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 Messrs. Morgan Crossley & Co. Ltd. requesting information on a suitable friction lining material for a brake servo motor.
| Identifier | ExFiles\Box 141\1\ scan0036 | |
| Date | 12th June 1935 | |
| X1181 Exptl. Dept. Hs{Lord Ernest Hives - Chair}/FJH.{Fred J. Hardy - Chief Dev. Engineer}19/KW. 12th June, 1935. Messrs. Morgan Crossley & Co.Ltd., Miles Platting, Manchester. Dear Sirs, We are in search of a better friction lining material for the servo motor of our brake system and are writing to ask whether you make a material suitable for this application. The conditions of operation in our servo motor differ from those in the brake drums principally by the lower rubbing speed; for instance, 50 m.p.h. corresponds to a surface speed of 300 ft/min. The unit pressure is of the order of 100 lbs/sq.in. and the metal mating surface is of 3% nickel steel. The maximum temperature attained in service is 350°F.{Mr Friese} Our requirements are that the coefficient of friction should not fall with temperature and we should prefer a slightly rising coefficient. There must, of course, be complete absence of squeaking. We should like to mention that we have an apparatus by which we can measure the coefficient of friction and the temperature accurately, and that, up to date, we have tested about 30 types of lining without finding one which fulfills all our requirements. In the case of some of the linings we have tested, the decrease in coefficient has been as low as 10% at 350°F.{Mr Friese}, but the linings have been unsuitable owing to violent squeaking. The material we are using at present has a fade of 28% at 350°F.{Mr Friese} and is silent in operation. | ||