 The remainder of the class was unstreamlined.In service, the 620 class replaced the Q and S classes on branchline services, where they proved quite successful.With the introduction of the more powerful and modern 520 class from 1943, these locomotives were relegated to the Willunga, Bridgewater and Tailem Bend passenger services, as well as continued service on Murray Mallee line services (the locomotives' light axle loading providing good route ability plus the "get up and go" characteristics common to large wheeled Pacific type locomotives.