Mexicano del Pacifico 2-8-2 Locomotives in Mexico

Class Details by Steve Llanso of Sweat House Media

Class 4 (Locobase 14989)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Vol 65, p. 385. Works number was 55645 in September 1922.

Very few standard-gauge Mikados, whether superheated or not, were as small as this plantation engine and even fewer burned wood as this one did. The tender weighed seven tons (6.4 metric tons) more than the engine, an unusual inversion of proportions that occurred despite the fuel load amounting to 10 cords. Purchased by the United Sugar Company, the 4 was delivered to Los Mochis in Sinaloa State. They ran on the railway opened in 1909 and covered about 300 km (186 miles) between Guadalajara and Manzanillo by way of Colima

For all its diminuitive stature, the locomotive employed a relatively high degree of superheat. 8" (203 mm) piston valves supplied steam to the cylinders. And its 12 tons of tractive effort implied some pulling power on 50 lb/yard (25 kg/metre) rail over which it had to travel. Use of a 2-8-2 arrangement as a way to spread the weight over six axles is further suggested by the note in the specs that notes "Company's track is not ballasted, and ties are laid on dirt fill." Gradients and curves were gentle, however.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID14989
RailroadMexicano del Pacifico
Number in Class1
Road Numbers4
Number Built1
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12.50 / 3.81
Engine Wheelbase (ft / m)27.50 / 8.38
Ratio of driving wheelbase to overall engine wheelbase 0.45
Overall Wheelbase (engine & tender) (ft / m)67.85 / 20.68
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)98,000 / 44,452
Engine Weight (lbs / kg)128,500 / 58,287
Tender Loaded Weight (lbs / kg)142,500 / 64,637
Total Engine and Tender Weight (lbs / kg)271,000 / 122,924
Tender Water Capacity (gals / ML)6000 / 22.73
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)41 / 20.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)44 / 1118
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x610
Tractive Effort (lbs / kg)24,118 / 10939.75
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.06
Heating Ability
Tubes (number - dia) (in / mm)94 - 2" / 51
Flues (number - dia) (in / mm)18 - 5.375" / 137
Flue/Tube length (ft / m)13.17 / 4.01
Firebox Area (sq ft / m2)102 / 9.48
Grate Area (sq ft / m2)22.20 / 2.06
Evaporative Heating Surface (sq ft / m2)1087 / 100.98
Superheating Surface (sq ft / m2)274 / 25.46
Combined Heating Surface (sq ft / m2)1361 / 126.44
Evaporative Heating Surface/Cylinder Volume172.27
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation3996
Same as above plus superheater percentage4795
Same as above but substitute firebox area for grate area22,032
Power L18499
Power MT764.78

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