South Australian Railways 620 class

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 typeSteam
DesignerFred Shea
BuilderIslington Railway Workshops
Model5782
Build date1936-1938
Total produced10
Specifications
Configuration:
​
 • Whyte4-6-2 2′C1′ 2′2′
Gauge5 ft 3 in (1,600 mm)
Driver dia.5 ft 6 in (1.676 m)
Length69 ft 8 in (21.23 m)
Height3.81 Metres
Axle load15 long tons 18 cwt (35,600 lb or 16.2 t)
Adhesive weight47 long tons 5 cwt (105,800 lb or 48 t)
Loco weight81 long tons 10 cwt (182,600 lb or 82.8 t)
Total weight140 long tons 15 cwt (315,300 lb or 143 t)
Fuel typeCoal
Fuel capacity9 long tons 0 cwt (20,200 lb or 9.1 t)
Water cap5,200 imp gal (24,000 l)
Firebox:
 • Firegrate area		33.4 sq ft (3.10 m2)
Boiler pressure200 psi (1,379 kPa)
Heating surface:
 • Tubes		1,560 sq ft (145 m2)
 • Firebox175 sq ft (16.3 m2)
Superheater:
​
 • Heating area421 sq ft (39.1 m2)
Cylinders2
Cylinder size18.5 in × 28 in (470 mm × 711 mm)
Valve gearBaker
Performance figures
Tractive effort25,239 lbf (112.27 kN)
Career
OperatorsSouth Australian Railways
Class620
Numbers620-629
First run26/6/1936
Withdrawn1961-1969
Preserved621 & 624
Scrapped1963-1969
Disposition2 preserved, 8 scrapped

History
620 Sir Winston Dugan in decorated in green and silver for the Centenary Train which toured the state during the Centenary of South Australia in 1936

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 (200 t; 220-short-ton) 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-ton 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, and painted Hawthorn green with yellow stripes.[2] 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:

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 ever 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
NumberDate in ServiceDate CondemnedName
62026 June 1936July 1961Sir Winston Dugan
6217 September 1936Preserved, operationalDuke of Edinburgh
6227 October 1936February 1969-
62321 July 1937July 1964-
62417 July 1937Static Display-
62524 August 1937June 1968-
6268 October 1937February 1969-
62726 November 1937February 1969-
62820 December 1937June 1968-
62922 March 1938February 1969-
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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
  1. Oberg, Leon (1984). Locomotives of Australia 1850s-1980s. Frenchs Forest: Reed Books. p. 163. ISBN 0 7301 0005 7.
  2. "National Railway Museum - Port Adelaide (620-class 4-6-2 locomotive No.624)". www.nationalrailmuseum.org.au. Retrieved 18 June 2007.
  3. "SteamRanger Enthusiast Page - Steam Locos". www.steamranger.org.au. Retrieved 18 June 2007.
  4. 624 National Railway Museum
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