FC Central Argentino 4-8-4 Locomotives in Argentina


Class Details by Steve Llanso of Sweat House Media

Class MS6A (Locobase 11216)

Data from [], last accessed 17 April 2010. The diagram gives details for the later batch of 20 -- AW works numbers 1038-1057 -- that arrived in 1930; the 1927 batch of 10 (works 875-884) were similar except for smaller tank and bunker capacity.. See also Daniel Cazenave, "Las tanques mas de guerra que ferroviarias - Clase MS6A del FCCA", Todotrenes de Argentina at [], last accessed 18 April 2010.

Percy Deakin, this British-owned railway's locomotive superintendent, wanted to procure some powerful tank engines for that part of FCCA's urban section that was not electrified. According to Cazenave, Deakin had to consider the likelihood that their career in suburban passenger service would likely be short and that new locomotives would need to adapt to other duties.

In keeping with the FCCA's satisfactory experience with cross-compounds in passenger service, Deakin ordered the only 4-8-4Ts to be delivered with two-stage expansion. Adopting the cylinder and valve train of the CS8A class and the standard C-23 boiler used in the CS8 and CS9 classes, the first ten arrived from AW in 1927. They could carry 1,040 gallons in each side tank and 1,460 gallons in the tank under the coal bunker, which held 3 1/2 tons of coal.

Deakin soon realized that the tank and bunker capacities would need to grow if these engines were to fulfill their multiple obligations on the FCCA. So the last 20 had smaller tanks under the bunker (which increased coal capacity) and longer side tanks that ended just short of the smokebox. These changes increased axle loading from the 16.2 tonnes (35,714 lb) to the 18.3 tonnes per axle shown in the specs for the last 20.

"Las Burras Chicas" were big locomotives on a broad gauge and their Belpaire fireboxes and high-volume bunkers enhanced their presence on the railway. Both piston valves measured a capacious 14" in diameter; maximum valve travel on the HP (left-hand) side was 6", on the LP (right-hand) side 8 1/2". Both batches had flangeless 2nd and 3rd drivers and internally expanding brakes (like drum brakes on an automobile) on the eight smaller wheels carried in the leading and trailing trucks.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassMS6A
Locobase ID11216
RailroadFC Central Argentino (FCCA)
CountryArgentina
Whyte4-8-4T
Number in Class30
Road Numbers501-530
Gauge5'6"
Number Built30
BuilderArmstrong Whitworth
Year1927
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)16.50 / 5.03
Engine Wheelbase (ft / m)39.83 / 12.14
Ratio of driving wheelbase to overall engine wheelbase 0.41
Overall Wheelbase (engine & tender) (ft / m)39.83 / 12.14
Axle Loading (Maximum Weight per Axle) (lbs / kg)40,320 / 18,289
Weight on Drivers (lbs / kg)161,280 / 73,155
Engine Weight (lbs / kg)275,352 / 124,898
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)275,352 / 124,898
Tender Water Capacity (gals / ML)4860 / 18.41
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)5 / 5
Minimum weight of rail (calculated) (lb/yd / kg/m)67 / 33.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)62 / 1575
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)22.5" x 26" / 572x660 (1)
Low Pressure Cylinders (dia x stroke) (in / mm)31.5" x 26" / 800x660 (1)
Tractive Effort (lbs / kg)23,898 / 10839.96
Factor of Adhesion (Weight on Drivers/Tractive Effort) 6.75
Heating Ability
Tubes (number - dia) (in / mm)121 - 2" / 51
Flues (number - dia) (in / mm)24 - 5.25" / 133
Flue/Tube length (ft / m)15.04 / 4.58
Firebox Area (sq ft / m2)165 / 15.33
Grate Area (sq ft / m2)27.80 / 2.58
Evaporative Heating Surface (sq ft / m2)1602 / 148.88
Superheating Surface (sq ft / m2)375 / 34.85
Combined Heating Surface (sq ft / m2)1977 / 183.73
Evaporative Heating Surface/Cylinder Volume267.78
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5560
Same as above plus superheater percentage6616
Same as above but substitute firebox area for grate area39,270
Power L110,226
Power MT559.14

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