| South Australian Railways W and Wx class | |
| Powertype: | Steam |
| Builder: | Beyer, Peacock & Co |
| Builddate: | 1877-1882 |
| Totalproduction: | 35 |
| Whytetype: | 2-6-0 |
| Driverdiameter: | 3feet |
| Weightondrivers: | 330400NaN0 |
| Locoweight: | 420000NaN0 |
| Fueltype: | Coal |
| Boilerpressure: | W: 1300NaN0 Wx: 1450NaN0 |
| Firearea: | 45square feet |
| Totalsurface: | 544square feet |
| Cylindercount: | 2 |
| Cylindersize: | 12x |
| Tractiveeffort: | 8159lbf |
| Factorofadhesion: | 4.05 |
| Operator: | South Australian Railways 1877–1929 Commonwealth Railways 1911–1950 |
| Operatorclass: | W/Wx |
| Preservedunits: | W 53 (as North Australia Railway NF5) and Wx 18 |
| Disposition: | 1 destroyed in air raid, 32 scrapped, 2 preserved |
The South Australian Railways W and Wx class was a class of 2-6-0 steam locomotives operated by the South Australian Railways. Some were used by the Commonwealth Railways in the Northern Territory and by contractors.
The W class was the second class of locomotive built to the 2-6-0 (Mogul) wheel arrangement to be supplied to the South Australian Railways (SAR) – the first being the U class, of which there were only eight. The class eventually totalled 35 in number and saw service on every SAR narrow gauge line. The locomotives were first introduced in 1878 during a period of rapid expansion of the railway system.
The class were ordered as light goods locomotives for use on the expanding South Australian Railways gauge lines, necessarily limited in size and weight by the lightweight 40 lb/yd rails used at the time.[1] The locomotives were built by Beyer, Peacock & Co. of Manchester. Early W class units were used during construction of the Central Australia Railway between Port Augusta and Quorn in 1878 before entering revenue service with SAR. During their operational career, the locomotives were used within South Australia on the isolated Eyre Peninsula Railway, in the south east on now closed lines in the Kingston, Naracoorte and Mount Gambier areas as well as the line north from Port Augusta. Many were sold or leased to contractors and they were also used by the Railways Construction Branch.[2] Several of the locomotives were sold to C&E Millar and used for construction of the Palmerston and Pine Creek Railway in the Northern Territory and would continue to work the isolated line for the remainder of their operational lives.[3]
From 1903, the SAR began to rebuild W class locomotives with upgraded boilers increased to 1450NaN0 pressure, which improved the tractive effort to 8566lbf.[1] 18 of the class were rebuilt and designated Wx class.
In 1911, administrative responsibility for the Northern Territory, including the Palmerston and Pine Creek Railway, was passed from South Australia to the Commonwealth. Five unmodified W class locomotives were transferred to Commonwealth Railways at the Parap railway workshops and designated NF class. The condition of these locomotives was such that W35 and W41 were stripped down and the parts from both used to make NF7 an operational locomotive. Commonwealth Railways purchased an additional two locomotives of the class in 1915 from private interests involved with building the Eyre Peninsula Railway.[4]
By 1929, unmodified W class units had been withdrawn from service by South Australian Railways and the majority sold for scrap. TW22 had been sold to Western Australian Government Railways in 1893 and was not withdrawn until 1958. W38, in private hands with Baxter and Saddler from 1896, was condemned in 1955. Several Wx class units were also withdrawn in 1929, but a small number endured until 1959[3] when the SAR's South-eastern Division narrow-gauge lines were converted to .
The six units converted by Commonwealth Railways to NF class were withdrawn between 1928 and 1945; three worked on the North Australia Railway operating the line during World War II. NF6 was destroyed during the first Japanese air raid on Darwin in 1942[4] while shunting munitions on the Stokes Hill jetty. The locomotive was blown into the harbour and although both driver and fireman survived, the fate of NF6 remains unknown as it has never been located.[5]
Two have been preserved: