page_title: Victorian Railways R class
section_title: Design features
hierarchical_section_title: Victorian Railways R class / History / Design features
caption_attribution_description: English: Detail of valve gear of Victorian Railways R class locomotive R 766
context_page_description: The R class was an express passenger steam locomotive that ran on Australia's Victorian Railways from 1951 to 1974. A long overdue replacement for the 1907-era A2 class 4-6-0, their development and construction was repeatedly delayed due to financial constraints caused by the Great Depression and later the manpower and materials shortages of World War II and the immediate postwar period.
  Orders eventually totalling 70 locomotives were placed with the North British Locomotive Company of Glasgow. Once initial teething problems were overcome, R class locomotives proved to be a success and their power and speed enabled faster timetabled services. However, they were almost immediately superseded by mainline diesel-electric and electric locomotives on the VR from 1952 onwards. With successive orders of diesel-electric locomotives through the 1950s and 1960s gradually displacing them, all but seven of the class were withdrawn and cut up for scrap.
  Four of the remaining locomotives were later restored to operating condition between 1984 and 1998.
context_section_description: 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 10,000 lb (4,536 kg) of coal per hour)  on a locomotive with only a 42-square-foot (3.9 m²) 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 50-square-foot (4.6 m²) 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.
caption: SCOA-P coupled wheels and Witte smoke deflectors, R 766, 1993
exif: {}