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).
Increased 'pitching' caused by American type front springs and potential solutions.
Identifier | ExFiles\Box 43\2\ Scan228 | |
Date | 28th October 1927 | |
To OY. from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Y3900 Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}2/LG28.10.27. AMERICAN FRONT SPRINGS. X 840 We have now had a considerable amount of experience with the American type frent springs on the road. We believe that our tests have thrown some light on your problem of 'pitching'. When we changed over to your American springs on the car without any other alteration, we found that the tendency to pitch increased very considerably. This is what we should expect as all our previous experience has shewn that pitching is mainly due to excessive flexibility on the front, and naturally, with the softer front springs the trouble is encountered unless increased damping is added simultaneously. Apart from increased flexibility the American type front spring appears to have less internal damping than our standard front springs. We have not yet evolved a successful damping loading to cope with these front springs without spoiling the riding of the car but we do suggest that in cases where a car pitches really badly, it would be of value for you to try our 3.1" initial deflection front springs. Incidentally, the stiffer stronger rear springs about which we wrote you some-time ago, are wizards for killing pitching. Our tests, increasing the viscosity and speed factors of the hydraulics at present go to shew that we shall get a better riding at low speed and contd :- | ||