Gotthardbahn Articulated Locomotives in Switzerland

Class Details by Steve Llanso of Sweat House Media

Class Goliath/Ed 2 x 3/3 (Locobase 5126)

Data from [], last accessed 19 January 2017, (First viewed August 2002). See also "Duplex Compound Locomotives for the St Gotthard Railway," Engineering News, Volume 26 (15 August 1891), p. 147; "Twelve-Wheel Locomotive - M. Mallet", Railway Review, Volume 32 (6 February 1892), p. 85; "Engines for the St Gothard [sic] Railway", American Engineer and Railroad Journal, Volume 69, No 3 (March 1895), pp. 119-121 ; and Gustav Reder, The World of Steam Locomotives (1974), p. 257. Works number was 1547 in 1890.

The only Mallet on the GB and the first of hundreds of articulated compounds built to the Mallet design to run on the standard gauge. The 1891 EN report repeated the reasons for adopting the layout from Schweizerische Bauzeitung ("Doppel-Compound-Locomotive furden Bergdienst der Gotthardbahn" Volume 18, No 4/25 July 1891, p. 24) noting that the goals were achieving the same efficiency as found in the then-operating eight-coupleds with tender with less fuel consumption while running more smoothly.

The design also reflected a debate over the relative merits of tank engines vs engines with separate tenders, the EN saying that the tank locomotive put more adhesive weight on the tracks. By operating the starting valve to let live steam into the LP cylinders, the maximum train load of 220 tons could easily get underway on the steepest 2.6% grade.

Railway Review described the Mallet as "an almost perfect type of locomotive, with powerful traction, and large degree of flexibility".

According to the site, this engine managed a max speed in the mountains of 20 kph (13 mph) and 45 kph (27 mph) on the level.

Tonnage ratings were as follows:

Mountain -- freight 200 tons

Mountain -- passenger 500 tons

Level -- freight 800 tons

Level -- passenger 800 tons.

Commentary from the site, however, says that this locomotive did not live up to expectations. It was too hard on the relatively light track and proved susceptible to breakdowns. The largest deficiency, they comment, was the boiler, which was too small to provide all the steam needed.

The report especially condemned fuel consumption, a reputed benefit of compounding: "The average consumption of fuel is 67 lbs. per mile, but on the steepest grades it. is no less than 1,666 lbs. per hour, or close upon 160 lbs. per mile. This is 2.5 times the average consumption of the engine and 3.5 times that of the average consumption of the other engines. The consumption of grease and oil of this engine is as much as 0 35 lb. per mile run, or nearly twice as much as the average of the other engines, which is 0.18 lb."

A real fuel hog, in other words. But there was more to say:

"[I]ts tractive power is only about one-tenth of its weight, and altogether the internal resistances of the engine are so enormous that its working results cannot be described as favorable."

Mallet, stung later by such criticism, attributed some of the failings to a lack of insulation around the pipe leading from the HP to the LP cylinders, which encouraged condensation in the steam. But that doesn't likely to have affected the locomotive to the degree mentioned in the report.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassGoliath/Ed 2 x 3/3
Locobase ID5126
Number in Class1
Road Numbers151
Number Built1
Valve GearHeusinger
Locomotive Length and Weight
Driver Wheelbase (ft / m) 8.86 / 2.70
Engine Wheelbase (ft / m)26.67 / 8.13
Ratio of driving wheelbase to overall engine wheelbase 0.33
Overall Wheelbase (engine & tender) (ft / m)26.67 / 8.13
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)192,243 / 87,200
Engine Weight (lbs / kg)192,243 / 87,200
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)192,243 / 87,200
Tender Water Capacity (gals / ML)1848 / 7
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 4.70 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)53 / 26.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)48.40 / 1230
Boiler Pressure (psi / kPa)174 / 12
High Pressure Cylinders (dia x stroke) (in / mm)15.75" x 25.2" / 400x640
Low Pressure Cylinders (dia x stroke) (in / mm)22.83" x 25.2" / 580x640
Tractive Effort (lbs / kg)25,885 / 11741.25
Factor of Adhesion (Weight on Drivers/Tractive Effort) 7.43
Heating Ability
Tubes (number - dia) (in / mm)190 - 2.126" / 54
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)14.76 / 4.50
Firebox Area (sq ft / m2)100.11 / 9.30
Grate Area (sq ft / m2)23.68 / 2.20
Evaporative Heating Surface (sq ft / m2)1661 / 154.30
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1661 / 154.30
Evaporative Heating Surface/Cylinder Volume292.30
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation4120
Same as above plus superheater percentage4120
Same as above but substitute firebox area for grate area17,419
Power L12541
Power MT174.84

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