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).
Devices for increasing road spring rating, including auxiliary springs, and an analysis of longitudinal pitching at speed.
| Identifier | ExFiles\Box 178\1\ img158 | |
| Date | 22th June 1926 | |
| - 4 - Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer}1/T22.6.26. (c) Devices for increasing road spring rating on max. bump. Some manufacturers prefer to fit the weakest possible leaf springs and to increase their rating for large deflections by means of an auxiliary spring interposed between the top leaf and the frame. A typical example of this type of auxiliary spring is the "NEVAJAH". It is rather difficult to enthuse over this device because the internal friction of the leaf spring, which is the chief cause of the trouble, remains unaltered. There is no doubt, however, that for this particular complaint some sort of variable rating suspension is required. The one well known example in existence is the "Lancia" whose front suspension consists of a light coil spring and two heavy coil springs which come into action on bump and rebound when the wheel has moved some little distance from its position at rest. There is, of course, no inter-leaf friction, fluid damping being employed. [Image of a NEVAJAH auxiliary spring] NEVAJAH. III. LONGITUDINAL PITCHING AT SPEED. (a) Effect of spring free periodicity. Every spring under load has a natural period. On a car the natural period of the suspension can be found by jumping up and down on the front or rear of the frame about 80 times per min. When the impulses thus imparted to the system are in step contd. | ||