Herbert William Garratt thought about how a powerful and flexible steam locomotive for narrow gauge railways should look like. His design consisted of a locomotive divided into three parts. Two running gears each contained a complete steam engine, on one side carrying a water tank and on the other a combined water and fuel tank. The third part consisted of a bridge frame that carried a boiler and a cab. The bridge frame was suspended centrally between the two running gears and supplied the two engines with steam.
For the implementation, he first turned to Kitson & Co., where he was unsuccessful. This can probably be explained by the fact that they were already producing articulated locomotives of the Kitson-Meyer design. He had more success with Beyer, Peacock & Co., so that the design is now also known as the Beyer-Garratt.
The first locomotive that can be called a Garratt was built for the North East Dundas Tramway in Tasmania and still had some deviations from the later standard form. It had the wheel arrangement 0-4-0+0-4-0 T and is known today as Tasmanian Government Railways class K. At the special request of the customer, the two locomotives worked in compound action and had the cylinders on the inside. This arrangement was very complex and also caused problems with the cylinders directly under the driver's cab. Later Garratts had single steam expansion and outside cylinders. The first model built for mainline service was the West Australian Government Railways class M with a 2-6-0+0-6-2T wheel arrangement.
![Herbert William Garratt (1864-1913)](./data/photos/Garratt.jpg)
Herbert William Garratt (1864-1913)
The biggest advantage of the Garratt was that the designer had a free hand in designing the boiler and there were no frames, axles or wheels in the way. This was particularly important on the narrow gauge, because they could create a wide firebox. In addition, the firebox could be manufactured inexpensively with straight side walls and the ash pan was more accessible. The boiler barrel could also be made short and with a large diameter in order to be able to develop optimal performance.
One disadvantage the Garratt shared with tank locomotives was the reduced adhesive weight as supplies dwindled. The train loads either had to be planned in such a way that the locomotive could pull them even when the supplies were almost empty, or water had to be taken more often than actually necessary to keep the mass high. In addition, during construction, care had to be taken to ensure that the space between the smoke box and the front water tank is large enough to open the smoke box door. This could be ensured by an indentation in the water tank or a sufficiently large distance between both.
The running characteristics were characterized by the fact that the chassis was symmetrical and high speeds could be run in both directions. Especially on routes with many tunnels, they often ran with the cab first, i.e. “bunker leading”. Because the boiler, unlike that of the Mallet, didn't swing outward in turns, tighter curves could be negotiated and the running was better at higher speeds.
![Tasmanian Government Railways Class K, the first ever Garratt](./data/photos/TGR_K_2.jpg)
Tasmanian Government Railways Class K, the first ever Garratt
Phil Parker ![CC BY: Attribution](./images/CC-BY.png)
A special form was the Union Garratt. The front water tank was still on its own frame, but the rear water and coal tanks were on the frame that also carried the boiler and driver's cab. The rear chassis was designed as a bogie. So it was a hybrid of Garratt and Modified Fairlie.
Most Garratts were built for Africa and many for Australia and South America. Others were used in Asia and only a few in Europe. This can be attributed to the fact that there were many narrow-gauge routes in the main areas of application, which had many curves and were often only designed for low axle loads, which made the Garratt an ideal option. Since there were large quantities of raw materials to be transported in these countries, large Garratts were built, especially for the Cape gauge and meter gauge, which were more powerful than the most powerful steam locomotives in Europe. The most powerful Garratt is the class 59 of the East African Railways with the wheel arrangement 4-8-2+2-8-4T. Although it only ran on the meter gauge, it had an operating mass of over 250 tons, had a grate surface of 72 square feet and had a starting tractive effort of around 83,000 pounds.
Since the general speeds were often low, the Garratts were mostly used for mixed traffic. Depending on the route network, vehicles with larger drivers were also built, which were then primarily used for passenger trains. So it was possible that a railroad would purchase a small-wheel 4-8-2+2-8-4T “Double Mountain” for freight trains and a large-wheel 4-6-2+2-6-4T “Double Pacific” for passenger trains. The standard-gauge 231-132.AT and BT from PLM Algérie with 71 inch coupled wheels are considered the fastest Garratts at 82 mph.
![Express Garratt of the Central de Aragón, later RENFE 462 F](./data/photos/Renfe_462.jpg)
Express Garratt of the Central de Aragón, later RENFE 462 F
collection Jean-Pierre Vergez-Larrouy ![CC0: Public Domain Dedication](./images/CC-Zero.png)
After the patent for the design expired, other manufacturers in other countries also made Garratts. For example, the South African Railways had a larger number manufactured by the German companies Hanomag, Henschel and Maffei. The last Garratt built was the South African Railways Class NG G16, the last of which left the Hunslet-Taylor factory in South Africa in 1968 and were fitted with boilers from the parent company in England. Like the very first Garratt, these ran on the small two-foot gauge.
A total of 1,704 Garratts were built, of which 1,124 went to Africa alone. Especially there, some operators were still dependent on their services for a very long time. In Zimbabwe, for example, Garratts were still used regularly in front of passenger trains after the turn of the millennium. It is currently assumed that there are still around 250 existing locomotives in a wide variety of conditions. Of these, however, there are probably fewer than 100 in reasonably decent condition and around 15 are still roadworthy.
For the expected increase in traffic towards the French border, the Central de Aragón ordered two types of Garratts for express and freight traffic. The locomotives for express service were designed as double Pacifics and were built by Babcock & Wilcox after plans by Beyer, Peacock & Co.
They were the most powerful express locomotives in Europe at the time and at the same time the only Garratts that were used on express trains. When they were incorporated into the RENFE, they became 462-0401 to 0406, whereby the 462 was to be understood as “two times 231”. Between 1955 and 1962 they were converted to oil firing and renamed 462F. Their use on express trains ended in 1966 and they were used in freight transport for another four years. Today only the non-operational 0401 exists. ![](./images/status_hasBaseData.png)
General |
Built | 1931 |
Manufacturer | Babcock & Wilcox |
Axle config | 4-6-2+2-6-4T (Double Pacific (Garratt)) |
Gauge | 5 ft 5 11/16 in (Iberian broad gauge) |
Dimensions and Weights |
Length | 93 ft 8 in |
Rigid wheelbase | 12 ft 7 in |
Total wheelbase | 82 ft 11 in |
Service weight | 404,327 lbs |
Adhesive weight | 206,793 lbs |
Axle load | 34,392 lbs |
Water capacity | 22,000 us gal |
Fuel capacity | 8,000 lbs (coal) |
Boiler |
Grate area | 53 sq ft |
Firebox area | 275 sq ft |
Tube heating area | 3,156 sq ft |
Evaporative heating area | 3,431 sq ft |
Superheater area | 742 sq ft |
Total heating area | 4,173 sq ft |
Power Plant |
Driver diameter | 69 in |
Boiler pressure | 200 psi |
Expansion type | simple |
Cylinders | four, 19 x 26 in |
Power |
Power source | steam |
Estimated power | 2,350 hp (1,752 kW) |
Optimal speed | 32 mph |
Starting effort | 46,250 lbf |
Calculated Values |
Factor of adhesion | 1 : 4.47 |
Power-to-weight ratio | 0.0058 hp/lb |
Heating Area Equivalent | 6,290 sq ft |
Cylinder volume/HAE | 1 : 826.90 |
Adhesive weight/Total | 1 : 1.96 |
Tractive force/Heating area | 1 : 2491.59 |
Grate area/Heating area | 1 : 73.55 |
Firebox/Tube area | 1 : 14.17 |
Total/Superheater | 1 : 4.62 |
For the expected increase in traffic towards the French border, the Central de Aragón ordered two types of Garratts for express and freight traffic. The locomotives for freight service were designed as double Mikados and were built by Babcock & Wilcox after plans by Maffei of Munich. The six locomotives delivered in 1931 were numbered 201 to 206 and dubbed “Garratts pequeñas” (small Garratts) in reference to their express counterparts.
When they were incorporated into the RENFE, they became 282-0401 to 0406, whereby the 282 was to be understood as “two times 141”. Between 1955 and 1958 they were converted to oil firing and renamed 282F. In 1961, ten more were built which were among the last Garratts to be completed. They were retired between 1971 and 1973 and 282F-0421 was preserved in running condition.
General |
Built | 1931 | 1961 |
Manufacturer | Babcock & Wilcox |
Axle config | 2-8-2+2-8-2T (Double Mikado (Garratt)) |
Gauge | 5 ft 5 11/16 in (Iberian broad gauge) |
Dimensions and Weights |
Length | 83 ft 2 7/16 in |
Wheelbase | 73 ft 9 13/16 in |
Rigid wheelbase | 18 ft 0 9/16 in |
Service weight | 361,558 lbs | 381,399 lbs |
Adhesive weight | 241,847 lbs | 255,736 lbs |
Axle load | 30,203 lbs | 32,628 lbs |
Water capacity | 5,812 us gal |
Fuel capacity | coal | oil |
Boiler |
Grate area | 45.2 sq ft |
Firebox area | 171 sq ft | 169 sq ft |
Tube heating area | 1,947.2 sq ft | 1,951.5 sq ft |
Evaporative heating area | 2,118.2 sq ft | 2,120.5 sq ft |
Superheater area | 736.3 sq ft | 747 sq ft |
Total heating area | 2,854.5 sq ft | 2,867.5 sq ft |
Power Plant |
Driver diameter | 47.2 in |
Boiler pressure | 213 psi |
Expansion type | simple |
Cylinders | four, 17 5/16 x 24 in |
Power |
Power source | steam |
Estimated power | 1,877 hp (1,400 kW) |
Optimal speed | 22 mph |
Top speed | 37 mph |
Starting effort | 55,289 lbf |
Calculated Values |
Factor of adhesion | 1 : 4.38 | 1 : 4.63 |
Power-to-weight ratio | 0.0052 hp/lb | 0.0049 hp/lb |
Heating Area Equivalent | 4,445.9 sq ft | 4,459.5 sq ft |
Cylinder volume/HAE | 1 : 898.24 | 1 : 895.51 |
Adhesive weight/Total | 1 : 1.49 |
Tractive force/Heating area | 1 : 4354.37 | 1 : 4334.59 |
Grate area/Heating area | 1 : 59.36 | 1 : 59.69 |
Firebox/Tube area | 1 : 15.69 | 1 : 15.97 |
Total/Superheater | 1 : 2.88 | 1 : 2.84 |
The class 59 of the East African Railways wasn't only the most powerful and heaviest Garratt locomotive ever built for meter gauge, but most likely also heavier than all built for cape gauge and nearly as heavy as the heaviest standard gauge Garratts in Australia and the Soviet Union. They were designed to accelerate freight traffic on the 330 miles between Mombasa and Nairobi. While Mombasa is located on the coast, Nairobi's elevation is 1.661 m or 5.450 ft above sea level.
Their wheel arrangement 4-8-2+2-8-4 is also called “Double Mountain”, since it resembles two 4-8-2 “Mountain” locomotives coupled back to back. In fact, the 34 locomotives built by Beyer-Peacock in 1955 were named after mountains. Their task was to haul 1,200 ton trains up long inclines of 1.5 percent. When needed, they also had to take over express trains with 35 coaches.
For the whole of their lives, they operated on the same line. Many of their crews only consisted of Sikhs. These always kept their locomotive in the best and cleanest condition and decorated their cab in a special way. After all had been withdrawn between 1973 and 1980, No. 5918 “Mount Gelai” was overhauled at the Nairobi Railway Museum. Until 2005, it wasn't only used to haul excursion trains, but sometimes even had to stand in when there was a shortage of diesel locomotives.
General |
Built | 1955 |
Manufacturer | Beyer, Peacock & Co. |
Axle config | 4-8-2+2-8-4T (Double Mountain (Garratt)) |
Dimensions and Weights |
Length | 102 ft 11 in |
Wheelbase | 92 ft 6 1/2 in |
Rigid wheelbase | 15 ft |
Service weight | 563,763 lbs |
Adhesive weight | 357,347 lbs |
Axle load | 47,040 lbs |
Water capacity | 8,600 us gal |
Fuel capacity | 3,243 us gal (oil) |
Boiler |
Grate area | 72 sq ft |
Firebox area | 247 sq ft |
Tube heating area | 3,313 sq ft |
Evaporative heating area | 3,560 sq ft |
Superheater area | 747 sq ft |
Total heating area | 4,307 sq ft |
Power Plant |
Driver diameter | 54 in |
Boiler pressure | 225 psi |
Expansion type | simple |
Cylinders | four, 20 1/2 x 28 in |
Power |
Power source | steam |
Estimated power | 2,700 hp (2,013 kW) |
Optimal speed | 21 mph |
Top speed | 43 mph |
Starting effort | 83,350 lbf |
Calculated Values |
Factor of adhesion | 1 : 4.29 |
Power-to-weight ratio | 0.0048 hp/lb |
Heating Area Equivalent | 6,289 sq ft |
Cylinder volume/HAE | 1 : 1036.82 |
Adhesive weight/Total | 1 : 1.58 |
Tractive force/Heating area | 1 : 4350.55 |
Grate area/Heating area | 1 : 56.39 |
Firebox/Tube area | 1 : 16.44 |
Total/Superheater | 1 : 4.77 |
The unsatisfactory results of the unreliable and high-maintenance M-class Mallets led the Kenya-Uganda Railway to switch to Garratt-type locomotives. They weighed over 120 tons loaded, had a Belpaire firebox and were among the most powerful meter gauge locomotives of their time. The first four machines to be delivered came in 1926 from Beyer, Peacock & Co. and were designated class EC. They were fired with eucalyptus wood, which soon proved inefficient and dangerous for the crew. Thus, a conversion to coal firing took place, but they were already sold to Indochina in 1939.
In 1927, 20 examples of the EC1 were purchased, which were essentially identical to the EC but were coal-fired from the start. Two more examples followed in 1930, which differed from the 1927 machines in minimal details. For this reason, the first series later became the class 50 and the second the class 51 in the East African Railways. Ten more oil-fired machines followed in 1931, which ran as the EC2 on the KUR and later became class 52 on the EAR.
![Works photo of EC Nr. 41](./data/photos/KUR_EC.jpg)
Works photo of EC Nr. 41
Beyer, Peacock & Co. ![Public Domain](./images/PD.png)
With the Garratts, the train loads could be significantly increased compared to the older locomotives. Up to 440 tons could now be towed on the old stretches with a gradient of up to two percent, on which the older eigth-coupled vehicles could tow a maximum of 200 tons. They also hauled passenger trains at higher speeds on the upgraded line between Mombasa and Nairobi. They were mostly phased out in the 1950s and some of the bogies were reused to rebuild class 13 tank locomotives from a 4-8-2 to 4-8-4 wheel arrangement.
General |
Built | 1926 | 1927, 1930 | 1931 |
Manufacturer | Beyer, Peacock & Co. | North British |
Axle config | 4-8-2+2-8-4T (Double Mountain (Garratt)) |
Gauge | 3 ft 3 3/8 in (Meter gauge) |
Dimensions and Weights |
Wheelbase | 49 ft 8 in | |
Rigid wheelbase | 12 ft 3 in | |
Service weight | 280,896 lbs | 293,216 lbs | 318,304 lbs |
Adhesive weight | 177,856 lbs | 187,936 lbs | 197,120 lbs |
Water capacity | 5,104 us gal | 6,035 us gal | 6,305 us gal |
Fuel capacity | 13,440 lbs (wood) | 13,440 lbs (coal) | 2,852 us gal (oil) |
Boiler |
Grate area | 43.6 sq ft |
Firebox area | 174 sq ft | 194 sq ft |
Tube heating area | 1,863 sq ft | 1,856 sq ft |
Evaporative heating area | 2,037 sq ft | 2,050 sq ft |
Superheater area | 380 sq ft |
Total heating area | 2,417 sq ft | 2,430 sq ft |
Power Plant |
Driver diameter | 43 in |
Boiler pressure | 170 psi | 180 psi |
Expansion type | simple |
Cylinders | four, 16 1/2 x 22 in |
Power |
Power source | steam |
Estimated power | 1,100 hp (820 kW) | 1,300 hp (969 kW) | 1,400 hp (1,044 kW) |
Optimal speed | 17 mph | 21 mph |
Starting effort | 40,255 lbf | 42,623 lbf |
Calculated Values |
Factor of adhesion | 1 : 4.42 | 1 : 4.67 | 1 : 4.63 |
Power-to-weight ratio | 0.0039 hp/lb | 0.0044 hp/lb |
Heating Area Equivalent | 3,667 sq ft | 3,780 sq ft |
Cylinder volume/HAE | 1 : 905.11 | 1 : 878.05 |
Adhesive weight/Total | 1 : 1.58 | 1 : 1.56 | 1 : 1.61 |
Tractive force/Heating area | 1 : 3744.18 | 1 : 3943.23 |
Grate area/Heating area | 1 : 51.44 | 1 : 51.28 |
Firebox/Tube area | 1 : 12.89 | 1 : 11.53 |
Total/Superheater | 1 : 5.36 | 1 : 5.39 |
For the requirements of the Second World War, the KUR had seven Garratts of the EC4 class built from 1944, which had a high power despite their light construction. In 1945, the KUR received two more or less identical EC5s, four of which went to the Tanganyika Railways and others to India and Burma. The KUR soon received the machines from Tanganyika and five from Burma. Six more, slightly revised locomotives were ordered in 1949. These entered service directly for the East African Railways and were designated the Class 56, while the EC4 and EC5 formed the Classes 54 and 55. ![](./images/status_hasBaseData.png)
General |
Built | 1944-1945 | 1949 |
Manufacturer | Beyer, Peacock & Co. |
Axle config | 4-8-2+2-8-4T (Double Mountain (Garratt)) |
Gauge | 3 ft 3 3/8 in (Meter gauge) |
Dimensions and Weights |
Wheelbase | 77 ft 9 in | 79 ft 1 in |
Service weight | 384,160 lbs | 328,830 lbs |
Adhesive weight | 250,880 lbs | 197,120 lbs |
Axle load | 31,360 lbs | 23,968 lbs |
Water capacity | 7,206 us gal | 5,044 us gal |
Fuel capacity | 2,852 lbs (oil) | 2,861 lbs (oil) |
Boiler |
Grate area | 51.3 sq ft | 48.8 sq ft |
Firebox area | 212 sq ft | 164 sq ft |
Tube heating area | 2,328 sq ft | 1,753 sq ft |
Evaporative heating area | 2,540 sq ft | 1,917 sq ft |
Superheater area | 470 sq ft | 370 sq ft |
Total heating area | 3,010 sq ft | 2,287 sq ft |
Power Plant |
Driver diameter | 45.5 in | 48 in |
Boiler pressure | 180 psi | 200 psi |
Expansion type | simple |
Cylinders | four, 19 x 24 in | four, 16 x 24 in |
Power |
Power source | steam |
Estimated power | 1,700 hp (1,268 kW) | 1,625 hp (1,212 kW) |
Optimal speed | 19 mph | 24 mph |
Starting effort | 58,268 lbf | 43,520 lbf |
Calculated Values |
Factor of adhesion | 1 : 4.31 | 1 : 4.53 |
Power-to-weight ratio | 0.0044 hp/lb | 0.0049 hp/lb |
Heating Area Equivalent | 4,540 sq ft | 3,477 sq ft |
Cylinder volume/HAE | 1 : 1057.52 | 1 : 1380.82 |
Adhesive weight/Total | 1 : 1.53 | 1 : 1.67 |
Tractive force/Heating area | 1 : 4351.89 | 1 : 4277.96 |
Grate area/Heating area | 1 : 54.54 | 1 : 43.50 |
Firebox/Tube area | 1 : 13.20 | 1 : 12.95 |
Total/Superheater | 1 : 5.40 | 1 : 5.18 |
At the beginning of the thirties, the PLM in Algeria needed very powerful express locomotives, as the compound ten-wheelers used there had reached their limits, even when running in double. The specifications stipulated that the new locomotive alone should be able to pull trains with 19 to 29 cars sufficiently quickly over the ramps, which had often two percent, and should also have a maximum speed of 110 km/h or 68 mph. The result was a Garratt as a “Double Pacific” with 1.80 m (5 ft 11 in) driving wheels.
In 1932, a first prototype was built at Franco-Belge, which was tested first in France and then in Algeria. A special feature was the rotating coal bunker patented by Beyer-Peacock, which automatically transported the coal towards the cab. The cab was generously sized and had a fan to improve comfort in high temperatures. There were also controls in both directions and the Cossart valve gear was electrically actuated.
During the tests, up to 73 cars were successfully transported and the required speed was easily achieved with normal trains. The pulling power of the Garratt was now equated with the pulling power of 2.4 ten-wheelers. Only the special design of the coal bunker led to vibrations above 120 km/h, so it was no longer used in series production. The Kylchap exhaust system was replaced in the series by the usual double chimney of the PLM. The series locomotives were also given a streamlined casing.
After the 231-132 AT, twelve 231-132 BT were built in 1936, which reached up to 132 km/h (82 mph) and were therefore probably the fastest Garratts ever. On a better track, it was even expected that up to 140 km/h would be possible. When the first diesel locomotives were introduced after the Second World War, maintenance of the Garratts decreased. They were brought to Spain and scrapped at the beginning of the fifties. ![](./images/status_hasBaseData.png)
Variant | 231-132 AT | 231-132 BT |
---|
General |
Built | 1932 | 1936 |
Manufacturer | Franco-Belge |
Axle config | 4-6-2+2-6-4T (Double Pacific (Garratt)) |
Gauge | 4 ft 8 1/2 in (Standard gauge) |
Dimensions and Weights |
Length | 96 ft 4 11/16 in |
Wheelbase | 31 ft 0 1/16 in |
Rigid wheelbase | 12 ft 10 5/16 in |
Total wheelbase | 86 ft 11 11/16 in |
Service weight | 423,287 lbs | 466,498 lbs |
Adhesive weight | 224,871 lbs | 238,099 lbs |
Axle load | 37,479 lbs | 39,683 lbs |
Water capacity | 6,604 us gal | 7,529 us gal |
Fuel capacity | 15,432 lbs (coal) | coal |
Boiler |
Grate area | 54.6 sq ft | 58.1 sq ft |
Firebox area | 236.8 sq ft | 220.3 sq ft |
Tube heating area | 2,543.3 sq ft | 2,574.6 sq ft |
Evaporative heating area | 2,780.1 sq ft | 2,795 sq ft |
Superheater area | 742.7 sq ft | 975.2 sq ft |
Total heating area | 3,522.8 sq ft | 3,770.2 sq ft |
Power Plant |
Driver diameter | 70.9 in |
Boiler pressure | 232 psi | 290 psi |
Expansion type | simple |
Cylinders | four, 19 5/16 x 26 in |
Power |
Power source | steam |
Estimated power | 2,280 hp (1,700 kW) | 2,548 hp (1,900 kW) |
Optimal speed | 27 mph | 24 mph |
Top speed | 68 mph |
Starting effort | 53,840 lbf | 67,294 lbf |
Calculated Values |
Factor of adhesion | 1 : 4.18 | 1 : 3.54 |
Power-to-weight ratio | 0.0054 hp/lb | 0.0055 hp/lb |
Heating Area Equivalent | 5,449.6 sq ft | 5,847.1 sq ft |
Cylinder volume/HAE | 1 : 983.32 | 1 : 916.47 |
Adhesive weight/Total | 1 : 1.88 | 1 : 1.96 |
Tractive force/Heating area | 1 : 3435.81 | 1 : 4012.63 |
Grate area/Heating area | 1 : 60.21 | 1 : 61.07 |
Firebox/Tube area | 1 : 13.88 | 1 : 16.11 |
Total/Superheater | 1 : 3.74 | 1 : 2.87 |