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 maximum stress in spring leaves and a summary of spring standardisation for the 25 HP and 40/50 models.
| Identifier | ExFiles\Box 17\1\ Scan031 | |
| Date | 13th May 1931 | |
| - 2 - Ha/Rm.{William Robotham - Chief Engineer}3/KT.13.5.31.cont'd.{John DeLooze - Company Secretary} (3) Maximum Stress in the spring Leaves. In spite of greatly reducing the top leaf thickness of all springs (the 25 HP. front is now only .225" thick) and making the initial camber of this leaf less than that of the other leaves, we find with the low rating springs that the maximum stress is very high. We believe it is only the very high quality of material and workmanship in the spring that enables us to get through a bump test. It will be remembered that front springs with 2" initial deflection used to give us trouble on the 25 HP. We attach (R & D's copy) details of the top leaf deflection, camber and thickness of the 25 HP. springs. Summary. We have circulated standardisation sheets for the 40/50 springs and for the 25 HP. rear. We are now sending out a sheet for the 25 HP. front. We hope to get a 25 HP. to France to complete the test of these springs because on the bump we do not get the braking torque nor do we alt the buffers. However roads generally becoming better, springs have an easier time. We think that improvement in riding comfort is of such vital importance to R.R. customers (who mostly sit in the back) and the results we have obtained are so much better than standard, that we should use these soft springs as soon as possible. At the same time there is a considerable amount of experimental and design work necessary to overcome the difficulties which we mention. At the present we have the satisfaction of knowing that, if a customer drives fast and puts car control before comfort in the back seats, we can give him the stiffer type spring. Ha/Rm.{William Robotham - Chief Engineer} | ||