Unidos de Yucatan 4-4-2 Locomotives in Mexico

Class Details by Steve Llanso of Sweat House Media

Class Union (Locobase 11538)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 26, p. 142. Works number was 23735 in February 1904.

One can only suppose that this was the prestige locomotive for the FCUdeY in the early years of the 20th Century. It was the only Atlantic.A delivery detail notes that the original stack used a straight, thin pipe with a half-round conical top. A note in the specs advises that future engines should use the Radley & Hunter cabbage stack.

Painting instructions depict a black locomotive with silver stripes edged with maroon. Likewise, silver letters and numbers were edged in maroon.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID11538
RailroadUnidos de Yucatan
Number in Class1
Road Numbers16
Number Built1
BuilderBurnham, Williams & Co
Valve GearStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)6 / 1.83
Engine Wheelbase (ft / m)23 / 7.01
Ratio of driving wheelbase to overall engine wheelbase 0.26
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)62,000 / 28,123
Engine Weight (lbs / kg)120,000 / 54,431
Tender Loaded Weight (lbs / kg)80,000 / 36,287
Total Engine and Tender Weight (lbs / kg)200,000 / 90,718
Tender Water Capacity (gals / ML)4000 / 15.15
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)52 / 26
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)68 / 1727
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)18" x 24" / 457x610
Tractive Effort (lbs / kg)17,496 / 7936.06
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.54
Heating Ability
Tubes (number - dia) (in / mm)244 - 2" / 51
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)14.62 / 4.46
Firebox Area (sq ft / m2)134 / 12.45
Grate Area (sq ft / m2)24.80 / 2.30
Evaporative Heating Surface (sq ft / m2)1982 / 184.20
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1982 / 184.20
Evaporative Heating Surface/Cylinder Volume280.34
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation4464
Same as above plus superheater percentage4464
Same as above but substitute firebox area for grate area24,120
Power L17652
Power MT544.19

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