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).
Letter to Borg & Beck Ltd. regarding an investigation into lever flutter on a 10 C.F. clutch, detailing compression and stiffness test results.
| Identifier | ExFiles\Box 130\3\ scan0148 | |
| Date | 31th December 1940 | |
| 1110 Rm{William Robotham - Chief Engineer}/GB.11/RT. 31st December, 1940. A.M. SHINKINS, Esq., Messrs. Borg & Beck Ltd., Tachbrook Road, LEAMINGTON SPA, Warwickshire. Your ref. Sales.2/AMS/DN. Dear Sir, We thank you for your reply to our note on lever flutter on the 10 C.F. clutch. We note that you "feel that in all probability flutter is due to centrifugal load just beginning to compress the clutch plates..." We have made a compression test on a 10" clutch plate and we found that the springs alone compressed the plate almost to its limit (Please see enclosed graph No.1). The compression due to the centrifugal effect is .0015", which is equivalent to .0015x4.73 or .007" at the thrust race. If you refer to our report on lever flutter, you will see that, apart from the period, we require a much stiffer clutch to reduce the pedal movement at other than the flutter speeds. The compression test on the disc showed that the latter accounts for less than 25% of the movement at the thrust race. Clearly some other part of the clutch assembly is lacking in stiffness. We have made stiffness tests on complete clutches bolted to flywheels. The assemblies were laid face downwards and the levers were extended outwards and weights hung on them. An indicator clock reading to "1/1000" was fixed to the flywheel, so that it registered on the inner end of one of the levers. In this way a clutch with a standard cover was compared with a clutch with a stiffened cover. The results are shown on graph No. 2. | ||