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FM "H10-44" Locomotives

Last revised: February 12, 2024

By: Adam Burns

The H10-44 was Fairbanks-Morse's first cataloged locomotive, 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 switching to branch line duties.

The engine had proven itself in marine applications and when well understood by maintenance personnel operated 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).

H10-44's could be found in operation on many Class Is, from time they were cataloged in 1944 through the late 1970s, with some even surviving into the 1980's.


92835273572356237628768378.jpgPennsylvania H10-44 #9185 in Detroit during January of 1966. Warren Calloway collection.


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 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 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.

2679234982735627172768970.jpgMilwaukee Road H10-44 #704 is seen here between assignments at Ottumwa, Iowa in December, 1969. Fred Byerly photo. American-Rails.com collection.

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


While the H10-44 was only marginally successful from a sales standpoint (195 units were ultimately produced), 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.

9273523752357237858925398278689378.jpgWabash H10-44 #380 was photographed here at Decatur, Illinois on October 31, 1965. Photographer unknown. American-Rails.com collection.

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.

In addition, during the course of production, FM tried to enter the field of traction motors and its auxiliary equipment (generators, fans, etc.).  

The first locomotives to use Westinghouse traction motors in conjunction with FM generators was a batch of nine units manufactured for the Nickel Plate Road between December, 1948 and April, 1949 (#125-133).

Later, the first units to roll out of Beloit with all FM electrical equipment was Wabash #382-383 in March, 1949.  As Mr. Kirkland notes, FM's designs proved unsatisfactory and some future switchers reverted back to Westinghouse equipment.

Data Sheet and Specifications

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
Truck TypeGSC 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

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
Truck TypeGSC 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

Production Roster

Total Built = 195

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
Pittsburgh & Lake Erie (New York Central)8800-8801L1023-L1024LD1512/1946
Union PacificDS1301-DS1304L1025-L1028LD172/1947
Terminal Railroad Association Of St. Louis700-701L1029-L1030LD183/1947
Apache Railway100L1081LD2310/1947
Kentucky & Indiana Terminal Railroad48L1082LD2710/1947
Kentucky & Indiana Terminal Railroad49-50L1083-L1084LD2711/1947
Chicago & North Western1052-1053L1085-L1086LD2411/1947
Chicago & North Western (Chicago, St. Paul, Minneapolis & Omaha)94L1171LD2612/1947
Chicago & North Western1054-1055L1172-L1173LD241/1948
Chicago & North Western (Chicago, St. Paul, Minneapolis & Omaha)95-9810L40-10L43LD262/1948
Kentucky & Indiana Terminal Railroad5110L44LD273/1948
Milwaukee Road181910L45LD843/1948
Kentucky & Indiana Terminal Railroad5210L46LD273/1948
St. Louis-San Francisco Railway (Frisco)270-27510L47-10L52LD303/1948
Denver & Rio Grande Western120-12210L53-10L55LD374/1948
Santa Fe501-50210L56-10L57LD324/1948
Denver & Rio Grande Western12310L58LD374/1948
Chicago & North Western108210L59LD256/1948
Weyerhaeuser Timber48110L60LD484/1948
Pittsburgh & Lake Erie (New York Central)8902-890310L64-10L65LD338/1948
St. Louis San Francisco Railway (Frisco)276-27810L83-10L85LD529/1948
Baltimore & Ohio300-30110L86-10L87LD5111/1948
Baltimore & Ohio302-30910L88-10L95LD5112/1948
St. Louis San Francisco Railway (Frisco)27910L99LD5210/1948
Apache Railway20010L100LD6811/1948
Wabash Railroad382-38310L101-10L102LD573/1949
New York, Chicago & St. Louis (Nickel Plate Road)12510L103LD6712/1948
New York, Chicago & St. Louis (Nickel Plate Road)12610L104LD671/1949
New York, Chicago & St. Louis (Nickel Plate Road)127-12810L105-10L106LD672/1949
New York, Chicago & St. Louis (Nickel Plate Road)129-13010L107-10L108LD673/1949
New York, Chicago & St. Louis (Nickel Plate Road)131-13310L109-10L111LD674/1949
Milwaukee Road1813-181510L112-10L114LD561/1949
Milwaukee Road1816-181810L115-10L117LD562/1949
Terminal Railroad Association Of St. Louis702-70310L118-10L119LD594/1949
St. Louis San Francisco Railway (Frisco)28010L132LD546/1949
St. Louis San Francisco Railway (Frisco)28110L133LD547/1949
Chicago & North Western105610L134LD636/1949
Chicago & North Western105710L135LD637/1949
Chicago & North Western105810L136LD638/1949
Chicago & North Western105910L137LD637/1949
Chicago & North Western1060-106210L138-10L140LD638/1949
Kentucky & Indiana Terminal Railroad55-5910L141-10L145LD695/1949
New York Central8904-890510L146-10L147LD606/1949
Chehalis Western Railroad (Weyerhaeuser)49210L148LD605/1949
Chehalis Western Railroad (Weyerhaeuser)49310L149LD606/1949
New York Central9106-910710L170-10L171LD7311/1949
New York Central9108-910910L172-10L173LD7312/1949
Columbia & Cowlitz Railway (Weyerhaeuser)D110L174LD756/1949
Pittsburgh, Chartiers & Youghiogheny Railway110L175LD796/1949
New York Central911010L176LD772/1950
Chicago & North Western106310L284LD7612/1949
Chicago & North Western1064-106510L285-10L286LD761/1950
Chicago & North Western107010L287LD761/1950
Indianapolis Union Railway10-1110L300-10L301LD818/1949
Indianapolis Union Railway12-1310L302-10L303LD8111/1949
Milwaukee Road1820-182210L325-10L327LD852/1950
Milwaukee Road1823-182510L328-10L330LD853/1950
Indianapolis Union Railway1410L363LD903/1950
Indianapolis Union Railway15-1810L364-10L367LD904/1950


  • 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.

8923842735826823498307398978.jpgRio Grande H10-44 #120 at Ogden, Utah, circa 1970. American-Rails.com collection.

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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