Unidos de Yucatan 4-4-0 Locomotives in Mexico


Class Details by Steve Llanso of Sweat House Media

Class 4 (Locobase 14492)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Vol 54, p. 293. Works number was 41676 in September 1914.

Fox Brothers bought this wood-burning light Eight-wheeler, which served the U de Y for decades. In 1963 it was relettered and renumbered as Unidos del Sureste #4.


Class 65 (Locobase 967)

Data from 1947 Locomotive Cyclopedia and from DeGolyer, Vol 54, pp 290-291. Works numbers were 42914-42915 in February 1916.

The first pair of this design burned wood and used a spark-arresting Radley & Hunter cabbage stack. They were sized to meet the requirements of a narrow gauge road with 35 lb/yard (17.5 kg/metre) rails.

The 65 and 66 were sold in 1963 to the Unidos de Sureste as their 250-251. Roger Broggie, Walt Disney's railroad designer, found this and three other locomotives in the Yucatan and bought them in February 1969. (See Locobases 12662 and 14494 for the 2-6-0 and the 4-6-0s that constitute the rest of the Disney stud.)

Like the others, the 251 underwent a number change (to 4), but didn't get its name until December 1971, when its reconstruction was completed. By that time, Walt's indispensable brother Roy, who had declined the honor earlier, had passed on and the 4 was named Roy O Disney.


Class 67 (Locobase 14981)

Data from 1947 Locomotive Cyclopedia and from DeGolyer, Vol 54, pp 290-291. Works numbers were 56387-56388 in April 1923, 58414 in May 1925 and 72206-72207 in 1944.

Locobase 967 shows the first pair of wood-burning Eight-wheelers built to this design for the U de Y in 1916. Seven years later the railroad ordered the same engine design from Eddystone, but specified oil fuel. Engine weight increased by 3 short tons (2.7 metric tons), but the locomotive still had to travel on 35 lb/yard (17.5 kg/metre) rails..

Nineteen years later, Baldwin built two more from the same specifications in 1944. These were the last 4-4-0s to be built by an American manufacturer.

Principal Dimensions by Steve Llanso of Sweat House Media
Class46567
Locobase ID14,492 967 14,981
RailroadUnidos de YucatanUnidos de YucatanUnidos de Yucatan
CountryMexicoMexicoMexico
Whyte4-4-04-4-04-4-0
Number in Class125
Road Numbers465-6667-68, 74, 80-81
GaugeStd3'3'
Number Built125
BuilderBaldwinBaldwinBaldwin
Year191419161923
Valve GearStephensonStephensonStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m) 6.50 / 1.988 / 2.448 / 2.44
Engine Wheelbase (ft / m)22.50 / 6.8619.75 / 6.0219.75 / 6.02
Ratio of driving wheelbase to overall engine wheebase 0.29 0.41 0.41
Overall Wheelbase (engine & tender) (ft / m)45.62 / 13.9041.48 / 12.6441.48 / 12.64
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)62,000 / 28,12333,000 / 14,96934,000 / 15,422
Engine Weight (lbs / kg)100,000 / 45,35951,000 / 23,13357,000 / 25,855
Tender Loaded Weight (lbs / kg)60,000 / 27,21650,000 / 22,68056,500 / 25,628
Total Engine and Tender Weight (lbs / kg)160,000 / 72,575101,000 / 45,813113,500 / 51,483
Tender Water Capacity (gals / ML)3000 / 11.362500 / 9.472500 / 9.47
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)120 / 0.50
Minimum weight of rail (calculated) (lb/yd / kg/m)52 / 2628 / 1428 / 14
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)66 / 167646 / 116846 / 1168
Boiler Pressure (psi / kPa)160 / 11160 / 11160 / 11
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x61013" x 18" / 330x45713" x 18" / 330x457
Tractive Effort (lbs / kg)14,292 / 6482.758994 / 4079.618994 / 4079.61
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.34 3.67 3.78
Heating Ability
Firebox Area (sq ft / m2)127 / 11.8067 / 6.2267 / 6.22
Grate Area (sq ft / m2)16.70 / 1.55 9.70 / 0.90 9.70 / 0.90
Evaporative Heating Surface (sq ft / m2)1449 / 134.62670 / 62.24670 / 62.24
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1449 / 134.62670 / 62.24670 / 62.24
Evaporative Heating Surface/Cylinder Volume229.82242.29242.29
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation267215521552
Same as above plus superheater percentage267215521552
Same as above but substitute firebox area for grate area20,32010,72010,720
Power L1581744584458
Power MT413.69595.65578.13

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