Middle Tennessee/SLSF 4-6-0 "Ten-Wheeler" Locomotives in 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 Rail Data Exchange. 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 (30.6 km) apart, the ruling grade was 3.3%, minimum curve radius bent to 18 degrees, rails weighed 70 lb/yard (35 kg/metre), and the turntable could handle up to 60-ft (18.29 m) engine-tender combinations. Somewhere along the line of ownerships shown below, the engine received a set of Southern valve gear, that remained with it at least until its arrival on the Frisco.

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.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID8550
RailroadMiddle Tennessee/SLSF
Number in Class1
Road Numbers25/37/75
Number Built1
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.50 / 4.11
Engine Wheelbase (ft / m)23.83 / 7.26
Ratio of driving wheelbase to overall engine wheelbase 0.57
Overall Wheelbase (engine & tender) (ft / m)55 / 16.76
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)120,800 / 54,794
Engine Weight (lbs / kg)157,900 / 71,622
Tender Loaded Weight (lbs / kg)274,600 / 124,557
Total Engine and Tender Weight (lbs / kg)432,500 / 196,179
Tender Water Capacity (gals / ML)5000 / 18.94
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)12 / 11
Minimum weight of rail (calculated) (lb/yd / kg/m)67 / 33.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)57 / 1448
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)19" x 24" / 483x610
Tractive Effort (lbs / kg)25,840 / 11720.84
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.67
Heating Ability
Tubes (number - dia) (in / mm)283 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)13.83 / 4.22
Firebox Area (sq ft / m2)150.30 / 13.97
Grate Area (sq ft / m2)28.50 / 2.65
Evaporative Heating Surface (sq ft / m2)2200 / 204.46
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)2200 / 204.46
Evaporative Heating Surface/Cylinder Volume279.19
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 L17117
Power MT389.66

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