The G-1/G-2 classes were known simply as "Big Mallies." The KCS measured the G-1s' compound tractive effort as 122,683 lb (55,648 kg). Purchase stimulated by success of 0-6-6-0s. Among John E Muhfeld's many points supporting the value of the KCS's Mallets was a refutation of the claim that Mallets were "difficult and expensive to maintain and that special facilities are required for engine house and back-shop repair work." Rather, he said, the G-1s used regular shop facilities, made "from 80,000 to 85,000 miles[128,800-136,850 km] between classified repairs ...and during busy months will all average as high as 3,500 miles [5,635 km] per locomotive."
Assigned to KCS's Northern Division (KC to De Queen, Ark.). Two later refitted briefly to burn pulverized coal, but reverted to oil burning in 1930. Firebox heating surface included that provided by 92 sq ft (8.55 sq m) in four arch tubes and 127 sq ft (11.80 sq m) in a combustion chamber. Fourteen-inch (356 mm) piston valves fed steam to the HP cylinders, slide valves did for the LP cylinders ahead of the smokebox. Inside dry pipes conveyed steam from the dome to the superheater.
Delivered with the pressure set to 210 psi, 4 of the class -- 755, 752, 754, 750 -- had their settings changed to 220 psi. In 1927, the railroad increased the boiler pressure in 751, 752, 754, and 756 from 220 psi to 240 psi.
See Locobase 438 for the 1923 G-2 class.
Developments of the 1918 G-1s (Locobase 437) delivered by Schenectady with only detail differences between the two batches. Each of the ten locomotives cost about $100,000.
According to the KCS report of July 1923, the only significant changes were the adoption of piston valves for the low-pressure cylinders; each of the four valves measured 14" (356 mm) in diameter. The dry pipe carrying steam from the dome to the superheater now appeared outside the boiler cladding. A slight change in tube and flue counts (down eight in tubes, up two in flues) and a boiler pressure increase of 15 psi (1.03 bar), and a slight increase in an already generous superheater proportion of the combined heating surface area were other changes.
As in the G-1s, the G-2s' firebox heating surface area included the 121 sq ft (11.24 sq m) yielded by the combustion chamber and the 52 sq ft (4.83 sq m) in five arch tubes.
The Port Arthur Route said the new design could haul 2,700 tons (2,450 metric tonnes or 50 loaded cars each weighing 50 short tons) over a ruling grade of 1.5% southbound and 1.35% northbound. Each locomotive mile would consume 37 US gallons (140 litres) of fuel oil and 550 gallons (2,082 litres) of water.
Seven Big Mallies were rebuilt as four-cylinder simple articulateds by the KCS during World War II. Eliminating those massive, 41-inch diameter low-pressure cylinders permitted a speed increase of up to 50%. Firebox heating surface includes 102.5 sq ft (9.5 sq m) of thermic syphons and 28 sq ft (2.6 sq m) of arch tubes. Piston valves measured 12" (306 mm) in diameter. Fitted with a Worthington 6-A feedwater heater.
Although the diagram clearly shows a combustion chamber, its length isn't recorded.
|Principal Dimensions by Steve Llanso of Sweat House Media|
|Railroad||Kansas City Southern (KCS)||Kansas City Southern (KCS)||Kansas City Southern (KCS)|
|Number in Class||7||10||8|
|Road Numbers||750-756||757-766||752, 757-759,762,764,766|
|Locomotive Length and Weight|
|Driver Wheelbase (ft / m)||15.50 / 4.72||15.50 / 4.72||15.50 / 4.72|
|Engine Wheelbase (ft / m)||50.50 / 15.39||50.50 / 15.39||50.50 / 15.39|
|Ratio of driving wheelbase to overall engine wheebase||0.31||0.31||0.31|
|Overall Wheelbase (engine & tender) (ft / m)||84.70 / 25.82||84.70 / 25.82||84.70 / 25.82|
|Axle Loading (Maximum Weight per Axle) (lbs / kg)||61,700 / 27,987||63,000 / 28,576|
|Weight on Drivers (lbs / kg)||466,000 / 211,374||476,400 / 216,092||476,400 / 216,092|
|Engine Weight (lbs / kg)||495,000 / 224,528||507,300 / 230,108||507,300 / 230,108|
|Tender Loaded Weight (lbs / kg)||218,900 / 99,291||206,000 / 93,440||206,000 / 93,440|
|Total Engine and Tender Weight (lbs / kg)||713,900 / 323,819||713,300 / 323,548||713,300 / 323,548|
|Tender Water Capacity (gals / ML)||10,000 / 3.79||10,500 / 39.77||10,500 / 39.77|
|Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)||4266 / 16.20||4000 / 15.20||4266 / 16.20|
|Minimum weight of rail (calculated) (lb/yd / kg/m)||97 / 48.50||99 / 49.50||99 / 49.50|
|Geometry Relating to Tractive Effort|
|Driver Diameter (in / mm)||57 / 1448||57 / 1448||57 / 1448|
|Boiler Pressure (psi / kPa)||210 / 14.50||225 / 15.50||250 / 17.20|
|High Pressure Cylinders (dia x stroke) (in / mm)||26" x 32" / 660x813||26" x 32" / 660x813||22.5" x 32" / 572x813 (4)|
|Low Pressure Cylinders (dia x stroke) (in / mm)||41" x 32" / 1041x813||41" x 32" / 1041x813|
|Tractive Effort (lbs / kg)||96,627 / 43829.32||103,529 / 46960.02||120,789 / 54789.03|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.82||4.60||3.94|
|Firebox Area (sq ft / m2)||420 / 42.19||414 / 38.46||371.50 / 34.53|
|Grate Area (sq ft / m2)||88.30 / 8.21||88.30 / 8.20||88.31 / 8.21|
|Evaporative Heating Surface (sq ft / m2)||5251 / 486.15||5222 / 485.14||5304 / 492.94|
|Superheating Surface (sq ft / m2)||1434 / 133.27||1459 / 135.54||1459 / 135.59|
|Combined Heating Surface (sq ft / m2)||6685 / 619.42||6681 / 620.68||6763 / 628.53|
|Evaporative Heating Surface/Cylinder Volume||267.04||265.56||180.09|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||18,543||19,868||22,078|
|Same as above plus superheater percentage||22,437||24,238||26,935|
|Same as above but substitute firebox area for grate area||106,722||113,643||113,308|