Station in 2003 Within a few years of the introduction of the
A2 class 4-6-0 in 1907, it was clear that increasingly heavy train loads would require a more powerful locomotive on principal main lines. From as early as 1918, a series of drawings for potential
4-6-2 'Pacific' type locomotives began to emerge from the VR's Locomotive Design Section, some of which were ultimately developed into the 3 cylinder
S class heavy Pacific of 1928. However, plans for a smaller 2 cylinder Pacific, with an axle load below 20 tons to allow operation across the VR mainline network, were put on hold during the 1930s. This was partly due to the decline in traffic and revenue due to the
Great Depression, and partly due to the improved power outputs and efficiency from the A2 locomotives after the application of a series of
smokebox design and draughting changes referred to as
'Modified Front End' in the mid-1930s. By 1943 however, the situation had changed. There was a massive increase in traffic brought by the advent of
World War II, and the A2s were by this point well past their prime. The VR Locomotive Design Section once again turned their attention to the proposed Pacific replacement. The addition of a
mechanical stoker, the enlarging of the
grate from for increased performance and the use of heavy bar-frame construction for increased durability significantly increased the projected weight of the locomotive. To keep the
axle load to 19.5 tons, the design by 1944 had changed from a 4-6-2 'Pacific' to a
4-6-4 'Hudson' wheel arrangement.
Design features coupled wheels and Witte
smoke deflectors, R 766, 1993 The R class reflected an ongoing evolution of VR locomotive design and a response to the changing operational environment of the VR in the postwar era. The R class adopted the bar frame construction of the
H and
S class express passenger locomotives, which had proven to be far more robust in coping with the VR's varying track quality than the fracture-prone plate frames of the A2. The decision to install MB Type 1
mechanical stoker equipment (capable of feeding up to of coal per hour) on a locomotive with only a grate reflected improved postwar working conditions for locomotive firemen, the varying quality of postwar coal and the expectation of sustained high speed operation of the locomotive. The manually fired prewar VR S class
Pacific, although capable of 2,300
drawbar horsepower (1,700
kW), was limited by the physical ability of the fireman to feed its grate and as such was reliant on coal with a high
calorific value. Online locomotive database steamlocomotive.com notes: "They showed an interesting blend of European, British, American, and Australian practice. The slotted pilot is Australian, the long sand dome American, the Belpaire firebox and cab British, and the mid-line smoke lifters ('elephant ears') European." Other modern features included
SKF roller bearings on all axles and the innovative, lightweight
SCOA-P type
driving wheels, which were specially developed for the R class by the Steel Company of Australia.
Production An order for 20 locomotives was placed with the VR's
Newport Workshops in 1946, but remained unfulfilled for years, because shortages of steel and manpower saw other projects given precedence, such as the overhaul of badly run-down infrastructure and the building of extra
X class goods locomotives. By the late 1940s, the A2 class was at the end of its life, and new motive power was desperately required. Australian Federal Government restrictions on the availability of US dollars, designed to favour trade within the
British Empire, precluded the VR from purchasing American diesel-electric locomotives. The VR broke with a long-standing policy of in-house steam locomotive construction and called for tenders to construct an additional 50 R class. The contract was awarded to
North British Locomotive Company of
Glasgow, Scotland on 21 September 1949. On 12 January 1950, the order was increased to 70, with the cancellation of the original order of 20 of the locomotives from VR's Newport Workshops. Parts manufactured for the Newport order were used to complete the North British-built locomotives. Further delays were experienced after the locomotives began arriving in May 1951. Corrosion had already set in during their sea voyage from Scotland to Australia as deck cargo, and there were numerous manufacturing defects requiring rectification. R 703 was the first of the class in service, on 27 June 1951, and the last of the fleet, R 769, did not enter service until 23 September 1953. == Service life ==