Carolina, Clinchfield & Ohio 2-6-6-2 "Mallet Mogul" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class M-1 (Locobase 12371)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Volume 45, pp. 303-307. Works number was 33551 in July 1909.

Although the Clinchfield would be better known for its large 2-8-8-2s and the Challengers that came much later, the road started with 6-axle Mallets. Its prototype was this locomotive, which was followed very quickly by 10 with more cylinder volume and a bigger boiler; see Locobase 11078 for a full discussion of the Clinchfield's motivation in buying these articulateds.

500 was never superheated and operated for almost 20 years before being scrapped in September 1938.

Class M-2 (Locobase 11078)

Data from "Freight (2-6-6-2) and Passsenger Locomotives for a Low Grade Line," American Engineer and Railroad Journal (September 1910 ), pp. 357-358. See also DeGolyer, Volume 45, pp. 309+. Works numbers were 34865-34867 in June 1910; 34922, 34966, 34969-34970, 35001 in July; and 35053-35054 in August.

Although the Clinchfield would be better known for its large 2-8-8-2s and the Challengers that came much later, the road started with 6-axle Mallets. The 1910 AERJ report describes the Clinch taking practically a straight north-south line between Elkhorn City, Kentucky and Spartanburg, SC. "The line is built in the most modern manner throughout," the writer observed,"with no hesitating at expensive cuts and tunnels or extensive trestle work to obtain the straightest line with a minimum grade."

Because the result was a ruling grade of 1/2% and relatively gentle curves and the traffic primarily coal trains, the aligment offered "...apparently almost ideal conditions for the general use of articulated compound locomotives." After working with a single M-1 engine produced in July 1909 (Locobase 12371) and finding that it could "very comfortably handle" 4,000-ton trains, the railway went to Baldwin for ten somewhat larger and more powerful locomotives.

The design was very similar to several other classes then in service on other roads. It made use of the then-fashionable Baldwin smokebox superheater, which intercepted the exhausted steam from the HP cylinders and reheated it before transmitting it to the LP cylinders. All four cylinders used 15"(381 mm) piston valves, the HP set for inside admission, the LP using outside admission. Because the big grate was handfired, the locomotives had two firedoors and were referred to as "double-door Mallets."

Baldwin rebuilt some of these engines with Schmidt superheaters in 1923

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID12,371 11,078
RailroadCarolina, Clinchfield & Ohio (Clinchfield)Carolina, Clinchfield & Ohio (Clinchfield)
Number in Class110
Road Numbers500550-559/510-519
Number Built110
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)29.67 / 9.0431 / 9.45
Engine Wheelbase (ft / m)44.83 / 13.6646.50 / 14.17
Ratio of driving wheelbase to overall engine wheebase 0.66 0.67
Overall Wheelbase (engine & tender) (ft / m)73.67 / 22.4574.92 / 22.84
Axle Loading (Maximum Weight per Axle) (lbs / kg)50,300 / 22,81658,500
Weight on Drivers (lbs / kg)299,250 / 135,738325,850 / 147,803
Engine Weight (lbs / kg)342,650 / 155,424378,650 / 171,753
Tender Loaded Weight (lbs / kg)157,250 / 71,327179,000 / 77,723
Total Engine and Tender Weight (lbs / kg)499,900 / 226,751557,650 / 249,476
Tender Water Capacity (gals / ML)8000 / 30.3010,000 / 30.30
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)14 / 12.7015 / 12.70
Minimum weight of rail (calculated) (lb/yd / kg/m)83 / 41.5091 / 45.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)57 / 144857 / 1448
Boiler Pressure (psi / kPa)200 / 13.80200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)23" x 32" / 584x81324" x 32" / 610x813
Low Pressure Cylinders (dia x stroke) (in / mm)32" x 32" / 813x81337" x 32" / 940x813
Tractive Effort (lbs / kg)66,579 / 30199.7677,386 / 35101.74
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.49 4.21
Heating Ability
Firebox Area (sq ft / m2)223.30 / 20.75233 / 21.65
Grate Area (sq ft / m2)78 / 7.2578 / 7.25
Evaporative Heating Surface (sq ft / m2)5607 / 521.105752 / 534.57
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)5607 / 521.105752 / 534.57
Evaporative Heating Surface/Cylinder Volume364.38343.30
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation15,60015,600
Same as above plus superheater percentage15,60015,600
Same as above but substitute firebox area for grate area44,66046,600
Power L142893300
Power MT189.59133.96

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