As a follow on to the original eleven locomotives ordered by the Commonwealth Railways for their system, a further thirty-six units GM Class were ordered to allow for network expansion, albeit in the now common Co-Co wheel arrangement. To assist with the heavy coal traffic at Leigh Creek, the final eleven members of the class were delivered with dynamic brakes. Rather than creating a new class designation, these locomotives were numbered to follow on from the GM1 Class. To help distinguish between the two classes, Australian National further classed these units as “S Class” - six motor, compared to the GM1 Class (known as the “F Class” - four motor).

In the post-privatisation world, a number of these veteran units survive in commercial operation today. GM’s 22 and 27 are owned and operated in NSW/Victoria by Southern Shorthaul Rail, having been purchased from CFCLA , while the remaining operating members of the class are employed on grain and infrastructure trains in South Australia with US-based operator Genesee & Wyoming Australia. One unit is operationally preserved (GM36) by Seymour Rail Heritage Centre, Victoria.

Text courtesy of Trackside