FM "H10-44" Locomotives

The H10-44 was Fairbanks-Morse's first cataloged locomotive it offered, and the first in its switcher line. It was constructed during the latter half of the 1940s and sold relatively well.

The H10-44 was originally designed for yard service. However, as is so often the case, railroads found the switcher suitable in all types of work, from shunting cars to branch line duty.

The engine had proven itself in marine applications and when well understood by maintenance personnel operated just fine in rail service. 

The Southern Pacific and Canadian Pacific, for example, operated theirs for more than 20 years before age led to retirement.

Purely on the stance of reliability, FM's 38D8 1/8 opposed-piston (O-P) prime mover was the most reliable diesel engine of all the smaller builders (Alco and Baldwin).

In any event, H10-44's could be found in operation on many Class Is from time they were cataloged in 1944 through the late 1970s and early 1980s.

Milwaukee Road H10-44 #766 is tied down in Ottumwa, Iowa during August of 1978. The Milwaukee operated several Fairbanks-Morse units well into the 1970's. Rob Kitchen photo.

A Brief History Of The H10-44

As John Kirkland points out in his book, "The Diesel Builders: Fairbanks-Morse And Lima-Hamilton," the heritage of what became the H10-44 has many "firsts" but can essentially be traced back to two test-bed models FM manufactured for the Southern Railway and Reading: a diesel-powered rail car and a small switcher. 

The former was the first to utilize FM's 2-cycle, 38D8 1/8 O-P prime mover.  The cars were essentially used for baggage with the carbodies manufactured by the St. Louis Car Company.

The six units numbered as Southern 1-4 and Alabama Great Southern 40-41, entered service in 1939.  The rail cars could produce 800 horsepower and pulled powerless, 76-seat coaches (also built by St. Louis Car), numbered as Southern MT1-MT4 and Alabama Great Southern MT40-MT41.

All internal electrical equipment was supplied by Westinghouse, which also supplied Baldwin with most of its diesel locomotives.

The Reading's switcher, numbered 35, also entered service in 1939.  It was, however, not powered by an O-P engine but  nevertheless did utilize an FM prime mover.  As such, it is recognized as the first locomotive to feature an FM diesel engine.

The switcher was also manufactured by St. Louis Car and somewhat resembled a beefed-up General Electric design from the same era.  

It featured a pair of model 46A86, 4-cycle engines that could produce 300 horsepower each for a total of 600 horsepower.

Once again Westinghouse supplied all electrical equipment.  After delivery to Reading on December 31, 1939 it entered service at Wayne Junction, Philadelphia on January 4, 1940.  Soon after, the locomotive was renumbered 97.

The H10-44 began production in August, 1944; it was capable of producing 1,000 horsepower using Fairbanks Morse's 2-cycle 38D8 1/8 opposed-piston prime mover.

The 8-cylinder, 1,600 version of the O-P prime mover was touted by FM as having "237 fewer working parts than an EMD model 567-16 cylinder 8 ½" x 10" engine (1,500 horsepower) and 118 fewer working parts than an Alco model 244 12-cylinder 9" x 10 ½" engine (1,500 horsepower)."

There was also the advantage of having headless cylinders; the two pistons worked vertically within a central chamber.

Of course, the trade off was excess burn-off during startup as lube oil occasionally found its way into the exhaust gas passages and two crankshafts meant a more finely detailed understanding of maintaining the power plant.

The H10-44 featured B-B trucks and a high hood with the cab off-set to one end.  As Mr. Kirkland notes, the switcher was essentially a Baldwin design with an O-P engine.

Fairbanks-Morse adopted many Baldwin features into its initial including the use, once more, of Westinghouse for all electrical equipment.

Fairbanks-Morse's Catalog Of Diesels





H16-66, "Baby Train Master"

H24-66, "Train Master"

FM's "Erie Builts"

FM's "C-Liners"

While some railroads and shop forces complained of FM's complicated opposed-piston design no one could argue with the incredible tractive effort and pulling power its locomotives offered.

For instance, the H10-44 could produce 72,000 pounds of starting tractive effort and 34,000 pounds continuous. Similar models offered by Alco and EMD could simply not match this; this ability, among other things, helped immensely in getting a train moving quickly. 

FM's modeling designation was rather straightforward, although the use of "H" to designate "Hood" became confusing when the company released road-switchers with a similar hood only on a longer carbody.

The H10-44 stood for the following:

  • "H" stood for Hood

  • "10" was for 1,000 horsepower

  • Each 4 regarded four axles and four traction motors
Baltimore & Ohio H10-44 #9207 is seen here at Riverside Yard in Baltimore, Maryland on January 19, 1969. This unit was built as #302 in 1948. Roger Puta photo.

While the H10-44 was only marginally successful from a sales standpoint it is not necessarily because Fairbanks Morse's models were unreliable.  

The engine was a proven rugged design as Kirkland notes; their issue were largely one of maintenance personnel being unfamiliar with them during an era when Electro-Motive was the primary motive power on many railroads.

During the course of production there was one major change to the H10-44, a switch from a 125-volt to 75-volt control system.

This was to conform to Association of American Railroads (AAR), industry standards.  In doing so, Westinghouse switched to slightly different models of the electrical equipment it supplied FM, which will be noted in the below data sheets.

Baltimore & Ohio #306-307, completed in December, 1948, were the first units to feature the updated 75-volt system and internal equipment.

H10-44 Data Sheet (125 Volt)

Entered Production8/21/1944 (Milwaukee Road #1802)
Years Produced8/1944 - 12/1948
Fairbanks-Morse ClassH10-44
Engine38D8 1/8, 6-cylinder Opposed-Piston
Engine BuilderFairbanks-Morse
Carbody StylingRaymond Loewy
Length (Inside Couplers)48' 10"
Height (Top Of Rail To Top Of Cab)14' 6"
Width10' 2"
Weight240,000 Lbs
TrucksGSC Rigid Bolster, Drop-Side Equalizer
Truck Wheelbase8'
Wheel Size40"
Traction Motors362D (4), Westinghouse
Traction Generator481A, Westinghouse
Auxiliary GeneratorYG40C, Westinghouse
MU (Multiple-Unit)Yes
Gear Ratio68:14
Tractive Effort34,000 Lbs at 9 mph
Top Speed60 mph

H10-44 Data Sheet (75 Volt)

Entered Production12/1948 (Baltimore & Ohio #306-307)
Years Produced12/1948 - 4/1950
Fairbanks-Morse ClassH10-44
Engine38D8 1/8, 6-cylinder Opposed-Piston
Engine BuilderFairbanks-Morse
Carbody StylingRaymond Loewy
Length (Inside Couplers)48' 10"
Height (Top Of Rail To Top Of Cab)14' 6"
Width10' 2"
Weight240,000 Lbs
TrucksGSC Rigid Bolster, Drop-Side Equalizer
Truck Wheelbase8'
Wheel Size40"
Traction Motors362D (4), Westinghouse
Traction Generator481F, Westinghouse
Auxiliary GeneratorYG42A, Westinghouse
MU (Multiple-Unit)Yes
Gear Ratio68:14
Tractive Effort34,000 Lbs at 9 mph
Top Speed60 mph

H10-44 Production Roster

Owner Road Number Construction Number Contract Number Completion Date
Milwaukee Road1802L1001LD18/1944
Chicago & North Western1036L1002LD211/1944
Santa Fe500L1003LD34/1945
Union PacificDS1300L1004LD45/1945
Milwaukee Road1803-1812L1005-L1014LD56/1945-12/1945
Chicago & North Western1048-1050L1015-L1017LD79/1946
Chicago & North Western1051L1018LD710/1946
Minnesota Western Railway51L1019LD109/1946
Monon Railroad18L1020LD1311/1946
Wabash Railroad380-381L1021-L1022LD1411/1946


  • Kirkland, John F. Diesel Builders, The:  Fairbanks-Morse And Lima-Hamilton. Glendale: Interurban Press, 1985.

  • Pinkepank, Jerry A. Diesel Spotter's Guide.  Milwaukee: Kalmbach Publishing Company, 1967.

  • Schafer, Mike. Vintage Diesel Locomotives. Osceola: MBI Publishing, 1998.

St. Louis-San Francisco Railway H10-44 #280 is seen here in Tulsa, Oklahoma during the 1960's. The Frisco owned 12 such units, acquired between 1948-1949. Mac Owen photo.

By the time production had ended on the H10-44 in April of 1950 Fairbanks Morse had sold 195 units to a wide range of Class I and smaller railroads (the PRR purchased the most, 55).  

Today, at least three FM H10-44s are known to be preserved, all of which are former Milwaukee Road units; #760, #767, and #781.

The former unit #760) was the first ever produced by Fairbanks Morse and is one of the only examples of its diesels that is still in operating condition at the Illinois Railway Museum.

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Wes Barris's is simply the best web resource in the study of steam locomotives. 

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A popular pastime for many is studying and/or exploring abandoned rights-of-way. 

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