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).
Experiments with rubber rear engine mountings on a Bentley to improve smoothness and reduce engine boom.
| Identifier | ExFiles\Box 86\5\ scan0095 | |
| Date | 11th December 1933 | |
| X222 To Sg.{Arthur F. Sidgreaves - MD} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer} c. By.{R.W. Bailey - Chief Engineer} Rn.{Mr Robinson} c. Ev.{Ivan Evernden - coachwork} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/RT.11.12.33. BENTLEY SMOOTHNESS. RUBBER REAR ENGINE MOUNTING. For some considerable time we have been concentrating on improving the smoothness of the Bentley and reducing the tendency for the engine to create booms in the bodies. We have already mentioned floorboards. Apart from alterations in the power unit itself, we have been working on the engine mounting. We find that if we support the cross member carrying the single rear engine support on rubber we get a definite improvement in high speed smoothness, and also a reduction in the boom period round about 3000 R.P.M. which we attribute to the flywheel. Attached is a sketch indicating how the experiment was carried out. We made a second test increasing the thickness of rubber considerably and got improved results. In any design we recommend that a considerable depth, say at least 1.5" of rubber is used, and a generous area provided for the load to be carried so that a very soft grade material can be utilised. This is following the tendency of present American practice. We are now making tests mounting the front of the engine on rubber. It will be remembered that we have for some time past utilised rubber to take the engine torque, but have not previously obtained any great benefit from supporting the mass of the engine in this manner. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||