The NZASM 18 Tonner 0-6-0ST of 1890 was a South African steam locomotive from the pre-Union era in Transvaal.
In 1890, the Nederlandsche-Zuid-Afrikaansche Spoorweg-Maatschappij of the Zuid-Afrikaansche Republiek (Transvaal Republic) placed six locomotives in service on construction work. Since the railway classified its locomotives according to their weight, these engines were known as 18 Tonners.
The Delagoa Bay line
To have an outlet to a harbour, a railway from Delagoa Bay in the Portuguese colony of Mozambique to Pretoria had been proposed to the Volksraad of the Zuid-Afrikaansche Republiek (ZAR) by President F.T. Burgers as far back as 1872. At that time, the Cape Government Railways had not yet begun with its inland expansion from Wellington and the Natal Government Railways had not yet been established.
The Portuguese supported the idea, since it would open a trade route from Mozambique into the interior. In 1883, Major Joachim Machado was sent to Transvaal to report on a proposed route through the Komati river and Crocodile river valleys towards the Highveld and Pretoria. The resulting agreement was for the Portuguese to construct the section from Delagoa Bay (now Maputo) to the border at Komatipoort, while the ZAR would be responsible for the continuation of the railway to Pretoria.
The Nederlandsche-Zuid-Afrikaansche Spoorweg-Maatschappij (NZASM) was established on 21 June 1887 and proposed to construct two railway lines simultaneously. One was a railway from Johannesburg to Boksburg, which became known as the Randtram line. The other was the first section of the Delagoa Bay railway from the Mozambique border, via Nelspruit to Pretoria.
The Randtram line was officially opened on 17 March 1890. The Portuguese line from Delagoa Bay had already reached the Transvaal border on 14 December 1887, but the first train from Delagoa Bay only entered Komatipoort on 1 July 1891 when the NZASM's contractors completed the bridge across the Komati river. The section from Komatipoort to Nelspruit was completed by 20 June 1892. Waterval Boven was reached on 20 June 1894 and Balmoral, near Witbank, on 20 October 1894. Here, connection was made with the section which had simultaneously been built eastwards from Pretoria.
Manufacturer
Six locomotives, built by Manning Wardle and Company, were placed in service by the NZASM in 1890 and were used mainly on construction work. Since the NZASM classified its locomotives according to their weight, they were known as .
As was often the practice at the time, the locomotives were purchased from the manufacturer and imported by agents acting on behalf of the end customer, the agent in the case of the 18 Tonners being Mynssen and Company. They were built in two batches of three and shipped from the factory between March and June 1890.
Characteristics
The locomotives had inside cylinders, arranged at an incline, with slide valves which were actuated by Stephenson valve gear through rocker shafts. The cylinders and valve gear were placed between the plate frames and hidden from view by the wheels, which were coupled with external connecting rods. Together with the Cape Town Railway & Dock’s Blackie of 1859, these were the only two-cylinder locomotives with an inside cylinder and valve gear arrangement to see service in South Africa.
There were minor differences between the locomotives of the two batches, the most notable being different footplate contours and buffer beams on the second batch. All six were equipped with capacity water tanks.
Numbering conundrum
The engine numbers on record for the 18 Tonners are a source of some confusion. They were rostered on the NZASM in the number range from 9 to 14, following on from the NZASM 10 Tonner engine numbers. The Manning Wardle works records, however, listed them as being numbered in the Delagoa Bay Railway number range from 53 to 58, following on from the engine numbers of the 10 Tonners which also served on the Delagoa Bay Railway. Furthermore, a Manning Wardle builder's picture of an 18 Tonner shows it with the Delagoa Bay Railway engine number 57.
Similarly, in the works list of the Dutch manufacturer Machinefabriek Breda in respect of the 10 Tonners, those locomotives are also recorded with Delagoa Bay Railway engine numbers 50 to 52 instead of NZASM engine numbers 6 to 8.
It appears, therefore, that the 10 Tonners and 18 Tonners entered service on, or were at least delivered to, the Delagoa Bay Railway and were only rostered on the NZASM at a later stage.