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The South Australian Railways 620 class is a class of 10 4-6-2 Pacific steam locomotives built in the late 1930s, designed to operate on lightly laid 60-pound lines. ==Development of the 620class == The completion of the South Australian Railways (SAR) broad gauge route between Adelaide and Port Pirie created a need for a fast, light passenger locomotive to haul this service, as well as other traffic on the lightly laid rail branch lines of the SAR. The specification included the ability to haul a train up a 1-in-45 (2.2%) grade at . Mr P.J. Shea, Chief Mechanical Engineer of the SAR designed a 140-ton Pacific type. A notable feature of the design, unique to South Australian Railways,〔(【引用サイトリンク】 title= National Railway Museum - Port Adelaide (620-class 4-6-2 locomotive No.624) )〕 was the use of Baker valve gear in lieu of the more common Walschaerts valve gear.〔(【引用サイトリンク】 title= SteamRanger Enthusiast Page - Steam Locos )〕 The first locomotive (620) was completed at the SAR workshops at the Islington Railway Workshops in 1936, with the tenth and final locomotive of the class (629) completed in 1938. Class leader No. 620 was also notable for being Australia's first streamlined locomotive, the smokebox being covered with a chromed steel grille similar to those fitted to motor cars of the period, and painted Hawthorn green with yellow stripes.〔 The press of the time described 620's appearance as 'a bit of fluff'. The remainder of the class were unstreamlined. In service, the 620 class replaced the Q and S 4-4-0 types on branchline services, where they proved quite successful. With the introduction of the more powerful and modern 520 class from 1943, these locomotives were relegated to the Willunga, Bridgewater and Tailem Bend passenger services, as well as continued service on Mallee line services (the locomotives light axle loading providing good route ability plus the "get up and go" characteristics common to large wheeled Pacific type locomotives. The 620 class was phased out in favour of Bluebird Railcars, although a spate of railcar failures in 1954–55 saw the 620 class return to service on the Port Pirie line.〔 In 1994, the 'Duke of Edinburgh' steam locomotive number 621 ran a one-off special steam hauled tour into Victoria just before the Melbourne to Adelaide mainline was converted from broad gauge rail line to a standard gauge track. This was the first ever time a South Australian Railways steam locomotive had ever worked east into Victoria and with the gauge conversion imminent the tour would also be the last. The train travelled as far east as Bacchus Marsh in Victoria, due to the locomotive being too wide for the stations situated along the Melbourne suburban railway system. The locomotive combined with Victorian Railways R Class Steam locomotive 761 for the majority of the tour from Wolseley in South Australia to Bacchus Marsh in Victoria. All but two of the locomotives were scrapped by 1969. One is preserved in working condition by SteamRanger (621) with the second (624) held in the National Railway Museum, Port Adelaide. 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「South Australian Railways 620 class」の詳細全文を読む スポンサード リンク
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