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Specifications
Specifications
Configuration:;
• Whyte	2-8-4 1′D2′ 3′3′
Gauge	1,600 mm (5 ft 3 in)
Leading dia.	2 ft 9 in (838 mm)
Driver dia.	4 ft 9 in (1,448 mm)
Trailing dia.	3 ft 0 in (914 mm); 3 ft 6 in (1,067 mm)
Length	83 ft 6 in (25.45 m)
Height	13 ft 11+5⁄8 in (4,256.1 mm)
Axle load	19.85 long tons 0 cwt (44,500 lb or 20.2 t)
Adhesive weight	77.10 long tons 0 cwt (172,700 lb or 78.3 t)
Loco weight	123.80 long tons 0 cwt (277,300 lb or 125.8 t)
Tender weight	104.00 long tons 0 cwt (233,000 lb or 105.7 t)
Total weight	227 long tons 4 cwt (508,900 lb or 230.8 t)
Fuel type	Coal; Oil
Fuel capacity	17 long tons 0 cwt (38,100 lb or 17.3 t); 3,060 imp gal; (3,670 US gal; 13,900 L) oil (locos converted to oil burning only)
Water cap.	9,000 imp gal; (11,000 US gal; 41,000 L); 9,400 imp gal; (11,300 US gal; 43,000 L) (when oil fired)
Firebox:
• Grate area	59.5 sq ft (5.53 m2)
Boiler pressure	215 psi (1,482 kPa)
Heating surface:
• Firebox	360 sq ft (33 m2)
• Tubes	2,615 sq ft (242.9 m2)
Superheater:;
• Heating area	751 sq ft (69.8 m2)
Cylinders	2
Cylinder size	22 in × 28 in (559 mm × 711 mm)
Valve gear	Walschaerts valve gear
Valve type	Piston

Type and origin
Type and origin
Power type	Steam
Designer	Fred Shea
Builder	Islington Railway Workshops
Build date	1930-1943
Total produced	17

South Australian Railways 720 Class
South Australian Railways 720 Class
	724 at North Adelaide station in 1952
Power type
Type and origin
Power type	Steam
Designer	Fred Shea
Builder	Islington Railway Workshops
Build date	1930-1943
Total produced	17
Configuration:;
Specifications
Configuration:;
• Whyte	2-8-4 1′D2′ 3′3′
Gauge	1,600 mm (5 ft 3 in)
Leading dia.	2 ft 9 in (838 mm)
Driver dia.	4 ft 9 in (1,448 mm)
Trailing dia.	3 ft 0 in (914 mm); 3 ft 6 in (1,067 mm)
Length	83 ft 6 in (25.45 m)
Height	13 ft 11+5⁄8 in (4,256.1 mm)
Axle load	19.85 long tons 0 cwt (44,500 lb or 20.2 t)
Adhesive weight	77.10 long tons 0 cwt (172,700 lb or 78.3 t)
Loco weight	123.80 long tons 0 cwt (277,300 lb or 125.8 t)
Tender weight	104.00 long tons 0 cwt (233,000 lb or 105.7 t)
Total weight	227 long tons 4 cwt (508,900 lb or 230.8 t)
Fuel type	Coal; Oil
Fuel capacity	17 long tons 0 cwt (38,100 lb or 17.3 t); 3,060 imp gal; (3,670 US gal; 13,900 L) oil (locos converted to oil burning only)
Water cap.	9,000 imp gal; (11,000 US gal; 41,000 L); 9,400 imp gal; (11,300 US gal; 43,000 L) (when oil fired)
Firebox:
• Grate area	59.5 sq ft (5.53 m2)
Boiler pressure	215 psi (1,482 kPa)
Heating surface:
• Firebox	360 sq ft (33 m2)
• Tubes	2,615 sq ft (242.9 m2)
Superheater:;
• Heating area	751 sq ft (69.8 m2)
Cylinders	2
Cylinder size	22 in × 28 in (559 mm × 711 mm)
Valve gear	Walschaerts valve gear
Valve type	Piston
Tractive effort
Performance figures
Tractive effort	43,450 lbf (193.28 kN); 52,000 lbf (231.31 kN) with booster engine cut in
Factor of adh.	4.0
Operators
Career
Operators	South Australian Railways
Class	720
Number in class	17
Numbers	720-736
First run	26/11/1930
Withdrawn	1958-1960
Scrapped	1958-1963
Disposition	All scrapped

The South Australian Railways 720 class was a class of 2-8-4 steam locomotives operated by the South Australian Railways.

Design

The 720 class were built by the South Australian Railways as an improved version of the 710 class locomotives. The cylinders and running gear were broadly similar, but the boiler was enlarged and its pressure raised from 200 psi to 215 psi. The grate area was increased by nearly a third.

The 710 had been fitted with a Franklin C-2 booster engine^[1] on the trailing truck and this was repeated for the 720. However the additional weight of the booster had led to axle load problems on the lines laid with lighter 60 lb rail and some had their boosters removed.^[2] Partly to reduce this axle load, partly to support the increased weight of the enlarged firebox, the 720 changed from the 710's 2-8-2 Mikado wheel arrangement to a 2-8-4 Berkshire. The trailing wheels of this bogie were of different sizes, the larger rear wheels being driven by the booster and a smaller wheelset used under the front of the ashpan to give more clearance.

History

The initial order was for five locomotives. They were intended to operate on the lighter broad gauge lines, but after they began to spread rails, they were confined to the heavier lines. A further twelve were built between 1938 and 1943. The final twelve differed in having streamlined valances and boiler lagging tinwear. Coal shortages after World War II saw 14 converted to burn oil. All were later converted back to coal burners.

The last were withdrawn in April 1960.^[2]^[3]

References

^ The Locomotive Booster (PDF). Franklin Railway Supply Company. 1942.
^ ^a ^b "720 class". Chris' Commonwealth Railways Information.
^ Oberg, Leon (1984). Locomotives of Australia 1850s-1980s. Frenchs Forest: Reed Books. p. 161. ISBN 0730100057.