Beyer Garratt Locomotives
A Beyer Garratt is essentially two locomotives fed by one large boiler. The Garratt Website is devoted to these interesting products of the Beyer-Peacock company of Great Britain.
Amazingly, India was the first country in the world to embrace the Beyer-Garratt concept, if that term is reserved solely to denote an articulated locomotive with four or more cylinders positioned on the outer ends of the two power bogies, rather than the inner ends, in which case, the Tasmanian Railways should get the credit for buying the world's first Beyer-Garratt. India's Darjeeling Himalaya 2 ft gauge railway obtained, in 1911, a 0-4-0 + 0-4-0 Garratt. Unfortunately, it was not considered a success and was used only infrequently until its withdrawal in 1954.
Broad Gauge Garratts
Five broad-gauge Garratt locomotive classes served India until the 1980s. In chronological order, they were:
GA/S Class 2-6-2+2-6-2: Only one specimen of India's second Garratt, the GA/S class was built. It ran on the North Western Railway (NWR). On the Quetta line through the Bolan Pass in Baluchistan, the NWR used up to four BESA standard HGS 2-8-0s to haul heavy trains up a 1 in 25 gradient (angle = arcsin(1/25), or 4 % grade in American usage). Since this was not economical, the NWR, in the middle 1920s, ordered an American Baldwin 2-6-6-2 compound Mallet engine and the GA/S, with a view to comparing these articulated locomotives with the Consolidations. The GA/S was able to haul about 30 tons more load than a pair of 2-8-0s - but only in good weather. It was transferred to the Rawalpindi section where the gradient is only 1 in 100. Then, the NWR bought some thirty powerful N-Class four cylinder 2-10-0s from the Great Indian Peninsula Railway (GIPR) which had been made superfluous due to the electrification of the Poona-Bombay line. After this apparently inexpensive purchase, NWR had no need to order more brand new GA/S Garratts. Thus, India's second Garratt class was retired in 1937, only 12 years after it had been built. 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. Its salient features were:
Boiler Pressure: 180 psig, Boiler Diameter: 6'-10", Heating Surface: 3254 sq.ft, Grate Area: 56.5 sq.ft, Cylinders: (4), 18 1/2" Bore x 26" Stroke, Wheel Diameter: 4'-3", Tractive Effort: 53,390 lb, Nominal Axle Load: 19.5 tonnes, Adhesive Weight: 115.4 tonnes, Engine Weight 178.4 tonnes, Maximum Train Load: 2400 tonnes on level track, 354 tonnes (?) on 1 in 25 gradient, Water Capacity: 6500 imp. gal, Coal Capacity: 11 tonnes
HSG Class 2-8-0+0-8-2: While the NWR was experimenting with the GA/S Class Garratt to replace a pair of 2-8-0s, the Bengal Nagpur Railway (BNR) too decided to do the same for a similar reason - with much happier results. They bought 2 Garratts from the Beyer Peacock company whose parts were largely common with the BESA 2-8-0s. On the Chakradarpur-Jharsaguda section of the BNR, these Garratts were as good as two Consolidations. They provided yeoman service to the BNR and its post-independence successors, the Eastern and South Eastern Railways. After electrification, there was no further need for them. As late as 1969, they were still stationed at the Kharagpur Workshop. The HSG Class must be regarded as the first successful Garratts in India and they paved the way for 3 more broad gauge Garratt classes.
Boiler Pressure: 180 psig, Boiler Diameter: 7'-1 9/16", Heating Surfaces in firebox, boiler, superheater:: 263, 2954, 642 sq.ft, Grate Area: 67.3 sq.ft, Cylinders: (4), 20" Bore x 26" Stroke, Wheel Diameter: 4'-8", Tractive Effort: 56,825 lb, Nominal Axle Load: 18.75 tonnes, Adhesive Weight: 148.5 tonnes, Engine Weight 180.5 tonnes, Maximum Train Load: 2550 tonnes on level track, Water Capacity: 5000 imp. gal, Coal Capacity: 8 tonnes
They were the only 4-8-0+0-8-4 Garratts to run anywhere in the world and had the largest water capacity of any Garratt ever manufactured. The N Class holds the distinction of being the largest railway locomotive to run in India, yet its axle load was barely over 20 tonnes. However, its 234 tonne weight, which restricted it to rails weighing 90 lb/yard.
Sixteen of them were built. Unlike the HSG Class, they had more modern straight-ported cylinders with piston valves. Whether such features gave better performance while hauling slow, heavy coal traffic is an open question. Three of them had rotary cam poppet valves and another three had Caprotti valve gear. They were used on the Chakradarpur - Jharsaguda and Anara-Tatanagar sections. After electrification, they were to be found west of Rourkela in Orissa. They could reach speeds of up to 45 mph and could haul 2400 tonne trains up a 1 in 100 gradient. As of the middle 1970s, they were still in use - a tribute to their capabilities. Happily, an N Class Garratt is preserved at the New Delhi Rail Museum.
Boiler Pressure: 210 psig, Boiler Diameter: 7'-1 13/16", Heating Surfaces in firebox, boiler, superheater:: 286, 3118, 642 sq.ft, Grate Area: 69.8 sq.ft, Cylinders: (4), 20 1/2" Bore x 26" Stroke, Wheel Diameter: 4'-8", Tractive Effort: 69,655 lb, Nominal Axle Load: 20.25 tonnes, Adhesive Weight: 159.4 tonnes, Engine Weight 234 tonnes, Maximum Train Load: 3000 tonnes on level track, Water Capacity: 10000 imp. gal, Coal Capacity: 14 tonnes
NM Class 4-8-0+0-8-4: The NM was simply an N Class with Lentz or Caprotti valves and greatly reduced coal and water capacities. Its firebox had thermic syphons and arch tubes to give better performance. At 17 tonnes, its axle load was less than that of the N Class Garratts, but had almost the same tractive effort. The reduced axle load enable it to work on the Bilaspur-Katni line and on the Anuppur-Chirmiri branch line where it hauled coal trains. Ten of them were built around 1931, by Beyer Peacock. Perhaps because of their poppet valves, they were withdrawn by the late 1960s. In other words, the older N Class Garratts actually lasted longer. The salient features of the NM Class were:
Boiler Pressure: 210 psig, Boiler Diameter: 7'-1 13/16", Heating Surfaces in firebox, boiler, superheater:: 330, 2961, 642 sq.ft, Grate Area: 67.6 sq.ft, Cylinders: (4), 20" Bore x 26" Stroke, Wheel Diameter: 4'-8", Tractive Effort: 69,660 lb, Nominal Axle Load: 17.15 tonnes, Adhesive Weight: 138.55 tonnes, Engine Weight 204.15 tonnes, Maximum Train Load: 3000 tonnes on level track, Water Capacity: 6000 imp. gal, Coal Capacity: 8 tonnes
P Class 4-8-2+2-8-4: The ultimate and the largest Indian Garratt, the P Class, was a development of the N and NM Class Garratts. On the Anuppur-Chirmiri branch, with its severe curvature, it was deemed necessary to have a Garratt with a trailing bogie. Four of them were obtained from Beyer Peacock in 1939. The P Class had a slightly enlarged boiler similar to the NM's. Since its coal and water capacities were less than that of the N Class, it could run on 75 lb/yard rails. The P Class Garratts routinely hauled 1500 tonne loads up a 1 in 91 gradient. In their final years - the early 1970s - they were shedded at Bhilai. Their salient features were:
Boiler Pressure: 210 psig, Boiler Diameter: 7'-1 13/16", Heating Surfaces in firebox, boiler, superheater:: 333, 3120, 661 sq.ft, Grate Area: 70.0 sq.ft, Cylinders: (4), 20 1/2" Bore x 26" Stroke, Wheel Diameter: 4'-8", Tractive Effort: 69,655 lb, Nominal Axle Load: 17.0 tonnes, Adhesive Weight: 136 tonnes, Engine Weight 230 tonnes, Maximum Train Load: 3165 tonnes on level track, Water Capacity: 7500 imp. gal, Coal Capacity: 10 tonnes
Metre Gauge Garratts
The Assam Bengal Railway (ABR), which later oddly renamed itself the Bengal Assam Railway (BAR) and later became the North East Frontier Railway (NEFR) bought, in 1927, five 2-6-2+2-6-2 Garratts. These T Class superheated engines could haul 300 ton trains between Jatinga and Harangajao though it needed assistance over the steepest sections. They were later renamed Class GT Garratts when the ABR started calling itself the BAR!
Seventeen 4-8-2+2-8-4 War Department Class MWGX Garratts were assigned to the BAR and 9 of them stayed with that railway after the second World War ended. Some of its members ended up in East Africa like the one in the photograph. This class of Garratts had an interesting history. In the late 1930s, the Great Western Railway of Brazil ordered four metre gauge 4-8-2+2-8-4 Garratts. The War interrupted the design work being done at Beyer Peacock. Then the War Department wanted metre gauge Garratts to work in North-Eastern India and Burma. Therefore, Beyer Peacock modified the drawings intended for Brazil to suit India's smaller loading gauge. The MWGX Garratts had round fireboxes, superheated boilers and plate frames. They had 4 ft diameter driving wheels and 16" x 24" cylinders. These light Garratts were such successful designs that they were also supplied to South Australian Railways.
Ten War Department Garratts of the 2-8-0+0-8-2 wheel arrangement were assigned to the Bengal Assam Railway in 1944. After the War, they were transferred to Burma where they constituted the GB Class Garratts.
Two War Department Garratts of the 2-8-2+2-8-2 wheel arrangement were assigned to the Bengal Assam Railway in 1943. After the War, they were transferred to Burma where they joined the other 9 of its GC Class Garratt sisters.
A few War Department Garratts of the 4-8-2+2-8-4 wheel arrangement were assigned to the Bengal Assam Railway in 1945. After the War, some of them were transferred to Burma where they joined its GD Class Garratt sisters. The rest went to East Africa in 1952.
Four specimens of yet another Garratt Class of the 4-8-2+2-8-4 wheel arrangement meant for Burma instead went to the North East Frontier Railway in 1949 where they constituted the GE Class. They had 4 ft diameter driving wheels and 16" x 24" cylinders.
Thus, a total of 6 Garratt classes served on the Indian metre gauge.
References: 1) "The Garratt Locomotive" by A.E.Durrant, 2) "Indian Locomotives, Part IV", by Hugh Hughes, 3) Garratt Website