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).
Explaining the purpose and benefits of oil springs for vehicle suspension.
| Identifier | ExFiles\Box 46\1\ Scan132 | |
| Date | 3rd June 1919 guessed | |
| X4131 PURPOSE OF THE OIL SPRINGS Experience has shown that for slow speed and good road conditions very flexible springs assure the greatest passenger comfort. However, to guard against dangerous road shocks, the automobile manu-facturer is obliged to sacrifice passenger comfort to safety against damage to the car under high speed and bad road conditions. The Oil Spring makes it practical to equip a motor with high flexibility springs, their action being such as to interpose re-sistance in proportion to the relative magnitude of the motion between the axle and frame. This is due to the fact that under normal periods the Oil Spring presents but slight resistance against small movements of the axle and an increasingly greater resistance as this movement in-creases. In effect a car equipped with Oil Springs and springs of high flexibility gives a combined action equivalent to flexible springs over good road conditions and increasingly stiffer springs as the road conditions become worse. On the attached blueprint is shown five curves: O.A.A.O. - the curve of compression and recoil of a 200# to the inch spring. O.B.B.O. - the curve of compression and recoil of a 300# to the inch spring. O.X.X.c.c.X.X.O. - the combined curve of compression and recoil of the Oil Spring and 200# spring under 2" of deflection and normal period. O.Y.Y.a.a.Y.Y.O. - the combined curve of the Oil Spring and the 200# spring under 4" of deflection and normal period. O.Z.Z.a.a.Y.Y.O. - the combined curve of the Oil Spring and 200# spring under forced vi-bration and distortion of 4". Comparing these three curves, it will be seen that under slight vibrations the combined action of the Oil Springs and car spring approximates that of a flexible spring, while the curve o.z.z.etc. shows considerably greater resistance against impact than the 300# spring, or equivalent to a 400# spring for its first 2" of impact. It is self-evident that for distortions of less than 2" the combined curve will more nearly approximate the curve of reaction of a 200# spring, and with forced vibrations of a higher velocity than that shown in the z.z. curve would give a reaction greater than the 400# spring. To the advantage obtained against damage to the car by the use of the flexible spring there is, of course, less recoil against any given distortion. Also, and most important, there is a less varia-tion in the supporting effort of the high flexibility spring under move-ment over a given road obstruction. | ||