The T-31 class consisted of ten Ten-wheelers built for the Southern Pacific in 1912. They were used on local and branch line passenger trains. In contrast to their predecessors, the locomotives had superheaters ex works. Boiler pressure was initially 200 and later 210 psi. They were phased out of passenger service in the forties and used for freight trains and for switching until the late fifties. Today number 2353, which was operational again from 1996 to 2001, and number 2355, which is being cosmetically restored part by part since 2008, are still existing. 