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).
Letter from André Dubonnet discussing the results of suspension system tests.
| Identifier | ExFiles\Box 154\1\ scan0233 | |
| Date | 18th December 1934 | |
| +3873 ANDRÉ DUBONNET 33, RUE DES GRAVIERS (114, BOULEVARD MAURICE-BARRÈS) NEUILLY TÉL. MAILLOT 19-96 34-44 Neuilly, 18th December 1934 Mr. HIVES ROLLS ROYCE, Ltd DERBY Dear Mr.Hives, We have made, with Mr.Leslie, numerous different tests with my system of suspension, trying both variable and constant flexibility. For the variable flexibility we noticed that the actual curve augmented too much the force of the spring in a total deflection. It is for this reason that I am sending you a new scheme for variable flexibility with a curve which gives the spring, in a total deflection a force of 220 pounds inferior to the present one. I hope that this new scheme will prevent rolling on the turns and at the same time will permit the necessary deflection Concerning the damping, we tried many kinds of needles but not obtaining a good result by this means, we think it necessary to use a system of valve in which you have a considerable experience. I have set up a shock absorber with valves and have obtained excellent results on a normal road. However, I must state that on a bad road the results are not as satisfactory as they should be. I think this is due to the fact that at present we can not give sufficient evacuation to the shock absorber in the instantaneous shocks. This had been intended to function with a needle and the modifications which we have made are insufficient to obtain the desired result. All adjusting is extremely long and can only function properly after innumerable tests. Mr Leslie is impatient to return to England, which I understand perfectly, we can not keep him on here indefinitely with us. ...... | ||