Texas & Pacific 4-4-2 "Atlantic" Locomotives of the USA

Class Details by Steve Llanso of Sweat House Media

Class E-1-s (Locobase 8494)

Data from T&P 1 - 1950ca Locomotive Diagrams supplied in May 2005 by Allen Stanley from his extensive Raildata collection.

Although only 2 in number and home-built, these Atlantics followed the lines of the classic express locomotive in many respects. Although the boiler was relatively small in relation to the cylinders, the firebox ratios stood almost squarely in the middle of the more than 100 designs examined in this comparison. And a look at the profile shows large-diameter trailing wheels (51") under the firebox.

Unfortunately, says Drury (1993) "They turned out to be rear-heavy and unstable, and their 28,000 lb of tractive effort was no more than that of the considerably lighter D-9 Ten-Wheelers that preceded them."

Delivered as saturated-steam engines in 1906, they were superheated in 1917, at which time they were fitted with 14" piston valves and Southern valve gear. Thus equipped, they served the T & P for another decade.

Specifications by Steve Llanso of Sweat House Media
Locobase ID8494
RailroadTexas & Pacific (T&P)
Number in Class2
Road Numbers339-340
Number Built2
BuilderTexas & Pacific
Valve GearSouthern
Locomotive Length and Weight
Driver Wheelbase (ft)7
Engine Wheelbase (ft)27.58
Ratio of driving wheelbase to overall engine wheebase 0.25
Overall Wheelbase (engine & tender) (ft)56.87
Axle Loading (Maximum Weight per Axle) (lbs)
Weight on Drivers (lbs)123,900
Engine Weight (lbs)213,986
Tender Loaded Weight (lbs)114,879
Total Engine and Tender Weight (lbs)328,865
Tender Water Capacity (gals)6500
Tender Fuel Capacity (oil/coal) (gals/tons)3000
Minimum weight of rail (calculated) (lb/yd)103
Geometry Relating to Tractive Effort
Driver Diameter (in)75
Boiler Pressure (psi)185
High Pressure Cylinders (dia x stroke) (in)22" x 28"
Tractive Effort (lbs)28,414
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.36
Heating Ability
Firebox Area (sq ft)180
Grate Area (sq ft)45
Evaporative Heating Surface (sq ft)2470
Superheating Surface (sq ft)525
Combined Heating Surface (sq ft)2995
Evaporative Heating Surface/Cylinder Volume200.50
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation8325
Same as above plus superheater percentage9824
Same as above but substitute firebox area for grate area39,294
Power L115,196
Power MT540.78


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