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).
Valve spring stress testing, material suggestions, and design considerations.
| Identifier | ExFiles\Box 80\3\ scan0116 | |
| Date | 7th March 1912 guessed | |
| (4) stress until it is found that the spring breaks after running, and it will then be ascertained what maximum stress the metal will stand. Batches of six springs should be tested at a time. Generally it appears that the stress on these valve springs must not exceed 50,000 lbs.per.sq. in. anywhere in the spring, because of the repeated application of the stress without much rest. 10,000 miles equals 10,000,000 vibrations. The test rig for testing above I think very good and full advantage should be taken of it as regards experiments to obtain the best springs. The lift of valves might, if necessary, be increased so as to obtain more rapid tests. A test could be made on the above rig with springs made of chrome steel. Will they stand better? This, I think, is an excellent opportunity of testing this steel and should be specially noted. If found better they should be made with increased stresses until it is found at what stress they will bear 10,000,000 vibrations. Every effort should be made to keep the valve mechan- ism light, especially parts attached to the valve, as it all tends to shear the cotter and hammer the valves on their seats, as weight of spring does. | ||