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).
The causes and mitigation of chassis and coachwork vibrations and noise.
| Identifier | ExFiles\Box 5\2\ 02-page352 | |
| Date | 14th October 1930 | |
| -2- SG{Arthur F. Sidgreaves - MD}12/E14.10.30. Contd. ibility ceased at this point and that my subsequent troubles which might arise as a result of bodies being fitted are the fault of the coachbuilder, and on the other hand, there is, as mentioned above, a tendency for the coachbuilder to take the view that his coachwork is entirely quiet and free from booming so long as it is apart from the chassis and, therefore, any troubles which arise may be the fault of the chassis. So far as we ourselves are concerned it is quite obvious that, where a mechanism such as a chassis has to contain a large number of parts moving at widely varying speeds, tendencies are set up from time to time for vibrations and "fusses" to develop, some of a periodic nature which we cannot entirely obliterate, others of a description that are more amenable to treatment. From the earliest history of the chassis there is of course evidence that a struggle has been continuously made to reduce these tendencies as much as possible, whether by the provision of torque reaction dampers or slipper flywheels on crankshaft etc. Your efforts have been continuous in trying to produce a smooth sweet running mechanism. In this we have achieved probably a marked degree of success, but only to a degree, as it would undoubtedly be unreasonable to expect a 100% of achievement in this direction. One of our difficulties has been to obtain a condition of consistency in our production and to be able to rely upon these devices referred to above remaining "put" so that the amplitude of vibrations between one chassis and another does not unduly vary, or during the running of any one chassis. We are constantly being reminded by car owners that our P.I. model was much smoother and quieter running than is P.II. We know ourselves that is generally the case, and now all our difficulties of the description became more intensive synchronously with the alteration of design in respect of frame and engine mounting whereby the latter was supported on four points, and we, in consequence, had to drop any benefit which the torque reaction dampers of P.I. might have given. Exhaust noises and booms with P.II. have to be taken account of in a way which was not experienced with previous models. Some months ago we obtained one of the latest six-cylinder Bentleys which was tested by many of the Company's officials on the arterial roads, when it was agreed that the engine appeared to be practically free from any noticeable vibration or roughness at any point within its range of useful speed, certainly up to 80 M.P.H. What an immense advantage this must be in the avoidance of resonance sounds and booms in coachwork. | ||