Design and issues of the Wraith independent suspension system.
| Identifier | ExFiles\Box 9\5\ 05-page037 | |
| Date | 22th March 1937 | |
| SECRET 646 To Ba. from E. {Mr Elliott - Chief Engineer} c.c. Sg. {Arthur F. Sidgreaves - MD} and Ws. Rm. {William Robotham - Chief Engineer} /Gry. {Shadwell Grylls} BV. Ltd. E.1/HP.22.3.37. Wraith Independent Suspension. With reference to the cable received from Hs. {Lord Ernest Hives - Chair} Sunday 21/3/37, and our reply of even date, the closer the suspension springs are to the wishbone hinge the greater is the bending in the spring until finally when the spring is at the hinge the effect is entirely bending. This alters the rating and also as the steel is only one fifth effective in bending compared with shear the weight of spring is correspondingly increased. For some reason too the life is not as good apparently in bending moment as in shear. Another feature is the increased load on the wishbone bearings tends to increase suspension stiffness or residual friction which has the effect of spoiling ride at low speeds. Furthermore with the spring near the base of the wishbone triangle it is necessary to bridge over a larger gap to make a base for carrying the spring load on the triangle which increases weight. We mentioned in our cable the question of rubber bushings for the wishbone. There is no doubt that some increase of lateral flexibility is required to cushion shocks. The wishbone suspension is about 4 times as rigid as Dubonnet laterally, and still more compared with old conventional scheme. For this reason rubber bushings are required to reduce lateral shocks, and it is desirable to avoid high loads so that the rubber bushings will not have to be large. All this of course is against a close in spring | ||
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).