4-8-2 Steam Locomotives in New Zealand

Class J/Ja, Jb (Locobase 2486)

See also

North British works numbers were 24523-24562 in 1939.

Some of the first 40 engines (all from North British and shipped 12,000 miles by sea after World War II had begun) were delivered with streamlining, a cosmetic adornment only given that these engines ran on 53-56-lb rail and were normally limited to 55 mph. The Westconn Manifest, published by Western Connecticut chapter of the NRHS, says in its January 2005 issue ([] , accessed 22 January 2007), that the JA's streamlining was based on the New Haven's I-5 4-6-4s.

They had 4" (102 mm) bar frames, high-tensile-strength steel alloy main and side rods to reduce weight. Tonnage ratings were 400-ton passenger trains or 800-ton freight trains (OS Nock (RWC VI, pl 107) says 1,000 tons for freights.).

Ja engines (35 built at Hillside) were the principal engines on South Island; they had roller bearings that produced, says The "Steam Incas" website ([]), "...a very friction-free and quiet-running engine requiring the minimum of greasing and preparation time"

Jb (16 of the original 40) were oil-fired and used near Auckland on the North Island. These engines--1200, 1203, 1205-1206, 1213, 1218, 1224, 1228-1230, 1233, 1239--occasionally reached 70 mphv(113 kph).

The Steam Incas say further: "...they were to prove to be a very free-running and generally trouble-free locomotive capable of further refinement in later years. They were intended to provide more powerful locomotives for use on those routes laid with lighter track that would not carry the much heavier Ka." In describing the popularity of the surviving J1234 with railfans, the website notes: "Like most of the J and Ja classes it ...has that typical ability to whip a train into frantic activity when accelerating away from a stop."

Class X (Locobase 5195)

Data from John Garner's comprehensive site at [] ... (October 2002; last accessed 28 June 2025), supplemented by diagrams supplied by NZR's general manager T Ronayne in "Locomotive Building in New Zealand", Railway Engineer, Volume 34, No 6 (June 1913), pp. 183-186; and "NZR X class" in Wikipedia at [], last accessed 28 June 2025. See also Will Lawson, "New Zealand's Mountain Railways", Railway Magazine, Volume 26, (August 1909), pp. 120-129. Works numbers were 94-95 in 1908, 96-101 in 1909, 152-153 in 1913, 154-160 in 1914, 161 in 1915.

NZR's Chief Mechanical Engineer AM Beattie designed these large de Glehn compounds to provide passenger power in the North Island's central region, an area of tough grades. Their boiler pressures were set to 250 psi (17.25 bar), the highest of any New Zealand locomotive with an orthodox boiler. Built at the Addington shops, these might have been the very first "Mountains" built anywhere, Garner suggested.

Will Lawson's 1909 report noted the cape gauge and loading gauge restraints combined to initially confine the class to the Taumarunui to Taihape section of 70-lb/yard (35 kg/m) rail. Only later did the NZL update track weights from 53 lb/yard (26.5 kg/m). He highlighted the 50 tons of adhesion and "30,000 lbs" of tractive effort and stated that "with the design and construction of this engine," New Zealand had "taken a stride which brings her narrow gauge on almost level terms with the standard one."

Although Lawson felt the wide firebox might induce a rolling motion at high speeds, he admitted that X-class locomotives rarely exceed 30 mph (48 kph), its "business being to pull a heavy train up the hills at a fair pace."

[] (16 May 2003; link no longer active) featured a long post from Derek Brown dated Wed Jan 3, 2001 6:51 pm on this design:

"...They were a hybrid De Glehn with divided drive & Walschaerts's [sic] valve gear. They had two reversing levers, one for the inside HP valve gear, the other for the outside LP valve gear. Brown says they were "... a low speed machine (30 mph [48 kph] max), but had heaps of power. The Firemen hated them because the front section of grate area sloped down between the 3rd & 4th axles, & this section had to be kept clear of green fuel or else steaming would become inhibited."

One of RE's diagrams clearly shows the de Glehn layout from overhead. The two HP cylinders lay between the frames and under the smokebox. They had very short rods driving on the lead axle. Outside of the frames, behind, and just clear of overlapping the HP cylinders were the two LP cylinders, which turned the second set of drivers. Loading gauge limitations may have led A L Beattie to adopt unusually square cylinder diameter/cylinder stroke for the low-pressure cylinders' dimensions.

The NZR rebuilt eleven were rebuilt from June 1943 to May 1951 as four-cylinder simple superheated engines; see Locobase 5196. Engines 441, 445, 589-590, 595-597 retained their compound gear 445 and 489 left in May-June 1949 while the other two joined twelve others in a bloc retirement on 2 March 1957

Class X - rebuilt (Locobase 5196)

Data from John Garner's comprehensive site at [] ... (October 2002; last accessed at [] 28 June 2025). Works numbers were 94-95 in 1908, 96-101 in 1909, 152-153 in 1913, 154-160 in 1914, and 161 in 1915.

AM Beattie designed these de Glehn-type four-cylinder compound X-class Mountains (Locobase 5195) for use on the mountainous section of the North Island main line . NZR-Hutt made over ten and Hillside modified two more. Simpling the four cylinders was one thing, but the rebuild also seems to have reduced the boiler dimensions considerably if Garner's figures are correct.

In the 1940s on, the NZR converted eleven Xs to four-cylinder simple machines, using the original cylinder castings with the LP cylinders sleeved down in diameter; boilers were superheated; some boilers were fitted with two Nicholson thermic syphons. Air operated power reverse was also fitted."

[] (16 May 2003; no longer active) offered a long post from Derek Brown dated Wed Jan 3, 2001 6:51 pm on this design.

After discussing the compound X, Brown continuesd: "I knew this class of loco intimately, they rode well, pulled well, & Fireman (I was one), still hated them, probably even more than when they were compounds. They were a mobile work house because the bunker was not of the self trimming type, therefore the poor old Fireman spent a lot of time heaving coal from the back of the bunker to the front, & from the front into the firebox. It was a rare occasion to pass a water tank without stopping, their appetite for water was out of this world."

After his extended dissection of the design's shortcomings, however, Brown concludes: "To sum up, it is believed that in spite of their faults these locos were a success - they did what they were designed to do - to haul heavy trains over our mountainous central section."

The Ohai Railway Board, a private Southland coal company operating between Ohai and Wairio bought two of the rebuilds. 442 left the NZR in March 1944 and served the ORB until 1968. Leased by the New Zealand Railway Locomotive Society, it went to the Feilding & District Steam Rail Society for restoration.

446 followed in December 1946. It left the ORB roster by 1960.

NZR retired all but four en bloc on 2 March 1957.