[3] At this time, the Sydney Express was regularly double-headed in both directions between Melbourne and Seymour, due primarily to the gradients either side of the Great Dividing Range.

[1] For over forty years, the A2was the main express passenger locomotive on the VR, hauling intrastate and interstate services.

With a maximum permitted speed of 70 miles per hour (115 km/h),[6] the A2was instrumental in the acceleration of timetables on many lines in the years following its introduction.

[9] Due to their comparatively heavy axle load, A2 locomotives were initially limited to the principal mainlines, but gradual upgrades to secondary lines saw the route-availability of the class expand, together with the range of services they hauled.

[1] As early as the 1920s, it was reported as normal practice that A2 class locomotives requiring adjustment to axle boxes and other moving parts be swapped from passenger to lower-speed freight service to extract more work from them between overhauls.

[14] A2s were also used to haul a number of special services, such as the Royal Trains for Australian tours of Prince of Wales and the Duke of York, in 1920[15] and 1927 respectively.

Towards the end of their lives, A2995 and 996 also had the distinction of hauling the last broad gauge Spirit of Progress service into Melbourne on 16 April 1962.

[16] In 1928, the A2 was replaced on the principal North East line Sydney Limited and Albury Express services by the considerably more powerful three-cylinder S class Pacifics.

In 1933, two A2 class locomotives set a haulage record for Victorian Railways when they headed a 75-truck 1,598-long-ton (1,624 t) wheat train from Benalla to Seymour.

[18] Pairs of A2 class engines were regularly worked on the Melbourne-Ararat and Ararat-Serviceton portions of The Overland; common candidates included A2940, A2942, A2947, A2955, A2966, A2973, A2976, A2993 and A2994.

In 1933, C class heavy goods locomotive C 5 was equipped with a new front end, based on the Association of American Railroads (AAR) design of self-cleaning smokebox, to improve steaming qualities.

[20] Victorian Railways' Rolling Stock branch engineer Edgar Brownbill continued this work from May 1933, conducting tests with A2 974 between Melbourne, Bendigo and Seymour with 1+1⁄2 in (0 m) diameter superheater tubes, for a net improvement of 40% increased drawbar horsepower at 24 mph (39 km/h).

[21] These results were very promising, and in April 1934 A2998 was selected for a series of additional tests aimed at further front end improvement.

[3][4] Experiments were conducted, based on the work of Dr Wagner of the Deutsche Reichsbahn and E. C. Young of the University of Illinois, with final modifications to the A2 locomotive including:[22] The sum result of the changes was a significant improvement in power and available tractive effort.

A similar, but shorter and reduced capacity, version of this design was provided for the DD class locomotives delivered from Walkers, Queensland in 1913.

[19] The original five locomotives had their Westinghouse air brake compressors mounted on the right-hand side of the firebox; all later engines had this changed to the smokebox, and within a few years the first five were amended to suit.

[11] The equipment was, however, retained for significantly longer than equivalent experiments by the New South Wales, Commonwealth and Western Australian Railways.

[27] By the 1930s the original plate frames of the A2 class had proven prone to cracking, particularly around the axle box cut-outs and the draw-gear (coupler) pockets.

Additional benefits included less time needed for enroute engine maintenance, e.g. breaking up clinker in the firebox and dumping of ash.

[28] These wheels were reputed to give the engines a very rough ride,[14] but apparently reduced the amount of maintenance required to the axle boxes.

[29] In July 1951, engine A2888 was fitted with a different style of driving wheel, described as "fabricated welded", but restricted to freight work from that point on.

[4] Other alterations not noted above included fitting of Flaman speed recorders, solid bush big ends and hard grease lubrication, exhaust steam injectors (for a while), flanged smokebox doors, automatic couplers, conversion to all-steel boilers (most locomotives), trick-ported valves on A2963, Cardew track depression indicator gear on A2980 and later A2951, and tender scale buoy and continuous blowdown for A2875.

[2] Some of the last changes involved fitting of integral water treatment units to the tenders, with a blow-down valve operated manually from the cab.

The massive increase in traffic on the VR the war effort brought saw these ageing locomotives subjected to a punishing regime of heavy utilisation and minimal maintenance.

[11] However, many of the class (particularly the later Walschaerts variants) continued on in secondary roles such as branch-line passenger and goods services and a number lasted into the 1960s.

Their last regular mainline duty was hauling services between Flinders Street and Leongatha, on the South Gippsland line.

Except where otherwise marked, these tables are based on: Only one of the original batch of 125 Stephenson A2 locomotives survives; 1913-built A2884 is today preserved at the Newport Railway Museum, along with (Walschaerts) A2995.