Southern 4-6-2 Locomotives in Great_Britain

Class Merchant Navy (Locobase 1432)

Data from Graham Glover 1967, Brian Hollingsworth, The Great Book of Trains (New York: Portland House, 1987), pp.170-171, Edward Cecil Poultney, British Express Locomotive Development (London: George Allen and Unwin, 1952), pp. 165, 167. Steamindex's detailed summary of OVS Bulleid's paper presented to the Institution of Mechanical Engineers in 1946 and discussion by several enginers can be found at [], last accessed 23 May 2020. For a defense of the Bulleid designs, see Dave Michell, "Bulleid WC/BB 'West Country' and 'Battle of Britain' class 4-6-2 -Notes from a Bulleid Fundamentalist" at[], also last accessed 23 May 2020. (Thanks to Alexander Blessing for his 27 April 2020 email pointing out an error in the description of the valve gear.)

First twenty locomotives built between February 1941 and June 1945. The last ten were produced from September 1948 and April 1949.

Designed by Oliver Vaughan Snell (OVS) Bulleid, these engines were novel from valve gear to boiler jacket. The design emphasized the ability to meet schedules regardless of coal quality and despite a much wider range in crew competence than British railroads had been used to; they had serious shortcomings in their original form.

A large boiler and relatively wide and deep Belpaire firebox with two Nicholson syphons generated the steam. According to Glover, the taper of the boiler barrel, in which the top line remained horizontal while the bottom sloped down to meet the foundation ring, was unique in British locomotive design. Moreover, the smokebox top line sloped down toward the front to make room for the Lemaitre multi-jet blastpipe and its placement over the rear bogie axle was also unusual. "[V] ery curious these engines would have looked had they not been shrouded in an overall casing." Expressing his regret that these engines were never run without the casing, Glover adds: "They would have shocked the conventional and given satisfaction to those whose interest in locomotive design is more than skin deep."

A chain-driven valve gear, which was housed in an oil bath for lubrication, acuated the 11" (279 mm) piston valves that supplied three cylinders that drove the middle of the three axles. Glover concedes that the chain-driven valve gear and oil bath "gave considerable trouble in operation." Hollingsworth chose a blunter verdict: "Bulleid's locomotives were amazingly good in some ways, yet almost unbelievably bad in others."

All sources pronounce the boiler sound, concede that the high coal consumption was inevitable but not necessarily fatal, but excoriate the valve-gear design. A firmly opposing opinion on both counts should be read at the Southern Railway E-Group cite listed above.

What strikes the Locobase is how much lighter these engines were than other great 4-6-2s of British design. One factor in this reduction was the use of Bulleid Firth Brown (BFB) cast-steel drivers. Clearly, Bulleid studiously interwove features in a clean-sheet effort that in most respects deserved high praise. When the Southern was nationalized as part of British Rail, these engines were rebuilt. See Locobase 1433.

Class West Country/Battle of Britain (Locobase 1434)

Data from Graham Glover 1967, Brian Hollingsworth, The Great Book of Trains (New York: Portland House, 1987), pp.170-171. See also "Bulleid WC/BB 'West Country' and

'Battle of Britain' class 4-6-2" on the Southern Railway E-Group website at [], and a defense of the Bulleid designs. see Dave Michell, "Bulleid WC/BB 'West Country' and 'Battle of Britain' class 4-6-2 -Notes from a Bulleid Fundamentalist" at [], both last accessed 23 May 2020; and "1940s express steam locomotive 'Eddystone' returns after a three-year ú350,000 overhaul" on the Swanage Railway Trust's website at [], last accessed 24 July 2021 . (Thanks to Alexander Blessing for his 27 April 2020 email pointing out an error in the description of the valve gear.)

Designed by Oliver Vaughan Snell (OVS) Bulleid, these engines were smaller "light" Pacifics based on the Merchant Navy class (see general comments in Locobase 1432). Their lighter axle load and smaller dimensions suited them for a much wider operational range and the class appeared in much greater numbers. After the first 48 were named for West Country locations, naming switched to famous air squadrons and wartime leaders.

Like the Merchant Navies, these engines were beset with the pangs of novelty, including an oil consumption rate seven times that of conventional engines, chain-driven valve gear, which was housed in an oil bath for lubrication, the air-smoothed casing that inspired the nickname "Spam Cans", Bulleid Firth Brown (BFB) cast type wheel centers for all wheels, thermic syphons. Among the differences were a slight reduction in the piston valve diameter to 10" (254 mm).

Hollingsworth notes that they, like the Navies, were prone to slipping at the start, but once underway, they were "superb ...Both classes were good, but since the smaller ...class seemed able to equal anything the larger [one] could do, one's admiration goes more strongly to the former." 61 were rebuilt in the mid-1950s by British Rail (see Locobase 1435).