NZR AA class

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NZR AA class
Aa class steam locomotive (NZR number 650, 4-6-2) ATLIB 257167.png
No. 650 at Petone between 1915 and 1920
Type and origin
Power typeSteam
Builder Baldwin Locomotive Works
Build date1915
Total produced10
Specifications
Configuration:
   Whyte 4-6-2
Gauge 3 ft 6 in (1,067 mm)
Driver dia.49 in (1.245 m)
Length34 ft 9 in (10.59 m)
Adhesive weight 34 long tons 14 cwt (77,700 lb or 35.3 t)
34  long tons 14  cwt (35.3  t; 38.9 short tons)
Total weight88.5 long tons (89.9 tonnes; 99.1 short tons)
Fuel type Coal
Firebox:
  Firegrate area
28.3 sq ft (2.63 m2)
Boiler pressure170 psi (1.17 MPa) (as coumpound)
Heating surface1,465 sq ft (136.1 m2)
Cylinders 2
Cylinder size 18 in × 24 in (457 mm × 610 mm)
Performance figures
Tractive effort 21,580 lbf (96.0 kN)
Career
Operators NZGR
Numbers648 - 647
Withdrawn1955–1957
DispositionAll scrapped

The NZR AA class consisted of ten steam locomotives built by Baldwin Locomotive Works in 1914 to an order by Chief Mechanical Engineer, H. H. Jackson for operation on New Zealand's national rail network.

Contents

Introduction and design

Built to a similar but vastly improved design to the Q class of 1901, they had a wheel arrangement of 4-6-2 and were suited to hauling freight services in the North Island (Originally they were to be classed QB but as they were to supplement the A class, given their aforementioned designation.) The United States built locomotives were an urgent order needed due to heavy demand with both New Zealand and British workshops unable to supply as the First World War was draining resources and manpower for the war effort. Construction was completed less than two months after the order was placed and all ten entered service in New Zealand in June 1915. Bar frames were used by the American builders instead of NZR's preferred plate frames, and the class had superheaters as built. Water capacity was double that of the A class and coal a quarter more. [1]

Service

They were worked hard for four decades before being supplanted by the more powerful "K" and "J" class families. In 1919 No. 654 was used for a very short experiment in the use of pulverized coal. Only one trip is known to have been made before the engine was converted back. They were initially equipped with grates smaller than either the A or AB class. Not an issue with hard coal, increasing use of soft Waikato coal meant a larger grate was desirable. [1] Thus the entire class had their boilers replaced with AB class types starting in 1940 giving the reliable locomotives more life. This soon became a blessing when they were worked hard through the Second World War. They were used extensively on the steeply graded central North Island Main Trunk, Wanganui and Gisborne sections. In the mid-1950s most of the class were still in reasonable condition and the engines were regarded as a very successful class, capable of taking somewhat heavier loads than an AB class. The first withdrawals occurred in December 1955, when six were taken out of service with their boilers returned to the AB class boiler repair pool. The remaining four continued to operate until February 1957. [2] None were preserved.

See also

Related Research Articles

<span class="mw-page-title-main">NZR A class (1906)</span>

The NZR A class were a class of steam locomotives built in 1906 with a 4-6-2 wheel arrangement for the New Zealand Railways Department (NZR). The class should not be confused with the older and more obscure A class of 1873. They were designed by the NZR's Chief Mechanical Engineer, A. L. Beattie and his Chief Draughtsman, G. A. Pearson to replace less powerful locomotives struggling with increasing loads on the South Island Main Trunk Railway, and in anticipation of the traffic volumes that would be created upon the completion of the North Island Main Trunk railway.

NZR A<sup>B</sup> class

The NZR AB class was a class of 4-6-2 Pacific tender steam locomotive that operated on New Zealand's national railway system for New Zealand Railways (NZR). Originally an improvement on the 1906 A class, 141 were built between 1915 and 1927 by NZR's Addington Workshops, A & G Price of Thames, New Zealand, and North British Locomotive Company, making the AB class the largest class of steam locomotives ever to run in New Zealand. An additional eleven were rebuilt from the tank version of the AB – the WAB class – between 1947 and 1957. Two North British-made locomotives were lost in the wreck of the SS Wiltshire in May 1922.

NZR W<sup>D</sup> class

The NZR WD class was a class of tank locomotive built by Baldwin Locomotive Works to operate on New Zealand's national rail network.

<span class="mw-page-title-main">NZR O class</span>

The NZR O class consisted of six steam locomotives that operated on New Zealand's national rail network. Ordered from the Baldwin Locomotive Works of Pennsylvania in 1885, three arrived in time to begin work in December 1885, while two more were placed in service in January 1886 and the sixth in February 1886. After almost four decades of service, all six were withdrawn in May 1922. None survived to be preserved, although two engine frames and 5 tenders from O class locomotives are known to exist near Summit on the former Rimutaka Incline.

<span class="mw-page-title-main">NZR E class (1906)</span>

The New Zealand E class locomotive comprised a single Mallet steam locomotive operated by New Zealand Railways (NZR) from 1906 until 1917. Classified as E 66 and nicknamed Pearson's Dream after its designer, it was an experimental Mallet locomotive designed to work on the Rimutaka Incline. The "E" classification was previously used by the Double Fairlie E class of 1872-75, but the classification was free as they had all been withdrawn by the time E 66 entered service. After the withdrawal of E 66, "E" was again re-used on the battery-electric E class of 1922. It was the only Mallet locomotive to operate for the NZR

<span class="mw-page-title-main">NZR B class (1899)</span>

The NZR B class of 1899 was a class of steam locomotives that operated on New Zealand's national rail network. An earlier B class of Double Fairlies had entered service in 1874, but as they had departed from the ownership of the New Zealand Railways (NZR) by the end of 1896, the B classification was free to be re-used. Despite early difficulties, they were amongst NZR's most influential designs.

NZR W<sup>AB</sup> 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.

NZR J<sup>A</sup> class

The NZR JA class were a type of 4-8-2 steam locomotive used on the New Zealand railway network. The class was built in two batches, the first batch was built at Dunedin's Hillside Workshops between 1946 and 1956 and the second batch by the North British Locomotive Works in 1951. To distinguish between the batches, locomotives are identified by their maker.

<span class="mw-page-title-main">NZR K class (1932)</span>

The NZR K class of 1932 was a class of mixed traffic 4-8-4 steam locomotives built by the New Zealand Railways Department (NZR) that operated on New Zealand's railway network. The locomotives were developed following the failure of the G class Garratts. The class should not be confused with the much earlier K class of 1877-78, the first American-built engines to arrive in New Zealand.

<span class="mw-page-title-main">NZR G class (1928)</span>

The NZR G class was a type of Garratt steam locomotive used in New Zealand, the only such Garratt type steam locomotives ever used by the New Zealand Railways (NZR). They were ordered to deal with traffic growth over the heavy gradients of the North Island Main Trunk (NIMT) and to do away with the use of banking engines on steep grades. They were one of the few Garratt designs to employ six cylinders. A mechanical stoker was used to feed coal into the locomotive.

<span class="mw-page-title-main">NZR J class (1939)</span>

The NZR J class steam locomotives were a type of 4-8-2 steam locomotive built for the New Zealand Railways Department (NZR) and used on the New Zealand railway network. Built by the North British Locomotive Works, although designed to work on the lighter secondary lines the class was frequently used on mainline express passenger trains as well as freight. The class first appeared in distinctive streamlining, which was later removed from 1947 onwards for maintenance reasons. The class should not be confused with the earlier 1874 J class. Three J class lasted until the end of steam-hauled services on 26 October 1971, three locomotives of the forty built have been preserved.

<span class="mw-page-title-main">NZR Q class (1901)</span>

The NZR Q class was an important steam locomotive class not only in the history of New Zealand's railway network but also in worldwide railways in general. Designed by New Zealand Government Railways' (NZR) Chief Mechanical Engineer A. L. Beattie and ordered from the Baldwin Locomotive Works in 1901, they were the first locomotives in the world to be built with the wheel arrangement of 4-6-2. This wheel arrangement came to be known as the Pacific type after the voyage the completed locomotives had to make across the Pacific Ocean to New Zealand. A few instances of the 4-6-2 wheel arrangement are known to have existed prior to 1901, but these were all reconstructions of locomotives that were originally built with a different wheel arrangement, thereby making the thirteen members of the Q class the first "true" Pacifics in the world. The Pacific style went on to become arguably the most famous wheel arrangement in the world.

NZR W<sup>J</sup> class

The NZR WJ class was a class of one steam locomotive built by Baldwin Locomotive Works for service on New Zealand's private Wellington and Manawatu Railway (WMR). She acquired the WJ classification when the publicly owned New Zealand Railways Department (NZR) purchased the WMR and its locomotive fleet in 1908.

NZR F<sup>A</sup> class

The NZR FA class was a class of tank steam locomotives that was built as a larger version of the NZR F class 0-6-0T. The requirements were for larger water and coal capacity on a locomotive that could handle grades better than the F class. Due to costs involved in producing new machines, NZR chose to rebuild existing machines with larger coal and water capacity, larger boiler and firebox, higher boiler pressure and larger diameter pistons. Seven F class engines were rebuilt between 1892 and 1897. Another seven were built new, one at Newmarket Workshops in 1896 and six at Addington Workshops in 1902–03.

NZR U class

The NZR U class, the first tender locomotives built in New Zealand, were a class of 4-6-0 Ten Wheeler locomotive designed to the requirements of Mr T. F. Rotherham and built at NZR Addington between 1894 and 1903. They were amongst NZRs' longest lived tender engines.

NZR U<sup>A</sup> 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.

<span class="mw-page-title-main">NZR M class</span>

The NZR M class were a series of four tank engines built in England for the Otago railways Bluff to Winton section. They were acquired by NZR in the late 1870s and rebuilt in the late 1880s. As rebuilt they were not very successful and were used in shunting duties until retirement in the 1920s.

NZR U<sup>B</sup> 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. The earlier engines had slide valves and inside Stephenson motion, the later had piston valves and Walschaerts valve gear, as well as a higher boiler pressure.

NZR U<sup>C</sup> class

The NZR UC class were a group of ten 4-6-0 steam locomotives obtained from Scottish builders Sharp, Stewart and Company for New Zealand Railways (NZR). Essentially they were developments of the firm's previous batch of 4-6-0s' for NZR.

NZR W<sup>W</sup> class Class of 50 (+14) New Zealand 4-6-4T locomotives

The New Zealand WW class was a class of 4-6-4T tank locomotives that operated on the New Zealand national railway network. They were built for New Zealand Railways Department (NZR), and were the final development of the six-coupled tank engine in New Zealand, the penultimate class of tank locomotives to be built for NZR, and the first class of tank locomotives to be built with superheaters.

References

Citations

Bibliography

  • Lloyd, W. G. (1974). Register of New Zealand Railways Steam Locomotives 1863-1971 (2nd ed.). ISBN   0-9582072-1-6.
  • Millar, Sean (2011). The NZR Steam Locomotive. Wellington: New Zealand Railway and Locomotive Society. ISBN   978-0-908573-89-9.
  • Stewart, W. W. (1974). When Steam was King. Wellington: A. H. & A. W. Reed Ltd. ISBN   978-0-589-00382-1.
  • Palmer, A. N.; Stewart, W. W. (1965). Cavalcade of New Zealand Locomotives. Wellington: A H. & A W. Reed. ISBN   978-0-207-94500-7.