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).
Comparison of the Dubonnet and Wishbone types of independent suspension systems.
| Identifier | ExFiles\Box 154\1\ scan0144 | |
| Date | 3rd May 1934 | |
| X3873 ANDRÉ DUBONNET 33, RUE DES GRAVIERS (114, BOULEVARD MAURICE-BARRÈS) NEUILLY TÉL. MAILLOT 19.93, 34-44 May 3rd, 1934. INDEPENDENT SUSPENSION Mr. Maurice Olley has stated that the Goodyear's dynamic tire research of the last two years has helped to clear up ideas on the "Wishbone" and Dubonnet types of suspension. This is rather inaccurate as the Dubonnet type was not even known in the United States two years ago. Mr. Olley has made a comparison of the "Wishbone" type of Suspension and the Dubonnet system with twelve pistons as exhibited in the Paris Salon in 1932. (1) The Dubonnet system as now in use is not more expensive to manufacture and is even very probably less as it requires fewer modifications for the frame. (2) The steering geometry can not possibly be as good in the Wishbone system because the king pin moves with the wheel and changes track and camber Whereas in the Dubonnet system the kingpin being fixed to the frame, the steering geometry is at all times perfect regardless of the movement of the wheel. (3) In the Dubonnet system it is necessary to have a very rigid frame, the housing of the suspension being near the wheel can cause a certain amount of torsion to the frame although it is unquestionable that the shocks of the road are absorbed by the suspension previous to being transmitted to the frame; this depends on the flexibility of the suspension in relation to the chassis. It is undoubtedly necessary in order to have any system of independent wheel suspension satisfactory the frame must be extremely rigid. (4) Use of spring steel is just as efficient in both systems as the stress is equally distributed on the inside and outside of the coil. In the Dubonnet system the ratio of the wire diameter to coil diameter is not too high as the length of the coil spring never exceeds three times the diameter of the spring. (5) For bump and rebound stops---in the wishbone system there is a ratio for the coil spring and a much higher ratio for the shock absorber whereas in the present Dubonnet system the ratio of the coil spring and the ratio of shock absorber are exactly the same and form one ensemble, as this ensemble is housed in one box, the shock absorber being inside the spring, the entire box serves as an oil reservoir permitting a constant renewal of | ||