123Movies. For nearly 47 years, the Southern Pacific Railroad relied upon its massive AC-type steam locomotives to haul freight and passenger trains throughout California and neighboring states. Built to provide the power and flexibility demanded by the mountainous passes they traversed, these giants were constructed with their cab in front of the boiler, thus earning them the name Cab Forwards. The last Cab Forward revenue train ran in 1956, after which all but one were scrapped. From then on, film coverage of these AC-class engines was eagerly sought, hard to locate, and highly prized. Now, after years of research, Pentrex has assembled an awesome collection of footage and still images of SP AC-1s through AC-12s spanning the years 1927 to 1956.