Rx Class 4-6-0 Ten Wheelers
The Rx were a development of the R class, giving them higher pressure boilers and larger tenders, to improve their performance and availability. Their original purpose was as main line locomotives, but such was their success that they became very utilitarian locomotives even after the larger Webb locomotives were introduced in the mid-1920s, and survived until the very end of steam, even outliving some of the Webb classes that displaced them.
The 30 R class were all rebuilt as Rx from 1900 through to 1911, and an additional 54 were constructed originally as Rx, by a range of builders including Dubs, James Martin of Gawler (the original 30 R), SAR's Islington workshops, North British and Walkers of Maryborough, Queensland. Most were scrapped in the late 1960s, but 8 survive in various parks throughout the state, with 2 kept in running order on the Mount Barker-Victor Harbour tourist line.