Unidentified Caledonian Railway Class 139 "Dunalastair IV" Superheater 4-4-0 steam locomotive on a train
The Caledonian Railway 721 Class (known as the "Dunalastair" class) was a class of 4-4-0 steam locomotives designed by John F. McIntosh for the Caledonian Railway (CR) and introduced in 1896. All survived to be absorbed by the London, Midland and Scottish Railway (LMS) in 1923 and a few survived into British Railways (BR) ownership in 1948. The "Dunalastair" class was very successful and developed in four different versions: Dunalastair I (721 Class) built 1896 Dunalastair II (766 Class) built 1897 (some rebuilt with superheaters 1914) Dunalastair III (900 Class) built 1899–1900 (some rebuilt with superheaters 1914–18) Dunalastair IV (140 Class) built 1904–10 (some rebuilt with superheaters 1915–17) The rebuilding with superheaters was accompanied by a reduction in boiler pressure and an increase in cylinder diameter. There are two further classes of McIntosh 4-4-0 locomotives which some authors have included in the Dunalastair series. These are: 139 Class, built 1910–12 with Schmidt superheaters 43 Class, built 1913–14 with Robinson superheaters Classes 766 and 900 were built with eight-wheel bogie tenders with capacities for 4,125 imperial gallons (18,750 l) of water and tons of coal. In the 1930s newer and more powerful LMS locomotives took over their most long-distance duties and the company cascaded the 900 Class to other work. This made eight-wheel tenders superfluous so the company substituted smaller, lighter and simpler six-wheel tenders from scrapped Caledonian locomotives. Most members of the class received McIntosh tenders that had been built for classes 179, 600, 908 and 918. The six-wheel tenders had the same ton coal capacity but carried only 3,570 imperial gallons (16,200 l) of water.
Size: 3243px × 2145px
Location: Unknown
Photo credit: © Digbydachshund / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: 4-4-0, caledonian, class139, dunalastair, iv, locomotive, railway, steam, superheater, train
