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).
The design considerations and rationale for the free camber of front road springs.
| Identifier | ExFiles\Box 17\1\ Scan035 | |
| Date | 1st June 1931 | |
| DA.{Bernard Day - Chassis Design} c. R.{Sir Henry Royce} c. Hs.{Lord Ernest Hives - Chair} 87410 BY4/G.1.6.31. RECEIVED 1931 JUN x7410 x5410 ROAD SPRINGS. Referring to DAL/M19.5.31. this particular question of what is the best free camber to give the main leaf of the front spring has been a matter of discussion on more than one occasion, and one which we ourselves have spent time on in discussing with Mr. Stansfield of the Brown Firth Research Laboratories, who is responsible for the design of the springs at Firths. The reason why in the past we did not press for the position you are now raising, was that in going into the matter we found there were certain debits which were very real, and which made in our opinion a compromise necessary from what appeared to be the generally accepted idea :- 1/- The range of stress which is one of the particular factors in determining the life of the spring is not affected, as this is simply proportional to the thickness of the plate and the deflection range, and inversely proportional to the square of the span. 2/- It necessitated an increased stress in the lower plates, unless the thickness of the plates was seriously reduced and this was not desirable since it materially increased the cost of production of the spring, as each plate costs more due to more rolling, and more plates were required. 3/- Further increased nip is required in order to deflect the main plate, and this in turn is a serious danger from the point of setting up 'digging in' of the tips of the second plate into the back of the main plate. We still think that the present position justified as it has been by increased life of the springs, is the safest policy to continue with, and we rather deprecate at this stage making any change to the design without considerable experimental work being done to justify it. BY.{R.W. Bailey - Chief Engineer} V29 | ||