North Western Railways Beyer-Garratt Locomotives in India

Class Details by Steve Llanso of Sweat House Media

Class GAS (Locobase 686)

Data from Lionel Wiener, Articulated Locomotives (1930) and Gavin Hamilton. See also "Articulated Locomotive Tests in India and Burma", Railway Engineer, Volume 46, No.11 (November 1925), pp. 399-402; and "Indian State (North Western Railway) -Design 111", Beyer-Garrrat Patent Articulated Locomotives (Manchester, England: Beyer-Peacock & Company Limited, 1931), archived on flickr's Historical Railway Images at [], et seq, p. 78..

In comparison to earlier locomotives used on the 63-mile Sibi-Kolpur section of this mountainous railway, the Garratts were credited with pulling 75% tons than the earlier Mikados, a total of 640 tons unassisted between Sibi and Agibum. The home stretch into Kolpur saw an tonnage increase from 160 to 354 tons.

Gavin Hamilton wrote the Garratt ran in trials to compare performance with a Mallet design and that both types were replaced by 2-10-0 Decapods.

The website [] (visited 14 Nov 2003) said that a comparison with two 2-8-0s in hauls up the 1 in 25 (4%) grade of the Bolan Pass showed the GAS able to pull about 30 tons more train "but only in good weather." Later the locomotive was transferred to the gentler 1% grade in the Rawalpindi area.

Dr. Sundar says that once the NWR was able to obtain 30 N-class decapods, there was no real need for the Garratt and it went out of service in 1937.

He concludes: "Though it seems to have been a good design with then up-to-date features like superheating, Belpaire firebox, and straight-ported cylinders with piston valves, it was too small for the NWR's requirements."

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID686
RailroadNorth Western Railways
Number in Class1
Road Numbers480
Number Built1
BuilderBeyer, Peacock
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)22 / 7.01
Engine Wheelbase (ft / m)46 / 21.95
Ratio of driving wheelbase to overall engine wheelbase 0.48
Overall Wheelbase (engine & tender) (ft / m)70.62 / 21.52
Axle Loading (Maximum Weight per Axle) (lbs / kg)43,232 / 19,610
Weight on Drivers (lbs / kg)258,496 / 117,252
Engine Weight (lbs / kg)399,616 / 181,263
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)399,616 / 181,263
Tender Water Capacity (gals / ML)6500 / 24.62
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)12.30 / 11
Minimum weight of rail (calculated) (lb/yd / kg/m)72 / 36
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)51 / 1295
Boiler Pressure (psi / kPa)180 / 12.40
High Pressure Cylinders (dia x stroke) (in / mm)18.5" x 26" / 470x660 (4)
Tractive Effort (lbs / kg)53,391 / 24217.78
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.84
Heating Ability
Tubes (number - dia) (in / mm)285 - 2" / 51
Flues (number - dia) (in / mm)44 - 5.5" / 140
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)236 / 21.93
Grate Area (sq ft / m2)56.50 / 5.25
Evaporative Heating Surface (sq ft / m2)2780 / 258.36
Superheating Surface (sq ft / m2)565 / 52.51
Combined Heating Surface (sq ft / m2)3345 / 310.87
Evaporative Heating Surface/Cylinder Volume171.84
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation10,170
Same as above plus superheater percentage11,899
Same as above but substitute firebox area for grate area49,702
Power L18554
Power MT437.72

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