[1] They had a fundamental design flaw that affected their original role as light-line passenger locomotives, relegating them eventually to shunting duties exclusively.

At a time of fierce competition between the Australian colonies, a railway line was extended from Kapunda to Morgan[note 1] on the River Murray, opening in 1878.

The link allowed goods brought downstream on riverboats from New South Wales and Victoria to reach Port Adelaide for export more quickly and safely than by continuing on the river to the sea, since Morgan was only 160 km (99 mi) by rail to Adelaide but 306 km (190 mi) to the mouth of the river.

[5] A major design weakness was the lack of a leading bogie ("pilot truck"), which led to frequent derailments, especially on the Adelaide Hills line, with its sharp curves, difficult gradients, and uncompensated track.

A partial solution was to run the locomotives in reverse – i.e., with cab leading – so that the rear bogie led, providing guidance for the driving wheels.

In their final role as shunting locomotives, the pilot was removed as a safety measure, since its presence made coupling and uncoupling difficult.

When they worked on longer country lines, such as to Terowie, 225 km (140 mi) from Adelaide, where goods were transferred to the narrow gauge, a supplementary water tank wagon was attached.

Changes were made to the cab roof and capacity of the coal bunkers; Ramsbottom safety valves replaced Salter type; and Westinghouse brakes were fitted.