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.
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
|Specifications by Steve Llanso of Sweat House Media|
|Railroad||Carolina, Clinchfield & Ohio (Clinchfield)||Carolina, Clinchfield & Ohio (Clinchfield)|
|Number in Class||1||10|
|Locomotive Length and Weight|
|Ratio of driving wheelbase to overall engine wheebase||0.66||0.67|
|Overall Wheelbase (engine & tender)||73.67'||74.92'|
|Axle Loading (Maximum Weight per Axle)||50300 lbs||58500 lbs|
|Weight on Drivers||299250 lbs||325850 lbs|
|Engine Weight||342650 lbs||378650 lbs|
|Tender Light Weight||157250 lbs||179000 lbs|
|Total Engine and Tender Weight||499900 lbs||557650 lbs|
|Tender Water Capacity||8000 gals||10000 gals|
|Tender Fuel Capacity (oil/coal)||14 tons||15 tons|
|Minimum weight of rail (calculated)||83 lb/yard||91 lb/yard|
|Geometry Relating to Tractive Effort|
|Boiler Pressure||200 psi||200 psi|
|High Pressure Cylinders (dia x stroke)||23" x 32"||24" x 32"|
|Low Pressure Cylinders (dia x stroke)||32" x 32" (2)||37" x 32" (2)|
|Tractive Effort||66579 lbs||77386 lbs|
|Factor of Adhesion (Weight on Drivers/Tractive Effort)||4.49||4.21|
|Firebox Area||223.30 sq. ft||233 sq. ft|
|Grate Area||78 sq. ft||78 sq. ft|
|Evaporative Heating Surface||5607 sq. ft||5752 sq. ft|
|Combined Heating Surface||5607 sq. ft||5752 sq. ft|
|Evaporative Heating Surface/Cylinder Volume||364.38||343.30|
|Computations Relating to Power Output (More Information)|
|Robert LeMassena's Power Computation||15600||15600|
|Same as above plus superheater percentage||15600||15600|
|Same as above but substitute firebox area for grate area||44660||46600|