| Weight | 19t |
| Driving Wheels | 3ft 3 in |
| Boiler Pressure | W 130psi Wx 145psi |
| Cylinders | Two Outside – 12in x 20in |
| Tractive Effort | W 8,159lbf Wx 8,566lbf |
This locomotive was built by Beyer Peacock at Gorton, Manchester in 1879 as one of 35 supplied to the South Australian Railways (SAR) which became the W class. They were designed as light goods engines which were capable of operating on the 40lb/yd rails in use on the SAR.
The locomotives of the W class were supplied between 1877 and 1882 and those delivered at the start of this period were employed on the construction of the Central Australia Railway between Port Augusta and Quorn in 1878 prior to 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. 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.
From 1903, the SAR began to rebuild W class locomotives with upgraded boilers. This allowed for an increase in boiler pressure and an improved tractive effort. 18 locomotives were rebuilt in this way including this locomotive Wx 18 in 1911.
In 1911, South Australia handed administrative responsibility for the Northern Territory, including the Palmerston and Pine Creek Railway to the Commonwealth Railways. Five unmodified W class locomotives were transferred to Commonwealth Railways at the Parap Railway Workshops and designated NF class.
One of these NF class locomotives (Beyer Peacock works number 1721) was destroyed in a Japanese air raid on Darwin during the Second World War. It was believe the locomotive was blown into the harbour but it has never been found.
By 1929 the unmodified W class locomotives had been withdrawn from service as well as a number of the Wx engines. Some of the Wx class locomotives survived until 1959 when the south eastern narrow gauge lines were converted to 5 ft 3 in.
In March 1959 Wx 18 hauled the last narrow gauge (3ft 6in) goods train on the Kingston – Naracoorte line. It was then placed on a plinth in Pioneer Park in Naracoorte until it was acquired by the Pichi Richi Railway in July 1985 and moved to Quorn for restoration.
The locomotive has been dismantled but restoration appears to have stalled and it remained dismantled many years later.
One W class locomotive built by Beyer Peacock for the South Australian Railways and subsequently operated on the Commonwealth Railways has been preserved.
- Commonwealth Railways NF 5 – Works number 1717
ed Outside Britain – By Country
Preserved British Steam Locomotives 