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 Ltd discussing the relationship between brake lining wear, temperature, and energy dissipation.
| Identifier | ExFiles\Box 121\1\ scan0318 | |
| Date | 28th September 1940 | |
| Brakes FERODO LTD CHAPEL-EN-LE-FRITH STOCKPORT ENGLAND Telephone CHAPEL-EN-LE-FRITH 250 (7 lines) Telegrams FRICTIO PHONE CHAPEL-EN-LE-FRITH TECHNICAL DEPT. 28th September, 1940. Rm{William Robotham - Chief Engineer}/MHR.{M. H. Rigby}3/ET. WES/ET. Rm{William Robotham - Chief Engineer}/17H.R. See me please Rm{William Robotham - Chief Engineer} Messrs. Rolls-Royce Limited, D E R B Y. Dear Sirs, We would refer to your letter of the 16th instant, which we have already acknowledged, and would reply to your three questions as follows:- 1. The rate of wear of a brake lining increases with temperature rise, but so far we have been unable to evolve an experimental apparatus which would enable us to determine the exact relationship between the rate of wear at one steady temperature as compared with say, a higher or lower value. The nearest approach to determining the appropriate curve has resulted from running a given piece of lining against the same drum for the same length of time, and increasing the rate of energy dissipation per sq.in. of lining. We are enclosing a copy of the curve which we obtained, from which it will be seen that the loss in weight at 2 H.P. per sq.in. is approximately twelve times that at ½ H.P. per sq.in., and this rises to approximately fifty-two times as much at 3 H.P. per sq.in. Unfortunately, we were unable to determine the ruling temperatures with any degree of satisfaction, though it could be taken that this value did not increase quite as rapidly as the rate of energy dissipation in B.H.P. per sq.in., radiation becoming a greater and greater factor as temperature increased. These tests were taken some little time ago, and the writer is inclined to think, might be usefully repeated, on perhaps both non-metallic and metallic lining. 2. Referring again to the enclosed curve, we would not expect pre-heating of the brake lining up to 300°C. to have any appreciable effect on the rate of wear. When all is said and done, we expect that all the linings we produce for automotive work will, at some -continued- | ||