Western Australian Government 4-8-2 Locomotives in Australia

Class Details by Steve Llanso of Sweat House Media

Class W (Locobase 2874)

These little Mountains ("hills?") are an instructive example of how tractive effort and adhesive weight could be spread out over several axles in a steam locomotive. The requirement, says Nock (RWC VI, pl 43), was for an engine that could tolerate highly saline water and low-calorie Collie coal.

Nicholas Pusenjak of [] notes that after several different chief engineers in 1947 and 1949, the new CME tweaked the firebox design to ensure good combustion. Beyer, Peacock supplied 40 partially assembled locomotives in 1951. These were completed at the WAGR's Midland shops. Twenty more arrived ready to run; these had larger tenders holding 600 gallons more water.

(Pusenjak notes that the Silverton Tramway Company, of Broken Hill in NSW, had 4 engines of a very similar design and built at the same time.) Those are described in Railway Transportation, February 1952

"They gained a reputation of being free-steaming, smooth riding and capable of a good burst of speed. And so they should, having taken nearly 3 years to design, and having a lot of 'State of the Art' equipment fitted" The Specs page shows some of this equipment, including a thermic syphon and two arch tubes in the firebox as well as a generous combustion chamber. They were, however, hand-stoked

Photographs show a handsome, straightforward design in green livery and red running gear trim. The steam and sand domes are combined in a single long and tall "bin".

Pusenjak adds that their working life "...lasted until 1972, withdrawals started in 1971 and the last were set aside Christmas Eve 1972. Most were scrapped, however the WAGR stored 19 of the W Class as Emergency power should it be needed, eventually disposing of them as more diesels were acquired. This proved to be most fortunate, as 15 have been preserved at various sites around Australia, of which at least 10 are in operation."

NB: Tube length is an estimate based on the calculation of tube surface area by subtracting reported firebox heating surface from reported total evaporative heating surface

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID2874
RailroadWestern Australian Government
Number in Class60
Road Numbers901-960
Number Built60
BuilderBeyer, Peacock
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.37 / 4.08
Engine Wheelbase (ft / m)31.50 / 9.60
Ratio of driving wheelbase to overall engine wheelbase 0.42
Overall Wheelbase (engine & tender) (ft / m)
Axle Loading (Maximum Weight per Axle) (lbs / kg)22,050 / 10,002
Weight on Drivers (lbs / kg)87,040 / 39,481
Engine Weight (lbs / kg)
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)
Tender Water Capacity (gals / ML)
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT)
Minimum weight of rail (calculated) (lb/yd / kg/m)36 / 18
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)48 / 1219
Boiler Pressure (psi / kPa)204.50 / 14.10
High Pressure Cylinders (dia x stroke) (in / mm)16" x 24" / 406x610
Tractive Effort (lbs / kg)22,250 / 10092.44
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.91
Heating Ability
Tubes (number - dia) (in / mm)70 - 2" / 51
Flues (number - dia) (in / mm)22 - 5.25" / 133
Flue/Tube length (ft / m)14 / 4.27
Firebox Area (sq ft / m2)187 / 17.38
Grate Area (sq ft / m2)27 / 2.51
Evaporative Heating Surface (sq ft / m2)1117 / 103.81
Superheating Surface (sq ft / m2)305 / 28.35
Combined Heating Surface (sq ft / m2)1422 / 132.16
Evaporative Heating Surface/Cylinder Volume200.00
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation5522
Same as above plus superheater percentage6681
Same as above but substitute firebox area for grate area46,272
Power L114,052
Power MT1423.68

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