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 Middle Run Media | |
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Class | GAS |
Locobase ID | 686 |
Railroad | North Western Railways |
Country | India |
Whyte | 2-6-2+2-6-2 |
Number in Class | 1 |
Road Numbers | 480 |
Gauge | 5'6" |
Number Built | 1 |
Builder | Beyer, Peacock |
Year | 1925 |
Valve Gear | Walschaert |
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) | |
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 / 1240 |
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 Volume | 171.84 |
Computations Relating to Power Output (More Information) | |
Robert LeMassena's Power Computation | 10,170 |
Same as above plus superheater percentage | 11,899 |
Same as above but substitute firebox area for grate area | 49,702 |
Power L1 | 8554 |
Power MT | 437.72 |