NZR D class (1874)

NZR D class
D 140, preserved and in operation at the Ferrymead Railway
Type and origin Power type Steam Builder Dübs and Company (5), Neilson and Company (19), Scott Brothers (11) Build date 1874–1890
Specifications Configuration: ​  • Whyte 2-4-0T  • UIC 1B nt Gauge 3 ft 6 in (1,067 mm) Driver dia. 36 in (914 mm) Length 21 ft 6 in (6.55 m) Adhesive weight 11 long tons 10 cwt (25,800 lb or 11.7 t) Loco weight 14 long tons 14 cwt (32,900 lb or 14.9 t) Fuel type Coal Fuel capacity 0 long tons 11 cwt (1,200 lb or 0.6 t) Water cap 300 imp gal (1,400 l; 360 US gal) Firebox:  • Firegrate area 7.3 sq ft (0.68 m2) Boiler pressure 130 psi (0.90 MPa) Heating surface 392 sq ft (36.4 m2) Cylinders Two, outside Cylinder size 9.5 in × 18 in (241 mm × 457 mm)
Performance figures Tractive effort 4,693 lbf (20.88 kN)
Career Operators Public Works Department New Zealand Railways Department Number in class 35 Numbers 6, 16, 18, 46-51, 108-9, 130-1, 137-145, 149, 169-171, 195-98, 221-2, 240, 315, 578 First run May 1874 Last run March 1927 Disposition Seven preserved, one converted into diesel-mechanical, remainder scrapped

Type and origin
Power type	Steam
Builder	Dübs and Company (5), Neilson and Company (19), Scott Brothers (11)
Build date	1874–1890

NZR D class steam tank locomotives operated on New Zealand's national railway network. The first entered service in 1874 all had been withdrawn by the end of 1927, which allowed the D classification to be used again in 1929.

The boiler and cylinders were the same as the slightly earlier C class, but its driving wheels had a larger diameter and it was aesthetically different from the C. The class was ordered in a number of batches: eight from Neilson and Company in 1874, five from Dübs and Company and four from Neilson in 1878, seven from Neilson in 1880, ten from Scott Brothers in 1887, and the final D from Scott Brothers in 1890. The order with Scott Brothers, placed in 1884, was the first large-scale construction of locomotives in New Zealand.

Four of the 1874 locomotives were named:

The class was not particularly powerful and was employed on light duties, sometimes achieving speeds of 72.4 km/h (45 mph) on a level grade. They often saw service on commuter trains between Christchurch and Lyttelton until superior locomotives took their place, and they were utilised at other major locations on the South Island's east coast. In the North Island, D 137 was used in 1905 as part of a "railcar" trial service between Lower Hutt and Upper Hutt, hauling a carriage that seated 24 first class passengers, 48 second class passengers, and had a guard's compartment. It was inspired by locomotive/carriage combinations the General Manager of NZR witnessed in the eastern United States. The combination was overpowered and uneconomic and did not last long in service.