Tasmanian Government 4-8-2 Locomotives in Australia


Class Details by Steve Llanso of Sweat House Media

Class H (Locobase 8579)

Data from [link], [link], and [link], all accessed 14 July 2007.

These small Mountains (Hills?) were works #5949-5956. They had cast-steel SCOA-P drivers and roller bearings on every axle including the four under the tender, the main (connecting) rod, and the side (coupling) rods. As delivered, the superheater measured 372 sq ft, but the diagram prepared by the Tasmanian's chief mechanical engineer H Townsend showed substantially less area and slightly more firebox area. Locobase adopted Townsend's numbers because they were taken from locomotives in service.


Class Q-original (Locobase 21251)

Data from TGR locomotive diagram L 12 at [link], last accessed 13 March 2025.. See also "The Railways of Tasmania", Locomotive Magazine, Volume XXVIII [28] (14 October 1922), pp. 88-91 (15 November 1922), pp. 323-326; and (14 April 1923, p. 97.. (Thanks to Oz Pete (Peter Dunn) for his 13 March 2025 email correcting the valve gear. A review of Locobase 9559, which first appeared in 2008, led to the addition of this entry.)

As delivered, these "heavy goods" (freight) engines had somewhat small boilers with Belpaire fireboxes.Their Schmidt British-pattern superheaters dispensed with dampers (as many other designs had done) but had a "patent circulatory system. Its "neat arrangement" of the radial constant-lead valve gear actuated 9" (229 mm) inside-admission piston valves and drove the second coupled axle.

LM noted the class's "somewhat severe" operating environment: :[I]t abounds in continuous grades of 1 in 40 (2.5%), together with many curves of five chains interspersed only with 40 ft (12.2 m) straights." Locobase considers LM's judgement to be "somewhat" understated.

This class was supplied in several batches from several Australian builders throughout the country. Perry Engineering of Gawler, South Australia delivered the first 6 in 1922 (along with 4 R-class 4-6-2). The TGR turned to Walkers Engineering across the continent in Queensland for the next 3 in 1929. And Clyde Engineering of New South Wales finished off the class with 6 in the late 1930s and 4 more in 1940. Two of the latter were delivered in 1944 while parts for the last two were sent to the TGR, which assembled them in 1945.

According to the Tasmanian Transport Museum's Q5 exhibit page ([link], last accessed 6 September 2008), these locomotives "...the class handled the majority of mainline goods trains around the state."

Locobase notices that not even the Vulcan H class had cylinders as large, nor did they have thermic syphons. TGR applied a signficant design change to the later Qs; see Locobase 9559.


Class Q-rebuilt-combustion chamber (Locobase 9559)

Data from TGR locomotive diagram L13 at [link], last accessed 13 March 2025.(Thanks to Oz Pete (Peter Dunn) for his 13 March 2025 email correcting the valve gear.)

Locobase 21251 describes the TGR's Q class as delivered. When they debuted in 1922, these "heavy goods" (freight) engines had somewhat small boilers with Belpaire fireboxes.

Over the next 20 years the TGR either built or modified the boilers and fireboses of at least fourteen in several respects. A combustion chamber reduced tube length by 31 1/2". Superheater counts remained the same but the update sacrificed 38 small tubes and reduced evaporative heating surface area in order to increase the direct heating surface area afforded by the combustion chamber and two Nicholson thermic syphons.

TGR retired the first Q (Q9) in 1956; Q4 and Q12 completed the withdrawls in 1963.

The last four saw their boilers set to 180 psi (12.4 bar).

Principal Dimensions by Steve Llanso of Middle Run Media
ClassHQ-originalQ-rebuilt-combustion chamber
Locobase ID8579 21251 9559
RailroadTasmanian GovernmentTasmanian GovernmentTasmanian Government
CountryAustraliaAustraliaAustralia
Whyte4-8-24-8-24-8-2
Number in Class8614
Road NumbersH1-H8Q1-Q6Q3, Q5, Q7-Q9, Q11-Q19
Gauge3'6"3'6"3'6"
Number Built8612
BuilderVulcan Foundryseveralseveral
Year195119221929
Valve GearWalschaertWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)13.28 / 4.0512.87 / 3.9212.87 / 3.92
Engine Wheelbase (ft / m)31.80 / 9.6929.87 / 9.1029.87 / 9.10
Ratio of driving wheelbase to overall engine wheelbase 0.42 0.43 0.43
Overall Wheelbase (engine & tender) (ft / m)55.46 / 16.9053.48 / 16.3053.48 / 16.30
Axle Loading (Maximum Weight per Axle) (lbs / kg)29,120 / 13,20927,720 / 12,57427,720 / 12,574
Weight on Drivers (lbs / kg)112,000 / 50,802106,512 / 48,313108,752 / 49,329
Engine Weight (lbs / kg)152,992 / 69,396145,488 / 65,992145,488 / 65,992
Tender Loaded Weight (lbs / kg)94,976 / 43,08087,360 / 39,62687,360 / 39,626
Total Engine and Tender Weight (lbs / kg)247,968 / 112,476232,848 / 105,618232,848 / 105,618
Tender Water Capacity (gals / ML)4800 / 18.184200 / 15.914200 / 15.91
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 6.60 / 6 6.60 / 6 6.60 / 6
Minimum weight of rail (calculated) (lb/yd / kg/m)47 / 23.5044 / 2245 / 22.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)48 / 121948 / 121948 / 1219
Boiler Pressure (psi / kPa)200 / 1380160 / 1100160 / 1100
High Pressure Cylinders (dia x stroke) (in / mm)18" x 24" / 457x61020" x 24" / 508x61020" x 24" / 508x610
Tractive Effort (lbs / kg)27,540 / 12491.9527,200 / 12337.7327,200 / 12337.73
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.07 3.92 4.00
Heating Ability
Tubes (number - dia) (in / mm)109 - 2" / 51125 - 2" / 5187 - 2" / 51
Flues (number - dia) (in / mm)20 - 5.5" / 14018 - 5.25" / 13318 - 5.25" / 133
Flue/Tube length (ft / m)16.52 / 5.0418.37 / 5.6015.75 / 4.80
Firebox Area (sq ft / m2)176 / 16.36134 / 12.45166 / 15.42
Grate Area (sq ft / m2)34 / 3.1632.50 / 3.0232.50 / 3.02
Evaporative Heating Surface (sq ft / m2)1624 / 150.931757 / 163.231272 / 118.17
Superheating Surface (sq ft / m2)298 / 27.70382 / 35.49320 / 29.73
Combined Heating Surface (sq ft / m2)1922 / 178.632139 / 198.721592 / 147.90
Evaporative Heating Surface/Cylinder Volume229.75201.34145.76
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation680052005200
Same as above plus superheater percentage788861366240
Same as above but substitute firebox area for grate area40,83225,29931,872
Power L111,73986037307
Power MT924.29712.27592.51

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