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).
Table of suggested total stress for helical compression springs made from various materials.
| Identifier | ExFiles\Box 154\1\ scan0275 | |
| Date | 7th April 1936 guessed | |
| -6- Suggested Total Stress - Helical Compression Springs. Material Max. Working Stress Max. Solid Stress lbs.per Sq.In. lbs.per Sq.In. Steel 1. Music Wire 60 - 70,000 110 - 120,000 2. Tempered Wire 50 - 60,000 80 - 100,000 3. Hard Drawn Spring wire - 40 - 50,000 60 - 80,000 Monel 25 - 35,000 60 - 70,000 Phosphor Bronze 25 - 35,000 60 - 70,000 Brass 20 - 25,000 40 - 50,000 These stresses are not an absolute quantity. The smaller the stress range the safer the spring. We suggest where possible that springs be designed so that the stress range be not over one-half to two-thirds the maximum working stress. For example, a spring stressed at 25,000 to 60,000 from tempered wire should give many millions of load applications, unless working under corrosive conditions. There is no surety of spring life if the springs corrode. | ||