South Australian Railways 600 class (diesel)

The South Australian Railways 600 class was a class of diesel-electric locomotives operated by the South Australian Railways (SAR) from 1951. They were the first mainline diesel locomotives to operate on the SAR, marking a significant transition from steam power.

The locomotives were built by the British Thomson-Houston Company (BTH) in Rugby, England. They were of a Co-Co wheel arrangement, meaning they had two three-axle bogies. Their design was heavily influenced by contemporary British railway practice.

The 600 class locomotives were initially used primarily on mainline freight services, proving particularly effective in the arduous conditions of the South Australian outback. They were later also employed on passenger services, demonstrating their versatility.

Over their operational life, the 600 class locomotives underwent some modifications and upgrades. However, they remained largely unchanged from their original design. They were gradually withdrawn from service from the late 1970s as newer and more powerful locomotives became available. Several examples have been preserved and are displayed at railway museums around South Australia.

Key features of the 600 class included their BTH power plant, their robust construction, and their distinctive appearance. They played a vital role in the modernization of the South Australian Railways and are remembered as important pioneers of diesel traction in the state.