NZR UA class

The NZR UA class were a class of 4-6-0 Ten Wheeler locomotive built by the Scottish firm of Sharp Stewart and Company to ease a motive power shortage. They lived relatively short lives amongst NZR ten wheelers, mostly at the southern end of the country where they were seldom photographed.

NZR UA class
UA class 4-6-0 steam locomotive NZR number 176
Type and origin
Power typeSteam
BuilderSharp Stewart and Company, Glasgow
Build date1899
Total produced6
Specifications
Configuration:
  Whyte4-6-0
Gauge3 ft 6 in (1,067 mm)
Driver dia.49.125 in (1.248 m)
Length49 ft 3 in (15.01 m)
Loco weight38.2 long tons (38.8 tonnes; 42.8 short tons)
Tender weight24 long tons (24.4 tonnes; 26.9 short tons)
Total weight62.2 long tons (63.2 tonnes; 69.7 short tons)
Fuel typeCoal
Fuel capacity4.0 long tons (4.1 tonnes; 4.5 short tons)
Water cap1,700 imp gal (7,700 l; 2,000 US gal)
Firebox:
  Firegrate area
16 sq ft (1.5 m2)
Boiler pressure175 lbf/in2 (1,207 kPa)
Heating surface:
  Tubes
972 sq ft (90.3 m2)
CylindersTwo, outside
Cylinder size16 in × 20 in (406 mm × 508 mm)
Performance figures
Maximum speed50 mph (80 km/h)
Tractive effort14,591 lbf (64.90 kN)
Career
OperatorsNZR
Numbers172-177
LocaleOtago, Southland
Withdrawn1933-1936
DispositionWithdrawn, Scrapped
Classified U until 1902

Origin and design

As New Zealand rapidly recovered from the 1880s depression, NZR developed a motive power shortage that its own workshops could not keep up with.[1] After his 1898 annual report indicated it was "absolutely necessary" to obtain more locomotives the Locomotive Superintendent obtained permission to buy sixteen 4-6-0 locomotives, ten from Baldwin, and six from Sharp Stewart and Co. All were delivered in 1899.[1]

Unlike the Addington U class the new locomotives were of uniform appearance, with low mounted running boards and splashers over the drivers. The design was based on and very similar to the U class, differing primarily in the provision of smaller driving wheels delivering higher tractive effort. Although they used the same type of boiler they carried a higher pressure and were fitted with piston valves. Overall their appearance was similar to their predecessors.

Service

Initially three each were stationed at Invercargill and Dunedin to run express passenger services between those cities. Later the Dunedin-based engines joined their siblings in the south. The only known report from footplate men indicated that while finely built they were difficult to fire. However annual returns indicate that they ran greater annual miles and at lower cost than other 4-6-0's at the time.

Modifications included lengthening the smokebox, a common procedure on many early NZR types, and sand domes were provided, while the running boards were raised. In the 1920s either two or three (sources vary) received superheated boilers of 200 lb sq in working pressure. However, the class was gone before the end of the 1930s, the superheated boilers going to members of the UC class of the same maker. One was reportedly dumped on the Oamaru foreshore.

References

Bibliography

  • Lloyd, W. G. (1974). Register of New Zealand Railways Steam Locomotives 1863-1971 (2nd ed.). ISBN 0-9582072-1-6.
  • Palmer, A. N.; Stewart, W. W. (1965). Cavalcade of New Zealand Locomotives. Wellington: A H. & A W. Reed. ISBN 978-0-207-94500-7.
  • Millar, Sean (2011). The NZR Steam Locomotive. Wellington: New Zealand Railway and Locomotive Society. ISBN 978-0-908573-89-9.
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