Buenos Aires Pacific Beyer-Garratt Locomotives in Argentina

Class Details by Steve Llanso of Sweat House Media

Class 951 (Locobase 530)

Some data from Carlos Alberto Fernandez Priotti in Bryan Attewell ([] Steam Locomotive simulator program (April 2000) supplemented by data from Gavin Hamilton's excellent compilation of Garratt data posted at []

(6 September 2005); and See also "Buenos Aires and Pacific Railway-Design 1168", Beyer-Garrrat Patent Articulated Locomotives (Manchester, England: Beyer-Peacock & Company Limited, 1931), archived on flickr's Historical Railway Images at [], pp.75-76. Works numbers were 6532-6534 in 1930 and sister engine 954 (works 6715) was delivered in 1931. Information about the class supplied in Coronel Gustavo Adolfo Tamaño, "Las Locomotoras Garratt en Argentina," in PDF.

Fernandez says that four engines were delivered altogether to the FC Gran Oeste Argentino (FC GOA), a subsidiary of the BAP, and they were the largest and heaviest Garratts to operate in Argentina. Like almost all Beyer-Garratts, these had Belpaire fireboxes and large barrels. The photograph in Tamaño's survey shows how much of the powered wheelbase in each bogie rode under the water supply (in front) and the fuel supply (behind the firebox). As the raw materials for steam were drawn down during a run, the adhesion weight declined as well.

The BAP was later taken into the Ferrocarril General Roca.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID530
RailroadBuenos Aires Pacific (BAP)
Number in Class4
Road Numbers951-954
Number Built4
BuilderBeyer, Peacock
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)22 / 6.71
Engine Wheelbase (ft / m)66.17 / 20.17
Ratio of driving wheelbase to overall engine wheelbase 0.33
Overall Wheelbase (engine & tender) (ft / m)88.16 / 26.87
Axle Loading (Maximum Weight per Axle) (lbs / kg)31,651 / 14,357
Weight on Drivers (lbs / kg)253,120 / 114,813
Engine Weight (lbs / kg)434,560 / 197,113
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)434,560 / 197,113
Tender Water Capacity (gals / ML)7200 / 27.27
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)12.10 / 11
Minimum weight of rail (calculated) (lb/yd / kg/m)53 / 26.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)60 / 1524
Boiler Pressure (psi / kPa)204.50 / 14.10
High Pressure Cylinders (dia x stroke) (in / mm)18.5" x 26" / 470x660 (4)
Tractive Effort (lbs / kg)51,559 / 23386.80
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.91
Heating Ability
Tubes (number - dia) (in / mm)222 - 1.875" / 48
Flues (number - dia) (in / mm)40 - 5.25" / 133
Flue/Tube length (ft / m)11.09 / 3.38
Firebox Area (sq ft / m2)281 / 26.11
Grate Area (sq ft / m2)49.40 / 4.59
Evaporative Heating Surface (sq ft / m2)2442 / 226.87
Superheating Surface (sq ft / m2)516 / 47.94
Combined Heating Surface (sq ft / m2)2958 / 274.81
Evaporative Heating Surface/Cylinder Volume150.95
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10,102
Same as above plus superheater percentage11,820
Same as above but substitute firebox area for grate area67,233
Power L110,733
Power MT747.86

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