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 review and survey of hydraulic spring dampers, detailing their development, types, global usage, and trends.
| Identifier | ExFiles\Box 152\2\ scan0118 | |
| Date | 3rd May 1938 | |
| The Motor TECHNICAL REVIEW A SURVEY OF CURRENT WORLD PRACTICE HYDRAULIC SPRING DAMPERS DEVELOPMENT Spring dampers, or shock absorbers, as they are more commonly termed, were developed between 1908 and 1910 and first used on racing cars. Vane hydraulic types were then widely used, particularly by French manufacturers. In post-war times, during the decade 1919-1929, the position of the hydraulic damper was strongly challenged by friction types, of which a variety of designs were marketed. From that time onwards the hydraulic form has been increasingly used and it is now standard on the great majority of cars used throughout the world. TYPES AVAILABLE There are three main types of hydraulic spring damper built: the vane type as exemplified by Luvax and others; the piston type operated by an external arm connected to the wheel; and the direct acting piston type pioneered by Newton and now manufactured in addition by Delco. Some designs employ a tapered orifice to restrict the oil flow and the advantage claimed for this is that the resistance put up by the damper increases with rapidity of movement. This type is, however, adversely affected by a fall in oil viscosity as a result of the shock absorber warming up under heavy duty conditions. The most widely used method of restriction is a spring-loaded valve, many examples of which are shown in the accompanying illustrations. WORLD POSITION U.S.A. The vane type is used by Ford. Piston types are used by the rest of the industry. Direct-acting types are becoming increasingly used. ENGLAND. Vane types with orifice control are used by the majority of manufacturers, piston types being employed by Morris on their smaller chassis, Lagonda, Rolls-Royce, Singer and Vauxhall. FRANCE and ITALY. There is no predominant type in these countries. Friction dampers are still popular on many cars. GERMANY. Piston type is used exclusively. GENERAL TRENDS There is an increasing use of piston shock absorbers and many of these are of the direct acting type. In cases where independent front suspension is employed some manufacturers (who do not employ direct acting models) build the unit in one with the spring linkage. In Great Britain alone a considerable number of manufacturers give a driver override control whereby the damping of the shock absorber can be varied in accordance with road and speed conditions. There are, in addition, other schemes whereby the resistance is built up with the increase in road speed, manufacturers using these being Alvis, Armstrong Siddeley, Aston Martin, Autovia, Daimler, Lagonda, M.G., Rolls-Royce and Wolseley. PROBLEMS As spring rates become progressively lowered and suspension generally made softer, there is increasing demand for shock absorbers that will considerably modify the spring characteristics so that stability at high speeds is maintained. This has involved the production of shock absorbers which are capable of standing up to a heavy load and, at the same time, has encouraged the use of manual controls so that the natural advantage of soft springing at low speeds is not sacrificed. Diagram Labels: DELCO, LUVAX FINGER TIP CONTROL | ||