| NZR JA class | |
| Powertype: | Steam |
| Builddate: | 1946–1956 |
| Builder: | NZR Hillside Workshops (35) North British Locomotive Company (16) |
| Locoweight: | 69.1LT |
| Tenderweight: | 40.35LT |
| Locotenderweight: | 109.45LT |
| Whytetype: | 4-8-2 |
| Firstrundate: | 1947 – 1956 (Hillside) 1952 (North British) |
| Lastrundate: | 16 November 1971 |
| Disposition: | Seven preserved, remainder scrapped |
| Numinclass: | 51 |
| Weightondrivers: | 44.45LT |
| Wheelbase: | 34feet |
| Boilerpressure: | 200psi |
| Feedwaterheater: | None: Fitted with Davies & Metcalfe Exhaust Injector |
| Wheeldiameter: | 543NaN3 |
| Cylindercount: | Two |
| Cylindersize: | 18x |
| Valvegear: | Baker |
| Tractiveeffort: | 24960lbf |
| Maxspeed: | 75mph |
| Retiredate: | 1967–1971 |
| Scrapdate: | 1969–1972 |
| Locale: | All of New Zealand |
| Fleetnumbers: | 1240 – 1274 (Hillside) 1275 – 1290 (North British) |
| Length: | 66feet |
| Fueltype: | Coal (Hillside) Oil (North British) |
| Fuelcap: | 6LT coal 1350impgal oil |
| Watercap: | 4000impgal |
| Firearea: | 39square feet |
| Totalsurface: | 1469square feet |
| Superheaterarea: | 283square feet |
The NZR JA class was a class of fifty-one 4-8-2 steam locomotives operated by the New Zealand Railways Department (NZR). The locomotives were built in two batches; the first batch was constructed in-home at the Hillside Workshops at Dunedin between 1946 and 1956, while the second batch was produced by the North British Locomotive Company (NBL) of Glasgow, Scotland in 1951. To differentiate between the two batches, the locomotives were identified by their builder.
The JA class was the last steam locomotive class to be produced by the NZR, with the Hillside-built JA 1274 being the final steam locomotive ever built. The North British JAs were also the last steam locomotives imported for the NZR.
The JA class had relatively short service lives of between 12 and 24 years as they were replaced by diesel locomotives as part of the dieselisation process of the NZR. Nine JAs managed to last until the end of steam on 26 October 1971.
The class was an improved version of the J class locomotives. Unlike the J class, which were built overseas by the North British (NBL), the new locomotives were instead constructed by the NZR's Hillside Workshops in Dunedin. Much of the components, such as the bar frames, were still sourced from NBL as the Hillside lacked the means to construct such components.
In most other respects, the class was virtually identical to the earlier J class, except for being fitted with a bullet-nose streamlining. In mechanical respects, the JAs class had some notable improvements from the J class. These include the use of the Westinghouse cross-compound pump, Ashton double pressure gauge, the Sellars injector in the cab, and combined gauges in the cab. Instead of taking steam for the pump from the outlet on the steam dome, these were collected from the manifold in the cab. Except for the first two JAs to be produced, No. 1242 and 1243, the locomotives were fitted with roller bearings to their driving and connecting rods. On the rest of the locomotives numbered in the 124X range, roller bearings were only present at the connection between the driving and connecting rods.
The first of the JA class was constructed in 1946, but it was not until 1953 that the last ten Hillside JA boilers and two spare boilers were delivered by NBL.[1] For this and several other factors, the last member of the class was not turned out from the workshops until December 1956. That last locomotive, JA 1274, turned out to be the last steam locomotive constructed for and by the NZR.
The JA class was intended for fast passenger trains in the South Island before the introduction of 88-seater railcars in 1956 and the decline in long-distance rail passenger services. Thus the class only ever worked in the South Island during their NZR career. The first members were based out of Dunedin, despite being intended for allocation to Christchurch. Over time, enough of the class were in service to displace the 10 members of the J class based out of Dunedin, which then headed north to join the rest of their class members on the North Island.
The JAs were mainly used for both express passenger and express freight services running from Invercargill to Christchurch. During their brief prime on the South Island Main Trunk, they extended their duties from Bluff to Parnassus in the north, and as far west as Arthur's Pass on the Midland Line. Before the full delivery of the JA class, English Electric diesel locomotives had already taken over the main freight services and summer express on the Dunedin-Oamaru section. The class was also restricted from running on long branch lines like the Otago Central Railway or Kingston Branch for being too large.
Despite some restrictions, the JAs remained the mainstay of the South Island network. They proved to be excellent when hauling the South Island Limited between Invercargill and Christchurch. All of the roller-bearing equipped JA locomotives, Nos. 1265-1270 were allocated to the Linwood locomotive depot in Christchurch and were used to haul this service wherever possible between 1952 and 1968. Of these locomotives, the fastest was JA 1270 (scrapped in mid-1969). They were particularly efficient on the relatively flat Invercargill-Dunedin section, as well as the fast run across the Canterbury Plains between Christchurch and Oamaru. The evening run back on train 144 to Christchurch was well known for being speedy, especially when the train was running late and racing to get to the Lyttelton-Wellington Ferry before its sailing.[2]
Although the official passenger train speed limit in New Zealand in that era was 50mph, the class was known to operate at higher speeds, especially across the Canterbury Plains, where they were officially allowed to run at 55mph. For instance, JA 1267 pulled ten carriages weighing 300 tons and covered the 42miles from Tinwald to Washdyke at 59.4mph.
According to anecdotal accounts around the performance of the JAs on the South Island Limited during the late 1960s, the speedometer was reading over 75mph, and the train was moving away rapidly from the traffic on State Highway 1 adjacent to the railway. Rail writer David Leitch believed that the drivers' accounts of 85mph running were accurate.[3] Additional support comes from an official source, the 1966 Encyclopaedia of New Zealand, which states that "The speedy and graceful "JA" has demonstrated its remarkable performance in express service on the level plains of Canterbury, and on occasions has attained speeds in excess of 70 miles an hour."[4] The official NZR speed record of 125.5km/h was set by a Vulcan RM class railcar on a delivery trial run in 1940.
The JA 1249 and 1272 were the first of their class and were not withdrawn until March 1968, in contrast to their J, JB, and North British JA cousins. Twelve JAs, in addition to four Js, were fully overhauled in 1966. These were followed by six more in 1967 and two in 1968.[5]
The use of steam locomotives on freight trains on the East Coast of the South Island ended in March 1969. 15 JAs and three Js (rebuilt with North Island JA tenders and trailing engine bogies) remained operational.
The NZR provided a full overhaul on the last JA 1267 in November 1968 with extensive use of parts from JA 1268, including fitting a different boiler. JA 1273 and 1274 had their low mileage boilers transferred to other class members in 1967-68,[6] and continued in service until 1971 with older boilers. The last three Js and these locomotives were frequently used on the South Island Limited in 1968 and 1969, on train 143 out of Christchurch and train 144 return of the Oamaru-Christchurch leg, providing one of the last high-speed steam-hauled passenger services in the world. They continued in that role until November 1970, when diesel-hauled Southerner replaced them.
It was also planned to dieselise the overnight Friday and Sunday express with surplus steam heat vans when the North Island Limited was replaced by the Silver Star, but delayed arrival of the carriages from Japan by a year meant that steam heat vans, which allowed diesel to operate night trains, would not be available until late 1971. Thus the JAs remained ready for service into November, but in the end, were never called upon.
Some locomotives like JA 1271 were often sidelined due to mechanical defects or repairs. These locomotives were commonly used as stationary boilers and stripped of parts to keep the rest of the fleet operational, as was common practice at the time.
It was evident in 1950 that additional motive power was required in the North Island, but dieselisation had not yet begun. Consequently, the NZR decided to order new locomotives from NBL to the design of the successful J class of 1939.
In January 1951, the order was placed for 16 JA class locomotives as coal burners, which made NBL regard it as essentially a repeat order for the J class. In April of the same year, the NZR Chief Mechanical Engineer requested the order be changed to oil-burning due to the perceived long-term coal shortage caused by the 1951 New Zealand waterfront dispute. The associated strike by miners, unavailability of shipping for coal, the expected long-term high imported coal price, and the long time it would take to build up coal stocks to safe levels were the main reasons for the change.[7] [8] [9] The locomotives were eventually completed with oil burning equipment, with no grate, ash pan, or fire door, making them the only locomotives on the NZR to be built entirely as oil burners.
These engines had several differences from both the J class and the Hillside JA class. They were manufactured with the cross-compound pump and had roller bearings limited at the connection between the driving and connecting rods, while mechanical lubrication was employed.
ACFL blowdown was incorporated late in their construction. A significant improvement was made with the incorporation of French TIA, blowdown equipment which enabled rapid ejection of boiler sludge, reduced boiler scale, and enabled much faster turnaround and higher availability. The system of injection of the oil flow into the burners was different and far more effective than in 1948–1950 conversion of 12 J class locomotives to oil burning.
Other detail differences were the use of Stone's headlights and electrical generator instead of the usual Pyle National equipment, the "Butterfly" number boards on the front headlight, and the absence of a smokebox number plate (although a smokebox plate was specified by the NZR).
The North British JAs were constrained to the North Island and were mostly used on routes that were commonly worked by oil-burning locomotives. Described by the author Stewart as "fine clean-lined machines", they handled almost every express train in that region for about twelve years.
The first eleven locomotives, JA 1275–1285, were based in Auckland, while the other five, JA 1286–1290, were initially based at Palmerston North before being moved to Napier in 1963.
The Auckland-based locomotives were regarded as specialised express engines and were more impressive performers than the KA class locomotives by most Auckland engine drivers. They were regularly assigned to the North Auckland Line (NAL), the Opua Express until 1959, the Helensville local until 1966, and the North Island Main Trunk (NIMT) services, such as the Auckland–Wellington, 227/626 Express Mail train, and faster Night Limited, and Auckland–Wellington express goods train 627. There are accounts of them being used elsewhere. For instance, there are surviving accounts of JA 1279 running on the Waiuku Branch in the early 1960s, and later on the Raetihi Branch during the same decade after coal-fired AB 700 caused several lineside fires. When working with other 4-8-2s on the NAL, they were required to have a bogie wagon such as a UB flat wagon between them to distribute weight more evenly on the light bridges along that line.
The five Palmerston North-based engines, by contrast, were less frequently assigned to the NIMT trains. Instead, they ran over the Marton - New Plymouth Line to Wanganui and the Palmerston North - Gisborne Line as far as Gisborne. By comparison, the Palmerston North-based JAs spent more time working freight trains, particularly with the arrival of the 88-seater railcars.
The rest of the steam fleet, excluding the J and JB classes, experienced increased mechanical failures and repair costs while moving the heavier post-war traffic on the NIMT. By 1955, the K and X classes of 4-8-2 locomotives were worn out. The 9 K class was rebuilt with KA frames in 1955–57 since it was unacceptable to write off the K class locomotives and retain useful Baldwin AA. The superiority of the DA class diesels and JAs meant that an A-grade overhaul for a K class member in 1961 turned out to be the last such work for that class.
An analysis done in 1959 found that the North British JA matched the availability of the new DA class, with each JA available for 252 days a year on the North Island. The cost per mile for the JA was much higher, with the locomotives achieving 82% of the DA class' mileage.
After the start of dieselisation in the 1960s, the locomotives were transferred to Frankton Junction. Although JA 1286 was briefly transferred to Auckland in the mid-1960s, it was felt that it did not perform as well as the eleven Auckland-based locomotives and was quickly reallocated to Frankton. After this, the locomotives were mostly assigned to the old East Coast Main Trunk Railway between Hamilton, Tauranga, and Taneatua, again largely on freight trains due to the reduction of passenger services from Taneatua to Te Puke, which was by then handled by the 88-seater railcars.
Although being a relatively young class, some of the North British JA members were among the first of the J types to be withdrawn. In 1964, JA 1279 was the first of the class to be withdrawn and sent to Hillside Workshops without at least one driving wheelset, which was taken to repair JA 1275 after it suffered an axle fracture while passing through Mercer that year. The rest of the locomotive became a source of spare parts for the J and Hillside JA class locomotives in the South Island. The oil-fired boiler was converted to coal-firing before being fitted to Greymouth-based J 1212 during a C-grade overhaul.
As the locomotives were withdrawn, most of them were stripped of parts to keep the South Island J and Hillside JA class locomotives running, along with the remaining North British JAs which, by then, were based out of Frankton Junction.
In November 1966, tenders from JA 1287, 1288, and 1290, which were in relatively good condition, were transferred south. They were rebuilt to accommodate a coal bunker in place of the fuel oil tank and coupled to J-class locomotives whose original 1939-built tenders were life-expired. Other surplus North Island JA parts were also refitted, including the trailing trucks, and approval was given to fit the JA 1288's boiler. Most of the North Island JA was withdrawn too late in 1967 or early 1968 to be reprocessed, as A-grade South Island J overhauls had ceased with dieselisation. JA 1281's boiler was refitted to J 1236 in an A-grade Hillside overhaul in 1967, with the firebox converted from oil to coal burning, but with all the oil firing fittings left in place, making it easier for restoration and reconversion to oil burning in 1991-2001 for rail excursions.[10]
The boiler of JA 1278 was withdrawn in March 1968 and installed that year in a C-grade overhaul of JA 1252 in Dunedin.[11]
Only three of the North British JA class managed to reach the end of North Island steam in 1968, JA 1275 being one of them. After the withdrawal and removal of all useful parts, the North British JAs were sold to Sims Pacific Metal Industries and towed to Sims Otahuhu scrapyard, adjacent to the Otahuhu Workshops, for scrapping. JA 1275 was the only locomotive to avoid this fate.
Six of the Hillside JAs survived to be preserved; by contrast, only one North British JA remains. Additionally, two preserved J-class locomotives have North British JA tenders.