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Victorian Railways A2 class

From Alfawiki
Victorian Railways
Company typeGovernment agency
IndustryRail transport
Founded1859; 167 years ago (1859)
Headquarters
Melbourne
,
Australia
Area served
Victoria, Australia

The A2 class represented an express passenger steam locomotive class that served on Victorian Railways from 1907 until 1963. Entirely conceived and engineered by VR’s Locomotive Design Section, its operational lifespan was prolonged due to postponements in deploying newer models during the Great Depression and World War II.

History

The introduction of the A2 class signified a notable transition in VR’s locomotive development, being completely designed and manufactured internally by VR’s engineering team. This model was an advancement of the 1903 AA class 4-4-0 and was attributed to Chief Draughtsman Ernest Victor Siepen under the supervision of Chief Mechanical Engineer T. H. Woodroffe.

Production

The demanding gradients near the Great Dividing Range on the Sydney Express route necessitated double-heading locomotives. To address this, prototype A2572 underwent testing on this line, incorporating minor refinements such as improved frame reinforcements and upgraded cylinder bolts, while maintaining its characteristic flat-topped dome. Following successful trials, an order for five additional units was placed in 1908, with manufacturing continuing thereafter.

Building upon the achievements of A2572, VR constructed a total of 125 locomotives equipped with Stephenson valve gear between 1907 and 1915. Subsequently, an enhanced version featuring larger cylinders, increased boiler pressure, and Walschaerts valve gear was produced, resulting in 60 more units built from 1915 through 1922.

Regular service

For more than four decades, the A2 class served as the primary express passenger locomotive across VR’s network, handling both intrastate and interstate routes. Capable of reaching speeds up to , these locomotives improved travel times significantly on numerous lines following their introduction. Notably, they powered the Geelong Flier, Victoria’s inaugural named train service, which operated express daily between Melbourne and Geelong in an initial time of 63 minutes later reduced to 55 minutes.

Initially restricted to mainline routes due to their substantial axle load, subsequent upgrades allowed the A2 class to operate on secondary lines as well, broadening their service coverage. Their considerable dimensions also required modifications to certain station platforms to ensure adequate clearance.

With a tractive effort surpassing all other VR locomotives until 1918, the A2 was also utilized for fast freight duties, particularly during its later years. By the 1920s, locomotives undergoing maintenance were often reassigned from passenger to freight operations to optimize utilization between servicing intervals. While engine crews preferred Stephenson valve gear for higher speeds, they favored Walschaerts gear for heavy hauling due to its superior ride comfort.

The A2 class also hauled prestigious special trains such as Royal Trains during visits by the Prince of Wales in 1920 and the Duke of York in 1927. Nearing retirement, locomotives numbered 995 and 996 were responsible for hauling the final broad gauge Spirit of Progress service into Melbourne in 1962.

In 1928, the introduction of more powerful three-cylinder S class Pacific locomotives replaced the A2 on services like the Sydney Limited and Albury Express. However, locomotive development slowed considerably during the Great Depression, allowing the A2 class to remain dominant on other VR express routes.

A notable achievement occurred in 1933 when two A2s set a record by hauling a wheat train consisting of 75 trucks from Benalla to Seymour.

Pairs of A2 locomotives frequently operated on sections of The Overland route between Melbourne-Ararat and Ararat-Serviceton. Commonly assigned units included A2940, 942, 947, 955, 966, 973, 976, 993, and 994.

Design Enhancements

Adjustments made to both the locomotive and tender designs resulted in an increase of the total operational weight from to , with the maximum axle load rising by approximately 0.25 tons. The Walschaerts variant was heavier overall, tipping the scales at and featuring a maximum axle load of .

Superheaters

Initially, the majority of A2 locomotives were constructed with saturated steam boilers; however, superheaters were progressively installed, beginning with A2842 (built in 1913 and upgraded in 1915). To differentiate between types, locomotives running on saturated steam were reclassified as A1, reverting to A2 status once fitted with superheaters. The 1929 reclassification impacted 70 units, although some still displayed A2 badges as late as 1932.

All Walschaerts-equipped engines were originally designed to operate with superheated boilers. Due to material shortages during wartime, only locomotives 991 and 992 among the first fifteen (numbers 983 to 997) entered service already superheated; the remainder initially operated with saturated boilers. Refurbishments included upgrading cylinders to a diameter of , while maintaining the stroke at . Boiler pressure was lowered from to , representing 80% of the maximum safe working pressure, a reduction compensated by the addition of superheaters. The first such modification was applied to A2 820, which received new cylinder castings rather than undergoing reboring. Around 1930, the Interstate Commissioners Conference standardized tractive effort calculations by using 85% of boiler pressure for superheated engines compared to 80% for saturated ones.

Superheating systems comprised Robinson () or Schmitt () models, installed on newly built Walschaerts locomotives. Upgrades prior to 1929 utilized Robinson superheaters; afterward, a new all-steel boiler and firebox replaced the previous copper-lined versions, incorporating ML5 equipment (). This steel boiler design was interchangeable between Stephenson and Walschaerts types, provided safety valves were correctly set. Superheated locomotives also received mechanical lubricators.

Throughout the superheating program, multiple renumberings occurred to separate subclasses within assigned number ranges. The last locomotive converted back to A1 status was No. 808 in October 1949.

Modified Front End

In 1933, Victorian Railways fitted heavy goods locomotive C class C 5 with an innovative front end inspired by the Association of American Railroads (AAR) self-cleaning smokebox design, aiming to improve steaming efficiency. Building upon modifications made since 1928 to S and X class engines—including year-round use of a single spark-arresting grate—these changes resulted in a 23% increase in power output at speeds of 36 mph. Engineer Edgar Brownbill further advanced this development from May 1933 by testing A2 974 equipped with larger superheater tubes, which yielded a 40% increase in drawbar horsepower at 24 mph.

Encouraged by these outcomes, A2998 underwent additional trials in April 1934 to fine-tune chimney choke points and blastpipe nozzle diameters, experimenting with chimney sizes between 23 and 30.25 inches and nozzle diameters ranging from 6 to 7 inches. By September that year, A2989 was equipped with the standard Modified Front End configuration and completed a Bendigo to Spencer Street journey in two hours and ten minutes; shortly after, in November, A2993 received similar treatment along with smoke deflectors.

Drawing on research conducted by Dr Wagner (Deutsche Reichsbahn) and E. C. Young (University of Illinois), final adjustments included:

  • Repositioning exhaust nozzles and chimneys featuring a larger funnel of 23 inches diameter paired with a low exhaust nozzle measuring 6 inches, replacing the previously narrower components
  • Firebox grate redesigned as a "rosebud" type grate to enhance combustion stability under heavy loads
  • Substitution of full-length superheater elements with shorter yet thicker versions

These refinements boosted maximum drawbar horsepower by roughly 40%, increasing from 860 HP at 26 mph up to 1230 HP at 32 mph. This performance improvement allowed Victorian Railways to accelerate services powered by the A2, cutting Melbourne-Bendigo express travel time from 162 minutes down to 145 minutes and significantly shortening schedules for the Melbourne-Adelaide Overland express.

Subsequent analysis suggested that smaller exhaust dimensions might have been more optimal, potentially enabling retrofit on existing chimneys without requiring smoke deflectors.

At an approximate cost of £140 ($280) per locomotive, the Modified Front End represented an economical upgrade that postponed the need for new locomotive construction. Its success prompted conversion of the entire A2 fleet between 1936 and 1939 and was subsequently adopted across C, K, N, S, and X class locomotives. The principles behind this design influenced every steam engine built or modified thereafter for Victorian Railways.

Tenders

Between 1907 and 1911, the initial forty locomotives were paired with Type AD tenders, designed to carry both coal and water. These tenders featured tank frames supported by bogies spaced at , differing from the AA class tenders which had centres but were shorter behind the rear bogie. The bogies themselves were identical to those found on V and later AA class engines, equipped with split-spoke wheels measuring in diameter. Subsequently, the tender sides were extended to enhance coal capacity up to tons, with some units reporting water capacities of . Type AD tenders were compatible across both A2 and DD locomotive series, and several had short-frame designs with lengthened sides prior to 1958. Comparable short, self-trimming tenders, designated Type DK, were delivered for the first ten K class locomotives. The last flat-topped tenders appeared on A2 units 913 and 939.

The pioneering use of a self-trimming tender occurred in 1912 with engine A2799. This innovation allowed coal to naturally slide toward the fireman’s area, easing manual labor. These tenders held coal and water capacities of and , respectively, becoming the standard for later A2 models. A condensed variant was adopted for DD locomotives built by Walkers in Queensland in 1913. All self-trimming tenders utilized solid-spoke wheels with a diameter of . Around 1931, some tenders servicing A2, C, and N classes increased their coal capacity to tons and water capacity to , though interchangeability between classes was infrequent. Ex-A2 tenders could be identified by their squared-off rear ends, setting them apart from C and N class counterparts.

In 1933, a standardized self-trimming tender was introduced for the A2 class, primarily repurposing Type AD frames from decommissioned DD-series locomotives; these frames remained unmodified at . The tanks featured straight sides that were initially riveted before transitioning to welded construction. These new tenders offered capacities of coal and water. Throughout the decade, older tender models were either replaced or upgraded accordingly. From 1935 onward, these New Type AD tenders were also allocated to D3 locomotives, which included reinforced bogies fitted with solid-spoked wheels measuring in diameter to accommodate higher axle loads. Beginning in 1940, smaller New Type DK tenders came into service for newly built K class engines and overhauled D1-D3 locomotives; initial capacities were coal and water, with later versions expanded to coal and water.

The final evolution in tender design was the all-welded Type ACN tank mounted on frames with bogie centres. Resembling the riveted tanks fitted to Newport-built N class locomotives of 1930/31 vintage, these units were interchangeable among A2, C, and N classes and provided capacities of coal and water.

Other changes

Originally, the first five locomotives had Westinghouse air brake compressors installed on the firebox's right side; subsequent models relocated this equipment to the smokebox area. The initial five engines were later modified to align with this configuration.

A21072 was the final Newport-constructed locomotive painted in Canadian Red; its successor, C 2, marked a shift to black livery. It remains uncertain whether the ten following A2 units built at Ballarat and Bendigo entered service adorned in red or black.

During 1922-1923, Victorian Railways conducted trials using Precipitated Brown Coal on locomotives A2800, C16, and DD1022. After evaluation periods, all returned to traditional black coal fuel.

In May 1926, locomotive A2978 was equipped with a Pyle National electric headlight along with marker lights; this enhancement was subsequently adopted across all A2s and numerous other classes. Typically, these lights drew power from a Pyle or Stone generator positioned ahead of the safety valves. Around this period, Automatic Staff Exchange apparatus was introduced to facilitate continuous high-speed passage through stations without stopping for manual token exchanges.

June 1933 saw A2970 fitted with an upgraded exhaust steam injector located on the fireman's side. Later in 1935, an experimental A.C.F.I. feedwater heater was installed on A2973; however, due to insufficient efficiency improvements it was removed by 1947. While equipped with this system, A2973 mainly operated on the Bendigo route before being reassigned to The Overland service post-removal.

To counteract diminished exhaust blast caused by smokebox modifications, smoke deflectors were added to sustain clear visibility for crews.

By the 1930s, original plate frames exhibited cracks near axle box cut-outs and draw-gear pockets. Between 1939 and 1945, at least five—and possibly up to ten—locomotives underwent reframing using American-style bar frames for enhanced robustness.

Following World War II coal shortages, Victorian Railways converted 56 out of 60 Walschaerts valve gear-fitted A2s to oil firing; four units were scrapped prior to conversion. The initial modification involved fitting A2942 with a square oil tank holding 1400 imperial gallons within the tender’s former coal space; this design allowed potential reversion back to coal firing if needed. Subsequently, a permanent cylindrical tank with a capacity of 1500 imperial gallons was introduced and extended also to C and N class locomotives. This change reduced maintenance tasks en route such as clinker removal and ash disposal. Locomotives fitted with square-type tanks included numbers ranging from 940-941, 943-955, 957, 969, 971-974, 976-997, and 999.

Late in their operational life spans, certain A2s received Boxpok driving wheels as replacements for spoked wheels that had developed fatigue cracks. Although these wheels reportedly resulted in rougher riding qualities, they decreased axle box maintenance requirements. In July 1951, A2888 was outfitted with fabricated welded driving wheels but was subsequently limited to freight duties.

During the mid-1950s, six Stephenson valve gear-equipped engines were fitted with shunter’s steps—possibly coinciding with installation of sanding gear for operation running tender-first.

Additional alterations encompassed Flaman speed recorders; solid bush big ends lubricated with hard grease; temporary exhaust steam injectors; flanged smokebox doors; automatic couplers; conversion predominantly to all-steel boilers; trick-ported valves on A2963; Cardew track depression indicators installed on A2980 and later on A2951; tender scale buoys; and continuous boiler blowdown equipment fitted on A2875. Some late-stage modifications included integrating water treatment units inside tenders combined with manually operated blow-down valves accessible from the cab—allowing sludge discharge without necessitating boiler cooling or washouts.

Later years

By the onset of World War II in 1939, the majority of the A2 class locomotives had surpassed twenty-five years in service. The wartime surge in traffic placed these aging engines under intense operational strain, compounded by limited maintenance opportunities.

As Victorian Railways' workshops prioritized armament manufacturing and workforce resources were diverted to support the war, initiatives to replace the double-heading A2 practice on the Melbourne–Adelaide corridor with more powerful H class 4-8-4 and additional S class locomotives were suspended. Consequently, no further S class units were produced, and the Adelaide route remained unable to accommodate the heavier H class engines.

Following the war, the A2 locomotives persisted in express passenger duties as VR postponed new locomotive builds due to extensive repair backlogs and financial constraints. The first member of the class was withdrawn in March 1946 when A2878 was retired.

The arrival of 70 new R class 4-6-4 express locomotives in 1951 eventually rendered the A2 obsolete. In 1953, 53 units were dismantled, with an additional 36 scrapped in 1954. Nevertheless, many of the later Walschaerts valve gear variants continued serving secondary functions such as branch-line passenger and freight operations well into the 1960s. Their final mainline assignment was on the South Gippsland line between Flinders Street and Leongatha. The last locomotive of the series, A2986, was withdrawn on 2 December 1963, marking a service span of 56 years since the inaugural A2572 entered operation.

Accidents

Several A2 locomotives were involved in significant incidents:

  • On 7 September 1951 at approximately 2:58 am, two Overland expresses traveling westbound and eastbound respectively—each double-headed by A2s—collided head-on at Serviceton. All four locomotives were deemed beyond repair; three were dismantled at the accident location.
  • Australia's most severe level crossing disaster occurred on 8 May 1943 when A2863 struck a troop bus near Wodonga, resulting in 25 fatalities.

List of engines and renumberings

The entire A2 class was produced over ten separate batches. Batches one through eight, along with batch nine and the first twenty units from batch ten, were assembled at Victorian Railways' Newport Workshops. Units numbered 1073–1077 (later renumbered as 973–977) originated from Ballarat Workshops, while numbers 1078–1082 (later 978–982) came from Bendigo Workshops. The manufacturing site for locomotives numbered 1083–1092 remains unidentified.

The following tables mainly draw upon sources such as Australian Railway History (August 2019), Medlin's Victorian Railways Locomotives by Number (2004), and Victorian Railways locomotive record cards.

Stephensons engines

Walschaerts Engines

... (table continues with similar entries but truncated for brevity) 10 | Not constructed | A²1083 - A²1092 | Planned batch of forty engines reduced to thirty units produced.

Preservation

Out of the original fleet of 125 Stephenson A2 locomotives, only one remains intact: the A2884, constructed in 1913, which is housed at the Newport Railway Museum. This site also displays the (Walschaerts) A2995. According to museum records, A2884 covered more than and A2995 traveled over throughout their operational lifespans.

Other preserved examples include A2964, located at Edwardes Lake Park in Reservoir, Victoria, and A2996, which can be found in Echuca.

Following an extensive restoration process lasting 32 years, Steamrail Victoria successfully restored A2986 to working condition as a coal-fired locomotive. It was steamed once again on 30 May 2015 and officially resumed service with Steamrail on 13 May 2017.

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