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).
Failing 20/25 brake servo and requesting investigation into alternative materials and other technical measurements.
| Identifier | ExFiles\Box 47\3\ Scan468 | |
| Date | 5th September 1932 | |
| X4117. 2vo To Hs. {Lord Ernest Hives - Chair} from E. {Mr Elliott - Chief Engineer} E.5/HP.5.9.32. X5370. c. By. {R.W. Bailey - Chief Engineer} Da. {Bernard Day - Chassis Design} re 20/25 Brake Servo. -------------------- We had R. {Sir Henry Royce} through personally on the telephone this afternoon, and he wishes me to tell you that they are having some trouble on a car belonging to Dr. Leslie of Chichester in connection with the brake servo. This servo appears to be fitted with cotton fabric and has failed twice. R. {Sir Henry Royce} says that he thinks this material is too delicate for the job, and is not suitable where there is no oiling. This appears to be an old car not fitted with central lubrication. R. {Sir Henry Royce} would like you to send a new plate fitted with linings of the original material which he presumes was Ferodo. He also suggests that even when central oiling is fitted to the car the cotton fabric is still liable to fail and should not depend on the supply of oil being maintained, and he would like you to try some alternative materials such as the material used on the Borg and Beck clutch, and on the Bendix brakes. As it is reported that Dr. Leslie's car is being continually towed in due to servo failure he thinks it is not a good advertisement for Rolls-Royce. The other point on which R. {Sir Henry Royce} would like some information is regarding the amount of end force exerted in the sliding splined joint of the propeller shaft due to the bumping of the back axle. Da {Bernard Day - Chassis Design} has calculated that this force would be 50 lbs on top gear torque, assuming a coefficient of friction of .1. R. {Sir Henry Royce} would like you to measure it if possible under the normal engine torque as he does not think the lower gears matter, and suggests that the surfaces of the splines might be nitro hardened with a view to reducing the friction since the lubrication at this point is not necessarily well maintained. E. {Mr Elliott - Chief Engineer} | ||