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 Automobile Engineers detailing the points made about brake temperature.
Identifier | ExFiles\Box 141\2\ scan0252 | |
Date | 4th February 1939 | |
4029 1181. Experimental Dept. Rm{William Robotham - Chief Engineer}/AFM.{Anthony F. Martindale}1/MH.{M. Huckerby} 4th. February, 1939. The Director of Research, The Institution of Automobile Engineers, Great West Road, Brentford, MIDDX. Dear Sir, The writer wishes to thank you for the courteous reception of himself and Mr. Dixon last Thursday. The point we were trying to make on Thursday can be briefly put as follows:- When a brake is working at a steady rate the surface temperature is t + T_max degrees. where t = average drum temperature and T_max = maximum temperature difference between surface and average temperature of the bulk of the drum due to temperature gradient at a particular work rate. When the brake starts working at this particular rate, as determined by pressure and rubbing speed, the surface temperature is only t°, and some (small) time must elapse before the surface temperature becomes t + T°_max In order to determine the μ-speed curve the effect of temperature must be eliminated as much as possible. t can be controlled but T is an unknown. By measuring μ during rapid acceleration the surface temperature of t + T_max can never be reached; the rate of work is constantly increasing and therefore, one rate of work is held for an infinitesimal period only, consequently t + T_max for that | ||