Chicago Great Western 2-6-6-2 "Mallet Mogul" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class H1 (Locobase 3091)

Data from DeGolyer, Volume 35, p. 176 and "Locomotive Performance on the Chicago Great Western" Railway Age Gazette, Volume 57, No 18 (30 October 1914), pp. 796-798. (Thanks to Chris Hohl for his 17 March 2019 email noting the correct tender fuel capacity.) Works numbers were 35365-35374 in October 1910.

Firebox heating surface included 25 sq ft (2.32 sq m) of "water tubes."

The design was essentially identical to the Western Maryland M-1a engines produced in the same month; see Locobase 13938.

After March 1914 tests among ten each of the CGW's Consolidations (Locobase 3090), these Mallets, and the newer Mikados (Locobase 3093) over the Eastern Division between Oelwein, Iowa and Stockton, Ill, the Railway Age Gazette summarized the Prairie Mallet's performance: "It is surprising to note the relatively small amount of gross tons per mile for the Mallet locomotives with such a high percentage of gross to potential ton miles." It isn't surprising, therefore, to find these engines moving on to the Clinchfield by 1916. The CGW simply found the Mikados they were buying more suitable to their requirements.

Picked up by the Clinchfield after the Chicago Great Western found them unsuitable, they lasted only a few years. As Drury (1993) comments: "Their early retirement in 1925 is probably a good indication of their performance."

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID3091
RailroadChicago Great Western (CGW)
Number in Class10
Road Numbers600-609
Number Built10
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)10 / 3.05
Engine Wheelbase (ft / m)45.33 / 13.82
Ratio of driving wheelbase to overall engine wheebase 0.22
Overall Wheelbase (engine & tender) (ft / m)72 / 21.95
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)307,000 / 139,253
Engine Weight (lbs / kg)353,100 / 160,164
Tender Loaded Weight (lbs / kg)146,900 / 66,633
Total Engine and Tender Weight (lbs / kg)500,000 / 226,797
Tender Water Capacity (gals / ML)8000 / 30.30
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)16 / 14.50
Minimum weight of rail (calculated) (lb/yd / kg/m)85 / 42.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)57 / 1448
Boiler Pressure (psi / kPa)205 / 14.10
High Pressure Cylinders (dia x stroke) (in / mm)23" x 32" / 584x813
Low Pressure Cylinders (dia x stroke) (in / mm)35" x 32" / 889x813
Tractive Effort (lbs / kg)72,284 / 32787.51
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.25
Heating Ability
Firebox Area (sq ft / m2)250 / 23.23
Grate Area (sq ft / m2)78 / 7.25
Evaporative Heating Surface (sq ft / m2)5789 / 537.81
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)5789 / 537.81
Evaporative Heating Surface/Cylinder Volume376.20
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation15,990
Same as above plus superheater percentage15,990
Same as above but substitute firebox area for grate area51,250
Power L13847
Power MT165.76

All material Copyright ©
Wes Barris