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English: A very crude model of a Victorian Railways 5'3" gauge A E Smith 'S' Class express passenger 4-6-2 at the Victoria Railway Museum, North Williamstown, 2 April 2016. Inspired by the GNR/LNER Gresley Class A1 4-6-2, A E Smith built 4 'S' Class Pacifics in 1928-29 to haul the top expresses on the North East Line (the only line that could cope with their high axle load) such as the Sydney Limited and Albury Express. However, initially they were poor performers but the fitting of long lap, long travel valves in the early 30's and then E E Brownbill's 'basher' Mofified Front End (with streamilned steam passages) transformed their performance. They also had smoke deflectors fitted. Later, they received new boilers with a combustion chamber, arch tubes and thermic syphons. This resulted in a designed power output of 2,300 dbhp. In 1951 they were converted to oil firing. Their only weakness was a tendency for their inside big end to overheat resulting from the Gresley derived motion and this problem was exacerbated by a streamilned shroud fitted to them in 1937-38 for hauling the prestigious 'Spirit of Progress'. They were withdrawn in 1953-54 because of dieselisation, their heavy axle loading preventing their transference to other lines. The 'S's' were intended to be the first of a triumverate of express classes in the 1920's - the 114 ton Heavy Pacific 'S' Class (although a further batch was cancelled when the upgrading of the Western Line was cancelled); a 4-8-2 intended for the heaviest expresses on the steeply graded Western Line which did not eventually appear until 1940 and then as the 'H' 4-8-4 of which only 1 was built because of the failure to upgrade the Western Lime to take it; and finally, a Light Pacific for lines which could not take a heavy axle load but which was delayed even longer, finally appearing in 1951 as a 4-6-4 - the 'R' Class, by which time diesels intended to replace steam express locos were being delivered at the same time!