EMD AB6

Infobox Locomotive
name=EMD AB6
powertype=Diesel-electric
gauge=RailGauge|ussg

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caption=Rock Island number 750
railroad=Rock Island
builder=General Motors Electro-Motive Division (EMD)
deliverydate=June 1940
totalproduction=2
roadnumber=750 and 751
poweroutput=convert|1000|hp|kW|abbr=on|lk=on as built
enginetype=EMD 567, 1 off, later 2 off
cylindercount=V12
retiredate=mid-1970s
disposition=Both scrapped 1973–74The EMD AB6 was a diesel locomotive type built exclusively for the Chicago, Rock Island and Pacific Railroad (the "Rock Island Line") by General Motors' Electro-Motive Division and delivered in June 1940. Two examples were built, numbered #750 and #751. They were built for the "Rocky Mountain Rocket" passenger train, which travelled as a unified train from Chicago, Illinois, to Limon, Colorado, but then divided, one segment going to Colorado Springs, Colorado, and the other to Denver, Colorado. The Rock Island desired a locomotive which could look like an integrated part of the train during the Chicago-Limon portion of the route, but could then be operated independently to take three cars to Colorado Springs. A regular, cab-equipped A-unit could have been purchased, but that would have ruined the streamlined look of the train, so the RI had EMD build a flat-fronted locomotive based on an E-series EMD E6B (B unit) but with an operating cab, headlight, pilot and other features to enable it to operate as an independent locomotive.

Since the small three- and four-car trains the units would have to haul independently were very light, the AB6 pair were built with only one 1,000 hp EMD 567 V12 engine, and a baggage compartment where the second engine would have been. Later, with increasing trainloads, the baggage compartment was replaced with a second engine.

In 1965, the units had their steam generators replaced with head-end power and were reassigned to push-pull suburban service in the Chicago area. In this form, they lasted until the mid 1970s.

References

* Marre, Louis A. (1995). "Diesel Locomotives: The First 50 Years", p.123. Kalmbach Publishing Co. ISBN 0-89024-258-5.
*cite book |author=Marre, Louis A. |year=1982 |title=Rock Island Diesel Locomotives 1930–1980| location=Cincinnati, Ohio |publisher-Railfax, Inc. |pages=pp.93–94 |isbn=0 942192 00 1