NZR A^B class

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NZR A^B Class

The Kingston Flyer approaching the terminus at Fairlight.
Power type	Steam
Builder	NZGR Addington Workshops (38) North British Locomotive Works, Scotland (83) A & G Price Limited, Thames (20)
Build date	1915 - 1918 1921 - 1927
Configuration	4-6-2
Gauge	3 ft 6 in (1,067 mm) Cape gauge
Driver size	54 in (1.37 m)
Wheelbase	52 ft 6 in (16.0 m)
Length	62 ft 5 in (19.0 m)
Locomotive weight	51.3 long tons (52.1 t)
Tender weight	33.4 long tons (33.9 t)
Locomotive and tender combined weight	84.7 long tons (86.1 t)
Fuel type	Coal
Fuel capacity	4.0 long tons (4.1 t)
Water capacity	3,500 imp gal (16,000 L)
Boiler pressure	180 psi (1,200 kPa)
Fire grate area	33 sq ft (3.1 m2)
Heating surface: Total	1,148 sq ft (106.7 m2)
Superheater area	204 sq ft (19.0 m2)
Cylinders	2
Cylinder size	17 in × 26 in (43 cm × 66 cm)
Top speed	60 mph (97 km/h)
Tractive effort	20,030 pounds-force (89.1 kN)
Number in class	141
Number	608 - 838
Locale	All of New Zealand
First run	October 1915
Retired	1963 - 1969
Preserved	7 (608, 663, 699, 745, 778, 795, 832)
Current owner	Kingston Flyer, Mainline Steam
Disposition	Withdrawn, Preserved

The NZR A^B class was a class of 4-6-2 Pacific tender steam locomotive that operated on New Zealand's national railway system. Originally an improvement on the 1906 A class 141 were built between 1915 and 1927 by NZR's Addington Workshops, A & G Price Limited of Thames, New Zealand, and North British Locomotive Works, making the A^B class the largest class of steam locomotives ever to run in New Zealand. An additional ten were rebuild from the tank version of the A^B - the W^AB class - between 1947 and 1957, while another two North British made locomotives were build, but were lost in the wreck of the SS Wiltshire in May 1922.

Reputedly the first engine able to generate one horsepower for every 100 pounds of weight, the A^B class was efficient and versatile, and the engines were easy to maintain and operate. Members of the class worked almost every part of the New Zealand rail network, and were used for both freight and passenger trains. The A^B class was easily able to pull an express passenger train at speeds of 100 km/h (62 mph), or haul 700-tonne goods trains on easy grades.

A unique feature of the A^B class's design is their Vandebuilt tenders, which gave them their unique cylindrical back. Several features of the class, notably their boilers, were used on other NZR locomotives.

The A^B class were superseded on principal express trains and heavy freight trains by the K class of 1932 and the J class of 1939, and were relegated to secondary duties. The majority of the class was withdrawn from NZR services during the 1960s, as diesel traction replaced steam, with a few members of the class lasting to the end of steam itself in 1971. Two were retained to operate the Kingston Flyer, possibly New Zealand's most famous heritage railway. The Flyer has now passed into private ownership and it is still run by A^B 778 and A^B 795. Five more have been preseved by various other preservation societies.

The W^AB class of 1917 was essentially a tank locomotive version of the A^B class.

[edit] Preservation

Seven members of the A^B class have been preserved.

[edit] External links

• NZR Steam locomotives - Ab class
• Official website of the Kingston Flyer
• Official website of the Pleasant Point Museum and Railway

[edit] References

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