Preface: I quite enjoy occasionally speculating about locomotives that EMD might have built but didn't: indeed, if the speculations include reflection on technical (etc!) feasibility and the explanation of WHY the imagined model was not built, I think they can teach useful lessons about "real" locomotive history. For clarity, however, I propose that model designations for imaginary locomotives ALWAYS be put in "scare quotes."
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EMD "SW750" (could have been built from 1966 into the 1970s):
SPECIFICATION: A 1966-line switcher with a six cylinder 645 engine.
APPEARANCE: The SW600, the six cylinder 567C powered switcher of the 1954 line, was externally just like the eight-cylinder SW900, so we can assume that its 645-engined successor would have looked like a SW1000. (And its low-cab industrial variant, the "SW751" would have been a ringer for the SW1001.)
TECHNICAL FEASIBILITY: No problem: design could have been left to junior members of the design staff, with instructions to compare SW600 and SW900 blueprints and prepare a set of similarly altered SW1000 blueprints. Note that -- contrary to the impression some American railfan literature gives -- the engine would NOT have been a problem. The 6-645 was never used on a domestic locomotive, but the engine WAS built. (It was used, for example, on the last two dozen Victorian Railways (Australia) Y-class: a lightweight (72 U.S. ton) end-cab switcher. Late Y-class were rated at 560 kw, which is equivalent to 750 hp when translated into the way American locomotive horsepower is measured: the Australian version of the F7 (VicRail's B class) is rated at 1120 kw.)
SO WHY WASN'T it built? The SW600 averaged about one unit built a year over its dozen-year catalogue life. The demand for low-powered switchers was not visibly increasing in the mid 1960s. If someone had come to EMD and promised to order enough to make it profitable, EMD could have designed it in (I'd guess) days, but nobody did.
--
EMD "SW750" (could have been built from 1966 into the 1970s):
SPECIFICATION: A 1966-line switcher with a six cylinder 645 engine.
APPEARANCE: The SW600, the six cylinder 567C powered switcher of the 1954 line, was externally just like the eight-cylinder SW900, so we can assume that its 645-engined successor would have looked like a SW1000. (And its low-cab industrial variant, the "SW751" would have been a ringer for the SW1001.)
TECHNICAL FEASIBILITY: No problem: design could have been left to junior members of the design staff, with instructions to compare SW600 and SW900 blueprints and prepare a set of similarly altered SW1000 blueprints. Note that -- contrary to the impression some American railfan literature gives -- the engine would NOT have been a problem. The 6-645 was never used on a domestic locomotive, but the engine WAS built. (It was used, for example, on the last two dozen Victorian Railways (Australia) Y-class: a lightweight (72 U.S. ton) end-cab switcher. Late Y-class were rated at 560 kw, which is equivalent to 750 hp when translated into the way American locomotive horsepower is measured: the Australian version of the F7 (VicRail's B class) is rated at 1120 kw.)
SO WHY WASN'T it built? The SW600 averaged about one unit built a year over its dozen-year catalogue life. The demand for low-powered switchers was not visibly increasing in the mid 1960s. If someone had come to EMD and promised to order enough to make it profitable, EMD could have designed it in (I'd guess) days, but nobody did.
