Burma Railways GA.I to GA.IV
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.
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 | |