NZR WAB class

The NZR WAB class locomotives were steam locomotives designed, built and used by New Zealand Railways Department (NZR). 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 AB class 4-6-2 Pacific locomotive. Initially, the locomotives were separated into two classes, designated WAB for mainline work and WS for suburban work.[2]

NZR WAB class
WAB 794 on its first excursion after restoration, with the Capital Connection rolling stock, on 31 August 2003.
Type and origin
Power typeSteam
BuilderNZR Addington Workshops, Christchurch (1+1)
NZR Hillside Workshops, Dunedin (12+8)
A & G Price Limited, Thames (3+5)
Build date1939
Specifications
Configuration:
​
 • Whyte4-6-4T
Gauge3 ft 6 in (1,067 mm)
Wheel diameter54 in (1.372 m)[1]
Wheelbase33 ft 1 in (10.08 m)
Length44 ft 6 in (13.56 m)[1]
Adhesive weight41.85 long tons (42.52 t; 46.87 short tons)[1]
Loco weight74 long tons (75 t; 83 short tons)[1]
Fuel typeCoal
Fuel capacity3.0 long tons (3.0 t; 3.4 short tons)[1]
Water cap.1,700 imp gal (7,700 L; 2,000 US gal)[1]
Firebox:
 • Firegrate area		33.0 sq ft (3.07 m2)[1]
Boiler pressure200 psi (1,379 kPa)[1]
Heating surface1,050 sq ft (98 m2)[1]
Superheater:
​
 • Heating area183 sq ft (17.0 m2)[1]
CylindersTwo[1]
Cylinder size17 in × 26 in (432 mm × 660 mm)[1]
Performance figures
Maximum speed60 mph (97 km/h)
Power output1,000 bhp (750 kW)[1]
Tractive effort22,250 lbf (99.0 kN)[1]
Career
Number in class30 (16 WAB+14 WS)
Numbers687 - 798
LocaleAll of New Zealand
First run1918 - 1926
Retired1967 - 1972
Scrapped1969 - 1972
Current ownerFeilding and District Steam Rail Society (1)
DispositionScrapped, three preserved

The remaining locomotives were kept in service until the last days of steam, operating short-haul mainline freight services and fast suburban services, particularly in Auckland. WAB 794 was sold to the Ohai Railway Board in Southland for running heavy coal trains. The locomotives were progressively withdrawn in the 1960s.[2]

Introduction

The first locomotives, WS 686 and WAB 687, were built from the boilers, frames and engine units initially destined for AB 666 and AB 667. These entered service in 1917, WS 686 in Wellington and WAB 687 at Taumarunui in the central North Island. Fourteen WS 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 WS class were converted to WAB in 1932-4. Sixteen WAB class were built between 1918 and 1926: one at Addington (687), 12 at Hillside (786-795) and three at A&G Price (796-798). In about 1922 the class was introduced on Auckland (until 1930 near Britomart) to Papakura suburban services.[3] Between 1947 and 1957 11 WAB class were converted to AB class.

Preserved locomotives

Only three examples of the class remain, with two in their original form as WABs:

See also

References

Citations
  1. "Wab794 - Technical Information". Feilding and District Steam Rail Society. Retrieved 26 October 2014.
  2. Palmer & Stewart 1965, p. 106.
  3. "THE NEW W.A.B. ENGINE RECENTLY PUT INTO COMMISSION ON THE PAPAKURA LINE". www.aucklandcity.govt.nz. 10 August 1922. Retrieved 1 May 2021.
  4. Cavalcade125 1988, p. 10.

Bibliography
  • Barry, Colin; Brouwer, John; Dash, Colin; Dickenson, Peter; Shalders, Bruce (1988). Cavalcade 125. Ferrymead 125 Committee. Retrieved 22 March 2019.
  • Palmer, A. N.; Stewart, W. W. (1965). Cavalcade of New Zealand Locomotives. Wellington: A H. & A W. Reed. ISBN 978-0-207-94500-7.
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