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).
Variable rating suspension devices, detailing the issues with leaf springs and the adoption of auxiliary coil springs.
| Identifier | ExFiles\Box 28\1\ Scan079 | |
| Date | 1st January 1926 | |
| -2- II. VARIABLE RATING SUSPENSION DEVICES. (a) Reasons for adoption. Owing to the internal friction of leaf springs, the suspension is harsh when riding over very small waves or irregularities such as can be encountered on ordinary British main roads. The speeds at which this trouble is most noticeable usually lie below 30 M.P.H. The trouble also occurs to a minor degree even when the leaves of the spring are well lubricated. This is because the lubricant is squeezed out from the spots where the leaves are in contact, and also the spring is really too strong to give the maximum riding comfort over such small obstructions. If a weaker spring was fitted the axle would always be hitting the car frame or buffers over small humped-back bridges and other relatively large obstacles. There are two types of shock absorber which are fitted to overcome this complaint. (b) Devices to decrease initial road spring rating. As a compromise to give freer movement over small obstacles a small auxiliary coil spring having a limited travel is fitted between the main springs and the axle. The coil spring has a very much lower rating than the main spring. In addition it has no internal friction. Therefore [Text from diagram] LIMITED TRAVEL APCO. | ||