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).
Page 2 of a report detailing the construction, benefits, and real-world testing of an improved leaf spring design.
| Identifier | ExFiles\Box 67a\1\ scan0287 | |
| Date | 5th April 1927 guessed | |
| -2- The result of this construction is that there is no marked increase in the strength or stiffness of the main spring when merely carrying the load or running slowly over good roads where the amplitude of spring oscillation is slight, but these two additional leaves do very considerably add to the strength of the spring under compression and whenever the amplitude of oscillation is considerable. Being anchored to the supporting leaves underneath the main leaf of the spring they are compelled to take their share of any load thrown upon the spring and compressing same. Again, when the rebound occurs, that is whenever the positive camber of the spring is in excess of the loaded camber or is approaching initial camber or even something in excess of this, these two extra leaves offer resistance in the other direction and have considerable value as dampers. Perhaps the greatest advantage of this type of spring lies in the fact that the main leaf is housed and supported both above and below within a very short distance of its total length, that is right up to the spring eye and it is this which apparently has resulted in the remarkable immunity of this type of spring to breakage. It should be pointed out that not only do the two uppermost leaves oppose rebound but also the two supporting leaves to which they are anchored. I have actually made this type of spring in Australia and tried it out with remarkably good results on several makes of cars and not once has there been a recurrence of the breakage trouble, whilst the riding has been vastly improved in every case, even without the addition of shock absorbers. I am not familiar with the present type car fitted with hydraulic shock absorbers and low pressure tyres, both of which, of course, must have a very marked bearing on this question of springing, but I do think that even with these two improvements the design of our springs for Australian conditions could be improved upon the lines set out above. It is four years since I carried out these experiments and I notice that Woodhead of Leeds now advertise a spring which looks very much like the one I have described. I have never seen this spring and of course I do not know anything about Woodhead's methods of cambering or setting the rebound leaves or of the ideal he is striving for. I hope that this somewhat involved description is clear to you. Pt. | ||