Thompson Brothers Logging Company / Thompson Brothers Lumber Company 2-6-2 "Prairie" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class 10 (Locobase 13642)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volumes 34, p. 295. See also the Tap-Line Case summary at . (Thanks to Chris Hohl for his 28 February 2015 email giving the tender's fuel capacity.) Works numbers were 34465, 34555 in April 1910; 35574 in November; and 36571 in May 1911.

This lumber company was based in Doucette, Texas and clearly had some money - at least enough to buy four small wood-burning Prairies. The relatively light tenders held only 2 1/4 cords of wood.

They logged about 38,500 acres of timber in Tyler County. The 6 worked for the Thompson & Tucker Lumber Company. 11 and 12 were eventually sold to the Rock Creek Lumber Company of Trinity, Texas, which was bought out by Texas Long-Leaf Lumber Company.

Class 100 (Locobase 14305)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Vol 52, pp. 340. (Thanks to Chris Hohl for his 22 February 2015 email supplying the tender's fuel capacity.) Works number was 42615 in October 1915.

When this Texas timber company came back to Baldwin for another locomotive, they opted for a larger engine than the design they'd stocked up with in 1910-1911 (Locobase 13642). It too was a wood-burner and its tender held 3 1/2 cords of wood.

In its first couple of years of service, the 100 served several lumber companies in the area, starting with Rock Creek Lumber of New Willard, then its parent Texas Long Leaf Lumber. Texas Long Leaf's Burton Swartz Supply sold the 100 to Carbur Logging.

Specifications by Steve Llanso of Sweat House Media
Locobase ID13,642 14,305
RailroadThompson Brothers Lumber CompanyThompson Brothers Logging Company
Number in Class41
Road Numbers10, 6, 11-12100
Number Built41
Valve GearStephensonWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft) 9.17 9.17
Engine Wheelbase (ft)23.7524.67
Ratio of driving wheelbase to overall engine wheebase 0.39 0.37
Overall Wheelbase (engine & tender) (ft)48.83
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)63,30088,000
Engine Weight (lbs)87,600117,500
Tender Loaded Weight (lbs)60,00080,000
Total Engine and Tender Weight (lbs)147,600197,500
Tender Water Capacity (gals)30004000
Tender Fuel Capacity (oil/coal) (gals/tons)
Minimum weight of rail (calculated) (lb/yd)3549
Geometry Relating to Tractive Effort
Driver Diameter (in)4144
Boiler Pressure (psi)180170
High Pressure Cylinders (dia x stroke) (in)15" x 20"16" x 24"
Tractive Effort (lbs)16,79320,177
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.77 4.36
Heating Ability
Firebox Area (sq ft)93120
Grate Area (sq ft)1415.60
Evaporative Heating Surface (sq ft)10001602
Superheating Surface (sq ft)
Combined Heating Surface (sq ft)10001602
Evaporative Heating Surface/Cylinder Volume244.46286.84
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation25202652
Same as above plus superheater percentage25202652
Same as above but substitute firebox area for grate area16,74020,400
Power L144054915
Power MT460.25369.40

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