NZR G class (1874)

The NZR G Class was a class of four saddle tank locomotives from English builders Black Hawthorn in the early 1870s. Like the similarly sized D class, they were an attempt to produce a passenger version of the already highly successful F class.[1]

NZR G Class (1874)
G Class steam locomotive, NZR 55
Type and origin Builder Black, Hawthorn & Co (4) Build date 1873
Specifications Configuration: ​  • Whyte 4-4-0T Driver dia. 36 in (0.914 m) Adhesive weight 13.2 long tons (13.4 t; 14.8 short tons) Loco weight 18.2 long tons (18.5 tonnes; 20.4 short tons) Firebox:  • Firegrate area 9 sq ft (0.84 m^2) Boiler pressure 130 lbf/in^2 (0.90 MPa) Heating surface 486 sq ft (45.2 m^2) Cylinders Two, outside Cylinder size 10.5 in × 18 in (267 mm × 457 mm)
Performance figures Tractive effort 4,893 lbf (21.77 kN)
Career Operators NZR Disposition All scrapped

Origin and design

The G class were ordered by the Canterbury Provincial Council. They were derived from the F class, replacing the first of the three driving axles with a four-wheel bogie. It was hoped that the reduced rigid wheelbase would allow the locomotive to provide higher speed passenger services. The type suffered from lack of weight on the driving axles, a driver stating that "it took the 'G' all its time to push its front bogie along, let alone pull a load".[2] They were followed by the L Class which were a more successful attempt to produce a faster F Class.

Service

In the early 1890s the locomotives were progressively transferred to the Picton section, where it was felt that they had been relegated to get rid of them from the busy Hurunui-Bluff section. Their maximum load on the 1 in 37 gradient from Picton was six 4-wheel wagons.[3]

Withdrawal and disposal

All of the locomotives were withdrawn between 1915 and 1919 and were sold for further service in industry.

References

1. Palmer & Stewart 1965, p. 32.
2. Millar 2011, p. 108.
3. Boult, A A (Sep 1960). "The G Class 4-4-0 tank locomotives". Railway Observer. 85 (reprinted Oct 2017): 160–161.

Bibliography

• Lloyd, W.G. (2002); Register of New Zealand Railways Steam Locomotives 1863-1971, Otago Railway & Locomotive Society/Triple M Publications
• Millar, Sean (2011). The NZR Steam Locomotive. Wellington: New Zealand Railway and Locomotive Society. ISBN 978-0-908573-89-9.
• W.W.Stewart (1970), When Steam Was King, REED
• Palmer, A. N.; Stewart, W. W. (1965). Cavalcade of New Zealand Locomotives. Wellington: A H. & A W. Reed. ISBN 978-0-207-94500-7.