South Australian Railways 620 class
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 The preserved example of the 620 class, the SteamRanger 621 Duke of Edinburgh. |
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| Power type | Steam |
|---|---|
| Designer | P. J. Shea |
| Builder | South Australian Railways, Islington Workshops |
| Build date | 1936–1938 |
| Total production | 10 |
| Configuration | 4-6-2 |
| UIC classification | 2'C1'h |
| Gauge | 5 ft 3 in (1,600 mm) |
| Driver size | 5 ft 6 in (1.676 m) |
| Length | 69 ft 8 in (21.23 m) |
| Axle load | 15.9 long tons (16.2 t) |
| Locomotive weight | 140.75 long tons (143.01 t) |
| Tender capacity | Coal: 9 long tons (9.1 t); Water: 5,200 imp gal (24,000 l) |
| Boiler pressure | 200 psi (1.4 MPa) |
| Fire grate area | 33.4 sq ft (3.10 m²) |
| Heating surface: Tubes | 1,560 sq ft (145 m²) |
| Heating surface: Firebox | 175 sq ft (16.3 m²) |
| Superheater area | 421 sq ft (39.1 m²) |
| Cylinders | Two |
| Cylinder size | 18½×28 in (470 × 710 mm) |
| Valve gear | Baker |
| Tractive effort | 25,000 lbf (110 kN) at 85% BP |
| Career | South Australian Railways |
| Class | 620 |
| Number | 620–629 |
| Preserved | 621, 624 |
| Scrapped | 1964–1969 |
| Disposition | Two preserved, eight scrapped |
The South Australian Railways 620 class is a class of 10 4-6-2 Pacific steam locomotives built in the late 1930s, designed to operate on lightly laid 60-pound lines.
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[edit] Development of the 620 class
The completion of the South Australian Railways (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 (29.8 kg/m) rail branch lines of the SAR. The specification included the ability to haul a 200-long-ton (200 t) train up a 1-in-45 (2.2%) grade at 25 miles per hour (40 km/h).
Mr P.J. Shea, Chief Mechanical Engineer of the SAR designed a 140 ton Pacific type. A notable feature of the design, unique to South Australian Railways,[1] was the use of Baker valve gear in lieu of the more common Walschaerts valve gear.[2] The first locomotive (620) was completed at the SAR workshops at Islington in 1936, with the tenth and final locomotive of the class (629) completed in 1938.
Class leader No. 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.[1] The remainder of the class were unstreamlined.
In service, the 620 class replaced the Q and S 4-4-0 types 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 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.[2]
All but two of the locomotives were scrapped by 1969. One is preserved in working condition by SteamRanger (621) with the second (624) held in the Port Dock Museum.
[edit] References
- John Ramsey (1994). Pacific Power - 621. S.A.: A.R.H.S..
- Chris Drymalik. Comrails 620 class. Retrieved on 2008-04-16.
[edit] Specific:
- ^ a b National Railway Museum - Port Adelaide (620-class 4-6-2 locomotive No.624). www.nationalrailmuseum.org.au. Retrieved on 2007-06-18.
- ^ a b SteamRanger Enthusiast Page - Steam Locos. www.steamranger.org.au. Retrieved on 2007-06-18.
[edit] External links
- 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
- SteamRanger website steam locomotive information page
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