Kennecott Copper Corporation locomotive 201 on display at Snoqualmie Depot, Snoqualmie, Washington.

(Joe Mabel, CC BY-SA 3.0 <>, via Wikimedia Commons)



The ALCO RSD-4 was a 1,600 horsepower (1.2 MW) six axle diesel-electric locomotive built by the American Locomotive Company between 1951 and 1952. It was a derivative of the four-axle ALCO RS-3, with two additional powered axles which allowed better tractive effort at lower speeds. Due to the inadequate capacity of the main generator, this model was later superseded in production by the ALCO RSD-5.


Original owners

Railroad Quantity Road numbers Notes
Atchison, Topeka and Santa Fe Railway 10 2100–2109
Chicago and North Western Railway 5 1515–1517, 1619–1620
Central Railroad of New Jersey 14 1601–1614
Kennecott Copper Corporation 1 201 Preserved
Utah Railway 6 300–305
Total 36

Preserved units

The only ALCO RSD-4 that has survived is Kennecott Copper Corporation No. 201. It resided at the Northwest Railway Museum until November 2021 (formerly known as the Puget Sound & Snoqualmie Valley Railway) in Snoqualmie, Washington in its orange Kennecott paint scheme. As of 2021, it has been returned to Ely, Nevada (along with EMD SD7 No. 401) to the Nevada Northern Railway Museum.



Type and origin
Power type: Diesel-electric
Builder: ALCO
Model: RSD-4 (Specification E1663)
Build date: 1951–1952
Total produced: 36
Configuration: AAR C-C
Gauge: 4 ft 8+1⁄2 in (1,435 mm) standard gauge
Trucks: ALCO trimount
Wheel diameter: 40 in (1,000 mm)
Minimum curve: 21° (274.37 ft or 83.63 m)
Wheelbase: 42 ft 3 in (12.88 m)
Length: 56 ft 6 in (17.22 m)
Width: 10 ft 1+7⁄8 in (3.096 m)
Height: 14 ft 5+1⁄4 in (4.401 m)
Locomotive weight: 278,860 lb (126,490 kg)
Fuel capacity: 800 US gal (3,000 L)
Prime mover: ALCO 244
RPM range: 1000 (max)
Engine type: V12 Four-stroke engine diesel
Aspiration: Turbocharger
Displacement: 8,016 cu in (131.36 L)
Generator: GE 5GT-581A1
Traction motors: (6) GE 5GE752-C1
Cylinders: 12
Cylinder size: 9 in × 10.5 in (229 mm × 267 mm)
Performance figures
Power output: 1,600 hp (1.2 MW)
Tractive effort: 69,700 lb (31,600 kg)