Southern Pacific classes F-3 and F-4

After the class F-1 2-10-2s, the Southern Pacific ordered 15 F-3 in 1921 from Lima. They had larger cylinders, a larger boiler and had a trailing truck booster like their predecessors. Like most SP steam locomotives, they were oil-fired. To improve running characteristics in curves, they got lateral motion boxes on the lead drivers.

Since the SP didn't want to use the name „Santa Fe” for this wheel arrangement and didn't have real Decapod locomotives, they called all their 2-10-2s “Decks” as short form for “Decapods”. In 1922, they ordered 50 very similar locomotives from Baldwin which were designated class F-4 and delivered in a single train.

All 15 F-3 were converted to coal burning in 1924. Between 1940 and 1944, they were converted back to oil burning. Both classes were retired between 1951 and 1958.