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).
Tests on the 20 HP front axle, its effect on steering joggles, and future concerns for the 40/50 HP car.
| Identifier | ExFiles\Box 12\1\ 01-page139 | |
| Date | 21th November 1929 | |
| X7420 To Da.{Bernard Day - Chassis Design} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/AD21.11.29. X7420 X7420 20 HP. FRONT AXLE. We went to considerable trouble to prove that dropping the distance between the spring pads and the road had a bad effect on steering joggles. We proved it in England and then took the axle across to France and repeated the test. The outcome was that we considered the drop spring seat axle was 15% worse for steering joggles. This difference was not considered to be great enough to justify upsetting the whole of the S.S. production programme and reverting to the Phantom I front axle. We went so far as to make pads for the spring seats on the Phantom II axle in order to reproduce the Phantom I conditions on this car, and found that this confirmed our previous results. We know of no theory that has, as yet, been completely right with regard to high speed wobbles and shocks, and in this case we have accepted the fact without putting forward a theory which at the best can be only a guess. Reverting to the 40/50 HP. car we are not too happy about the steering for the future because we have a number of small features which have recently been introduced (or are about to be adopted) each of which are likely to make joggles worse. (1) Phantom II front axle. (2) More flexible engine mounting. This is necessitated by the demand for increased engine smoothness. (3) Front shock absorbers without dynamic restrictions. We have never been able to get such good results with a fixed loading as we obtained with the original dampers. (4) 20" wheels and tyres. We are being pushed into the 20" wheels which we want to accept if we possibly can, but it may be the last straw which breaks the camels back. The steerings on some of our present experimental cars that have run 20,000 miles are not good. | ||