NZR X class

NZR X class
X class 588, photographed leaving Petone Workshops circa 1913. Godber Collection, Alexander Turnbull Library.
Type and origin Power type Steam Builder NZR Addington Workshops Build date 1908 - 1909, 1913 - 1915 1943 - 1949 (rebuild)
Specifications Configuration: ​  • Whyte 4-8-2 Gauge 3 ft 6 in (1,067 mm) Driver dia. 45 in (1.143 m) Length 56 ft 9.75 in (17.32 m) Adhesive weight 46.7 long tons (47.4 t; 52.3 short tons) (original) 45.6 long tons (46.3 t; 51.1 short tons) (rebuild) Loco weight 66.7 long tons (67.8 t; 74.7 short tons) (original) 66.6 long tons (67.7 t; 74.6 short tons) (rebuild) Tender weight 27.3 long tons (27.7 t; 30.6 short tons) (original) 28.55 long tons (29.01 t; 31.98 short tons) (rebuild) Total weight 94.0 long tons (95.5 t; 105.3 short tons) (original) 95.15 long tons (96.68 t; 106.57 short tons) (rebuild) Fuel type Coal Fuel capacity 4.0 long tons (4.1 t; 4.5 short tons) (original) 5.0 long tons (5.1 t; 5.6 short tons) (rebuild) Water cap. 2,200 imp gal (10,000 L; 2,600 US gal) Firebox: ​  • Grate area 37.1 square feet (3.4 m2) (original) 37.5 square feet (3.5 m2) (rebuild) Boiler pressure 230 psi (1,586 kPa) (original) 215 psi (1,482 kPa) (rebuild) Heating surface 2,066 sq ft (191.9 m2) (original) 1,185 sq ft (110.1 m2) (rebuild) Superheater: ​  • Heating area None (original) 168 square feet (15.6 m2) (rebuild) Cylinders 2 high pressure + 2 low pressure (original) 4 high pressure (rebuild) High-pressure cylinder 13.5 in × 22 in (343 mm × 559 mm) Low-pressure cylinder 22 in × 22 in (559 mm × 559 mm)
Performance figures Maximum speed 30 mph (48 km/h) Tractive effort 26,620 lbf (118.4 kN) (original)/ 31,150 lbf (138.6 kN) (starting) 29,500 lbf (131 kN) (rebuild)
Career Number in class 18 Numbers 439–446 588–597 Locale North Island Main Trunk First run 1909 Last run 1957 Retired 1935–1950 Current owner Feilding & Districts Steam Rail Society (1) Disposition Withdrawn, one preserved

The New Zealand X class was a pioneering class of eighteen 4-8-2 steam locomotives built for New Zealand Railways Department (NZR) and designed by A. L. Beattie that operated on the national rail network of New Zealand. In 1908, a heavy and powerful locomotive was required to haul traffic on the newly completed mountainous central section of the North Island Main Trunk Railway, and as a logical progression of the 4-6-2 Q class design, the 4-8-2 wheel arrangement was created for the X class.^[1]