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).
The manufacturing process and stress analysis of leaf springs.
| Identifier | ExFiles\Box 154a\2\ scan0348 | |
| Date | 25th June 1941 | |
| -cont'd- - 3 - Rm{William Robotham - Chief Engineer}/GB.5/SW.25.6.41. (3) and bends the leaf to the radius of the first spring. After forming, the leaf drops into the quenching oil. (4) The springs are assembled and pulled down to the correct free radius. Clamps are placed over the spring at the ends of every leaf. Clamps are also placed across the springs. In this condition, the springs pass through the tempering furnace on walking beams. This system produces a spring in which the leaves fit each other extremely well, and there is no leaf hammering in the process. When this method is used, it is not possible to have leaves bent to different radii, consequently the stress in each leaf is proportional to the leaf thickness. If it is desired to keep the stress in the main leaf lower than in the others, it can only be done by making it thinner. Fox's claim that the additional stresses in the top leaf due to braking etc., are of such small magnitude compared with those due to bending, that they can almost always be neglected. On the Myth, the tensile load due to braking, assuming .5.G and no weight, transfer will be 4.5 lb. and the additional stress in a main leaf .203" thick, would be 1140 lb/sq.inch. The stress due to shackle offset, will be about 1000 lb/sq.inch. This gives a total additional stress in the main leaf of nearly one ton/sq.inch. Spring Stresses. The stress in which Fox's are most interested, is what they term the dynamic stress. This is the stress at two inches of bump. They try to keep this at about 35-36 tons/sq.inch. On the Myth rear spring in flat section steel the dynamic stress is 49 tons/sq.inch. The dynamic stresses in the Vauxhall 10 rear spring are main leaf 39.5 tons, leaves 2-5, 46.5 tons and 6-8, 50.6 tons. -continued- | ||