| Driving Wheels | 4ft 6ins |
| Weight | 109 tons |
| Boiler Pressure | 200psi |
| Cylinders | Outside – 18in x 26in |
| Tractive Effort | 24,960 lbf |
40 locomotives were built in 1939 by the North British Locomotive Company and became the J class. They were built by the North British Locomotive Company as the NZR workshops were already fully employed.
They were designed to provide a mixed traffic locomotive that was more powerful than the Ab class that was capable of running on the lighter secondary lines of the New Zealand Railways (NZR) network. They also had to be equally capable of running express passenger trains on main routes.
The J class incorporated roller bearing axles, hydrostatic lubrication and twin Westinghouse brake pumps.
They had bar frames instead of plate frames and were equipped with Baker Valve-gear. The locomotives were attached to Vanderbilt tenders and were outshopped with distinctive bullet-nosed streamlining.
The first 30 of the class in service were allocated to the North Island, with the last 10 allocated to the South Island for use on the hilly section between Dunedin and Oamaru. They were immediately placed into service on the main trunk routes in both islands in order to help move wartime traffic during the Second Word War. Although used on freight trains as well, the class was well suited to high-speed running on the passenger trains of the era.
Due to the wartime conditions, the streamlining became burdensome for maintenance and the skyline casing, which was open at the top proved to be a trap for soot from the locomotive’s exhaust. After a time, the skyline casing started to be removed from some examples of the class leaving them with just the bullet nose. The design was successful enough that NZR opted to build an improved variant called the Ja class in its Hillside workshops from 1946.
This locomotive (J 1234) ran on the NZR from 1939 until 1971 after which it was stored at Dunedin until 1972 when it was purchased by the Railway Enthusiasts Society for use on its South Pacific Steam Safari tour. This was possible because the schedule of the tour was consistent with the rules of the NZR which only allowed steam locomotives to be used on delivery trips after the end of steam on the railway. The locomotive was no longer required after the tour and was sold to Mr P. Bulcher who moved the locomotive to the Museum of Transport and Technology in Auckland.
In 1988 the locomotive was sold to Ian Welch of Mainline Steam and moved to the group’s Parnell depot where it was converted to oil burning. The locomotive carries the name Joanne after the owners daughter.
It returned to the main line in 2001, and after initially being based in Auckland it was transferred to Christchurch in 2004.
In 2011 it moved to the group’s Plimmerton depot for an overhaul and returned to service in 2017.
There are two other preserved J class locomotives built by the North British Locomotive Company.
• Works number 24534 – J 1211 Gloria
• Works number 24557 – J1234
Preserved Outside Britain – By Country
Preserved British Steam Locomotives 