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 from Ferodo Limited discussing the confidential results of composite brake drum trials and material expansion properties.
| Identifier | ExFiles\Box 141\1\ scan0057 | |
| Date | 26th September 1935 | |
| From FERODO LIMITED. Sheet No. 2 G.H.Grylls Esq., Messrs. Rolls-Royce Ltd. 26th. September 1935. to quote to you the results we obtained, but it will perhaps be as well to treat this report as confidential. He was using a drum having a liner of high nickel content etc. for which a high thermal expansion figure was claimed, namely .000018 and a special aluminium alloy casing with similar index i.e. specially low for aluminium. In point of fact, however, the steel did not have the figure claimed and possessed the ordinary steel expansion properties of around .000006. Thus, the first time the temperature reached around 500°F, which is not excessive, the liner began rotating in the aluminium casing and on removing the brake shoes whilst still at this temperature the steel ring came out with them. The whole point of the experiment was lost because the steel did not have the expansion value it was credited with. Probably, therefore, the idea is still a sound one, providing satisfactory materials are used. I suggest that if you proceed with this idea it would be quick and simple to avail yourselves of our test machine which is always at your disposal. An ideal drum radius would be 5 1/2". I have had a letter from your Mr. Hardy, and we are preparing some amended VM.30 and some amended RAD.13, both with female splines. These will be sent off as soon as ever possible. I shall look forward with interest to receiving further news of your composite brake drum trials. Yours sincerely, FERODO LIMITED. CHIEF CHEMIST. Enc. 1 specification. | ||