NZR OA class

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NZR OA class
Oa Class steam locomotive NZR 457, 2-8-0 type. ATLIB 276929.png
Oa class 2-8-0 steam locomotive NZR number 457
Type and origin
Power type Steam
Builder Baldwin Locomotive Works
Serial number 13908
Build date 1894
 • Whyte 2-8-0
Gauge 3 ft 6 in (1,067 mm)
Driver dia. 43 in (1.092 m)
Length 51 ft 8 in (15.75 m)
Adhesive weight 33.7 long tons (34.2 t; 37.7 short tons)
Total weight 57.4 long tons (58.3 t; 64.3 short tons)
Fuel type Coal
 • Firegrate area
16.7 sq ft (1.55 m2)
Boiler pressure 180 psi (1,241 kPa)
Heating surface 1,050 sq ft (98 m2)
Cylinders four, Vauclain
High-pressure cylinder 11 in × 20 in (279 mm × 508 mm)
Low-pressure cylinder 18 in × 20 in (457 mm × 508 mm)
Performance figures
Tractive effort 13,175 lbf (58.61 kN)
Operators Wellington and Manawatu Railway, New Zealand Government Railways
Number in class 1
Numbers WMR 13
NZR 457
Locale Wellington - Longburn section
Disposition Withdrawn

The OA class is a solitary steam locomotive built by the Baldwin Locomotive Works for the Wellington and Manawatu Railway (WMR) in New Zealand. Ordered in 1894, it entered service in August of that year as No. 13 and was the first narrow gauge Vauclain compound in the world. In 1908, the WMR and its locomotive fleet were purchased by New Zealand Railways Department (NZR) and incorporated into the national rail network, and, although No. 13 bore a likeness to members of the O class, it was sufficiently different that it warranted separate classification. The designation of OA was created and it was numbered OA 457. It operated for another two decades until it was withdrawn in December 1929 in Auckland. The locomotive was known to WMR staff as "The Lady".[1]

In 1896, a locomotive similar in appearance was ordered by the WMR, No. 16. Its technical specifications were such that when it was acquired by NZR it was classified separately and became the sole member of the OC class.



  • Palmer, A.N.; Stewart, W.W. (1965). Cavalcade of New Zealand Locomotives. A H. & A W. Reed. ISBN 9780207945007.
  • Stewart, W. W. (1974). When Steam was King. A. H. & A. W. Reed Ltd. ISBN 0-589-00382-8.

External links

  • Drawing of an OA/OC class locomotive from Derek Brown

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