NZR WAB class

NZR W^AB class

WAB 794 on its first excursion after restoration, with the Capital Connection rolling stock

Type and origin Power type Steam Builder NZR Addington Workshops, Christchurch (1+1) NZR Hillside Workshops, Dunedin (12+8) A & G Price Limited, Thames (3+5) Build date 1939

Specifications Configuration 4-6-4T Gauge 3 ft 6 in (1,067 mm) Wheel diameter 54 in (1.372 m) Wheelbase 33 ft 1 in (10.08 m) Length 44 ft 6 in (13.56 m) Adhesive weight 41.85 long tons (42.52 t; 46.87 short tons) Loco weight 71.5 long tons (72.6 t; 80.1 short tons) Fuel type Coal Fuel capacity 3.0 long tons (3.0 t; 3.4 short tons) Water cap 1,700 imp gal (7,700 L; 2,000 US gal) Firebox:  • Firegrate area 33.0 sq ft (3.07 m2) Boiler pressure 200 psi (1,379 kPa) Heating surface 1,050 sq ft (98 m2) Superheater: ​  • Heating area 183 sq ft (17.0 m2) Cylinders Two Cylinder size 17 in × 26 in (432 mm × 660 mm)

Performance figures Maximum speed 60 mph (97 km/h) Power output 1,000 bhp (750 kW) Tractive effort 22,250 lbf (99.0 kN)

Career Number in class 30 (16 WAB+14 WS) Numbers 687 - 798 Locale All of New Zealand First run 1918 - 1926 Retired 1967 - 1972 Scrapped 1969 - 1972 Current owner Feilding and District Steam Rail Society (1) Disposition Three preserved, remainders scrapped

The W^AB class locomotives were steam locomotives designed, built and used by New Zealand Railways Department. Their wheel arrangement is described by the Whyte notation 4-6-4T. The locomotives were designed by NZR chief draughtsman S.H. Jenkinson as tank versions of the A^B class 4-6-2 Pacific locomotive. Initially, the locomotives were separated into two classes, designated W^AB for mainline work and W^S for suburban work.

The first locomotives, W^S 686 and W^AB 687, were built from the boilers, frames and engine units initially destined for A^B 666 and A^B 667. These entered service in 1917, W^S 686 in Wellington and W^AB 687 at Taumarunui in the central North Island. Fourteen W^S class locomotives were built between 1917 and 1925: one at Addington workshops (686), five at A & G Price Ltd, Thames (799-803) and eight at Hillside workshops, Dunedin (764-771). All the W^S class were converted to W^AB in 1932-4. Sixteen W^AB class were built between 1918 and 1926: one at Addington (687), 12 at Hillside (786-795) and three at A&G Price (796-798). Between 1947 and 1957 11 W^AB class were converted to A^B class.

The remaining locomotives were kept in service until the last days of steam, operating short-haul main line freight services and fast suburban services, particularly in Auckland. W^AB 794 was sold to the Ohai Railway Board in Southland for running heavy coal trains.

The locomotives were progressively withdrawn in the 1960s.

Only three examples of the class remain, with two in their original form as W^ABs.

W^AB 794 is preserved at Feilding, and has been used on main line excursions and also on the regular Wellington - Auckland Overlander service.