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).
Stress levels and thickness variations in leaf springs.
| Identifier | ExFiles\Box 154a\2\ scan0151 | |
| Date | 8th July 1939 guessed | |
| 1305 COPY FOR FILES. To Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/FWK. LEAF SPRINGS. In answer to your query on the above subject, the tension shackle for B.V. production is 1 1/2° out of the vertical in full bump and the angle the spring makes with the shackle in this position is 99°. This will account for an increase of approximately 250 lbs/sq.in. on the stress on full bump. Since this stress is in the neighbourhood of 80,000 lbs/sq.in. the increase due to shackle angle can be regarded as negligible. With regard to the local high stress we are putting on the leaves, we suggest that the first way to obtain a more even stress is to maintain the thickness of the leaves within finer limits. On a leaf we recently tested the thickness varied as much as .010" on a .250" leaf. We mentioned this to Firths with the result that they are in future reducing the limits to ± .003. This should have an appreciable beneficial effect on the stress variation. Rm{William Robotham - Chief Engineer}/FWK. | ||