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The reference for locomotives and railcars

Burma Railways GA.I to GA.IV

Myanmar 1924 16 produced
GA.II No. 208, the only one with compound cylinders flickr/Historical Railway Images PD

On the line from Mandalay to Lashio, Burma Railways not only had curve radii starting at 330 ft (100 m), but also a long gradient of four percent. For this purpose, four class GA.I Garratts were built in 1924 as Double Consolidation, i.e. with the wheel arrangement 2-8-0+0-8-2. At the time they were put into service, they were probably the most powerful meter-gauge locomotives in the world.

Due to the narrow curve radii, the innermost driving axle had a lateral displacement of 3/8 inches (9.5 mm) in both directions. On the four percent steep gradient, the GA.Is were able to reach 9 mph or 14.5 km/h with a 200-ton train.

In 1927, a single compound locomotive was ordered for comparison and was designated GA.II. This also only had two cylinders at each end, with the high-pressure cylinders located behind the cab and the low-pressure cylinders in front of the smoke box. Since the additional complexity apparently didn't pay off, the other locomotives were built with simple expansion.

Three GA.IIIs followed in 1927, which were largely similar to the GA.I, but had the smaller superheater of the GA.II. In 1929 Krupp delivered eight GA.IVs, which were similar to the previous locomotives but again had a larger superheater. According to A.E. Durrant, all four classes were retired due to damage during World War II.

Standard variant with four equal cylinders flickr/Historical Railway Images / PD

Technical data

General

Property GA.I GA.II GA.III GA.IV
Built 1924 1927 1929
Manufacturers Beyer, Peacock & Co. Krupp
Wheel arrangement 2-8-0+0-8-2T (Double Consolidation (Garratt))
Gauge 1,000 mm (Meter gauge)

Dimensions and weights

Property GA.I GA.II GA.III GA.IV
Wheelbase 18.16 m
Service mass 100.7 t 105 t 103.2 t 106.2 t
Adhesion mass 81.6 t 85.8 t 85.1 t 85.9 t
Rigid wheelbase 2.24 m
Axle load 10.3 t 10.8 t 10.7 t 11.1 t
Water capacity 9,093 l 6,727 l 9,093 l
Fuel capacity 5.1 t (coal) 4.2 t (coal) 5.1 t (coal)

Boiler

Property GA.I GA.II GA.III GA.IV
Grate area 4.078 m²
Firebox surface 17.048 m²
Tube heating surface 144.139 m² 144.232 m²
Evaporative heating surface 161.187 m² 161.28 m²
Superheater surface 33.91 m² 29.636 m² 37.997 m²
Total heating surface 195.1 m² 190.8 m² 199.3 m²

Power plant

Property GA.I GA.II GA.III GA.IV
Driver diameter 991 mm
Boiler pressure 12.4 bar 14.1 bar 13.8 bar 14.1 bar
Expansion type simple expansion compound simple expansion
Cylinders four, 394 x 508 mm four, HP: 444 x 660 mm and LP: 673 x 660 mm four, 394 x 508 mm

Power

Property GA.I GA.II GA.III GA.IV
Power source steam
Estimated power 932 kW (1,267 PS) 988 kW (1,343 PS) 969 kW (1,317 PS) 1,007 kW (1,369 PS)
Starting effort 167.7 kN 220.4 kN 186.3 kN 191.0 kN
Starting effort simple 264.5 kN

Calculated values

Property GA.I GA.II GA.III GA.IV
Factor of adhesion 1 : 4.77 1 : 3.82 1 : 4.48 1 : 4.41
Optimal speed 34 km/h 27 km/h 32 km/h
Power-to-weight ratio 9.3 kW/t 9.4 kW/t 9.5 kW/t
Heating Surface Equivalent 314.2 m² 305.7 m² 322.5 m²
Cylinder volume/HSE 1 : 787.18 1 : 1,439.17 1 : 809.19 1 : 767.00
Adhesive weight/Total 1 : 1.23 1 : 1.22 1 : 1.21 1 : 1.24
Tractive force/Heating surface 1 : 17.95 1 : 24.12 1 : 20.39 1 : 20.02
Grate area/Heating surface 1 : 47.84 1 : 46.79 1 : 48.87
Firebox/Tube surface 1 : 8.45 1 : 8.46
Total/Superheater 1 : 4.75 1 : 5.44 1 : 4.24
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