Tasmanian Government Beyer-Garratt Locomotives in Australia

Class Details by Steve Llanso of Sweat House Media

Class L (Locobase 795)

Data from Wiener (1930), Gavin Hamilton. See also "Garratt Locomotives for the Tasmanian Government Railways," Locomotive Magazine, Volume 18 (15 October 1912), pp. 204-205; "Garratt Articulated Locomotives: High-Speed, Narrow-Gauge Engines for the Tasmanian Railways," Engineering Magazine, Volume 44, No. 6 (March 1913), pp. 941-943;.and the railtasmania site at [] (last accessed 12 June 2016). (Thanks to Peter Sharpe for his comments on the Tasmanian Garratts in an August 2013 email.). BP works numbers 5525-5526 in 1912.

These Double Prairie Garratts slogged away at heavy goods traffic and "performed sterling service on the TGR until the arrival of further conventional Q class locomotives," says [] . Like most BP Garratts, these had Belpaire fireboxes.

After being stored for most of the 1930s, they were revived briefly for wartime use, then scrapped in the late 1940s.

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

Class M (Locobase 796)

Data from Wiener (1930) and Gavin Hamilton ([], accessed 6 September 2005). See also "Garratt Locomotives for the Tasmanian Government Railways," Locomotive Magazine, Volume 18 (15 October 1912), pp. 204-205; and "Garratt Articulated Locomotives: High-Speed, Narrow-Gauge Engines for the Tasmanian Railways," Factory and Industrial Management Magazine, Volume 44, No. 6 (March 1913), pp. 941-943; and "Tasmanian Government Railway-Design 0303", Beyer-Garrrat Patent Articulated Locomotives (Manchester, England: Beyer-Peacock & Company Limited, 1931), archived on flickr's Historical Railway Images at [], pp. 34-35. (Thanks also to Peter Sharpe, whose August 2013 email alerted Locobase to some inaccuracies in this entry.) Works numbers were 5523-5524 in 1912.

Unique articulated locomotive in that they were among the few eight-cylinder simple-expansion locomotives to have entered service. (The other eight-cylinder design was the Edward T Johnson Meyer compound described in Locobase 5310.) They provided the power for the Hobart-Launceton passenger service at speeds up to 60 mph (97 kph) -- on 42" drivers!. BP's 1931 brochure reproduced an extract from the 30 November 1912 Launceston Examiner describing a "Highly Successful Test with Mr. Cameron".

This "Double Atlantic Garratt" perhaps overcomplicated the task of getting the steam to work on the drivers, but it must have had a distinctive sound.

F&IM credited the design to the WAGR's W R Deeble "to conform to a variety of difficult and rigid requirements" that only a Garratt could satisfy.

At the time, the M was "probably the most powerful articulated passenger engine" on the Cape Gauge. A high traveling speed " also imposed special conditions as to the site and distribution of the wheels and balancing of reciprocal forces to prevent side movement."

Wiener (1930) make this trenchant comment about this unusual solution to the need for power in a narrow-gauge setting: "It is because the Garratt design permits the use of a boiler of relatively high evaporative power that it is possible to use so many cylinders. This is, however," he adds drily, "not to be recommended."

On the other hand, there's Sharpe's comment (which resonates with Locobase) that "the Class M was a bit bonkers, but rather cool anyway."

Wiener and Gavin Hamilton agree that the Ms had the same Belpaire boilers as the Ls (Locobase 795), but used twice as many cylinders. Each bogie had the four cylinders arranged abreast, each outside one driven by Walschaerts, each inside counterpart operated by Gresley conjugated gear. All drove the leading coupled axles.

[] comments that "despite their haulage abilities and speed [they] were difficult to maintain and were withdrawn some time after the arrival of the R-class Pacifics in 1924."

Principal Dimensions by Steve Llanso of Sweat House Media

Locobase ID795 796
RailroadTasmanian GovernmentTasmanian Government
Number in Class22
Road NumbersL1-L2M1-M2
Number Built22
BuilderBeyer, PeacockBeyer, Peacock
Valve GearWalschaertWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m)16 / 4.8812 / 3.66
Engine Wheelbase (ft / m)56.67 / 17.2741.50 / 12.65
Ratio of driving wheelbase to overall engine wheelbase 0.28 0.29
Overall Wheelbase (engine & tender) (ft / m)56.67 / 17.2761.83 / 18.85
Axle Loading (Maximum Weight per Axle) (lbs / kg)21,280 / 965226,880 / 12,193
Weight on Drivers (lbs / kg)127,680 / 57,915107,520 / 48,770
Engine Weight (lbs / kg)201,600 / 91,444211,792 / 96,067
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)201,600 / 91,444211,792 / 96,067
Tender Water Capacity (gals / ML)3600 / 13.643600 / 13.64
Tender Fuel Capacity (oil/coal) (gals/tons / Liters/MT) 4.40 / 4 4.40 / 4
Minimum weight of rail (calculated) (lb/yd / kg/m)35 / 17.5045 / 22.50
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)42 / 106760 / 1524
Boiler Pressure (psi / kPa)160 / 11160 / 11
High Pressure Cylinders (dia x stroke) (in / mm)15" x 22" / 381x559 (4)12" x 20" / 305x508 (8)
Tractive Effort (lbs / kg)32,057 / 14540.8326,112 / 11844.22
Factor of Adhesion (Weight on Drivers/Tractive Effort) 3.98 4.12
Heating Ability
Tubes (number - dia) (in / mm)225 - 1.75" / 44225 - 1.75" / 44
Flues (number - dia) (in / mm)24 - 5.25" / 13324 - 5.25" / 133
Flue/Tube length (ft / m)11.25 / 3.4311.25 / 3.43
Firebox Area (sq ft / m2)157 / 14.59155.50 / 14.45
Grate Area (sq ft / m2)33.90 / 3.1533.90 / 3.15
Evaporative Heating Surface (sq ft / m2)1686 / 156.631686 / 156.63
Superheating Surface (sq ft / m2)333 / 30.94333 / 30.94
Combined Heating Surface (sq ft / m2)2019 / 187.572019 / 187.57
Evaporative Heating Surface/Cylinder Volume187.35161.00
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation54245424
Same as above plus superheater percentage62926292
Same as above but substitute firebox area for grate area29,13928,861
Power L168058343
Power MT705.00684.27

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