US Army 0-6-0 "Switcher" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class S100 - African Theatre (Locobase 1297)

Data from [] (July 2002), a web site by Nick Sbarounis specializing in Greek steam locomotives. Data added and confirmed by US Military Railway Service diagram book supplied in May 2005 by Allen Stanley from his extensive Rail Data Exchange and Kent Rail's extensive history at, last accessed 18 October 2011.

Colonel Howard G Hill was a "draftee" from the Southern Pacific who was given the task in November 1941. According to Kent Rail:"Hill worked long and hard to pencil a locomotive from scratch, and in under a week produced a complete set of drawings ...In 1945 ...Howard G. Hill was awarded the 'Legion of Meritª in recognition of his services to the US Military."

Among other features in these powerful little tanks were 8" (203 mm) piston valves.

According to the MRS booklet, the locomotives were supplied by 3 US builders - Davenport-Besler, HK Porter Co, and Vulcan Iron Works. US number series were 1252-1436, 1927-2031, 4006-4041, and 5000-5026. Also, it notes that after the first 50 locomotives the 66"-long grate was narrowed from 44" to 40", dropping the grate area from 19.4 sq ft to 18.3 sq ft.

Like other US Army locomotives, their postwar use ranged throughout the world, including 20 in Greece and 2 (converted to tender-pulling 0-6-0 engines) in Mexico.

The Project 62 renovation website, which documents the rehabilitation of a USATC 0-6-0T from Yugoslavia's Class 62 -- [], accessed 26 May 2006 -- notes that in addition to the 106 locomotives originally supplied by US manufacturers (62.001-62.106), a further 90 were delivered from the Djuro Djakovic works at Slavonski Brod in Croatia between 1951 and 1961. (Another 14 S100 apparently were consumed as spare parts.) The Yugoslavian loks used a plate frame rather than the original bar frame.

Also found on the Project 62 website is an interesting comment on the design's ride -- [] (visited 1 June 2005): In comparing the USATC design to that of another widely distributed postwar design -- the Polish Tkh 49 Ferrum, the Project 62 historian comments: "The crank drive [of the Ferrum] is to the centre wheel (On Class 62's the connecting rod drives the crank on the rear wheel). This shorter drive connection and therefore increased angular oscillation of the crankshaft gives an inferior ride quality with noticeable "waddle" which is virtually absent in the Class 62's with their rear wheel crank position."

Principal Dimensions by Steve Llanso of Sweat House Media
ClassS100 - African Theatre
Locobase ID1297
RailroadUS Army
Number in Class353
Road Numbers
Number Built353
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)10 / 3.05
Engine Wheelbase (ft / m)10 / 3.05
Ratio of driving wheelbase to overall engine wheebase1
Overall Wheelbase (engine & tender) (ft / m)10 / 3.05
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)100,650 / 45,654
Engine Weight (lbs / kg)100,650 / 45,654
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)100,650
Tender Water Capacity (gals / ML)1200 / 4.55
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT) 1.30 / 1.20
Minimum weight of rail (calculated) (lb/yd / kg/m)56 / 28
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)54 / 1372
Boiler Pressure (psi / kPa)211 / 14.50
High Pressure Cylinders (dia x stroke) (in / mm)16.5" x 24" / 420x610
Tractive Effort (lbs / kg)21,701 / 9843.42
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.64
Heating Ability
Firebox Area (sq ft / m2)86 / 7.99
Grate Area (sq ft / m2)19.40 / 1.80
Evaporative Heating Surface (sq ft / m2)876 / 81.41
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)876 / 81.41
Evaporative Heating Surface/Cylinder Volume147.49
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation4093
Same as above plus superheater percentage4093
Same as above but substitute firebox area for grate area18,146
Power L14176
Power MT274.41

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