| 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 design was successful enough that NZR opted to build an improved variant called the JA class in its Hillside workshops from 1946.
In 1950 it became clear additional motive power was required in the North Island, but the process of dieselisation was yet to begin. Consequently, NZR chose to order 16 steam locomotives from North British to the design of the successful J class of 1939. These locomotives contained a number of differences to both the J class and Hillside Ja class locomotives. Although they were turned out with the cross-compound pump, roller bearings on the rods were limited to the connection between the connecting and driving rod, mechanical lubrication was employed.
In January 1951 the order had been made for the 16 locomotives to be coal burners, and North British regarded the order as essentially a repeat order, virtually identical to 1939 J class locomotives. In April 1951 the NZR Chief Mechanical Engineer requested the order to be changed to oil burning due to perceived long term coal shortage in New Zealand. The class 16 engines were built as oil burners, with no grate, ash pan or fire door (the only class of locomotives on the NZR to be built completely as oil burners).
A significant improvement was the incorporation of French TIA, blow down equipment which enabled rapid ejection of boiler sludge and reduced the boiler scale, enabling much faster turnaround and higher availability.
By 1956 35 (coal burning) had been built at Hillside and 16 (oil burning) by the North British Locomotive Company in Glasgow. Many of the components for the locomotives constructed at Hillside, such as the bar frames, were still sourced from North British as Hillside lacked the means to construct such a frame.
Although the first Ja class member was built in 1946, the boilers for the last ten Hillside engines plus two spare boilers were not delivered from North British until 1953. This was one of the reasons that the last member of the class was not completed at Hillside until December 1956. The last locomotive built (JA 1274) was the last steam locomotive built to operate on the NZR.
The first eleven North British locomotives (1275–1285) were based in Auckland where they were employed on most tasks. They handled almost every express train in that area for a dozen years. The other five (1286–1290) were based initially at Palmerston North before being moved to Napier in 1963.
The first member of the class was withdrawn from service in 1964 was JA 1279 which provided at least one driving wheelset to this locomotive (JA 1275) after the latter had suffered an axle fracture while passing through Mercer that year. The rest of the locomotive then became a source of spares for the J and Hillside JA class locomotives in the South Island.
This locomotive was one of the last three North British engines in service when the end of steam on the North Island occurred in 1968. After withdrawal and removal of all useful parts the three were sold to Sims Pacific Metal Industries and towed to Sims Otahuhu scrapyard. JA 1275 was the only one of the three to avoid being scrapped.
This locomotive (JA 1275) was purchased by Les Hostick in 1968 and transported to the New Zealand Railway and Locomotive Society (NZR&LS) Waikato Branch’s Te Awamutu Railway Museum where it was on static display under a rudimentary shelter until 1994.
In 1994 it was leased to Ian Welch and transferred to the Mainline Steam Heritage Trust’s Parnell depot for restoration to mainline running condition.
Work began on restoring the locomotive in 2001 and three years later it returned to running on the mainline from its base in Auckland.
In August 2017 the locomotive was given the name Julie Anne.
The locomotive is currently stored awaiting an overhaul.
There are six preserved JA class locomotives built by the the New Zealand Railway at Hillside.
• J 1240 Jessica
• J 1250 Diana
• J 1260
• J 1267
• J 1271
• J 1274
Preserved Outside Britain – By Country
Preserved British Steam Locomotives 