Coahuila y Zacatecas 2-8-0 Locomotives in Mexico


Class Details by Steve Llanso of Sweat House Media

Class 12 (Locobase 12708)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 29, p 273. Works number was 35990 in January 1911.

The last of the Baldwin Consolidations delivered to this road differed from earlier designs (Locobases 12707-12708) in having a larger firebox (but no larger grate) and outside Walschaert radial valve gear.


Class 8 (Locobase 12707)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 29, p 273. Works number was 30178 in December 1906

At nearly the same time the C y Z ordered the 4-6-0 shown in Locobase 12706, it contracted for this stablemate Consolidation that shared the same power dimensions (including, unusually, the driver diameter) and firebox as the 7. Its boiler had fewer and longer tubes and the engine pressed down on the rails with greater adhesion (and a higher factor of adhesion, therefore).

The next step was to go a bit bigger with the 2-8-0 design; see Locobase 12709.


Class 9 (Locobase 12709)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University Volume 31, p 71. Works numbers were 32129 in November 1907, 32647 in February 1908, and 33554 in July 1909.

Building on the Consolidation produced earlier in the year (Locobase 12707), the C y Z changed a couple of key dimensions. The cylinders grew in both bore and stroke and the boiler-tube diameter increased to 2 1/4" while their length shrank 6" and the tube count remained the same. The firebox increased in area, but lost some grate area.

Like the other C y Z engines, these 2-8-0s were required to roll on 40 lb/yard (20 kg/metre) rail, up 2 1/2% grades, and around 14 degree compensated curves.

Principal Dimensions by Steve Llanso of Sweat House Media
Class1289
Locobase ID12,708 12,707 12,709
RailroadCoahuila y ZacatecasCoahuila y ZacatecasCoahuila y Zacatecas
CountryMexicoMexicoMexico
Whyte2-8-02-8-02-8-0
Number in Class113
Road Numbers1289-11
Gauge3'3'3'
Number Built113
BuilderBaldwinBurnham, Williams & CoBaldwin
Year191119071907
Valve GearWalschaertStephensonWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)12 / 3.6611.67 / 3.5612 / 3.66
Engine Wheelbase (ft / m)19.42 / 5.9218.33 / 5.5919.42 / 5.92
Ratio of driving wheelbase to overall engine wheebase 0.62 0.64 0.62
Overall Wheelbase (engine & tender) (ft / m)56.83 / 17.3247.50 / 14.4856.83 / 17.32
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)100,000 / 45,35986,000 / 39,009102,000 / 46,266
Engine Weight (lbs / kg)109,000 / 49,44295,000 / 43,091113,000 / 51,256
Tender Loaded Weight (lbs / kg)100,000 / 45,35975,000 / 34,01975,000 / 34,019
Total Engine and Tender Weight (lbs / kg)209,000 / 94,801170,000 / 77,110188,000 / 85,275
Tender Water Capacity (gals / ML)5000 / 18.944000 / 15.155000 / 18.94
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)6 / 5.50
Minimum weight of rail (calculated) (lb/yd / kg/m)42 / 2136 / 1843 / 21.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)42 / 106742 / 106742 / 1067
Boiler Pressure (psi / kPa)170 / 11.70180 / 12.40170 / 11.70
High Pressure Cylinders (dia x stroke) (in / mm)18" x 22" / 457x55917" x 20" / 432x50818" x 22" / 457x559
Tractive Effort (lbs / kg)24,524 / 11123.9121,056 / 9550.8524,524 / 11123.91
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.08 4.08 4.16
Heating Ability
Firebox Area (sq ft / m2)104 / 9.6770 / 6.5193.50 / 8.69
Grate Area (sq ft / m2)18.70 / 1.7419.60 / 1.8218.70 / 1.74
Evaporative Heating Surface (sq ft / m2)1685 / 156.601523 / 141.541674 / 155.58
Superheating Surface (sq ft / m2)
Combined Heating Surface (sq ft / m2)1685 / 156.601523 / 141.541674 / 155.58
Evaporative Heating Surface/Cylinder Volume260.05289.87258.35
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation317935283179
Same as above plus superheater percentage317935283179
Same as above but substitute firebox area for grate area17,68012,60015,895
Power L1405044923933
Power MT357.15460.61340.03

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