NZR UB class

The NZR UB class were a series of Ten Wheelers built by American manufacturers for New Zealand Railways (NZR) around the start of the twentieth century. Two batches were built by Baldwin in 1898 and 1901 (ten each).[1] The earlier engines had slide valves and Stephenson motion, the later had piston valves and Walschaerts valve gear, as well as a higher boiler pressure. Two additional locomotives were obtained in 1901 from ALCO, one each from Brooks and Richmond. The Brooks locomotive (#17) was heavier (30.1 long tons adhesive weight) with attendant increase in tractive effort (18340 lbf), and had a larger grate (17 sq ft). This locomotive was very popular with crews. This locomotive was dumped on the Oamaru foreshore. The Richmond locomotive had less evaporative heating surface but included a superheater. Boiler pressure was lower (180 psi) and tractive effort was marginally lower. The locomotives were initially assigned to Dunedin to Christchurch expresses and were reassigned as newer power replaced them. The last assignment for the class was on the West Coast Region.[1]

NZR UB class
A P Godber Collection, Alexander Turnbull Library
Type and origin
Power typeSteam
BuilderBaldwin Locomotive Works, Brooks Locomotive Works, Richmond Locomotive Works
Build date1898, 1901
Total produced22
Specifications
Configuration:
​
 • Whyte4-6-0
Gauge3 ft 6 in (1,067 mm)
Driver dia.49.125 in (1.248 m)
Adhesive weight26.4 long tons (26.8 tonnes; 29.6 short tons)
Total weight57.8 long tons (58.7 tonnes; 64.7 short tons)
Fuel typeCoal
Firebox:
 • Firegrate area		16 sq ft (1.5 m2)
Boiler pressure175 lbf/in2 (1,207 kPa) (1898)
200 psi (1,379 kPa) (1901)
Heating surface1,324 sq ft (123.0 m2)
CylindersTwo, outside
Cylinder size16 in × 20 in (406 mm × 508 mm)
Performance figures
Tractive effort14,590 lbf (64.90 kN) (1898)
16,670 lbf (74.15 kN) (1901)
Career
OperatorsNZR
DispositionWithdrawn

References
  1. Palmer & Stewart 1965, p. 65.

Bibliography
  • 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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