FM H-20-44

FM H-20-44
An FM H-20-44 locomotive, retired Union Pacific #1366
Type and origin
Power typeDiesel-electric
BuilderFairbanks-Morse
ModelH-20-44
Build dateJune 1947 — March 1954
Total produced96
Specifications
Configuration:
 • AARB-B
 • UICB′B′
Gauge1,435 mm (4 ft 8+12 in)
Length51 ft 0 in (15.54 m)
Loco weight254,000 lb (115.2 tonnes)
Prime moverFM 38D-8 1/8
Engine typeTwo-stroke diesel
AspirationRoots blower
Displacement10,369 cu in (169,920 cm3)
Cylinders10 (Opposed piston)
Cylinder size8.125 in × 10 in (206 mm × 254 mm)
TransmissionDC generator,
DC traction motors
Loco brakeStraight air
Train brakesAir
Performance figures
Maximum speed70 mph (113 km/h)
Power output2,000 hp (1.49 MW)
Tractive effort42,125 lbf (187.38 kN)
Career
LocaleNorth America
DispositionThree preserved, remainder scrapped
Union Pacific FM H-20-44 No. 410 at the Galveston Railroad Museum

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 preserved at railroad museums. These were former Southwest Portland Cement units donated in the early 1980s.

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