The South Australian Railways 620 class was a class of 4-6-2 steam locomotives operated by the South Australian Railways.

South Australian Railways 620 Class
South Australian Railways 620 Class Locomotive No. 620 "Sir Winston Dugan", 1936
Type and origin Power type Steam Designer Fred Shea Builder Islington Railway Workshops Serial number 620-629 Model 5782 Build date 1936-1938 Total produced 10
Specifications Configuration: ​  • Whyte 4-6-2 2′C1′ 2′2′ Gauge 5 ft 3 in (1,600 mm) Leading dia. 2 ft 9 in (838 mm) Driver dia. 5 ft 6 in (1,676 mm) Trailing dia. 3 ft 6 in (1,067 mm) Length 69 ft 8 in (21.23 m) Height 12 ft 6 in (3,810 mm) Axle load 15 long tons 18 cwt (35,600 lb or 16.2 t) 17.8 short tons Adhesive weight 47 long tons 5 cwt (105,800 lb or 48 t) 52.9 short tons Loco weight 81 long tons 10 cwt (182,600 lb or 82.8 t) 91.3 short tons Total weight 140 long tons 15 cwt (315,300 lb or 143 t) 157.6 short tons Fuel type Coal Fuel capacity 9 long tons 0 cwt (20,200 lb or 9.1 t) 10.1 short tons Water cap. 5,200 imp gal (6,200 US gal; 24,000 L) Firebox:  • Firegrate area 33.4 sq ft (3.10 m2) Boiler pressure 200 psi (1,379 kPa) Heating surface:  • Tubes 1,560 sq ft (145 m2)  • Firebox 175 sq ft (16.3 m2) Superheater: ​  • Heating area 421 sq ft (39.1 m2) Cylinders 2 Cylinder size 18.5 in × 28 in (470 mm × 711 mm) Valve gear Baker Valve type Piston
Performance figures Tractive effort 25,239 lbf (112.27 kN) Factor of adh. 4.2
Career Operators South Australian Railways Class 620 Number in class 10 Numbers 620-629 First run 26/6/1936 Withdrawn 1961-1969 Preserved 621 & 624 Scrapped 1963-1969 Disposition 2 preserved, 8 scrapped

History

The completion of the South Australian Railway (SAR) broad gauge route between Adelaide and Port Pirie created a need for a fast, light passenger locomotive to haul this service, as well as other traffic on the lightly laid 60 lb/yd (29.8 kg/m) rail branch lines of the SAR. The specification included the ability to haul a 200-long-ton (224-short-ton; 203 t) train up a 1-in-45 (2.2%) grade at 25 miles per hour (40 km/h).[1]

Fred Shea, Chief Mechanical Engineer of the SAR designed a 140-long-ton (157-short-ton; 142 t) Pacific type. A notable feature of the design, unique to South Australian Railways,[2] was the use of Baker valve gear in lieu of the more common Walschaerts valve gear.[3] The first locomotive was completed at the Islington Railway Workshops in 1936, with the last completed in 1938.

Class leader 620 was also notable for being Australia's first streamlined locomotive, the smokebox being covered with a chromed steel grille similar to those fitted to motor cars of the period,[2] painted in resplendent Hawthorn Green and Silver.[4] The press of the time described 620's appearance as 'a bit of fluff'. The remainder of the class was unstreamlined.

In service, the 620 class replaced the Q and S classes on branchline services, where they proved quite successful. With the introduction of the more powerful and modern 520 class from 1943, these locomotives were relegated to the Willunga, Bridgewater and Tailem Bend passenger services, as well as continued service on Murray Mallee line services (the locomotives' light axle loading providing good route ability plus the "get up and go" characteristics common to large wheeled Pacific type locomotives.

The 620 class was phased out in favour of Bluebird railcars, although a spate of railcar failures in 1954–55 saw the 620 class return to service on the Port Pirie line.[3] All were withdrawn between 1964 and 1969.[1]

Preservation

Two have been preserved:

• 621 by SteamRanger[5]
• 624 by the National Railway Museum, Port Adelaide[6]

In 1994, 621 ran a one-off steam hauled tour into Victoria shortly before the Adelaide to Melbourne line was converted from broad gauge to a standard gauge. This was the first and only time a South Australian Railways steam locomotive had worked east into Victoria and with the gauge conversion imminent, the tour would also be the last. The train travelled as far east as Bacchus Marsh, due to the locomotive being too wide for the stations situated along the Melbourne suburban railway system. The locomotive combined with R761 for the majority of the tour from Wolseley in South Australia to Bacchus Marsh in Victoria.

Class list

References

• Douglas Colquhoun; Ronald Stewien; Adrian Thomas (1971). 600 - The Pacific Locomotives of The South Australian Railways. Adelaide, South Australia: A.R.H.S. SA division.
• John Ramsey (1994). Pacific Power - 621. S.A.: A.R.H.S.
• Chris Drymalik. "Comrails 620 class". Retrieved 16 April 2008.

Specific

External links

• Media related to South Australian Railways 620 class at Wikimedia Commons
• South Australian Railways (SAR) promotional photograph of streamlined locomotive 620 Sir Winston Duggan
• State Library of South Australia photograph of streamlined locomotive 620 Sir Winston Duggan travelling through the Mount Lofty Ranges, South Australia
• 620class:SA:Trains:AJH Photographs and further details of the 620 class courtesy John Hurst