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).
Design and performance of front springs for experimental cars in France.
| Identifier | ExFiles\Box 72\3\ scan0117 | |
| Date | 9th September 1924 | |
| To BY.{R.W. Bailey - Chief Engineer} from R.{Sir Henry Royce} To HS.{Lord Ernest Hives - Chair} c. to CJ. BJ. Wor.{Arthur Wormald - General Works Manager} PN.{Mr Northey} EP.{G. Eric Platford - Chief Quality Engineer} H.{Arthur M. Hanbury - Head Complaints} X9410 (crossed out) SECRET. RL/M9.9.24. EAC.11. X. 8410 X. 9410 X. 9941. RE. FRONT SPRINGS FOR EXPERIMENTAL CARS IN FRANCE. You will remember that my original advise was to make these springs 25% stiffer and that principally owing to our mismanagement we have had very great difficulty in getting Sales to accept 12½%. Now we must get on with this business promptly, and to do so I personally agree with any strength between 12½% and 20%, the case being that the more flexible springs will have slightly less life, but will be more comfortable to ride on, whereas the stiffer springs will have slightly longer life, and less comfort. We have asked repeatedly that the front braking shall be reduced proportionately to the stiffness of the springs. We still think that this has not been done sufficiently and that it was quite wrong to send the cars to France until the reduced braking was carried out. Regarding the top plate of the spring we do not know how to do to much to improve the design and proportions of this. It should have a small initial camber because the rebound is perhaps more dangerous than the bump. This initial camber should be somewhere between ½" to 1". Regarding the lower plates these could be increase in number and made thinner until the whole spring is inconveniently thick and heavy, but we are sending you tomorrow some proportions which we think should leave the lower plates with very little risk of breaking. In addition to lessening the risk of these breaking we ought to have a spring in which the curvature and stresses in the top plate is uniform, and a spring in which there is increased damping within the spring, and so will help to steady the axle against the braking torque, the advantage being that the internal friction of the spring damps the torsional vibration, whereas the effect of the shock dampers does not assist to damp the torsional vibrations. Regarding the clips I understand from DA.{Bernard Day - Chassis Design} that the Woodhead scheme originated with R-R, but it is not a scheme we should have insisted upon, because of the difficulty of manufacture and personally, unless it is proved to the contrary I cannot see that it has much advantage over the earlier system of riveting the cross bar to one of the lower leaves. There is no need for the rivet holes to be large in diameter, and the plate can be slightly thickened to compensate for it. At the same time if there is no difficulty in manufacture the Woodhead scheme is to be preferred because it should leave the plate intact, and it is the lightest of all the schemes. contd :- | ||