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The AA class was an express passenger locomotive that ran on the Victorian Railways between 1900 and 1932. The largest, heaviest and most powerful 4-4-0 steam locomotive to run in Australia, it was the final development of this locomotive type in Australia. [1]
In 1900, Victorian Railways still ran express passenger trains with the successful but ageing B class 2-4-0 which dated back to 1862. The 'New A' class 4-4-0 of 1889 had proven to be a successful design, as had its close cousin and exact contemporary the X class 0-6-0. With traffic needs continuing to grow, the VR drafting office decided to take the best features of the New A and X class, but enlarge the locomotive with a larger, higher pressure boiler and larger cylinders. [2] [3]
Innovative design features of the AA class included air sanding equipment, improved Gresham No. 9 injectors, horizontal grid spark arrestors, steam for auxiliaries supplied directly from the dome, and a sloped ashpan to provide easier cleaning. [4]
With a comparatively high 185 pounds per square inch (1,280 kPa) boiler, later increased to 200 pounds per square inch (1,400 kPa), it was considered impractical to use traditional slide valves. A trial installation of overhead piston valves on New A class locomotive No. 422 demonstrated considerably greater efficiency and reduced maintenance, and the AA became the first of many subsequent VR locomotive classes to be built with piston valves. [2]
With an axle load of 16.85 long tons (17.12 t; 18.87 short tons), the AA had reached the design limits of size and power possible with a two-coupled axle locomotive type with Victoria's relatively lightweight track infrastructure. Its high tractive effort and limited adhesive weight (due to axle load constraints and having only two powered axles) combined to produce a less-than-ideal factor of adhesion of 3.5. Future VR locomotive designs were based on three or four coupled axles.
Twenty of the class were built by the Phoenix Foundry in Ballarat, entering service between 1900 and 1903. The first batch of ten, delivered in 1900–01, had a traditional three-axle tender. The second batch had a slightly larger firebox and grate, [2] 200 psi (1,379 kPa) boiler pressure, and larger, four-axle tenders.
Upon introduction in 1900, the AA went into service on mainline passenger service, hauling key express services such as the Sydney Express. They were chosen to haul the Royal Train of the Duke and Duchess of Cornwall in 1901. [5]
With the introduction of larger, heavier express passenger rolling stock in the form of the E type carriages of 1906, the VR introduced the considerably more powerful A2 class 4-6-0 in 1907, which superseded the AA class on premier services. However, the AA continued in service in assistant duties, as well as hauling show and race train specials. [2]
The AA class inherited a number of design improvements from the Dd class mixed-traffic locomotives which were introduced in 1902.
The second batch of AA locomotives utilised a bogie tender design based on that of the Dd in place of the original six wheel design, offering a far greater water capacity.
During 1923–24, Nos. 542, 544, 566 and 570 were fitted with Robinson superheaters, based on the successful trial of Schmidt pattern superheaters on Dd 882. As was common VR practice at the time for locomotives converted to superheating, the boiler pressure was reduced - in this case to 175 pounds per square inch (1.21 MPa) - to reduce maintenance and prolong boiler life. [2] Nominal tractive effort was reduced to a quoted 19,131 lbf (85.10 kN) at 85% boiler pressure, with total weight rising to 92.95 long tons (94.44 t; 104.10 short tons). [6]
Another key improvement was the fitting of tablet exchangers to No. 552 and 570 for non-stop running on single-track sections of the North-eastern line, [6] a portent of improvements on this line that would eventually lead to the non-stop Melbourne-Albury Spirit of Progress service of 1937.
Three AA class locomotives were involved in the Sunshine rail disaster of 1908, when an Up Bendigo service hauled by AA 564 and 544 crashed into the rear of an Up Ballarat excursion service hauled by AA 534 and 'Old A' 202, resulting in the deaths of 44 people and the injury of over 400. [6]
The AA class was gradually made redundant by the delivery of large numbers of 4-6-0 locomotives of the new Dd and A2 classes between 1902 and 1922, which eventually totalled 446 locomotives. [7] [8] The A2 offered considerably more power, while the Dd offered similar tractive effort to the AA but much greater route availability due to its lower axle load.
Withdrawals commenced in 1919 and, by 1926, only the superheated AA locomotives remained on the register. A number of the boilers of the withdrawn locomotives saw further use powering riverboats, while AA 532 served as a mobile boiler at Newport Workshops. [6]
By January 1932, the entire class had been recorded as withdrawn. [6] [9] They were all scrapped shortly after withdrawal, with the exception of Newport Workshops boiler locomotive AA 532, which lasted until 1940. [2]
Under the Whyte notation for the classification of steam locomotives, 4-8-4 represents the wheel arrangement of four leading wheels on two axles, eight powered and coupled driving wheels on four axles and four trailing wheels on two axles. The type was first used by the Northern Pacific Railway, and initially named the Northern Pacific, but railfans and railroad employees have shortened the name since its introduction. It is most-commonly known as a Northern.
The Victorian Railways X class was a mainline goods locomotive of the 2-8-2 'Mikado' type operated by the Victorian Railways (VR) between 1929 and 1960. They were the most powerful goods locomotive on the VR, aside from the single H class, H220, which was confined to the North East line, until the advent of diesel-electric traction, and operated over the key Bendigo, Wodonga, and Gippsland mainlines.
The C class was a mainline goods locomotive of the 2-8-0 'Consolidation' type that ran on the Victorian Railways between 1918 and 1962. Although its original design had some key shortcomings, a number of improvements were made over the class' long career on the VR, many of which were subsequently applied to other locomotive classes on the system.
The A2 class was an express passenger locomotive that ran on Victorian Railways from 1907 to 1963. A highly successful design entirely the work of Victorian Railways' own design office, its long service life was repeatedly extended as the Great Depression and later World War II delayed the introduction of more modern and powerful replacement locomotives.
The Victorian Railways S class was a class of 4-6-2 express passenger steam locomotive operated by the Victorian Railways (VR) in Australia between 1928 and 1954. Built when the VR was at its zenith and assigned to haul the broad gauge-leg of its Melbourne to Sydney interstate express passenger services, the S class remained the VR's most prestigious locomotive class until the advent of diesel electric locomotives in the early 1950s.
The K class was a branch line steam locomotive that ran on Victorian Railways in Australia from 1922 to 1979. Although its design was entirely conventional and its specifications unremarkable, the K class was in practice a remarkably versatile and dependable locomotive. It went on to outlast every other class of steam locomotive in regular service on the VR, and no fewer than 21 examples of the 53 originally built have survived into preservation.
The N class was a branch line steam locomotive that ran on the Victorian Railways (VR) from 1925 to 1966. A development of the successful K class 2-8-0, it was the first VR locomotive class designed for possible conversion from 5 ft 3 in to 4 ft 8+1⁄2 instandard gauge.
The Victorian Railways H class was an express passenger steam locomotive operated by the Victorian Railways from 1941 to 1958. Intended to eliminate the use of double heading A2 class locomotives on The Overland services on the steeply graded Western line to Adelaide, wartime restrictions led to only one locomotive being built. Nicknamed Heavy Harry, H220 was the largest locomotive ever built in Australia and the largest non-articulated steam locomotive to run on Australian railways.
The R class was an express passenger steam locomotive that ran on Australia's Victorian Railways (VR) 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.
The Victorian Railways J class was a branch line steam locomotive operated by the Victorian Railways (VR) between 1954 and 1972. A development of the successful Victorian Railways K class 2-8-0, it was the last new class of steam locomotive introduced on the VR. Introduced almost concurrently with the diesel-electric locomotives that ultimately superseded them, the locomotives were only in service for a relatively short time.
The DD class (later reclassified into D1, D2 and D3 subclasses) was a passenger and mixed traffic steam locomotive that ran on Victorian Railways from 1902 to 1974. Originally introduced on mainline express passenger services, they were quickly superseded by the much larger A2 class and were relegated to secondary and branch line passenger and goods service, where they gave excellent service for the next fifty years. The DD design was adapted into a 4-6-2T tank locomotive for suburban passenger use, the DDE (later D4) class. They were the most numerous locomotive class on the VR, with a total of 261 DD and 58 locomotives built.
The Victorian Railways L class was a class of electric locomotives built by English Electric and operated by the Victorian Railways and later V/Line from 1953 until 1987 primarily on the Gippsland line. They were the only class of main line electric locomotive operated in Victoria.
The mainline passenger locomotives, later classified as B class, ran on the Victorian Railways (VR) between 1862 and 1917. They used a 2-4-0 wheel arrangement, which provided greater traction on the new, more heavily graded Geelong–Ballarat railway and the Melbourne-Bendigo-Echuca railway, as opposed to the 2-2-2 arrangement previously selected for the relatively level Geelong line. The B class locomotives are regarded as the first mainline VR motive power, and were highly successful in passenger operations.
The Prussian S 6 was a class of German steam locomotive with a 4-4-0 wheel arrangement operated by the Prussian state railways for express train services.
The Victorian Railways V Class is a steam locomotive, used on the Victorian Railways in the period 1900-1930.
The South African Railways Class 12A 4-8-2 of 1919 was a steam locomotive.
The Russian locomotive class U was a Russian express passenger steam locomotive type. The class U was a 4-6-0 four-cylinder compound locomotive which used de Glehn compound system.
The Caledonian Railway 721 Class was a class of 4-4-0 steam locomotives designed by John F. McIntosh for the Caledonian Railway (CR) and introduced in 1896. All survived to be absorbed by the London, Midland and Scottish Railway (LMS) in 1923 and a few survived into British Railways (BR) ownership in 1948.
SG is the name of a class of Indian steam locomotives used for freight trains. In the designation stands S for Standard, G for Goods. It was by number of built locomotives one of the largest steam locomotive classes built in United Kingdom. The design originated from a BESA standard.
The Midland Great Western Railway (MGWR) A Class, later Inchicore Class D5, consisted of 6 4-4-0 express passenger locomotives built at Broadstone Works in the period 1902-1905. The largest express passenger locomotive in Ireland for a short while after introduction they were used on the MGWR's flagship services to Galway with most surviving until the 1950s albeit on less prestigious work.
