The 0-6-6-0 wheel arrangement was used mostly on Mallet locomotives, on which the engine units were mounted either in tandem or facing each other. Double Fairlies with the 0-6-0+0-6-0 arrangement were sometimes referred to as 0-6-6-0 despite both engine units pivoting.
Usage
Canada
The only compound Mallets to operate in Canada were the R1 class 0-6-6-0 Vaughan design locomotives, with the cylinder ends of the engine units facing each other. The class was owned by the Canadian Pacific Railway and served on the Big Hill in British Columbia, which had a 4.1% grade. Five locomotives were built between 1909 and 1911. A sixth one was built, but it was a simple expansion Mallet with two sets of high-pressure cylinders. All the locomotives in this class were later converted to 2-10-0 types and were used as shunting and transfer engines in Montreal.
The Saxon Class XV HTV was a class of goods train tank steam locomotive operated by the Royal Saxon State Railways, which had been conceived for hauling trains and acting as banking engines for routes in the Ore Mountains. The two CCh4v locomotives were built in 1916 at the Sächsischen Maschinenfabrik, formerly Hartmann. In 1925, the Deutsche Reichsbahn grouped them into their DRG Class 79.0. The locomotive was of unusual design with two fixed six-coupled engine units with a central double cylinder on each side, each with a high-pressure cylinder for the rear and a low-pressure cylinder for the front drive.[7][8]
Myanmar (Burma)
The first 0-6-6-0 type locomotive were a class of Double Fairlie 0-6-6-0T locomotives purchased for the Burma Railway. Built by the Vulcan Foundry of Newtown-le-Willows of Lancashire (now Merseyside), England in 1901. They were classified H on the railway for use on the brand new mountain line to Lashio. Five were built. They were of better use than the old D class of 0-4-4-0T fairlies on use prior. However with the growing demand of goods trains (such as ore trains from the mines at Namtu), the Fairlies by then were too weak to meet demands and were replaced by 1911.
As traffic on the mountain line to Lashio had increased on the railway, a second mountain line was built to Kalaw. The earlier Double Fairlie locomotives were unable to meet the demands of the new line. Instead of purchasing more Fairlie locomotives the Burma Railway insisted on purchasing 22 0-6-6-0 compound-expansionMallet-articulated type engines classified N. They replaced the H class locomotives before the Mallets themselves were outperformed by the later Garratt-articulated locomotives the company purchased later on.
India (then known as the British Raj) had 0-6-6-0 Mallet type locomotives for the Madras and Southern Mahratta Railway (M&SM) built by the North British Locomotive Company in 1910. They were the exact same appearance-wise to the Burma Railways N class as they are of extremely similar design, the only notable visual differences being the tender being shorter, fitted with three axles instead of four on the N class. And the metal rack on top of the tender being taller and larger.
Iraq
47 0-6-6-0 locomotives were built by the Baldwin Locomotive Works for Iraq on use for the Iraqi State Railways from 1917-1918 they were given the classification of M. for the Russia’s Archangel Railway, but owing to the Russian Revolution these were diverted to the British War Department, and most were used in Iraq.
There were at least two examples of the type in the Philippines. One is Pampanga Sugar Mill No. 8 built by Baldwin Locomotive Works in 1917. Originally built for the Murmansk–Arkhangelsk Railway, it was not delivered due to the Russian Revolution. It has been working for the company by 1959 though its status after that remains unknown, likely scrapped.[11]
No. 7 Siete located at the plaza of Sagay
The other is Insular Lumber Company No. 7 Siete. Another Baldwin locomotive built in 1925. It remains the sole articulated locomotive to be preserved in the country as well as the largest to be preserved, now located in the plaza of Sagay, Negros Occidental.[12]
The Zaragoza-Pamplona (Later Norte De España) railway ordered 2 locomotives based on a contemporary design by M. Petiet in 1863, however they were not very successful and were all withdrawn and scrapped by 1883.
The Central De Aragón railway had various classes of this wheel arrangement, most of them tender engines, and one class being one of the first superheated locomotives in Spain. But very notable were some tank engines of this design, built in between 1899 and 1900, which after a few years were turned into 2-6-6-0 tender engines due to being overweight.
United States
The first Mallet locomotive in North America was built in the United States was of this type, the Baltimore and Ohio RailroadClass O no. 2400. Nicknamed Old Maude after a cartoon mule, it had a 71,500 pounds-force (318 kilonewtons) tractive effort and was a great success despite a top speed of only 21 miles per hour (34 kilometres per hour).
The Kansas City Southern Railway used the type as freight engines, with pilots, and had the most of them with twelve locomotives. The 0-6-6-0 wheel arrangement was also used to a limited extent on logging railroads and in mountain terminals.
The Western Maryland Railway had a small fleet of 2-6-6-2 locomotives which, at one time, were the heaviest locomotives in the world, weighing 264 short tons (236 long tons; 239t). They were all converted to 0-6-6-0 locomotives for heavy switching.
They shared an extreme resemblance with the Burma Railways N/Ns class and the Madras and Southern Mahratta Railway 0-6-6-0. Main visual differences being the air resivor located atop the boiler between the smokestack and dome along with extra piping and piston valves inside of slide valves on the high pressure cylinders unlike the former two aforementioned Mallets.
1 2 Sagle, Laurence W. (1964). B&O Power: Steam, Diesel and Electric Power of the Baltimore and Ohio Railroad, 1829-1964. Alvin F. Staufer. p.168. LCCN64023526. OCLC2716907. SBN944513069.
1 2 Bruce, Alfred W. (1952). The Steam Locomotive in America. New York: Crown (Bonanza Books). p.314.
↑ Espitalier, T.J.; Day, W.A.J. (1943). The Locomotive in South Africa - A Brief History of Railway Development. Chapter II - The Adoption of the 3 ft. 6 in. Gauge on the Cape Government Railways (Continued). South African Railways and Harbours Magazine, August 1943. pp. 592-594.
↑ Holland, D.F. (1971). Steam Locomotives of the South African Railways. Vol.1: 1859–1910 (1sted.). Newton Abbott, England: David & Charles. pp.25–27. ISBN978-0-7153-5382-0.
↑ Dulez, Jean A. (2012). Railways of Southern Africa 150 Years (Commemorating One Hundred and Fifty Years of Railways on the Sub-Continent – Complete Motive Power Classifications and Famous Trains – 1860–2011) (1sted.). Garden View, Johannesburg, South Africa: Vidrail Productions. p.21. ISBN9 780620 512282.
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