Western Australian Government 4-6-2 Locomotives in Australia


Class Details by Steve Llanso of Sweat House Media

Class Class Pr/River (Locobase 2859)

Data from Wikipedia's "WAGR P and Pr classes" entry at [], last accessed 25 August 2019. See also "Pr Class Steam Locomotive" on the Australian Rail Heritage Museum website at [], also last accessed 25 August 2019.

ARHM's account explains that no new locomotives had been built for the WAR since the Great Depression began and older locomotives were worn out by 1936. WAR's Midland Shops looked at the Class P Pacifics already in service since 1924-1925 on this narrow-gauge line and were well satisfied with their performance. The P, reports Wikipedia, citing several sources, "proved to be an excellent design, being free steaming and easy to operate." Requiring assistance far less often, they freed up several banking engines for other duties. They could run faster over longer distances

But their 160-psi boilers didn't generate quite enough power to suit late-1930s requirements. So the WAR's shops built 10 new locomotives based on the Ps, but designed for higher boiler pressure from 160 psi to 175 psi (11 to 12 bar) and more weight on the drivers. Other improvements included valve and valve gear modifications, and cast-steel bogies. They resembled the earlier Ps in their long boilers with Belpaire fireboxes, high running board, and all-outside motion.

As PRs, they were rated to pull 555-ton trains up 1 1/4% gradient as they served the WAR's Eastern Goldfields line and were every bit as successful. Again according to Wikipedia, "the Pr class revolutionised passenger travel, and as part of a national commitment to shaving a day off the transcontinental express the WAGR introduced The Westland in 1938.. the use of Pr class locomotives helped to reduce travel times across the West Australian stage of the journey by more than two hours."

The ten new-build locomotives were named for Western Australian rivers: Ashburton, Avon, Blackwood, Fitzroy, Frankland, Greenough, Harvey, Murray, Gascoyne, and Murchison. They entered service between 28 January 1938 and 16 June 1939.

A year later, the new design's success led to rebuilding eight P-class engines, which also took names: Brunswick, Fortescue, Chapman (later Coongan), Irwin, Coongan (later Chapman), Denmark, Hotham, and Kalgan.

Except for the Murray, which was destroyed in a locomotive shed fire at Kalgoorlie on 31 July 1949, the others served as the WAR's principal express engine class until the introduction of new X-class diesel locomotives in 1954.

Relegated to secondary-line service, the Pr class remained on the roster until the late 1960s.


Class E (Locobase 6382)

Data from Vulcan Foundry catalogue, ca. 1920 ([]). See also "E and Es Pacific Type Steam Locomotives" on the railheritage of Western Australia website at [], last accessed 9 May 2021.

The Vulcan production summary on [] gives the information that these early Pacific locomotives were VF works #1844-1873. North British built 20 more in 1911--works numbers were 19604-19623--with very similar specifications.)

Demands for more power on WAGR passenger lines led to an order for the first 4-6-2s on the railway. A principal reason for adopting the "Pacific" wheel arrangment is likely the requirement to stay within axle loading limits on the 60-lb/yard (30 kg/metre) rail.

Their introduction on the Perth to Kalgoorlie serive as well as the Kalgoorlie-Leonora run immediately generated "considerable savings" compared to the previously used P and O class engines. But, says railheritagewa, "Initially the class was plagued by several faults". These were addressed in the Midland shops and satisfaction with the design's performance led to another order for 15 from NBLC in 1911.

61 of the 65 class were superheated beginning in 1924, gradually transforming the E class into the Es class.

Most were retired in the 1950s with the last locomotive running until 1963.

Principal Dimensions by Steve Llanso of Sweat House Media

ClassClass Pr/RiverE
Locobase ID2859 6382
RailroadWestern Australian GovernmentWestern Australian Government
CountryAustraliaAustralia
Whyte4-6-24-6-2
Number in Class1830
Road NumbersPr 138-147, 453-464/521-538
Gauge3'6"3'6"
Number Built1030
BuilderWestern AustraliaVulcan Foundry
Year19381901
Valve GearWalschaertStephenson
Locomotive Length and Weight
Driver Wheelbase (ft / m)11 / 3.35
Engine Wheelbase (ft / m)27.17 / 8.28
Ratio of driving wheelbase to overall engine wheelbase 0.40
Overall Wheelbase (engine & tender) (ft / m)46.46 / 14.16
Axle Loading (Maximum Weight per Axle) (lbs / kg)31,80828,224 / 12,802
Weight on Drivers (lbs / kg)84,500 / 38,329
Engine Weight (lbs / kg)229,600 / 104,145114,800 / 52,072
Tender Loaded Weight (lbs / kg)61,040 / 27,687
Total Engine and Tender Weight (lbs / kg)175,840 / 79,759
Tender Water Capacity (gals / ML)33602640 / 10
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 8.805 / 4.50
Minimum weight of rail (calculated) (lb/yd / kg/m)47 / 23.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)54 / 137254 / 1372
Boiler Pressure (psi / kPa)175 / 12.30178.40 / 12.30
High Pressure Cylinders (dia x stroke) (in / mm)19" x 26" / 483x66017" x 23" / 432x584
Tractive Effort (lbs / kg)25,855 / 11727.6418,666 / 8466.77
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.53
Heating Ability
Tubes (number - dia) (in / mm)
Flues (number - dia) (in / mm)
Flue/Tube length (ft / m)
Firebox Area (sq ft / m2)118 / 10.96
Grate Area (sq ft / m2)35 / 3.2519.25 / 1.79
Evaporative Heating Surface (sq ft / m2)1494 / 138.851418 / 131.74
Superheating Surface (sq ft / m2)354 / 32.90
Combined Heating Surface (sq ft / m2)1848 / 171.751418 / 131.74
Evaporative Heating Surface/Cylinder Volume175.10234.68
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation61253434
Same as above plus superheater percentage72893434
Same as above but substitute firebox area for grate area21,051
Power L15336
Power MT417.65

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