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The New Zealand FA class was built as a larger version of the tried and true NZR F class 0-6-0T. The requirements were for larger water and coal capacity on a locomotive that could handle grades better than the F class. Due to costs involved in producing new machines, NZR chose to rebuild existing machines with larger coal and water capacity, larger boiler and firebox, higher boiler preasure and larger diameter pistons. Seven F class engines were rebuilt between 1892 and 1897. Another seven were built new, one at Newmarket Railway Workshops in 1896 and six at Addington Workshops in 1902-03. ==Improvements== Due to longer distances being travelled, it became clear that the standard F class were unable to cope due to their limited coal and water capacity. The first twelve locomotives rebuilt to class FA between 1892 and 1895 were designed to overcome this problem. The locomotives were re-equipped with Walschaerts valve motion, new side tanks and cabs, and a larger boiler. Nominally, the extent of the changes meant that very little of these locomotives actually remained from the original.〔Millar, Sean, ''The NZR Steam Locomotive'', NZR&LS, 2011. p. 104.〕 Although they were now more powerful than the F class and were reasonably successful, the FA class was hampered like the LA 4-4-0T rebuilds in that their coal bunkers were too small. The decision was made in 1897 to extend the frames of F 9, then undergoing conversion at Addington Workshops, and fit an extended coal bunker. To accommodate this, a two-wheeled trailing truck would be added.〔Palmer, Bill and Stewart, W. W, ''Cavalcade of New Zealand Locomotives'', Reed, 1956, 1965. p. 64.〕 Initially, FA 9 was classified as an FB class locomotive to differentiate it from the 0-6-0T conversions. Once its success had been confirmed, all of the FA class locomotives were rebuilt to the FB class specifications between 1900 and 1905. Following the completion of the final conversion in 1905, all locomotives were reclassified as the FA class once more.〔Millar, p. 104.〕 Plans had existed in 1901 to rebuild further F class locomotives, but these were scrapped and in 1902-03 a further six FB class locomotives were built, numbers 315 and 372-376. These locomotives differed from the other rebuilds in having a redesigned frame and piston valves in place of the original slide valves fitted to the earlier rebuilds.〔Millar, p. 104.〕 FA 9 also differed from the standard rebuilds in that its trailing truck had outside journal boxes instead of the internal type used on the other engines. 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「NZR FA class」の詳細全文を読む スポンサード リンク
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