NZR UD class
Ud Class no 464 between 1909 and 1929
Type and origin
Power typeSteam
BuilderBaldwin Locomotive Works
Build date1904
Total produced2
Specifications
Configuration:
​
 • Whyte4-6-0
Gauge3 ft 6 in (1,067 mm)
Driver dia.58 in (1,473 mm)
Adhesive weight29.2 long tons (29.7 t; 32.7 short tons)[1]
Loco weight39.5 long tons (40.1 t; 44.2 short tons)
Tender weight27.4 long tons (27.8 t; 30.7 short tons)
Fuel typeCoal
Water cap.2,400 imp gal (11,000 L; 2,900 US gal)
Tender cap.5 long tons (5.1 t; 5.6 short tons)
Firebox:​
 • Grate area16.5 sq ft (1.53 m2)
Boiler pressure185 psi (1,276 kPa)
Heating surface1,095 sq ft (101.7 m2)
Cylinders2
Cylinder size16.5 in × 22 in (419 mm × 559 mm)
Valve gearStephenson
Performance figures
Tractive effort15,280 lbf (68.0 kN)
Career
Number in class2
Retired1929

The NZR UD class was a class of two 4-6-0 steam locomotives built by the Baldwin Locomotive Works in 1904 for the Wellington and Manawatu Railway Company. When that company was nationalised in 1908, they passed into the ownership of the New Zealand Railways and received the designation UD.[2]

Introduction

The two locomotives were the final new motive power ordered by the independent Wellington and Manawatu Railway Company.[2]

Specification

Weighing 39.5 long tons (40.1 t; 44.2 short tons) with a tender of 27.4 long tons (27.8 t; 30.7 short tons), they could haul express trains easily at 50 miles per hour (80 km/h) on track that was flat or only a light grade. The 58 inches (1,473 mm) coupled driving wheels were large for the period, [2] and were the largest to run in New Zealand.[3][4] Their working steam pressure was 185 pounds per square inch (1,276 kPa), and they had 16.5 inches (419 mm) diameter cylinders with 22 inches (559 mm) piston strokes.

The handsome UD locomotives were more than capable of making up lost time, with mile-a-minute runs recalled with pride by Manawatu railway employees.[2] Due to their power, the locomotives were capable of hauling mail trains without the need for a banking locomotive from Paekakariki south to Pukerua Bay,[5] and were used principally on mail trains north of Paekakariki.[3]

Withdrawal

Although they were fast and powerful, the UD locomotives were unable to survive a programme of standardisation undertaken between 1925 and 1935 to eliminate small locomotive classes that were costly to maintain in favour of large, homogeneous types that provided economies of scale. They were written off in 1929.

References

Citations

Bibliography

  • Cassells, KR (Ken) (1994). Uncommon Carrier - The History of the Wellington & Manawatu Railway Company, 1882-1908. New Zealand Railway and Locomotive Society. ISBN 0908573634.
  • Hoy, Douglas (1972). West of the Tararuas: An Illustrated History of the Wellington and Manawatu Railway Co. Dunedin: Southern Press.
  • Millar, Sean (2011). The NZR Steam Locomotive. Wellington: New Zealand Railway and Locomotive Society. ISBN 978-0-908573-89-9.
  • Palmer, A. N.; Stewart, W. W. (1965). Cavalcade of New Zealand Locomotives. Wellington: A H. & A W. Reed. ISBN 978-0-207-94500-7.
  • Stewart, W. W. (1974). When Steam was King. Wellington: A. H. & A. W. Reed Ltd. ISBN 978-0-589-00382-1.
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