoming perished provided that they were thoroughly soaked in oil. The temperature of the oil did not exceed 90°C when the leathers failed previously. We found that by insulating a portion of the relay chamber from the air we could increase the tendency of the leather to fail in that contd :- | ||