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).
Meeting minutes discussing breakages and potential design improvements for valve springs.
| Identifier | ExFiles\Box 80\3\ scan0080 | |
| Date | 8th January 1912 | |
| R.R. 235A (100 H) X 206. 8.1.12) G 2289 Valves and Valve Springs Contd. (1a) 84th Meeting Nov. 24th.11. Re Valve Springs Chassis 970 - H.Thomas. Mr Nadin read to the Committee a letter from Mr Henry Thomas, concerning a broken valvespring. Mr Wormald informed the Committee that the trouble we were experiencing with the breakages synchronised with the adoption of the new type of camshaft. Mr Nadin suggested that we should increase the number of turns by 1 1/2. Mr Barrington pointed out that this might be dangerous, owing to the necessary reduction of clearance between each turn. This might localise the stress in certain of the coils with the result that breakages might be still more frequent. He suggested as an alternative that we should increase the diameter of the coil. Mr Nadin suggested we should make the springs from steel ribbon, similar to the old inlet springs. Mr Swetnam suggested that the spring could be made with an extra coil, providing a stepped washer were fitted to accommodate it. The Committee agreed that Mr Swetnam should design two new springs, one having an extra coil, or a coil and a half in conjunction with a stepped washer, and one having a larger diameter of coil. 87th Meeting Nov. 28th.11. Re Chassis E.S. 500 - Murray; 944, - Joynson; 870 - Thomas. Broken Valve Springs. The Committee were informed that breakages of valve springs had occurred on these cars. They pointed out that the stress in the metal in springs is always very high, and that owing to the large quantity used, a certain number are almost sure to fail. The difficulty experienced in spring manufacture is that flaws and cracks due to the tempering processes cannot always be discovered on test. The Committee agreed that it is not always possible to guarantee valve springs from breakage, owing to difficulties of manufacture. They further agreed, however, that it is desirable to reduce the stress in the metal if possible in order to reduce the number of these breakages still further. | ||