New South Wales 73 class locomotive

New South Wales 73 class


Candy coloured 7318 shunts Grafton yard in January 1986
Type and origin
Power type Diesel-hydraulic
Builder Walkers Limited, Maryborough
Build date 1970-73
Total produced 50
AAR wheel arr. B-B
UIC class B'B'
Gauge 4 ft 8 12 in (1,435 mm)
Wheel diameter 40 in (1,016 mm)
Wheelbase 26 ft 6 in (8.08 m)
Length Over headstocks:
36 ft 0 in (10.97 m),
Over buffers:
39 ft 4 in (11.99 m)
Width 9 ft 3 in (2.82 m)
Height 13 ft 6 in (4.11 m)
Axle load 12 long tons 5 cwt (27,400 lb or 12.4 t)
Loco weight 49 long tons 0 cwt (109,800 lb or 49.8 t)
Fuel type Diesel
Fuel capacity 500 imp gal (2,300 l; 600 US gal)
Lubricant cap Engine:
42 imp gal (190 l; 50 US gal),
58 imp gal (260 l; 70 US gal),
Final drive:
3.25 imp gal (14.8 l; 3.90 US gal)
Coolant cap 80 imp gal (360 l; 96 US gal)
Sandbox cap 10 cu ft (0.28 m3)
Prime mover Caterpillar D379 series B
RPM range 550-1400
Engine type Four-stroke V8 diesel
Aspiration Turbocharged
Cylinders 8
Cylinder size 6.25 in × 8 in (159 mm × 203 mm)
Transmission Voith L4r4U2, with Gmeinder Type GM170/EHA/469 and GM170/E/327B drives
Performance figures
Maximum speed 40 mph (64 km/h)
Power output Gross:
700 hp (522 kW),
For traction:
650 hp (485 kW)
Tractive effort Continuous:
25,000 lbf (111.21 kN)
at 5.4 mph (8.69 km/h)
Operators New South Wales Government Railways
Number in class 50
Numbers 7301-7350
First run 5 October 1970
Preserved 7307, 7320, 7321, 7324, 7329, 7335, 7344, 7350
Current owner Invicta Sucrogen
Mackay Sugar
Plane Creek Sucrogen
Proserpine Mill
Disposition 15 in service, 8 preserved, 16 stored, 11 scrapped

The 73 class are a diesel-hydraulic locomotive built by Walkers Limited, Maryborough for the New South Wales Government Railways between 1970 and 1973.


7344 shunts at Sydney Central in October 1991 painted in experimental FreightCorp green livery

In October 1969 the New South Wales Government Railways placed an order in October 1969 with Walkers Limited, Maryborough for 20 Bo-Bo shunting locomotives.[1] These were the only New South Wales locomotives to be built in Queensland.[2]


The first unit was delivered in October 1970. When the whole of the first order had arrived, all steam shunting on the North Coast line and the Sydney Metropolitan area, as well as at Goulburn had been replaced. In July 1971 a further 30 units were ordered. The last of these arrived in March 1973 and this brought to an end all remaining steam shunting operations in New South Wales.[1]

In traffic

The New South Wales Government Railways purchased the class mainly for shunting and their prohibition from mainline use was 'officially' due to the lack of vigilance controls. However, despite its absence, the class was still seen on many suburban trip workings and when mainline operation was a necessity, there seemed to be no hesitation to use them.

One advantage a diesel-hydraulic locomotive has over a diesel-electric variety is its ability to negotiate up to 300mm of water over the tracks. Big floods in March 1976 gave 7323 an opportunity to show off its swimming ability when water covered the line near Bourke and this locomotive was used on a couple of freight trains and a ballast train from Nyngan to Bourke and return. At least two other occasions when their water resistance was put to use was Menindee in 1976 and Hexham in 1977.

Multiple unit operation was common, although the flood event at Hexham is the only known occurrence of triple-heading. A number of units were fitted with exhaust gas scrubbers for use on Eastern Suburbs Railway construction in the 1970s.[3]

Depot allocation

As an example of the spread of the members of the class throughout the system, the fleet was allocated as follows as at 30 August 1977:

Eveleigh7301–7314, 7317, 7321, 7339–7345
Goulburn7315, 7316
Junee7320 (actually working at Albury)
Dubbo7323, 7324
South Grafton7318
Werris Creek7346 (actually working at West Tamworth), 7347


CRT Group shunter 7334 at the Altona terminal in 2007

With a reduction in locomotive hauled passenger trains and the closure of a number of yards, withdrawals began in February 1987.[4] By October 1991 only three remained in service with FreightCorp.[5] One was repainted into CountryLink livery for use as a depot shunter at the XPT Service Centre.

Disposals commenced in 1990 with three sold to the Canberra Railway Museum.[6] Four were sold to the Manildra Group in 1991.[7] Many were sold to Queensland sugar cane companies for conversion to 610 mm (2 ft) gauge.[8] A number have also been preserved.[9][10][11]

7301 & 7344 were placed on RailCorp's Heritage & Conservation Register.[12][13] 7301 was subsequently scrapped in January 2014.[14][15]


The following are held by recognised preservation organisations:


The following units were sold for further commercial operation, some being converted to 610 mm (2 ft):

See also

Queensland Railways DH class


  1. 1 2 Oberg, Leon (2007). Locomotives of Australia 1854-2007. Rosenberg Publishing. p. 328. ISBN 1-877058-54-8.
  2. Clark, Peter J (1973). An Australian Diesel Locomotive Pocketbook. Australian Railway Historical Society NSW Division. ISBN 0-909650-02-0.
  3. Australian Model Railway Magazine. November–December 1978. pp. 18–25. Missing or empty |title= (help)
  4. "Locomotives" Railway Digest March 1987 page 80
  5. "73 Class" Railway Digest January 1992 page 22
  6. "Saving Diesels" Railway Digest September 1990 page 330
  7. "73 Class" Railway Digest November 1991 page 415
  8. 73 Class (Rebuilds, 610mm) Railpage
  9. "73 class get a new lease of life" Railway Digest May 2000 page 36
  10. 73 class Railpage
  11. 73 Class Vicsig
  12. Locomotive, Diesel Shunting 7301 Department of Environment & Heritage.
  13. Locomotive, Diesel Shunting 7344 Department of Environment & Heritage
  14. Railpage
  15. Vicsig
  16. 1 2 3 "Touring the Classics" Railway Digest June 2010 page 24
  17. Locomotives Orana Tarana Heritage Railway

Further reading

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