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).
Calculations for front spring stiffness, considering factors like encastrement and shackle inclination.
| Identifier | ExFiles\Box 4\6\ 06-page33 | |
| Date | 9th June 1926 | |
| To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to BJ. BY.{R.W. Bailey - Chief Engineer} c. to DA.{Bernard Day - Chassis Design} CY. X433 R2/M9.6.26. FRONT SPRING STIFFNESS. X.8410 X.433 Referring to your tests on the above, in our original spring calculations we allow for a certain proportion of the encastrement. We are not certain exactly what proportion should be taken. We believe however that when springs were tested before placing under the chassis, the necastrement was not taken into account. The result of this should have been that the bump was too great. Presumably then the next weaker spring is taken until the spring comes down to its proper deflection. This would result in an increased stress in the spring, but this stress is allowed for in the calculations, so all would be correct. We did not however anticipate that the effect of the inclination of the spring shackle would be as much as it is. It was not originally intended to lir at 21° but this was brought about by the desire at that time to use existing side members. The angle instructed is 10°, being about the best to anticipate the shortening of the spring by deflection and rebound. R.{Sir Henry Royce} | ||