• Never-built EMD: the "SW750"

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by Allen Hazen
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."
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.

  by mxdata
The market for switchers less than 1000HP was pretty slow by the mid-1960s, and the potential for one unit a year was not enough to justify keeping a design in the catalog in an organization the size of EMD. It is not just a question of the design work, it also involves the overhead costs of sales and technical support, plus keeping parts on hand for a locomotive that has some features which are different from your more popular products, and keeping your suppliers interested in building the parts when their potential for orders is only one piece per year.

The 6-645 was actually built for a number of applications, sometimes without the customers actually realizing what it was. If the 567 engine in a customer's SW1 had a particularly messy failure which required scrapping the crankcase, EMD would build a 6 cylinder 645 crankcase as a replacement, and fit it out as a 567 to suit the application.

As late as the mid-1970s there was generally one un-machined "blank" 6 cylinder 645 crankcase sitting in the plant ready to be used if a customer needed it. It was not needed very often.
  by Allen Hazen
Thanks, mxdata, for the information on 6-645 engines and EMD's practice in dealing with that small corner of its business!
(And if all posts about "imagineered" locomotives got such informative replies... Smile!)

  by emd_SD_60
Isn't EMD making a switcher, the GP20D? It doesn't quite look like a switcher...


  by Railpac
The GP20D is designed not only to be a flat switcher, but also a heavy industrial switcher, and even a very usable road unit at 2,000 HP (dynamic brake option too). Small units these days are all about *versatility*, no railroad wants a locomotive that's designed to do just one specific thing, because that limits what the RR can assign it to. They want a locomotive that can do almost anything.