Recently Davey, Paxman & Co. Ltd. have announced that they are making engines for certain variable speed duties operating on the Hi-Dyne principle. In this paper the characteristics of engines operating on this principle are compared with those of the conventional engine as applied to locomotives. The diesel locomotive with mechanical transmission does not compare on overall performance with the locomotive with electric or hydraulic transmission; on the other hand it has a higher transmission efficiency and it is less complicated. For these reasons it is generally built only in the relatively small sizes used for light industrial duties. Its shortcomings are largely in the shape of the tractive effort curve which takes the form of a series of steps. This is due to the fact that the torque remains approximately constant over the engine speed range with the conventional engine. In the broadest sense, the Hi-Dyne principle is that of controlling the engine torque to vary over the operating speed range to suit the requirements of the duty; in the particular case of diesel traction these requirements are that the torque should vary inversely with engine speed and the power remain approximately constant. By this means it is possible to obtain a tractive/effort speed characteristic similar to that of a diesel locomotive with electric or hydraulic transmission. The thermal and mechanical loads on an engine are dependent mainly upon the power developed and this remains approximately constant over the operating speed range on the Hi-Dyne constant horsepower engine. Results of engine tests show how certain individual factors which tend to limit the torque vary over the speed range and largely determine the maximum power that can be obtained at varying speeds. A Paxman engine operating on the Hi-Dyne principle and a Sinclair Dual Fluidrive transmission have been installed in a locomotive built by Hudswell, Clarke & Co. and the advantages of the principle have been demonstrated under service conditions. Tractive effort/speed curves are shown of this locomotive and of three locomotives proposed by the Fluidrive Engineering Co. Ltd. based on the use of the Hi-Dyne engine and Dual Fluidrive transmission.
The Paxman "Hi-Dyne" engine for diesel traction
Der Paxman-'Hi-Dyne'-Motor für Dieselantriebe
1955
17 Seiten, 13 Bilder
Conference paper
Storage medium
English
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