Nitrate Railways Beyer-Garratt Locomotives in Chile

Class Details by Steve Llanso of Sweat House Media

Class 120 (Locobase 581)

Data from Wiener, Articulated Locomotives (1930); and "Nitrate Railways-Design 119", Beyer-Garrrat Patent Articulated Locomotives (Manchester, England: Beyer-Peacock & Company Limited, 1931), archived on flickr's Historical Railway Images at [], et seq, p. 59. . First batch had BP works numbers 6291-6293; 6481-6483) were delivered in 1928.

Two batches of mammoth Double Mikado Garratts for the 20-mile (32.2 km) Iquique-Carpas section on 4% ruling grade with 200-ft radius curves. Note the unusual "over-square" cylinder diameter/stroke ratio and the use of a round-topped boiler.

In one test run, an 88-axle train "was actually on three curves at the same time. They proved capable of pulling a max load of 360 tons. As often proved the case, the Beyer-Garratts reduced both fuel (in this case, oil) and water consumption as well as train and shop crew costs compared to earlier motive power. Moreover, they continued the tradition of using boilers that "steam wonderfully and are a proof that it is not the amount of heating surface that counts, but where it is palced in relation to the grate."

Retired in 1959 in favor of diesels.

NB: Tube length is an estimate based on the calculation of tube surface area by subtracting reported firebox heating surface from reported total evaporative heating surface.

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID581
RailroadNitrate Railways
Number in Class6
Road Numbers120-122, 123-125
Number Built6
BuilderBeyer, Peacock
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)24 / 7.32
Engine Wheelbase (ft / m)45 / 13.72
Ratio of driving wheelbase to overall engine wheelbase 0.53
Overall Wheelbase (engine & tender) (ft / m)71.75 / 21.87
Axle Loading (Maximum Weight per Axle) (lbs / kg)40,320 / 18,289
Weight on Drivers (lbs / kg)314,720 / 142,755
Engine Weight (lbs / kg)419,216 / 190,153
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)419,216 / 190,153
Tender Water Capacity (gals / ML)6600 / 25
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)1692 / 6404.20
Minimum weight of rail (calculated) (lb/yd / kg/m)66 / 33
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)42 / 1067
Boiler Pressure (psi / kPa)200 / 13.80
High Pressure Cylinders (dia x stroke) (in / mm)22" x 20" / 559x508 (4)
Tractive Effort (lbs / kg)78,362 / 35544.45
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.02
Heating Ability
Tubes (number - dia) (in / mm)299 - 2" / 51
Flues (number - dia) (in / mm)50 - 5.375" / 137
Flue/Tube length (ft / m)13.53 / 4.12
Firebox Area (sq ft / m2)276 / 25.64
Grate Area (sq ft / m2)68.80 / 6.39
Evaporative Heating Surface (sq ft / m2)3346 / 310.85
Superheating Surface (sq ft / m2)744 / 69.12
Combined Heating Surface (sq ft / m2)4090 / 379.97
Evaporative Heating Surface/Cylinder Volume190.13
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation13,760
Same as above plus superheater percentage16,237
Same as above but substitute firebox area for grate area65,136
Power L19086
Power MT509.18

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