Middle Tennessee / SLSF 4-6-0 "Ten-wheeler" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 25 (Locobase 8550)

Data from SL&SF All Time Loco Diagrams HS Pub supplied in May 2005 by Allen Stanley from his extensive Raildata collection. See also DeGolyer, Volume 36, p. 43. Works numbers were 36168 in February 1911.

The Baldwin spec for this particular engine took special care to note that the water tanks were 19 miles apart, the ruling grade was 3.3%, minimum curve radius was 18 degrees, rails weighed 70 lb/yard (35 kg/metre), and the turntable could handle up to 60-ft engine-tender combinations.

This single Ten-wheeler went on the MT in February 1911 and operated there until the road was sold to the Nashville-Frankford line, which electrified the tracks and sold the 25 to locomotive rebuilder/reseller Southern Iron & Equipment. Locobase can't help but think that the turnaround sale to the Gainesville & Northwestern was perhaps a bit hasty when he considers the equally rapid return of the item to the SI & E. A year later in November 1925, SI & E found a buyer in the Jonesboro, Lake City & Eastern, which was immediately bought by the Frisco.

After serving the road for another 14 years, the 75 was "dismissed from service" in July 1939.

Specifications by Steve Llanso of Sweat House Media
Locobase ID8550
RailroadMiddle Tennessee / SLSF
Number in Class1
Road Numbers25 / 37/ 75
Number Built1
Valve GearSouthern
Locomotive Length and Weight
Driver Wheelbase (ft)13.50
Engine Wheelbase (ft)23.83
Ratio of driving wheelbase to overall engine wheebase 0.57
Overall Wheelbase (engine & tender) (ft)55
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)120,800
Engine Weight (lbs)157,900
Tender Loaded Weight (lbs)274,600
Total Engine and Tender Weight (lbs)432,500
Tender Water Capacity (gals)5000
Tender Fuel Capacity (oil/coal) (gals/tons)12
Minimum weight of rail (calculated) (lb/yd)67
Geometry Relating to Tractive Effort
Driver Diameter (in)57
Boiler Pressure (psi)200
High Pressure Cylinders (dia x stroke) (in)19" x 24"
Tractive Effort (lbs)25,840
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.67
Heating Ability
Firebox Area (sq ft)150.30
Grate Area (sq ft)28.50
Evaporative Heating Surface (sq ft)2200
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)2200
Evaporative Heating Surface/Cylinder Volume279.34
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5700
Same as above plus superheater percentage5700
Same as above but substitute firebox area for grate area30,060
Power L17120
Power MT389.82

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