NZR Q class (1901)

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NZR Q class
Q class.jpg
A NZR Q class locomotive
Type and origin
Power type Steam
Builder Baldwin Locomotive Works, Philadelphia, USA
Serial number 19202–19207
19248–19254[1]
Build date 1901
Total produced 13
Specifications
Configuration:
 • Whyte 4-6-2
Gauge 3 ft 6 in (1,067 mm)
Driver dia. 49.1 in (1.247 m)
Wheelbase 48 ft 4 in (14.73 m)
Length 55 ft 4 in (16.87 m)
Adhesive weight 30.7 long tons (31.2 t; 34.4 short tons)
Loco weight 48.0 long tons (48.8 t; 53.8 short tons)
Tender weight 24.1 long tons (24.5 t; 27.0 short tons)
Total weight 72.1 long tons (73.3 t; 80.8 short tons)
Fuel type Coal
Fuel capacity 5.0 long tons (5.1 t; 5.6 short tons)
Water cap 1,700 imp gal (7,700 L; 2,000 US gal)
Firebox:
 • Firegrate area
40 sq ft (3.7 m2)
Boiler pressure 200 psi (1,379 kPa)
Heating surface 1,683 sq ft (156.4 m2)
Cylinders Two
Cylinder size 16 in × 22 in (406 mm × 559 mm)
Loco brake Steam
Train brakes Air
Performance figures
Tractive effort 18,340 lbf (81.6 kN)
Career
Number in class 13
Numbers 338-350[1]
Locale Auckland - Rotorua
Oamaru - Dunedin
First run 1901-12-24
Retired 1957-12-07
Disposition All scrapped

The NZR Q class was an important steam locomotive not only in the history of New Zealand's railway network but also in worldwide railways in general. Designed by New Zealand Government Railways' 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.

Design[edit]

The Q class's design stems from the requirement for a locomotive similar to the Ub class with the inclusion of a wide firebox to burn poor quality lignite coal from the South Island and the Waikato. Originally plans to equip the new locomotives with a Wootten Firebox would have seen the "Camelback" configuration adopted.

Operation[edit]

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 AB classes; in fact, later in life, they were re-boilered with AB boilers. An improved slightly larger 'Q' type was ordered from Baldwins in 1914 but classified AA due to their dimensions similar to the A class.

Withdrawal[edit]

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[edit]

  1. ^ a b "Q Class 4-6-2 Register". Retrieved 2008-02-10. 

Further reading[edit]

  • Heath, Eric, and Stott, Bob; Classic Steam Locomotives Of New Zealand, Grantham House, 1993

External links[edit]