South Australian Railways 4-6-0 Locomotives in Australia

Class N (Locobase 5683)

Data from Douglas Colquhoun's entries presented in the Australian national railway museum site: [] (visited 14 October 2003). See also DeGolyer, Volume 10, p. 71. Works numbers were 5238 and 5241 in August 1880.

These Ten-wheelers were among the few SAR locomotives imported from the USA. Although among the most powerful engines in Australian service at the time of their delivery, increasing demands led to a significant rebuiild in 1904. See Locobase 5684.

Class N - rebuilt (Locobase 5684)

Data from Douglas Colquhoun's entries presented in the Australian national railway museum site: [] (visited 14 October 2003).

Originally imported in 1881 as 130-psi engines, this pair was rebuilt by the SAR shops with 25% larger boilers, a slightly deeper firebox, and a larger tender carrying 1/3 again more water. Adhesion weight increased by 18% while the maximum axle loading only increased by 4%, according to Colquhoun's specs. Locobase regards that as unlikely.

Whatever the details, the rebuild created locomotives as powerful as the Rx 4-6-0s, but with taller drivers. They continued in service until August 1925 (#52) and 18 June 1928 (#53).

Class R (Locobase 2423)

Data from diagram archived on []

W Thow designed these light-rail mixed-traffic engines. All of them were later converted to the Rx standard (Locobase 2424) beginning in the late 1890s.

Class Rx (Locobase 2424)

TS Roberts raised the boiler pressure of the R class (Locobase 2420) and later added a superheater to these light-rail mixed-traffic engines. [] (Peter Ormsby, an Australian steam artist) gives the resulting total heating surface as 1,437 sq ft, from which Locobase subtracts the superheater area to arrive at the heating surface given in the specs.

Ormsby says that the first Rx were 30 Rs (Locobase 2423) substantially modified, including the fitting of a Belpaire firebox and an extended smokebox. Of the 84 engines built in both classes, Walkers Ltd (Maryborough, Queensland) delivered 25, James Martin & Co (Gawler, South Australia) another 24, North British 15, Islington 14, and Dubs & Co 6.

[] (visited 20 October 2003) says that these were originally used for mainline service. "Up to three Rx class were used to haul the Overland over the Mt.Lofty Ranges - 2 pulling and 1 pushing." The site adds that once the 500-class 4-8-4s took over in 1926, the Rx spread out all over the SAR system.

Their relatively light axle loading meant that some would serve on branch lines until 1965.