friedman@uiucdcs.UUCP (12/16/83)
#R:ihuxq:-41700:uiucdcs:20600004:000:829 uiucdcs!friedman Dec 15 08:16:00 1983 Remember that a "diesel" engine is really a "diesel-electric"; an on-board diesel generator power for electric motors, which actually move the engine. Electric engines don't need variable gearing; it is characteristic of them that they give lots of power when started at relatively low voltages, and then speeded up gradually by increasing the voltage to the motors. The techniques of coupling more than one diesel-electric together were worked out for straight-electrics in the 1890s for rapid transit use, by Frank Sprague, who was one of the key developers of the electric trolley. There are a couple of systems (I think he invented one for GE and another for Westinghouse--how's that for versatility?); both are called multiple unit (MU). My understanding is that modern diesel-electrics use essentially the same methods.