An articulated steam locomotive built to run with the cab leading and the smoke stack trailing. This configuration was famously used by the Southern Pacific Railroad to prevent the crew from asphyxiating on exhaust fumes in long snow sheds and tunnels. It required oil firing, as coal could not be easily piped from the trailing tender to the front firebox.
Heard on the job
The museum out west just restored an old cab forward that used to haul freight over Donner Pass.