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).
Engine vibrations, torque reactions, and flexible versus rigid engine mountings in comparison with Hispano and Bentley.
| Identifier | ExFiles\Box 12\6\ 06-page030 | |
| Date | 18th March 1931 | |
| 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}/EV.{Ivan Evernden - coachwork} ) (At Le CanadelHenry Royce's French residence.) X7830. R1/M18.3.31. Copy to - SG.{Arthur F. Sidgreaves - MD} wOR.{Arthur Wormald - General Works Manager} P. 2. ENGINE MOUNTING. X.634. X.7005. X.7830. HS{Lord Ernest Hives - Chair}? will tell us if it is true that R.R., Bentley, and Hispano - i.e. all the big 'sixes' are in the same boat as regards these vibrations which cause 'booming' as well as torque reactions, because we cannot have a flexible engine mounting unless we get a jellying frame. If I understand rightly we must come to the conclusion that Hispano is accepting the vibration with their rigid engine mounting and have a steady frame, and Bentley is accepting the less good frame and have flexible mounting because they cannot get any help from the 3 point mounting as in P. 1., which car to some extent they may have copied. There is just one more chance that our frame is of greater vertical stiffness and so pushes up the period high enough for the over-running impulses to be vigorous enough to set the whole vibrating, whereas a frame weaker vertically might bring the period lower so that it is not so often touched in torque reactions, and the overrun vibrations are more feeble at this lower periodicity. It may be preferable to have a frame which is vertically weak and torsionally stiff. One would not expect such a frame to be good for bodies as we understand is the case with the Bentley 6 litre. I cannot believe that Bentley, and the others who are said to be beating us at the moment have not been favoured by luck, or copying our virtues, when we knew our sins and tried to avoid them and may have run into unfortunate proportions, but naturally if so we should have found them in our experimental models, so that they cannot be very serious if we can separate all the various phenomena of vibrations as we have torque reactions and master period. But we do know definitely what governs the periodicity at which we feel so acutely the torque reaction. I have suggested that it is the frame. It is strange that Bentley is the same speed, but their proportions cannot be far from ours. Naturally one would expect their torque reactions to be more vigorous with larger cyl. capacity and high compression ratio. When we know what is the spring we may be able to modify it. I have thought lately of many things as regards these vibrations, such as making the chassis in two parts, and also of making a frame which is damped, but cannot get | ||