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).
Chart of fatigue limits for valve spring wire, plotting final stress against initial stress.
| Identifier | ExFiles\Box 17\6\ Scan218 | |
| Date | 9th May 1934 guessed | |
| FATIGUE LIMITS FOR VALVE SPRINGWIRE. FINAL STRESS "#/□" CHART #2 KEUFFEL & ESSER CO. N.Y. CHROME VANADIUM 10% CARBON STEEL 10% SAFE STRESS RANGE 45° VALUES TAKEN FROM CHART #1 INITIAL STRESS "#/□" | ||