South Australian Railways '500B' class 4-8-4

Designed by Chief Mechanical Engineer Fred Shea.
Built at Newcastle-on-Tyne 1926.

CYLINDERS (2) 26 ins x 28 ins (660mm x 711mm)
COUPLED WHEEL DIAMETER 63 ins (1,600mm)
TOTAL HEATING SURFACE 4,483 square feet (416.5m²)
(including superheater)
GRATE AREA 66.6 square feet (6.2m²)
BOILER PRESSURE 200 PSI (1,379 kpa)
TRACTIVE EFFORT (INCLUDING BOOSTER) 59,000lbs (26,762kg)
TOTAL WEIGHT 222.6 tons (226.2 tonnes)
LENGTH OVERALL 84 feet 2 ins (25,654mm)

The 500 class 'Mountain types' were the largest non-articulated locomotives ever built in Britain. Similar to the US Railroad Administration standards of the time but designed in Australia to specifications acquired from ALCO, the task of building was finally given to Armstrong Whitworth of Newcastle on Tyne. Steel bar frames were cast by Baldwin and shipped to England where the construction phase began in earnest.

The locomotives were duly completed and began arriving at Port Adelaide in early 1926. After initial teething problems the 500's settled down to regular operation. They were however restricted to the mainlines owing to their heavy axle loadings. Apart from heavy freight work their most prestigious task was hauling the Melbourne Express over the steep, winding grades of The Mount Lofty Ranges.

A significant alteration was made in 1929 when all ten locomotives were fitted with boosters altering their wheel arrangement and increasing their hauling capacity to an even greater extent enabling them to pull 600 tons up the ruling grades. Further modifications were carried out to the front end and blast pipes and as a result the locomotives could haul the full summertime loading of the Express up the 11 miles of 1 in 45 grade from Eden Hills to Mount Lofty in 35 minutes at an average speed of 17.9 mph.

In 1936 South Australia celebrated its centenary year and in keeping with the theme the Melbourne Express was given a new green paint scheme and renamed 'The Overland'. Accordingly it was decided to smarten up the 500's as well and all but two of them received new smooth all over boiler casings, skirting below the running plates and a repaint. The smoke-box fronts being finished in silver leading to a new nickname for the locomotives: 'Palefaces'. This particular situation did help to quell the confusion that existed with the general public who insisted on referring to the 500's as 'Mountain types' even though their new wheel arrangements, after the fitting of boosters, did alter that terminology.

The 500 class locomotives gave sterling service until the diesel onslaught finally overtook them, firstly on The Overland in 1951 then right up until the last one was condemned in 1963. Number 504 can now be found sitting majestically in the National Railway Museum at Port Adelaide.