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 discussion on chassis suspension dynamics, spring calculations, and the prevention of pitching motion.
| Identifier | ExFiles\Box 67a\1\ scan0245 | |
| Date | 6th September 1926 | |
| - 2 - I am giving you the above information in detail so that you will appreciate that a distinct difference has recently been made in our method of calculating for the springs, and that therefore later chassis will differ very considerably from the chassis you are probably criticising at the moment. With reference to your last paragraph, the Experimental Dept. carried out a large number of experiments along similar lines, but our Sales Dept. are of the definite opinion that an increase on the front spring poundage, far from relieving the position, accentuates it. Experimentally we do not agree with this, but we do not find ourselves in agreement with your proposal for stiffening the springs, as with very flexible rears and fairly stiff fronts, there is a distinct possibility of the period of the rear spring being exactly one half that of the front spring, with the result that excessive shock damper friction is necessary to prevent a fore and aft motion, known as "pitching", which would occur if either the front springs were of the same period as the back, or if they were half the period, as then two complete oscillations of the front spring, which brings you back where you started from, would agree with one complete oscillation of the rear. We certainly consider that the springing of the squabs for the rear seats does affect the problem, and probably causes an unpleasant sensation, when the springing of the chassis as such would not be complained of. BY.{R.W. Bailey - Chief Engineer} | ||