New South Wales Z12 class locomotive

New South Wales Z12 class
Class Z12 (former Class C.79) Locomotive
Type and origin Power type Steam Builder Beyer, Peacock & Co. (34) Dübs & Co. (26) Atlas Engineering Works (8) Serial number BP 1620–1637, 1675–1676, 2060–2063 Build date 1877–1882 Total produced 68
Specifications Configuration: ​  • Whyte 4-4-0  • UIC 2'Bn Gauge 4 ft 8 1⁄2 in (1,435 mm) standard gauge Driver dia. 5 ft 6 in (1.676 m) Adhesive weight 57,000–62,000 lb (25,900–28,100 kg) Loco weight 84,000–95,000 lb (38,100–43,100 kg) Firebox:  • Firegrate area 15 sq ft (1.4 m2) Boiler pressure 130 psi (0.9 MPa) as built; 140 psi (1.0 MPa) later Heating surface 1,070–1,120 sq ft (99–104 m2) Superheater None Cylinders Two, outside Cylinder size 18 in × 24 in (457 mm × 610 mm) Train brakes Air
Performance figures Tractive effort 13,019–14,020 lbf (57.9–62.4 kN)
Career Operators New South Wales Government Railways Class C79 and C80 (Z12 from 1924) Numbers 79-92, 118-126, 143-157, 165-182, 27N-30N, 37N-39N, 47N-51N (1201-1248 from 1924) Disposition 20 rebuilt to Z13 class, 45 scrapped, 3 preserved

The Z12 class was a class of 4-4-0 steam locomotives built for and operated by the New South Wales Government Railways of Australia.

The Z12 Class (formerly C79 and C80 class) was the first class of locomotive on the New South Wales Government Railways to be built in relatively large numbers. They hauled all express passenger and mail trains for some 20 years.

The design derives from the Metropolitan Railway A Class 4-4-0T condensing steam locomotives built for the Metropolitan Railway by Beyer Peacock in 1864. The design of these locomotives was attributed to the Metropolitan Engineer John Fowler, but the design was a development of a locomotive Beyers had built for the Spanish Tudela & Bilbao Railway, Fowler only specifying the driving wheel diameter, axle weight and the ability to navigate sharp curves.

A total of 68 were built. The first batch of 30 were built by Beyer, Peacock and Company and placed in service as the 79 class between 1877 and 1879. They were the first locomotives to be imported with Westinghouse continuous air-brakes already fitted. The second batch of 26 came from Dübs and Company. These arrived between 1880 and 1881. A further four followed from Beyer, Peacock in 1881. To assist local industry, a contract for eight was awarded to the Atlas Engineering Works situated in Sydney's Haymarket and delivered in 1881–1882.

Their numbers were thinned from 1895 when No. 88 was converted to a 4-4-2T tank engine for Sydney suburban service with a further 19 following by 1902. These Tank Engines were reclassified the CC79 class. The remaining engines became the C80 class.

The arrival of newer locomotives such as the D255 (later Z15), D261 (later Z16), O446 (later Z23) and P6 (later C32) classes saw them relegated to hauling secondary and later branch line services radiating out of Dubbo, Werris Creek, Narrabri and Moree, where some were equipped with cowcatchers for operation on unfenced lines. In an attempt to prevent cinders blocking the lower boiler tubes between cleanings in December 1956 an extended smokebox was fitted to 1219 with 1243 similarly modified in the 1960s.