The X class was a development of the earlier
C class 2-8-0 goods locomotive, designed to be gauge convertible from to in the event of the Victorian Railways network being
converted to standard gauge. The C class, with a narrow firebox between the frames, could not be easily converted. The X class retained the same cylinder and driving wheel dimensions as the C class as well as its valve gear, but introduced a much larger boiler and a trailing truck behind the rear driving axle. The 2-8-2 layout of the X class allowed a wide, deep firebox suited to the high ash, low calorific coals from the
State Coal Mine typically used for goods haulage. This improved on some key shortcomings of the C class which were regarded as poor steaming and featured a very long manually stoked firebox that was difficult to fire and prone to clinkering. The X class was also equipped with a much larger capacity tender of similar design to the
S class Pacific introduced in 1928, enabling through runs from Melbourne to
Bendigo without intermediate stops to restock the tender.
Booster units All but two were built with a Franklin C2 type
Booster engine on the trailing truck axle, following a successful trial of a booster on the smaller
N class light lines 2-8-2. The booster allowed an additional tractive effort at starting and low speeds to increase the hauling power of the locomotive, particularly on heavy grades. X36 and X37 were built without boosters and were rostered for 'plains working' on the relatively flat line between
Gheringhap and
Maroona stations. X37 was equipped with a booster in March 1932, however X36 was never fitted with one, even though its trailing truck axle was equipped with the necessary pinion gear wheel. Some engines had their booster units "permanently removed", though in practice some such engines had the boosters disconnected without actually removing them from the trucks. As of April 1958, engines listed as such were 29, 33, 36 (never fitted), 44, 49, 50, 51 and 55. Later reporting noted that X29 was still running with its booster in July 1960, though it is not clear whether it was always in use, or restored to use after a period of non-service, though it is likely that it was restored using parts from some of the class members that had since been permanently withdrawn and scrapped.
Production The success of the original eleven locomotives delivered in 1929 (X27 to X37) led to further examples being built. X38 was assembled in 1937 from spare parts, helping to create work for workshops staff at a time of high unemployment. with a final four X class delivered by 1947.
Clyde Engineering cancelled order In May 1950, the Victorian Railways commissioned Clyde Engineering to provide a further fifteen X Class locomotives. Two months earlier the Commissioners had discussed difficulties in sourcing a reliable coal supply, and had already arranged for half the upcoming
J Class fleet to be delivered as oil burners, but they were also aware that this use of oil burning was far less efficient than diesel locomotives. At the same time, Clyde had been contracted to provide 17 of what would later be known as the
B Class diesel electric locomotives and the X Class order had not yet started construction, so the X Class order for £1,021,695 was cancelled and a further £51,501 paid, to bring the B Class order up to 26 locomotives. Had the fifteen additional X Class engines been delivered, they would have featured Witte-style smoke deflectors like the J and
R Class engines (probably painted red), a longer dome over the boiler, and a slightly shorter but taller tender to maintain the 9 tons coal, 8,600 gallons water capacity. Newsrail October 2025 p.399 includes a photograph of a scale model of the hypothesized locomotive, with a tender based on X32's Stug equipment for precipitated brown coal.
Regular service The X class locomotives were described as always the master of their task, fast steaming and easy riding. With their relatively heavy
axle load, the X class was initially confined to the Bendigo and Wodonga lines, with the occasional journey on the
Ballarat or
Geelong lines. In later years after they were allowed to cross the
Flinders Street Viaduct between
Spencer Street and
Flinders Street stations, they worked goods trains of over 1,000
tons between
Morwell and Melbourne, and even worked the
South Gippsland line to
Korumburra frequently until the late 1950s and as far as
Foster. Even in its original form, the X class locomotive was a marked improvement on the C class in terms of performance. Comparative tests between prototype X27 and C class locomotive C18 revealed that the X developed an
indicated horsepower output of between , compared with at for the C. With a later revised boiler design and other changes improving performance and increasing indicated horsepower to as much as , the X class was renowned for its ability to be driven extremely hard. As with the C class, it was also occasionally pressed into mainline passenger service on key intercity routes, particularly during Christmas and Easter peak times. The X class, in common with all broad gauge VR steam locomotives built from 1907 onwards, underwent design modifications to the
smokebox draughting and blastpipe dimensions referred to as
'Modified Front End', as well as other improvements such as the fitting of
smoke deflectors,
Automatic Staff Exchange apparatus and cross-compound air compressors. The copper firebox round-top boilers the original eleven locomotives were built with, prone to
priming if too much water was carried, The VR was so satisfied with the performance of the revised X class all-steel boiler design, a shortened barrel version was considered during the design phase of the
R class 4-6-4 express passenger locomotives of 1951. X38 introduced a new welded fabricated trailing truck in place of the cast steel units previously imported from the
Commonwealth Steel Company of
Illinois, USA. This design innovation was fitted to all subsequent examples built. Large numbers of locomotives were converted to fuel oil operation, but as a further step X32 was experimentally fitted with German 'Stug' (Studiengesellschaft) equipment in a specially modified tender for the burning of pulverised brown coal (PBC), a fuel in potentially abundant supply in Victoria. The trial was successful with the locomotive noted for its clean running and the elimination of smoke, spark hazard and spark arrestor cleaning. With the grate automatically stoked via a tender-mounted conveyor screw and blower motor, it was now possible to harness the full steam-raising potential of the locomotive's boiler without the stamina of the fireman being a limiting factor. The steam requirements for both engine and booster were able to be met for unlimited periods at maximum steam pressure even against the action of both injectors. Comparative performance tests with black coal-fired X30 revealed that X32 was able to generate a
drawbar horsepower output of at , exceeding by 5 to 10% that which could be produced by X30 with good quality
Maitland or
Lithgow coals. On 4 April 1951 it replaced a defective S class locomotive in hauling the
Spirit of Progress from Wallan to Melbourne, taking 43 minutes to cover the same distance the S class-hauled train would normally cover in 40 minutes, despite having to start the train from standstill and running with a lower permissible maximum speed. As early as July 1951 the Victorian Minister for Transport announced that the remaining 28 X class locomotives were to be converted to PBC operation. In September 1951 the Victorian Railways were considering purchasing 30 sets of PBC equipment for X Class conversions, and in early 1952 they and the State Electricity Commission of Victoria were exploring a wider project to convert 35 locomotives per year, to a total of 214 engines across the X, R and N classes (including engines then on order). The Victorian Railways went on to convert express passenger locomotive
R707 to PBC operation, and may well have converted the upcoming fifteen additional X Class locomotives from
Clyde Engineering to PBC at a later date. At the time, the State Electricity Commission was expecting to generate enough PBC to reliably fuel about thirty locomotives by 1954. However, by 1957 the price of PBC had doubled against a fall in the price of fuel oil and the increased availability of high quality NSW coal at good prices. This, coupled with the demonstrated efficiency and economical operation of
B class mainline diesel-electric locomotives introduced in 1952, made the high cost of installing storage and transport facilities for PBC uneconomic, particularly when combined with the additional maintenance costs associated with its PBC delivery equipment at and between the tender and firebox. Withdrawals commenced in 1957 and accelerated with the delivery of the
S class diesel-electric locomotives from August that year, with the diesel fleet by then large enough for the X class to be displaced from mainline goods haulage. A report comparing total operating costs per mile (including fuel, oil, crewing, maintenance, depreciation and interest) for locomotives in freight service found an S class diesel-electric cost 68.41
pence per mile versus 261.01 pence per mile for the X class steam locomotive. The X class locomotives were increasingly relegated to short-hop transfer goods haulage, a role that as mainline goods locomotives they were unsuitable for. ==Preservation==