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 the Institution of Auto. Engineers discussing experiments on brake lining friction and servo motors.
| Identifier | ExFiles\Box 141\1\ scan0003 | |
| Date | 3rd January 1934 | |
| x3609 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}15/KW. 3rd January, 1934. C. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Williams, Esq., Research Dept., The Institution of Auto. Engineers, 5, Bolton Road, Chiswick, London, W.4. Dear Sir, We were very interested by your recent report on "The Wear and Friction of Brake Linings and Drums", as we have been doing a considerable amount of work on similar lines ourselves. Our experiments have been concerned mainly with the Servo Motor, which we use in our brake operating systems; our problem being to obtain a constant or even slightly rising friction with increase of temperature. The conditions in our Servo Motor differ considerably from those in a brake drum. The max. surface speed, corresponding to 100 m.p.h., is 600 ft/min., the max. unit load is of the order of 100 lbs/sq.in., and the temperature range is from atmospheric to 350°F.{Mr Friese} (175°C.). The wear of the friction linings is so small that it hardly concerns us; our principal troubles being the decrease in friction when hot and the necessity for smooth and silent operation. In order to investigate the characteristics of various lining materials we constructed a rig by which we could apply a constant load on the friction linings and measure the output accurately by a hydraulic plunger. We also arranged a thermo-couple in the steel rubbing surface, completing the circuit by mercury troughs. Our standard test for lining materials consists of continuous running at 46 ft/min. surface speed, 100 lbs/sq.in. surface load, and a temperature range of from atmospheric to 325°F.{Mr Friese} We judge the performance of a lining by the percentage decrease in the coefficient of friction from atmospheric temperature to 325°F.{Mr Friese} | ||