New South Wales Z25 class locomotive

New South Wales Z25 class
Class Z25 Locomotive
Type and origin Power type Steam Builder Beyer, Peacock & Co. Serial number 2073–2092, 2308–2337, 2547–2565 Build date 1881–1885 Total produced 70
Specifications Configuration: ​  • Whyte 2-6-0  • UIC 1'Cn Gauge 4 ft 8 1⁄2 in (1,435 mm) Driver dia. 4 ft 0 in (1.219 m) Adhesive weight 77,000 lb (35 t) Loco weight 95,000 lb (43 t) Fuel type Coal Firebox:  • Firegrate area 21 sq ft (2.0 m2) Boiler pressure 140 psi (0.97 MPa) Heating surface 1,145 sq ft (106.4 m2) Superheater None Cylinders Two, outside Cylinder size 18.5 in × 26 in (470 mm × 660 mm)
Performance figures Tractive effort 22,060 lbf (98.1 kN) Factor of adh. 3.49
Career Operators New South Wales Government Railways Class B205, Z25 from 1924 Numbers 205-254, 314-333 (2501-2570 from 1924) Disposition 2 preserved, 68 scrapped

The Z25 class (formerly B.205 class) was a class of 2-6-0 wheel arrangement steam locomotives built by Beyer, Peacock & Co. for the New South Wales Government Railways of Australia.

In the late 1870s, only 11 of the 82 goods locomotives in service on the Southern and Western lines of the New South Wales Government Railways had a leading truck. The balance had a wheel arrangement of 0-6-0. To provide a more suitable locomotive for use over the 8 chain (161 m) radius curves of the Blue Mountains line, it was decided to incorporate a Bissell pony truck on an improved version of the A93 class.

Beyer, Peacock and Company prepared a design which was considered to be in advance of British contemporary practice. The first twenty 205 class entered service in 1882.

The new engines were found to be more sluggish than the 93 class when getting away with a load, but pulled decidedly better when running tender first. Following tests on the Blue Mountains, Commissioner Goodchap recommended the installation of 50 ft. (15.25 m) turntables at Sydney, Bathurst and Goulburn which were required to turn the new locomotives. Four were allocated to the then isolated Northern network.

At that time, there were thirty 93 class locomotives on order. As Locomotive Engineer W. Scott considered the new 205 class better suited to his requirements, the order was amended to thirty 205 class locomotives, but with some minor improvements. These entered service in 1883/84, eight being allocated to Northern network.

Both batches were found to be prone to slipping and additional weight was necessary to be added to the driving wheels.

A further twenty locomotives arrived in 1885, five of which going to the Northern system. This last batch had cabs with steel cutaway sides, an improvement on the open cabs of the earlier batches.