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).
Performance of graphite-impregnated Ferobestos clutch material.
| Identifier | ExFiles\Box 26\4\ Scan122 | |
| Date | 1st August 1921 | |
| Wd.{Mr Wood/Mr Whitehead} from HY{Tom Haldenby - Plant Engineer} c. to Hs.{Lord Ernest Hives - Chair} X3409 X719 BY3/P23. 8. 21. X.3409 GOSHAWK II. CLUTCH. X.4244 RE. GRAPHITE IMPREGNATED FEROBESTOS USED IN ABOVE CLUTCH. Acting on Mr. Frood's recommendation we have tested out Ferobestos impregnated with graphite in preference to standard Ferobestos without graphite. I am aware that correspondence has passed between Mr. Frood and our Design Department (Da{Bernard Day - Chassis Design}) in regard to the question of the co-efficient of friction of Ferobestos graphite impregnated, but Da{Bernard Day - Chassis Design}, is away from the works and his department are unable to trace the correspondence - I would therefore like you to put before Mr. Frood the following points for his attention. 1. From our spring pressures submitted to us on the design drawing originally, there is no question but that the Design Dept. reckoned on a co-efficient of friction of .300, which gave them a factor of safety of 1 1/4 to 1. 2. Certain co-efficient of frictions were quoted by Mr. Frood to us in regard to graphite impregnated Ferobestos, based upon the performance of the material in the Austin car. 3. Apparently our Experimental Department have either misunderstood the original position, or something peculiar is happening in our clutch, as co-efficient of friction of the graphite impregnated material appears to us to be actually less than .130, which entails a very high spring pressure and therefore increased effort to operate the clutch, features which we do not consider altogether desirable. 4. We would like to have Mr. Frood's views on the position. In order that he may check our figures the particulars of the clutch are as follows:- a.{Mr Adams} Inside and outside diameter of Ferobestos disc 8.400" and 10.00" respectively. b. The number of discs is one. c. The spring pressure applied by means of 8 springs which were originally specified has a total of 640 lbs. contd:- | ||