An FM H-20-44 locomotive, retired Union Pacific No. 1366.

(The original uploader was Can't Undo at English Wikipedia., CC BY-SA 3.0 <>, via Wikimedia Commons)



The FM H-20-44 was a diesel locomotive manufactured by Fairbanks-Morse from June 1947 – March 1954. It represented the company's first foray into the road switcher market. The 2,000 hp (1,490 kW), ten-cylinder opposed piston engine locomotive was referred to by F-M's engineering department as the "Heavy Duty" unit. It was configured in a B-B wheel arrangement mounted atop a pair of two-axle AAR Type-B road trucks with all axles powered. H-20-44s shared the same platform and much of the same carbody as the lighter-duty FM H-15-44, which began its production run three months later.

In the same manner as other F-M switcher models, the H-20-44 started out displaying a variety of Raymond Loewy-inspired contours, only to have the majority of these superfluous trim features stripped from the last few units built as a cost-cutting measure. Only 96 units were built for American railroads, as few firms saw sufficient value in moving freight in greater quantities or at a higher speeds than was possible with the typical 1,500 and 1,600 horsepower (1,200 kW) four-axle road switchers of the era. Also limiting the model's utility as a true road unit was its lack of a short hood, which the (ironically) lighter-duty H-15-44 did have. Three intact examples of the H-20-44 are known to survive today; all are the property of railroad museums.

A six axle version for better traction was catalogued, but no orders were placed, and no demos were built.


PRR FM H20-44 at Streigels, Baltimore, MD on August 22, 1970.

(Roger Puta, courtesy Marty Bernard, railfan 44, Public domain, via Wikimedia Commons)


Units produced

Railroad Quantity Road numbers Notes
Akron, Canton and Youngstown Railroad 6 500–505 500 preserved at the Galveston Railroad Museum as "Union Pacific 410"
Fairbanks-Morse (demonstrator units) 1 2000 Serial number #L1032; sold to the UP later in 1947 and assigned #DS1366; now preserved at the Illinois Railway Museum
New York Central Railroad 19 7100–7118
Pennsylvania Railroad 38 8917–8942, 9300–9311 #8931 and #8939 to Penn Central #7731 and #7739 in 1968, retired August 1970
Pittsburgh and West Virginia Railway 22 50–71
Union Pacific Railroad 10 DS1360–DS1365, DS1367–DS1370 DS 1369 preserved at the Pacific Southwest Railway Museum in San Diego
Total 96


Type and origin
Power type: Diesel-electric
Builder: Fairbanks-Morse
Model: H-20-44
Build date: June 1947 — March 1954
Total produced: 96
​• AAR B-B
• UIC B′B′
Gauge: 1,435 mm (4 ft 8+1⁄2 in)
Length: 51 ft 0 in (15.54 m)
Locomotive weight: 254,000 lb (115.2 tonnes)
Prime mover: FM 38D-8 1/8
Engine type: Two-stroke diesel
Aspiration: Roots blower
Displacement: 10,369 cu in (169,920 cm3)
Cylinders: 10 (Opposed piston)
Cylinder size: 8.125 in × 10 in (206 mm × 254 mm)
Transmission: DC generator, DC traction motors
Locomotive brake: Straight air
Train brakes: Air
Performance figures
Maximum speed: 70 mph (113 km/h)
Power output: 2,000 hp (1.49 MW)
Tractive effort: 42,125 lbf (187.38 kN)
Locale: North America
Disposition: Three preserved, remainder scrapped