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).
Letter to Ferodo Ltd. about the performance and squeaking issues of FF.239 servo discs.
| Identifier | ExFiles\Box 141\3\ scan0213 | |
| Date | 13th September 1933 | |
| 8319 Experimental Dept. Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls}5/KT. Sept 13th 1933. Messrs. Ferodo Ltd. Sovereign Mills, Chapel-en-le-Frith. For the attention of Mr.Field. Dear Sirs, We thank you for your letter of the 5th inst. and for sending the FF.239 Servo discs. These have behaved similarly to the first pair as regards coefficient of friction. We had to run them in at a very high temperature to obtain a good output. On allowing the servo to cool down, we obtained a /u of about .7 but accompanied by considerable squeaking. On the road the brakes are very good to begin with while the servo squeaks. The output when hot falls slightly and the squeaks vanish, but when cold the latter reappear. Is it your opinion that such a high /u as .7 is inevitably accompanied by squeaks; if so we shall have to content ourselves with a consistent value of .4 to .5. Yours faithfully, FOR ROLLS-ROYCE LIMITED. | ||