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The Paxman ''Hi-Dyne'' engine was a form of experimental diesel engine developed for rail transport use by the British engine makers Paxman of Colchester. They used variable supercharging to give a constant power output across their speed range. The name "Hi-Dyne" is a reference to dyne, a CGS unit of force, and implicitly to torque. == Diesel-mechanical locomotives == Diesel locomotives appeared in the 1930s, after the availability of reliable, compact diesel engines. The first were low-speed shunters with mechanical transmissions. These were followed by more powerful high-speed express locomotives with diesel-electric transmissions. These electric transmissions and their drive motors were expensive and complicated though, often requiring entirely new skills for their maintenance staff. Although Föttinger's torque converter was in use in light diesel railcars, no high-power diesel-hydraulic transmission had yet been developed. There was a clear demand for a powerful and reliable diesel locomotive, based on a mechanical transmission. One of the main needs for a transmission is to match the speed of the engine to the speed of the locomotive, so that the engine can work in its useful operating speed range. All locomotives need to deliver high torque from zero rail speed for startup. The overall range of gear ratios required from the transmission thus depends on the maximum speed of the train. The narrower the power band of the engine, the more precise control of gearbox ratio is required, either by using a continuously variable transmission or a discrete ratio transmission with more ratios. Rather than building increasingly complicated transmissions, Paxman chose instead to develop a more flexible engine. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Paxman Hi-Dyne engine」の詳細全文を読む スポンサード リンク
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