Victorian Railways D class (1887)

In the mid-1880s Richard Speight, the Victorian Railways chairman of commissioners, instituted a policy of standardised locomotive designs for new builds. This was intended to reduce maintenance costs and repair downtime, and was achieved by designing five new classes of locomotive - Main line passenger and goods, light lines passenger and goods, and suburban tank engines - which shared among them as many components as possible, reducing the range and quantity of spare parts required and allowing engines undergoing repair to swap out components as needed. These classes later became the New A, New R, D, Y and E classes respectively; the latter two having been based on pattern engines from Kitson & Co. at Leeds in England, and all designs "bearing similarities to contemporary locomotives on the Midland Railway."^[2]

Using the range of designs provided by Jeffreys, of the Monkbridge Iron and Steel Company of Leeds, twenty D Class engines were constructed at Phoenix Foundry, with builders numbers 200 to 219, entering service in 1887 and 1888. The engine numbers were 242, 244, 248, 250 and 260, from withdrawn ex-South Suburban tank engines, the even numbers of the range 322 to 344, and finally 82 and 92, recycled from engines destroyed at Little River in 1884, and 122, from an engine sold in 1888.^[2][3]

The necessary design drawings were nearing completion by the end of January 1887, and construction of some of the framing and castings had started in March.^[3]

Engine D242 was the 200th locomotive built by Phoenix Foundry.^[3] The engine was delivered from the Ballarat works on Friday 21 October 1888, and made a test run to Lal Lal the following day.^[3]

D92 was put on display at the Melbourne Centennial Exhibition in 1888, alongside the pattern Kitson E and Y Class engines; those two were named Tasmania and Victoria respectively, and later became Victorian Railways engines E426 and Y445 (later again, Y121), but D92 was not given a name for the event.^[3]

The engines were fairly standard for the era, with inside cylinders worked by Stephenson link gear, a round-top firebox and the same tender as the other standard classes (except that the Y Class tenders had a compensating beam between the leading and centre axles). New features included a drop-door for the firebox in lieu of the older sliding door type, which became the default for all locomotives built over the following forty years, a double-ended regulator handle, and the leading bogie was noted as an "outside frame swing link type with equalisers between the springs, much more suitable for passenger service than the Bissel truck of the Beyer, Peacock 4-4-0s."^[2]

From 1899 some engines were fitted with repaired New A class boilers in lieu of the original 140psi boilers.^[2][3] Later, between 1907 and 1909, the boilers were replaced with high pressure boilers from the New A and Y Classes, reduced from the nominal 175psi to 160psi to account for the low factor of adhesion of the light-lines engines, but even with this change the upgraded engines were prone to wheelslip. To rectify this, half the class were fitted with drag boxes under the cab floor, increasing weight by nearly three tons. These new boilers had a taller firebox, requiring alterations to the cab and a modified smoke-box with a shorter chimney.^[2]