|
The New Zealand WF class were steam locomotives designed, built and used by New Zealand Railways Department. Their wheel arrangement is described by the Whyte notation 2-6-4T and the first members of the class entered service in 1904. The locomotives were tank engines designed by the Railways Department's Chief Mechanical Engineer A. L. Beattie, and were mainly built for suburban duties such as those between Christchurch and Lyttelton. They also saw main-line service in the Taranaki region, but most of the class members were assigned to branch line and local services throughout the country. Two were experimentally converted to oil burners in 1909-1910. The tests were satisfactory, but as coal was much cheaper than oil at the time, no further conversions took place. There were 41 in the class; built by Addington Workshops (10), Hillside Workshops (16), and A & G Price of Thames (15). ==Construction and Design== In 1902, a drawing was made showing a 2-6-4T tank locomotive, based on a proposal to convert the NZR V class 2-6-2 tender locomotives to tank locomotives. It was noted that the new engine, with a tractive effort of 10,260lbs was considerably less that the 12,890lbs of the slightly smaller NZR W class 2-6-2T, and that a new boiler with a greater working pressure of 140psi would be required to have made the conversion of any real use. It was considered uneconomic to fit new boilers to the old V class frames and running gear, which would have retained the obsolete Stephenson link motion and so the proposal lapsed in favour of developing the last three engines of the WA class 2-6-2T tank locomotives, nos. 50, 68, and 137. In 1903, chief draftsman G. A. Pearson designed what was to become the eventual WF class tank locomotive. The new locomotive proposed was a modestly-sized 2-6-4T tank locomotive with 45-inch driving wheels and an adhesive weight of just under 27 tons. The Walschaerts valve gear actuated inside-admission piston valves, which would later become a standard on all subsequent NZR designs. With a maximum 9.3 tons axle loading on the driving wheels, the new locomotive would have a wide radius of action. Tractive effort was calculated at 15,330lbs with a working boiler pressure of 200psi.〔McClare, Edward Jack, ''Steam Locomotives of New Zealand, Part Two: 1900-1930'', NZR&LS, Wellington, 1988. pp. 92-4. 〕 Forty-one engines of the type were built: Of the forty-one WF class locomotives built, thirty-nine were built for NZR. The other two were built by A & G Price of Thames for the Public Works Department in 1906, who allocated them numbers PWD 501 and 502. These locomotives were taken over by the NZR in 1909, and were renumbered as WF 467 and WF 468 respectively.〔McClare, p. 94.〕 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 WF class」の詳細全文を読む スポンサード リンク
|