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).
Technical memorandum discussing issues with 20/25 rubber engine mountings and a proposed friction damper solution.
| Identifier | ExFiles\Box 104\1\ scan0247 | |
| Date | 17th December 1934 | |
| X5085 To Sg.{Arthur F. Sidgreaves - MD} and Wor.{Arthur Wormald - General Works Manager} from E.{Mr Elliott - Chief Engineer} c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux} E.S/HP.17.12.34. 20/25 Rubber Engine Mounting. We have always recognised that the rubber engine mountings which have come into general use are not without faults of their own, and one of these is that the normal vibration period of the mounting, which is very low, is likely to give trouble under certain conditions. One of these can be demonstrated almost on any make of car fitted with this type of mounting, and is a terrific shuddering and wobbling of the engine when accelerating at too low a speed in top gear. Another which GWH.{George W. Hancock - Head Chateauroux} demonstrated was that with the engine ticking over a slight missing produced a rocking of the engine which disturbed the whole car. Friction damping of course will go a long way towards curing these defects, but spoils the general smoothness of the result, but we think a slight amount of friction properly applied might be unobjectionable. Our original 20/25 torque reaction dampers were not designed for very light frictional loads, and are unsuitable. We, therefore, asked GWH.{George W. Hancock - Head Chateauroux} to try a light friction damper between the dashboard and the top of the cylinder block, and in the daily report on the 10,000 mile test car dated 10/12/34 he reported that the torque reaction period is almost negligible, and that the pulsations of engine idling cannot be felt through the seats, as previously. He also says slight boom brought up at 70 m.p.h. It will be seen how sensitive the engine mounting is to the presence of a slight amount of friction. The further action we propose to take is to | ||