The Mobile Locomotive Testing Plant of the London, Midland and Scottish Railway

Abstract

To measure the performance and efficiency characteristics of any type of locomotive under service conditions, it is necessary for the locomotive to be worked at different rates of speed and loading, and for the conditions of working to be maintained constant for sufficient time for the necessary observations to be made. Such conditions have been achieved on certain continental railways, over long stretches of straight and level track, by the use of various forms of loading capable of adjustment to maintain constant speed and to absorb the power of the locomotive. This method of testing has hitherto been impossible on the L.M.S. Railway, as no suitable section of line was available. A special testing train has now been constructed in which the power of the locomotive is absorbed by a number of electrically-braked vehicles, the loading of which is controlled by an electronic regulator so that constant speed is automatically maintained and the effects of gradients, curves, etc., are immediately compensated. The train consists of three braking units, having different gear ratios, which may be used in any combination, a dynamometer car which records the performance of the locomotive and from which the braking units are controlled, and a special tender for measuring the fuel and water consumption of steam locomotives.