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).
Analysis of a gear lever handle vibration problem on a Bentley and proposed modifications to cure it.
| Identifier | ExFiles\Box 86\4\ scan0060 | |
| Date | 14th September 1933 | |
| G.W.H. Will this lever be fitted to your car. To Hs.{Lord Ernest Hives - Chair} from E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} C. By.{R.W. Bailey - Chief Engineer} Mr. EP.{G. Eric Platford - Chief Quality Engineer} Hdy.{William Hardy} x22 E.3/HP.14.9.33. re Gear Lever Handle - Bentley. From an analysis of the results obtained by GWH{George W. Hancock - Head Chateauroux} with the sliding handle gear lever fitted on the last Bentley tested in France, we believe we have arrived at an explanation of this phenomenon which shews why some of the efforts made to cure it in the past have been ineffective. Hancock's observations shew that the vibrations are vertical relative to the gear lever and not lateral as was generally thought. We conclude that the mass of the handle and sliding rod on the Bentley lever was held rigidly against a stop by a reasonably strong spring, but the acceleration of the vibration affecting this lever at 40 m.p.h. roughly 2000 engine revs. or 6000 vibrations per minute was sufficient to unseat the mass and cause it to vibrate synchronously against the stop leading to the production of a very piercing noise. GWH.{George W. Hancock - Head Chateauroux} inserted a piece of rubber between the handle and the sliding rod, thus breaking up the combination of the two masses, and this cured the vibration as far as the observations were carried. With this scheme, however, the handle is still against a rigid stop, and we think there is a possibility of another vibration appearing at a still higher speed. We have, therefore, made a modification to the gear lever handle shewn on N. Sch. 3819 in which the whole of the mass is forced against a rubber stop by the operating spring, as we think by this means the vertical vibration and noise should be damped out entirely. We understand that the original sliding handle gear lever made by the Experimental Department - EX.3727 also suffered from the phenomenon of this vibration, but the noise produced was of a less piercing nature. This again bears out our conclusions as we find the stop in this case | ||