The T-31 class consisted of ten Ten-wheelers built for the Southern Pacific in 1912. Their area of application were 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 1940's and used in front of freight trains and for switching until the late 1950's. Today number 2353, which was operational again from 1996 to 2001, and number 2355, which is being cosmetically restored since 2008, are still existing. 