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The S class was an express passenger steam locomotive that ran on Victorian Railways, Australia, from 1928 to 1954. Built when the VR was at its zenith and assigned to haul the broad gauge-leg of its Melbourne to Sydney interstate express passenger services, the S class remained the VR's most prestigious locomotive class until the advent of diesel electric locomotives in the early 1950s. They were the first Pacific-type locomotives on the VR, as well as its first 3-cylinder locomotive type. Renowned for their power and speed, in the ten years that followed their introduction the running time of the premier Sydney express service they operated was progressively reduced by one and a half hours. These service improvements culminated in 1937 with the replacement of the ''Sydney Limited'' with the Art Deco streamliner ''Spirit of Progress'', and the S class locomotives were fitted with streamlined casings to match the new train set. They were also equipped with long-range tenders to enable the entire journey to be run non-stop at a speed that remained for the next 20 years Australia's fastest train service. Although only four S class locomotives were built, they were highly utilised. They ran up annual mileages double that of other classes of locomotives on the VR and by 1954 had run a combined total of approximately . However their size and heavy axle load made them unsuitable for regular service on any other lines than the North Eastern line, and so within six months of the introduction of the new B class diesel locomotives on the ''Spirit of Progress'' roster in April 1954 the S class had all been withdrawn and scrapped. Their scrapping was a catalyst for the rail preservation movement in Victoria to lobby for the preservation of remaining examples of other VR steam locomotives, resulting in the establishment in 1962 of the Australian Railway Historical Society's North Williamstown railway museum.〔(【引用サイトリンク】title=AHRS Railway Museum – About Us )〕 == History == The S class locomotives were built to speed up principal expresses and eliminate double-heading of these services by their A2 class 4-6-0 predecessors. Although designed for normal operation at , they were credited as being capable of . They were the final design of the VR Chief Mechanical Engineer Alfred E Smith, who had been responsible for the highly successful K class 2-8-0 and N class 2-8-2 designs and closely involved with the earlier A2 class 4-6-0, C class 2-8-0, and Dd class 4-6-0 designs.〔(AHRS Railway Museum History 1900–1950 ) – retrieved on 6 September 2006〕 The S class was VR's first three-cylinder locomotive, and A E Smith's design was influenced by Nigel Gresley's GNR A1 class 4-6-2 with its Gresley conjugated valve gear. The S class also showed American design influence in its use of a delta trailing truck and bar frames rather than plate frames. Built at Victorian Railways' Newport Workshops, the S class locomotives were, at the time of construction of the first three, the largest locomotives to have been built in Australia to date, and had the largest boilers to have yet been constructed in the southern hemisphere.〔Dunn et al., ''Super Power on the VR – Part 1'', p. 6〕 Another notable design innovation, the incorporation of all three cylinders and the smokebox saddle into a single casting,〔(【引用サイトリンク】 title=12800P1-page002013 – Public Record Office Victoria )〕 was the first of its type in the southern hemisphere and one of the largest single castings yet undertaken in Australia.〔 The S class spent its entire revenue service life on the main North East line, its axle load too high for regular service on any other VR lines. Although Annual Reports show the VR planned to upgrade the main Western line and build further S class locomotives to haul ''Overland'' services between Ararat and Serviceton, exigencies imposed by the Great Depression and World War II meant the planned upgrade of this service never eventuated. Although a numerically small class limited to a single line, the S class was highly utilised. By November 1929, the three locomotives then in service were reported as doing work would have taxed the capacity of five A2 class locomotives, yet their £53,000 ($106,000) capital cost was £2,000 ($4,000) cheaper than the five A2s and they were further saving an estimated £3,000 ($6,000) per year in comparative operating costs. By 1936 they were averaging per year with S 303 having set a record annual mileage for Victorian Railways locomotives, travelling in one year.〔(【引用サイトリンク】title=S class maintenance history cards )〕 They were also noted for running between major overhauls, compared to an average for other locomotive classes in the Victorian Railways fleet. By the time of their withdrawal from service all had travelled well in excess of a million miles, with S 302 the most travelled at over its 25 year, 2 month service life, averaging 4,773 miles (7,679 km) per month.〔Dunn et al., ''Super Power on the VR – Part 2'', p. 9〕 S 303 travelled in its service life of just 23 years, 6 months, averaging over per month.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Victorian Railways S class」の詳細全文を読む スポンサード リンク
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