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 mathematical investigation and stress testing of rear road springs.
| Identifier | ExFiles\Box 80\2\ scan0285 | |
| Date | 11th June 1920 | |
| To R.{Sir Henry Royce} from Da.{Bernard Day - Chassis Design} Copy to Bn.{W.O. Bentley / Mr Barrington} Copy to EFC. x 3981 Da{Bernard Day - Chassis Design}2/CB11.6.20. X.2628. REAR ROAD SPRINGS. X.3981. & With reference to Mr. Hives's report - Hs{Lord Ernest Hives - Chair}3/LG-10.6.20 and the question of road springs generally, we have been investigating this mathematically. It is a very lengthy and laborious job to work through one spring, and it appears to be necessary to go through all the springs in turn. We have ascertained that when the springs had nibs and slots, the plates broke at the slot in about 7 hours this being the weakest place. As soon as the slot was removed the short leaf became the weakest place the point of high stress in this leaf being where it is anchored at the centre. With springs having plain sheared ends fracture occurred in about 30 hours. As soon as this leaf goes, the point of high stress in the spring becomes the anchorage of the second leaf, and so on as the leaves break in turn. While this is demonstrated on the bumping rig it was anticipated by calculation. In the next lot of springs the sheared ends were also tapered in thickness and this evidently increased the stress in the short leaf because the spring broke in about 20 hours. We expected the stress would be increased. Though this work is somewhat laborious we are under the impression that it is going to be very useful and we hope that we are doing right in persevering with it. It appears that it will be possible to design a spring which has more indurance than the present spring, and the shape of the ends, the amount of length of taper as well as the thickness od the plates, appear to influence the spring throughout and to shift the point of maximum stress about in a way that cannot be anticipated except by calculation. One thing that we appear to be going towards is a return to the springs with graduated plates, the shortest being the thinnest. This work has taken longer than we at fiist expected, but we hope now to give you some results in a short while. Da.{Bernard Day - Chassis Design} | ||