||This article needs additional citations for verification. (July 2007)|
|An SDP40F leads the San Francisco Zephyr west at Emigrant Gap in 1978|
|Builder||General Motors Electro-Motive Division (EMD)|
|Build date||June 1973 – August 1974|
|AAR wheel arr.||C-C|
|Gauge||4 ft 8 1⁄2 in (1,435 mm)|
|Length||72 ft 4 in (22.05 m)|
|Width||10 ft 4 in (3.15 m)|
|Prime mover||EMD 645E3|
|Top speed||100 mph (160 km/h)|
|Power output||3,000 hp (2,240 kW)|
|Locomotive brake||straight air, dynamic brakes|
The SDP40F was a 6-axle diesel-electric locomotive built by General Motors Electro-Motive Division in 1973-74 for Amtrak. It had an EMD 645E3 16-cylinder turbocharged Diesel engine that generated 3,000 hp (2,240 kW).
The SDP40F was the first locomotive built new for Amtrak. Until then most of Amtrak's engines were EMD E-units and F-units that predecessor railroads had used for many years without good maintenance, resulting in breakdowns. The SDP40F was an interim solution.
Based on EMD's ubiquitous SD40-2 freight locomotive, 150 SDP40Fs were built in two years. They had a passenger style carbody instead of the narrow long hood of the freight unit and 57:20 gearing allowed 100 mph (160 km/h). Two Vapor steam generators and a 1,350 US gal (1,124 imp gal; 5,110 L) water tank at the rear of the engine room made the steam needed for heat (and sometimes cooling) and hot water on most of Amtrak's cars. (Another tank below the frame carried 2150 gallons more water.)
EMD based the SDP40F name on the existing SDP40. Several years earlier EMD had made similar versions of the SDP45 and SD45, which it named FP45 and F45. Although the SDP40F was externally nearly identical to the FP45, EMD chose not to give the new locomotive a similar name such as FP40. EMD wanted to avoid adding a new locomotive type to their catalog due to price controls in effect in the early 1970s. The following year the F40C name was used for a similar locomotive ordered by the Milwaukee Road, equipped with HEP instead of steam generators.
Eventually the SDP40F was phased out as all-electric cars, such as the Amfleet, displaced the old steam heat rolling stock. Amtrak was able to trade in the SDP40F to EMD as the head end power-equipped F40PH was acquired.
The SDP40F was mechanically reliable but experienced several high speed derailments, causing the railroads over which Amtrak ran to impose speed limits starting in 1976-77. Although the "hollow bolster" truck design was suspected, this was never proved, despite extensive investigation by EMD, Amtrak and the Federal Railroad Administration. It was supposed that the steam generators and water tank may have made the rear of the engine too heavy. Later FRA investigations concluded that the actual culprits were the lightweight baggage cars, which caused harmonic vibrations when placed directly behind the much heavier SDP40F. Also playing a role was the mediocre condition of much of the track on which the SDP40F ran.:126
Whatever the derailment cause, the speed restrictions, along with electrification of Amtrak's passenger car fleet, led Amtrak to adopt the EMD F40PH as the standard model, based on the proven GP40-2 freight locomotive.
Santa Fe traded lower-power locomotives to Amtrak for SDP40Fs, horsepower-for-horsepower. They replaced the hollow HT-C bolsters with conventional HT-C bolsters, converted the below-frame combination fuel/water tank to an all-fuel tank, removed the above-frame water tanks (replacing these with concrete ballast) and used the engines on freight trains for nearly 15 years.
As Amtrak F40PHs increased in number the SDP40F was withdrawn from service. The last revenue run of an SDP40F under Amtrak was in 1985. In an unusual move for modern railroading, 18 were traded by Amtrak to the Santa Fe Railroad in 1984 to be reconditioned for use as freight locomotives. In exchange, Amtrak received 43 smaller locomotives for use in switching service.:133
The last run of an SDF40-2 on BNSF took place in 2001. All units were retired in 2002, and most were scrapped in Topeka, Kansas between 2002 and 2004.
One locomotive of the type, former Amtrak 644, has been preserved by Northwest Rail Museum near Portland, OR and is in storage. The group plans to restore it to its Amtrak as-delivered state, minus the steam-generators and a few other details. Two heavily modified SDP40Fs in EMD livery exist as test beds at the AAR testing center in Pueblo, CO. It is unknown what their internal configuration is, or what the future holds for them.
- McDonnell, Greg (2002). Field Guide to Modern Diesel Locomotives. Waukesha, WI: Kalmbach Publishing Co. pp. 142–144. ISBN 0-89024-607-6.
- Graham-White, Sean (2002). Electro-Motive Division's Classic Cowl Units. La Mirada, CA: Four Way West Publications. pp. 97–98. ISBN 1-885614-53-5.
- Graham-White 2002, p. 105,107
- Sanders, Craig (2006). Amtrak in the Heartland. Indiana University Press. ISBN 0-253-34705-X.
- Pinkepank, Jerry A. (1973). The Second Diesel Spotter’s Guide. Milwaukee, WI: Kalmbach Publishing Company. ISBN 0-89024-026-4.
- "Santa Fe SDF40-2s". Santa Fe Subjects. Retrieved May 1, 2006.
|Wikimedia Commons has media related to: EMD SDP40F locomotives|