4-6-4 Steam Locomotives in New Zealand

Class Wab (Locobase 2490)

Data from John Garner's comprehensive site at [] ... (October 2002; last accessed 26 June 2025). See also "New Superheater Tank Engine No. 686, New Zealand Gov't Rys", Locomotive Magazine, Volume 24, No. 312 (15 August 1918). Works numbers (NZR Addington) 214 in 1918

(NZR Hillside) 223 in 1923, 232 in 1924

A G Price 113-117 in 1926, 118-120 in 1927.

Basically a tank-engine variant of the Ab Pacifics (Locobase 2489) designed by the NZR's chief mechanical engineer H H Jackson, these were used in suburban commuting service in Auckland and Wellington. Some also operated between Taihape and Taumarunui on the North Island. Others were used in short-haul mainline service on the South Island between Dunedin and Oamaru, where the grade could reach 2%.

In addition to the large side tanks, the boiler had an extra sand dome for more sanding capacity. As the tank engines were replaced by larger 4-8-2 tender engines, those on the South Island were converted to 4-6-2 Abs.

One preserved engine -- 794 -- racked up 837,400 miles in demanding service before it was retired.

Class We (Locobase 5189)

Data from John Garner's comprehensive site at [] ... (October 2002; last accessed 10 June 2025). See also "NZR WE class" in Wikipedia at [], last accessed 10 June 2025.)

These three tanks were rebuilt from Sharp, Stewart-built B-class 4-8-0s (Locobase 9568) for helper service over the Rimutaka Incline between Upper Hutt and Cross Creek. Long water tanks flanked the boiler; ahead of the first axle, a cut-out exposed the outside radial constant-lead gear. A center-rail brake provided added grip on the downgrades. Wikipedia notes the makeover couldn't deal with the 6 1/4% grade satisfactorily,

According to Garner, after 1908, one We moved to the Greymouth-Rewanui branch on the West Coast to tackle the 4% grade. Its success prompted the transfer of the other two.

Defying the odds, the trio remained on the NZR roster for another 50+ years.

Class Wg (Locobase 5191)

Data from John Garner's comprehensive site at [] ... (October 2002). supplemented by diagrams supplied by NZR's general manager T Ronayne in "Locomotive Building in New Zealand", Railway Engineer, Volume 34, No 5 (May 1913), pp. 183-186. Works numbers were 102, 103-108, 112 in 1910, 109-111, 113 in 1911, and 114-121 in 1912.

Handsome follow-ons to the Wf 2-6-4Ts (Locobase 5910), all from Hillside. These were slightly larger, but more important, they put more than 6,000 additional pounds (2,772 kg) on the drivers. CME Alfred Luther Beattie, usually referred to as AL described the result simply as the "Large Tank Locomotive."

Again the size and arrangement proved quite useful throughout the NZR system and these engines served for years as both commuter locomotives and mail-train engines.

Class Wg-suoerheated (Locobase 20576)

Data from "New Engines for the New Zealand Government Rys", Locomotive Magazine, Volume XXIII [23] (15 February 1917), p. 20.

Locobase 5191 shows the original Wg class engines with saturated boilers. Note the substantial proportion of total heating surface area devoted to superheating. 32% tops almost all installations regardless of size.

Yet it was not alone in offering such a large percentage among narrow-gauge locomotives. When a small boiler exchanged small tubes for large flues, even a minimum number of flues would require rermoving more of the original small tubes. (Moreover, Robinson's variant claimed more area than the Schmidt layout.)

During a long period of service, all but six of the class eventually underwent updates that mirrored the Ww design and they joined that class during World War II. See Locobase 5193.

Class Ws/Wab (Locobase 5192)

Data from John Garner's comprehensive site at [] ... (October 2002; last accessed 10 June 2025). Addington works number was 213 in 1917. Hillside works numbers were 224-227 in 1923, 228-231 in 1924. In 1926, Price added works numbers 116-117 in 1926 and 118-120 in 1927.

Like the 1917 Wabs (Locobase 2490), these were also tank-engine variants of the Ab Pacifics (Locobase 2489), but designed from the outset for suburban service. Note the difference in superheat. The class was later (1932-1933) redesignated Wab and grouped with the others.

Class Ww/"Bobtails" (Locobase 5193)

Data from John Garner's comprehensive site at [] ... (October 2002; last updated 24 June 2025); and "NZR WW class" in Wikipedia at [], last accessed 13 June 2024. See also Glenbrook Vintage Railway's 22 August 2016 Facebook entry at [], last accessed 24 June 2025.

Including the fourteen Wgs, NZR Hillside built 48 of the 51. Works numbers were 132-141 in 1913, 142-151 in 1914, 173-182 in 1915, 193-201 in 1916, 202-204, 207-208 in 1917, 209-212 in 1919.

Essentially superheated Wg (Locoabase 5191) engines, these had the usual differences of larger pistons supplied through piston valves and lower boiler pressure. Wikipedia's production summary includes the 50 built new at the NZR's Hillside shops in 1913-1919. Placed originally in the Wg class, the first 20 soon acquired their own class ID, the second "w" connoting commuter service around Wellington. The other 30 completed the Ww class. Fourteen Wg joined the Wws in 1942 and 1952.

Garner reported that all but three of the Ww operated on the North Island. They served Wellington and Auckland suburban traffic, some main-line and branch-line runs as well as heading up coal trains.

Twelve Wws--571, 573-575, 644, 669, 672, 678-680, 683-684--were fitted with new higher-pitched boilers that offered 100 sq ft (9.3 sq m) more heating surface area.

The Glenbrook Vintage Railway reported that RCR Energy's shops in Dannevirke completed manufacture of new boilers for both of their Wws in 2016. 480 reentered service in 2018.

644, the GVR's other Ww,, took a bit longer, but gained National Rail Network Certified status in 2022.As of 2025, the 644 ran on the National Rail Network for the first time in 50 years.