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).
Coefficient of friction and performance issues of graphite-impregnated Ferobestos used in the Goshawk 11 clutch.
| Identifier | ExFiles\Box 74\2\ scan0326 | |
| Date | 23th August 1921 | |
| R.R. 199 (250T) (SD676 19-7-17) MP180865 X 4244 COPY. FO 1 RECEIVED AUG 24 BY/P23.8.21. WD.{Mr Wood/Mr Whitehead} from BY.{R.W. Bailey - Chief Engineer} C. Hs.{Lord Ernest Hives - Chair} X.3409 X4244 GOSHAWK 11. CLUTCH. RE GRAPHITE IMPREGNATED FEROBESTOS USED IN ABOVE CLUTCH. Acting upon 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 1/2 to 1. (2) Certain co-efficient of frictions were quoted by Mr Frood of 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/- Inside and outside diameter of Ferobestos discs 8.400" and 10.600" 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. | ||