The Midland Railway of Western Australia, founded in 1890, received its first major order from Hawthorn, Leslie & Co. in England. There were nine 4-4-0 steam locomotives with a gauge of 3 ft 6 in. They were given the numbers B2 to B10 and with a driver diameter of 4 ft 4 in, the small railway could use them in front of any type of train. Decommissioning began in 1929, but stopped after four engines. The remaining five continued to be used as shunting locomotives and remained in service until the 1950s.

One of the last engines to be retired was the B6, which was exhibited in Geraldton in the park not far from its previous route after its end of service in 1956. It is the only MRWA steam locomotive still in existence today. It changed hands in 1995 and ended up unseen in a locomotive shed. After renewed interest in railroad history among Geraldton residents, it was retrieved in 2010 and placed in the Walkaway Railway Station Museum, where plans have been made for its restoration ever since.

After the train weights on the Trans-Australian Railway had increased in the 1930s and the line was extended to include a branch to Port Pirie, the existing class G passenger locomotives reached their limits. Even the rebuilding of seven units with superheaters could not solve the problem, so that additional engines were necessary. Eight heavier locomotives were therefore ordered from Walkers Limited, which were again based on the New South Wales Government Railways class C36 built from 1925. The locomotives themselves were again taken over almost unchanged, but significantly heavier tenders with six axles were attached.

These locomotives were built by Walkers Limited of Maryborough, Queensland and were delivered in four months in early 1938. They were used on the Trans-Australian Express right from the start and replaced the previously used class Ga locomotives within a very short time. The main reason was that they covered the distance in ten hours less. During the major strikes in the coal industry in 1949, four locomotives were temporarily converted to oil firing. The introduction of the GM class diesel locomotives from 1951 ensured that the C class steam locomotives were retired at the same time as their predecessors. After the last one had served its purpose in 1957, all pieces fell victim to the scrap press. Only the large tenders survived into the 1980s, as they were used as water tanks for weed-killing trains.

These two locomotives were built by Baldwin for the New Haven in 1905 and 1907 as part of the G-4 class and were used by them until 1943. At that time, there were already significantly more powerful steam locomotives with a significantly higher axle load in the USA, and so the G-4 class examples that were still in use became superfluous. The Second World War brought with it the Lend-Lease Act, which was intended to strengthen the US allies by supplying war-related technical equipment. This also included the railways in order to be able to cope with the increased transport tasks.

In this environment, two locomotives were sold cheaply to the Commonwealth Railways and numbered CA78 and CA79 there. These were tender locomotives with a 4-6-0 wheel arrangement, which were suitable for mixed traffic with a coupling wheel diameter of 73 inches and had an axle load of around 45,000 pounds. The two locomotives were not technically identical, but differed in the area of valve gear. While the CA79, built in 1905, had Baker-type gear, the CA78 had Southern-type gear. The service life of the locos in Australia was very short as the newer engine was retired immediately after the end of the war and the other in 1950. Both were scrapped in 1956. A similar history was shared by the eight CN class locos used by the Montreal Locomotive in 1907 and 1908 Works and bought by the Canadian National in 1942.

In 1912 construction began on the standard gauge Trans-Australian Railway, completing the west-east link across the continent. The newly built route was located in the states of Western Australia and South Australia and ran 1,063 miles from Kalgoorlie to Port Augusta. The Commonwealth Railways were founded to operate this route, which later also took over north-south connections on the Central Australia Railway. 26 class G locomotives were purchased for passenger service and were initially used to build the line. Work stalled somewhat during the First World War, but when it opened in 1917 the units were able to serve their intended purpose as passenger locomotives and also hauled the Trans-Australian Express.

G20 circa 1925 on the Trans-Australian Express at Tarcoola

The locomotives were based on the New South Wales Government Railways class P (later C32) built from 1892 to 1911. They differed from these mainly by having a four-axle tender instead of a three-axle tender to cover longer distances. On the locomotives built by Clyde Engineering, the tenders held five long tons of coal and 3,650 gallons of water. Baldwin and Toowoomba, on the other hand, used tenders carrying seven and a half long tons of coal and 4,500 gallons of water. Later they got an even bigger tender with ten long tons and 4,850 gallons. 

Schematic drawing with dimensions

Commonwealth Railways

In terms of boiler pressure and cylinder dimensions, they corresponded to the most recently built series of their prototypes and they were also initially operated using saturated steam. While the class P locomotives were retrofitted with a superheater as early as 1914, only seven class G units received one in the 1930s. In this form they were used as class Ga and from 1938 they were replaced by the heavier class C locomotives and gradually phased out. As the decommissioning dragged on, eleven class G and Ga locomotives were still available in 1951. However, the introduction of diesel locomotives that started now accelerated the phase-out, so that by the following year almost all of them had disappeared and only a single engine served as a shunting locomotive until 1958.

The good experiences with the first narrow-gauge Garratts led the Tasmanian Government Railways to order two Cape gauge Garratts each for passenger and freight trains in 1912. Two class M Double Atlantics were ordered for passenger service, which had four cylinders of the same size in each bogie. They were the only Garratts ever built with eight cylinders.

They used the same boiler as the class L freight locomotives. They were probably the most powerful articulated passenger locomotives in the world at the time of their entry into service and often reached speeds of 50 mph or 80 km/h in daily use. The top speed was about 60 mph or 97 km/h. Since the eight cylinders were very time consuming to maintain, they were phased out in the mid-1920s after the class R Pacifics had been introduced.

The class A of the Midland Railway of Western Australia consisted of nine Mikados built by Kitson & Co. in England. Three were delivered in 1926, three in 1927 and three in 1929. They had drivers of 3 ft 10 1/2 in and cylinders of 18 by 24 inches. They were all withdrawn in 1957 and 1958 and subsequently scrapped.