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).
Wear rate and coefficient of friction for Goshawk clutch material and related investigations with the supplier, Ferodo.
| Identifier | ExFiles\Box 26\4\ Scan179 | |
| Date | 1st March 1923 | |
| To E.{Mr Elliott - Chief Engineer} from Hs.{Lord Ernest Hives - Chair} Y/3459 X719 Hs{Lord Ernest Hives - Chair}2/LG1.3.23. CLUTCH MATERIAL. Y/3459 X4244 The rate of wear on a Goshawk Clutch used under normal conditions is practically nil. We measured one clutch, which after the first 11,000 miles, had reduced in thickness .010", and after a further 5,000 miles there was no increase in wear. Both for the clutch and brake material we are using the Ferodo bonded asbestos, which is woven asbestos bonded with brass wire. We have tried the other two kinds you mention but have not obtained such good results with them. The Ferodo people have just sent us some more material which is woven without the brass wire, for us to try. The co-efficient of friction is a point which we are working on. If we fit up a new clutch the co-efficient of friction is according to the makers specifications - .3 to .35. With use, however, the co-efficient of friction gets lower. The Ferodo people say they cannot reproduce this on any of their testing machines, so at the first opportunity we are going to demonstrate to them a clutch which by the spring pressure necessary, shows that the co-efficient of friction is much below their specification. We shall then carry out the investigations jointly to see why the co-efficient is varying. We are very interested in this point because we are frequently having complaints of ineffective brakes. We will let you know the result of our investigations. Hs.{Lord Ernest Hives - Chair} | ||