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).
Technical memo discussing and comparing different chassis suspension systems, particularly the Dubonnet type and an independent front wheel springing design.
| Identifier | ExFiles\Box 154\1\ scan0071 | |
| Date | 23th May 1933 | |
| x 387 3. To Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} Dr. E.4/HP.23.5.33. re Chassis Suspensions. Referring to Oy's letter of the 12th May, the views he puts forward are very interesting, but in one or two respects we do not think they are entirely borne out by experience. With regard to the toggling action of the radius arms in the Dubonnet, we believe this spragging effect is present on many suspension systems that we know of, but is at a minimum when the axle is controlled by parallel motion, in which case the radius of the sprag is infinity, and the upsetting effect of braking on the car backwards or forwards is a measure of the height of its centre of gravity above the ground and the softness of the springs. We suspect that the effect of which Oy. complains on the Dubonnet is more due to the specially soft springing than anything else. In the case of the RR. independent front wheel springing this will be above suspicion as the action is absolutely parallel. With regard to variable spring rating, we notice Cadillac are against this, but the War Office demonstration last year at Farnham showed some remarkable results with light cars and tanks running fast on open ground. These vehicles were equipped with so called "slow motion springing" which was nothing more or less than variable spring rating carried out with levers and helical springs, and no more damping in the system than was provided by the friction of the lever bearings. With the second page of Oy's letter we agree. We do not like the front end of the Dubonnet car, and think that the RR. scheme has none of the disadvantages mentioned. E.{Mr Elliott - Chief Engineer} | ||