New South Wales D58 class locomotive

New South Wales D58 class
Class D58 Locomotive
Type and origin Power type Steam Builder Eveleigh Railway Workshops (11) Cardiff Locomotive Workshops (2) Total produced 13
Specifications Configuration: ​  • Whyte 4-8-2  • UIC 2'D1'h Gauge 4 ft 8 1⁄2 in (1,435 mm) Driver dia. 5 ft 0 in (1.524 m) Adhesive weight 212,000 lb (96 t) Loco weight 311,000 lb (141 t) Firebox:  • Firegrate area 65 sq ft (6.04 m2) Boiler pressure 200 psi (1.38 MPa) Heating surface 3,390 sq ft (314.94 m2) Superheater: ​  • Heating area 775 sq ft (72.00 m2) Cylinders Three Cylinder size 21.5 in × 28 in (546 mm × 711 mm) Valve gear Rack and pinion
Performance figures Tractive effort 55,008 lbf (244.7 kN) Factor of adh. 3.84
Career Operators New South Wales Government Railways Class D58 Numbers 5801–5813 Disposition All scrapped

The D58 class was a class of steam locomotives built by the New South Wales Government Railways in Australia. They were built with the 4-8-2 wheel arrangement.

In 1943 approval was given for the New South Wales Government Railways Workshops to build 25 freight locomotives. The design was a modified version of the 57 class. The main alterations were the use of a rack and pinion valve gear in lieu of the Gresley 2:1 conjugated vale gear for the middle cylinder and the use of smaller cylinders to enable the locomotives to run to on the Main North line to Broadmeadow, a route which had a tighter loading gauge. They also used a Woodard divided drive of twin coupling rods between the second and third driving wheels. A valance was fitted over the valve gear on the front platform.

Eveleigh Railway Workshops built 11 locomotives and Cardiff Locomotive Workshops two. The first entered service in March 1950. The decision to move to diesel power saw only 13 locomotives completed.

Whilst the derived rack and pinion valve gear appeared superior in theory, in practice it required more maintenance and lubrication. The smaller diameter cylinders demanded a later cut-off and used more steam, thus making the locomotives uneconomical in the use of coal and water when compared with the 57 class. Despite the design being made to enable use on the Main Northern line from Sydney to Broadmeadow, few journeys were ever made on this route. They mainly were used on the Main Western line to Lithgow and in a limited capacity on the Main South line to Junee.