The NZR Q class was an important steam locomotive class not only in the history of

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

railway Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a pre ...

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 Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of four leading wheels on two axles, six powered and coupled driving wheels on three axles and two trailing wheels on one axle. The locomo ...

. This wheel arrangement came to be known as the ''Pacific'' type after the voyage the completed locomotives had to make across the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

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.

Design

The Q class's design stems from the requirement for a locomotive similar to the U^B class with the inclusion of a wide

firebox Firebox may refer to: *Firebox (steam engine), the area where the fuel is burned in a steam engine *Firebox (architecture), the part of a fireplace where fuel is combusted *Firebox Records Firebox Records was a Finnish record label based in S ...

to burn poor quality lignite

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...

from the South Island and the

Waikato Waikato () is a local government region of the upper North Island of New Zealand. It covers the Waikato District, Waipa District, Matamata-Piako District, South Waikato District and Hamilton City, as well as Hauraki, Coromandel Peninsul ...

. Originally plans to equip the new locomotives with a

Wootten Firebox The Wootten firebox is a type of firebox used on steam locomotives. The firebox was very wide to allow combustion of anthracite waste, known as " culm". Its size necessitated unusual placement of the crew, examples being camelback locomotives. The ...

would have seen the "Camelback" configuration adopted.

Operation

In operation, the locomotives proved to be satisfactory rather than brilliant and they suffered from occasional gear problems. They were soon displaced from the most important and difficult work by members of the A and A^B classes; in fact, later in life, they were re-boilered with A^B boilers. An improved slightly larger 'Q' type was ordered from Baldwins in 1914, but classified A^A due to their dimensions similar to the A class. In a 1902 trial of various locomotives between Invercargill and Gore, the Q class with large fire-grate area "gave the most efficient results" of the larger locomotives.

Withdrawal

They saw out their final years working in Otago and the West Coast and the last Q class locomotive was retired in 1957. No examples of the class were preserved.

References

Citations

Bibliography

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External links

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NZR Steam locomotives - Q class

{{NZR Locomotives Q class 4-6-2 locomotives Baldwin locomotives 3 ft 6 in gauge locomotives of New Zealand Railway locomotives introduced in 1901 Scrapped locomotives