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 memorandum discussing improvements to vehicle suspension, including shock dampers, tyres, and springs.
| Identifier | ExFiles\Box 67a\1\ scan0097 | |
| Date | 19th March 1926 guessed | |
| Contd :- -2- since the Phantom appeared) to make the engine and front of the chassis lighter: (this is in hand and should be hurried up). (4) Use hydraulic shock dampers all round. (5) Use semi-balloon tyres (either Dunlop or Michelin). In effect these are better than more flexible springs. Here they definitely reduce road shocks on the steering (and I believe really reduce the tendency for steering wobble because one does not feel the roughness of the road. This is supported by the fact that we never feel the slightest tendency to wobble, whereas on 11-EX (CWB's 10,000 miles car)- PN.{Mr Northey} says he had a high speed wobble with high pressure tyres. This difference of opinion between Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} and myself may be my prejudice, and it may be the difference between average practice and theoretical testing. Semiballoons also reduce body noises, increase comfort, and lessen wear and breakage. It must be realised we have done our best with front springs. We cannot make them more flexible because (a) they will break, (b) there is not sufficient clearance (too often on the buffers), (c) they will have insufficient control of the front axle against brakes and steering. We are equal or better than others, and even in the future any form we know has too many disadvantages for the promised advantages. They would need freak designs and we doubt if we have proved that these are justified. On EAC. we have added slightly to the length. You will understand that I recommend doing all we possibly can to get a slower rating of the back springs, but I cannot see any advantage in again using thick leaves. I certainly would use greater initial camber so that the flexibility could be greater without getting too little clearance. And there is still another possible variation in the rating of the present spring equal to the load. I mean by this: if a spring were 1000 lbs. for 5", would it be 200 lbs. per inch all the way from 0 deflection to 10" deflection at 2000 lbs. If not, how does the present compare with the earlier springs. I believe there is nothing in this but it was worth mentioning. If one ran over an obstruction and over a road depression and noticed the effect on the passenger when the front axle went over and then the back axle, one could judge the relative value of the springing and damping. 2" and 3" should be tried. Perhaps DA.{Bernard Day - Chassis Design} should go to Derby and see a car complained of, and send me a report on the subject. Owing to much other work the reports I have received are not very satisfactory. There has been no very definite complaint or investigation: much like my own they have been general - both complaints and ideas of the causes. R.{Sir Henry Royce} | ||