The WAGR had a diesel-electric railcar built by Armstrong Whitworth in Newcastle in 1937, which was the first rail vehicle in Australia to use this type of drive. Five more were prefabricated in assemblies in 1938 and assembled in Australia. Matching trailers were added a year later to increase capacity.
The motor cars were designated as class ADE and the trailers as class ADT. They were also called “Governor class” because they were named after Western Australian governors. Initially, they were mostly used in the Perth area, until the Wildflower class railcars appeared in 1949. After that they came to more rural areas and were retired between 1957 and 1962. More than ten years later, most of the vehicles were scrapped except for two trailers.