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).
Issues with an experimental 12-EX clutch, its design, and potential material solutions.
| Identifier | ExFiles\Box 13\7\ 07-page002 | |
| Date | 31th May 1926 | |
| X7300 R1/M31.5.26. To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to BJ. Wor.{Arthur Wormald - General Works Manager} RG.{Mr Rowledge} c. to BY.{R.W. Bailey - Chief Engineer} CWB. BY.{R.W. Bailey - Chief Engineer} c. to PN.{Mr Northey} E.{Mr Elliott - Chief Engineer} AJS. RE. 12-EX CLUTCH. X.7300 X.3409 With reference to the trouble with this it will be understood that this is not a standard one but entirely experimental with a single driven fabric instead of two driving ferodo fabrics acting on a steel disc. The object of this was to reduce the inertia of the revolving parts, and also as being favourable to the carrying away of the heat. We must not be surprised therefore at the difficulty to get it to act as well as the present arrangement. I understand that the back plate is still left loose by our special scheme so as to give a preliminary friction before actually gripping the plate. It has been thought that when the clutch springs are only just strong enough to drive the load at normal temperatures the clutch is extra smooth. Such practice would however be unreliable because of the loss of friction with the rise of temperature. The various materials offered should be tested to ascertain their percentage of loss of friction with rise of temperature. A clutch material which is more constant in friction co-efficient, even though it was lower, would give better results. It may be that the lower inertia and cooler working of the particular experimental clutch mentioned above accounts for its poor behaviour. I should imagine however that it is purely a question of the material, or the conditon of the material. We understand that Ferodo's make a non-squeaking low co-efficient material which has a percentage of oil. In spite of the low co-efficient this material may act extremely well in a clutch and might maintain its initial co-efficient better with rise of temperature; because it was never so high it has less to fall. I would not delay this car for this experimental clutch. Evidently it is not ready to go to France until we have tested it more fully at home. It might cause serious delay and cost over there. R.{Sir Henry Royce} | ||