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).
Analysis of vehicle dynamics concerning front springs, rear springs, and body construction, focusing on issues like 'jellying' and 'wandering'.
| Identifier | ExFiles\Box 19\3\ Scan256 | |
| Date | 5th March 1930 guessed | |
| -2- Front Springs. Very soft front springs (4½" deflection) may be better for jellying and are certainly a great improvement as regards freedom from pitching, but steering snatches and wanders. Soft front springs give a similar effect to very soft side steering tube springs. Very stiff front springs (2½" deflection) are good for steering, bad for pitching, bad for jellying. Body. Top heavy body bad for wandering. Loose-built body bolted down along length of chassis frame and well fastened at dash, appears good for jellying, bad for steering snatch. The damping action of the loose joints in the body itself tends to suppress jellying. The node of the torsional vibration shifts according to the mass-distribution and stiffness of the body. Rear Springs. Undoubtedly enter into the questions of snatch wandering jellying, as much as or more than the fronts. Also such matters as front and rear shock absorbers, reaction dampers, mounting of engine, mounting of radiator, dash connection, offset of front wheels, tires, axle masses and brakes, overhung masses such as side spare wheels, etc. etc. 404 MR is found very good for not jellying, but when it does, the whole body wriggles, the middle door pillars being approx. the node. It gives evidence of great damping action rather than stiffness, but the sharing up of stiffness as between front and rear enters into it and is not fully understood. The jellying test on the bumper will undoubtedly give conclusive results before long. In the meantime any basic difference in torsional stiffness between front and rear on chassis or complete cars at your disposal will certainly be useful, but should take second place since the important job is to find whether we can, with less cost and weight, make a standardised sill construction equal to or better than the subframe. oy. Maurice Olley | ||