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).
E.A.C. servo performance, comparing Ferodo and cast iron liners.
| Identifier | ExFiles\Box 26\4\ Scan240 | |
| Date | 26th January 1924 | |
| R.R. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. Expl. No. 3409 (9918 crossed out) REF: Hs{Lord Ernest Hives - Chair}/Rml/KG26.1.24. To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to CJ. RG.{Mr Rowledge} c. to DA.{Bernard Day - Chassis Design} E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} WOR.{Arthur Wormald - General Works Manager} S E C R E T. E.A.C. SERVO. We have confirmed the following points on the test rig :- (1) The increase of the co-efficient of friction of the Ferodo liners with heat is not due to the copper rivets wearing into contact with the drum but to the change of the nature of the Ferodo itself. (2) That for a given load and speed, with cast iron liners, the servo drum takes 30 % longer to attain red heat than with Ferodo liners, unless the latter have been worn down to the rivets. In the latter case the advantage of cast iron liners is considerably reduced. (3) If the servo drum is not allowed to attain a temperature above 250°C, new Ferodo liners rapidly reach a constant co-efficient of friction which does not appear to vary if the test is continued at this temperature. (4) The maximum torque out-put which the servo can sustain when running on the test rig and not get above 300°C is about 17 lbs.ft. at 500 r.p.m. We have calculated from this figure that with standard leverages a car should be able to descend a gradient of about 1 in 9¾ at 14¾ m.p.h. without the servo becoming red hot. GRADIENT UPON WHICH THE SERVO MAY BE EXPECTED TO FUNCTION SATISFACTORILY AT 14¾ M.P.H. We find from test rig experiments that the servo fitted with Ferodo liners will approximately maintain an out-put of contd:- | ||