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 frame twisting, engine movement, and wobbles, exploring solutions for 'jellying'.
| Identifier | ExFiles\Box 14\8\ Scan218 | |
| Date | 19th February 1930 guessed | |
| -3- from side to side, or .187" in either direction from the central position. The greatest amplitude of movement that we have produced by our artificially excited test is .650". Therefore the angle through which the frame is twisting on the road in the case of the worst S.S. car that has come to our notice is rather less than 1°. This indicates some of the difficulty we have experienced in reducing the small movement on such an awkward structure as a frame. (5) The engine does not move as much as the radiator when "jellying" occurs. We have measured the engine movement at the same height as the radiator cap. It is only 2/3rds. as much as the radiator. This is because the rubber engine mounting is sufficiently flexible to allow the frame to twist a little without moving the engine. This is quite clearly discernible on our test by the contortions of the hose pipe which connects the radiator to the engine. We also know that four solid engine feet are the easiest way to cure radiator movement. However, we cannot depart from our present flexibility or we should run into engine roughness. (6) Effect of Frame on Wobbles. Since the axle is the motive power that initiates and sustains "jellying" it might be thought that this should be altered rather than the chassis to overcome the trouble. However, the two are not independent at all and we actually find that practically, it is easier to alter the amplitude and frequency of the oscillation by attacking the torsional stiffness and moment of inertia of the chassis and body than by anything we can do within the scope of practical application. | ||