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).
Failure of a Bentley clutch pressure member and proposals for material improvements.
| Identifier | ExFiles\Box 85\2\ scan0054 | |
| Date | 7th December 1933 | |
| To BY.{R.W. Bailey - Chief Engineer} from E.{Mr Elliott - Chief Engineer} c. Wor.{Arthur Wormald - General Works Manager} Hs.{Lord Ernest Hives - Chair} Sft.{Mr Swift} Da.{Bernard Day - Chassis Design} Hl. re Bentley Clutch Pressure Member. Referring to the above piece which broke, we understand that this occurred on a production chassis. We believe the state of the ring clearly shows that it has burst due to centrifugal force and possibly other incidental loads. There is no doubt that we should like to make this as a steel forging or at least in some material superior to the present N.C.I. and we should therefore go slow on production while we are moving rapidly with an improvement. The fracture of the broken piece shows somewhat coarse and crystalline but Hl. has made an examination and there does not seem to be a great deal wrong with the material. When we get a breakage of this nature it definitely shows that we are rather near the bone and calls for a move which will make the job several times better. Our only anxiety in using mild steel is the possibility of the driving key-ways picking up in the flywheel, but we have run Peregrine clutches with mild steel pressure members and although these were not satisfactory due to using the mild steel for a driving face against the Ferodo rivetted to the driven member, so far as we are aware, there was no difficulty in connection with the driving keys picking up and these keys will not be called upon to rub against similar material since the flywheel is made from .6% carbon. It has also been pointed out that at the present moment we have driven member mounted on steel splines on which it has to float and that these do not pick up although of much smaller diameter. We are, therefore, very hopeful that mild steel will be satisfactory and pressure members in this material have been instructed for immediate trial by Da.{Bernard Day - Chassis Design}1/HP.6.12.33. Owing to the difficulty of balancing a forging in which the lightening features are incorporated, it is proposed to make the ring solid and drill out lightening holes, which at the same time makes the necessary provision for rivetting and | ||