SOUTH AUSTRALIAN RAILWAYS '620' CLASS 4-6-2

Designed by Chief Mechanical Engineer Fred Shea.
Built at Islington Railway Workshops 1936-1938

CYLINDERS (2) 18½ ins x 28 ins (470mm x 711mm)
COUPLED WHEEL DIAMETER 66 ins (1,676mm)
TOTAL HEATING SURFACE 2,156 square feet (200.3m²)
(including superheater)
GRATE AREA 33.4 square feet (3.1m²)
BOILER PRESSURE 200 PSI (1,379 kpa)
TRACTIVE EFFORT 25,000lb (11,340kg)
TOTAL WEIGHT 140.75 tons (143 tonnes)
LENGTH OVERALL 69 feet 7¾ ins (21,228mm)

As the 1930's unfolded and the effects of The Great Depression began to diminish it became obvious that increasing traffic on both the secondary and mainlines necessitated the need for more locomotives. This situation was resolved with the introduction of ten lightweight 'Pacific type' locomotives all available for service by early 1938.

The '620' class was Fred Shea's last design during his era as CME. Two significant departures from his earlier designs included the use of Baker Valve Gear borrowed from the Pilliod Co. of New York and the incorporation of a smoke deflection arrangement, not unlike and probably inspired by the swept back appearance of Gresley's P1 'Mikados'. After some initial teething problems with ad hoc streamlining attempts on class leader number 620 they went on to become a very successful 'mixed traffic' type, equally at home on suburban locals and the bulk of the light line passenger and sometimes freight services for which they were conceived.

Frequently sharing mainline express duties with the much larger '600' class 'Pacifics' on the northern lines to Port Pirie and Terowie, they also saw some service on the Main South Line as far as Serviceton. A few modifications were carried out over the years, 620 losing its streamlining and two of the class being converted to burn oil fuel. They were a favourite locomotive with enginemen being very good steamers and fairly light on the fireman's workload.

Scrapping commenced in 1961 and all had been condemned by 1969. Number 624 has been preserved and is on display at the National Railway Museum Port Adelaide and number 621, fully restored and named 'Duke of Edinburgh', is a member of the 'Steamranger' operational motive power team at Mount Barker.