EMD AB6

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EMD AB6

Rock Island number 750
Power type	Diesel
Builder	General Motors Electro-Motive Division (EMD)
Total production	2
Gauge	4 ft 8½ in (1435 mm)
Engine type	EMD 567
Cylinders	V12
Power output	1,000 hp as built
Career	Rock Island
Number	750 and 751
Delivered	June 1940
Retired	mid-1970s

The 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 driven independently to take 3 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 a driving cab, headlight, pilot and other features to enable it to operate as an independent locomotive.

Since the small 3 and 4 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.

[edit] References

• Marre, Louis A. (1995). Diesel Locomotives: The First 50 Years, p.123. Kalmbach Publishing Co. ISBN 0-89024-258-5.

Diesel cab and cowl locomotives built by GM-EMD
Cab units (F- & E-units):	FT, F2, F3, F7, FP7, F9, FP9, FL9, TA, EA/EB, E1, E2, E3, E4, E5, E6, E7, E8, E9, AB6
Cowl units:	F45, FP45, F40C, F40PH, F40PH-2, F40PH-2C, F40PH-2M, SDP40F, SD40-2F, SD50F, F59PH, F59PHI, SD60F, F69PHAC
See also:	List of GM-EMD locomotives