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).
'SS' engine mounting, vibration issues, and alternatives to the standard Phantom chassis.
| Identifier | ExFiles\Box 15\1\ Scan073 | |
| Date | 4th January 1929 | |
| Hs.{Lord Ernest Hives - Chair} E.{Mr Elliott - Chief Engineer} ) FROM R.{Sir Henry Royce} BY.{R.W. Bailey - Chief Engineer} DA.{Bernard Day - Chassis Design} ) c. to BJ. Wor.{Arthur Wormald - General Works Manager} c. to SG.{Arthur F. Sidgreaves - MD} C. x7250 R1/M4.1.29. 'SS{S. Smith}' ENGINE MOUNTING. X.7005 X.7250 X.7380 We ought to be better off than standard Phantom because we can have what that chassis has, or several alternatives At the moment I understand we can cure either of two objectionable features, but not both. There is a possibility that radiator vibrations are of big amplitude, whereas engine roughness is of small amplitude. Hence nearly rigid front mounting might prevent the former, and not transmit the latter. To test this we should use rubber harder, thinner, or of greater area. I have more faith however in our present standard scheme reversed as suggested by telegram. It appears that we may have raised the speed of torsional vibrations of the front of the frame - means itself and the parts rigidly fixed to it such as the radiator, but not engine and axle - and/or decreased the tramping speed of the axle until they are about equal, in which case the criss-cross movements of the front axle are very easily communicated to the frame, and axle and frame vibrate together through the springs and shock dampers. Now if we add the engine by firmly bolting it at the front we reduce the natural speed of the front of the frame very much indeed, and it is a long way from the tramping speed of the axle, (good also for quietening the axle) and would appear to be something better than we have had if we had not the feature of engine roughness. I rather like the low periodicity of this front end, and Mr. Elliott and I have often discussed our 3-point suspension reversed, and thought it might be better than our present, and after your report I have become very keen to get this tried at once, and hence my telegram to E.{Mr Elliott - Chief Engineer} Most of the experiments have indicated that there may be truth in the foregoing, and the matter is so important and urgent that one of our best experimenters (say Mr. Tresilian) who can be spared should be continually investigating the problem, because if we can thoroughly master it we shall prefer a 6-cyl. en to an 8 cyl. engine, because it is simpler, shorter, lighter and more efficient. Mr. Fuller and BJ. seem to think the 8-cyl. has greater acceleration, but there is nothing in that. The only advantage is less tendency to vibrations, but road shocks are so enormously greater, a good 6 cyl. that it is difficult to detect any difference. | ||