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The Unique Southern Pacific Cab Forwards

Cab Forwards were a very distinct locomotive found only on the Southern Pacific, in use over the Sierra Nevada mountain range as well as the railroad's main line between Dunsmuir, California to Portland, Oregon. The locomotive looks much like it’s backward and facing the wrong direction but this design was very deliberate and its purpose was to keep train crews away from the thick smoke and dangerous gases that would build up in the numerous tunnels and snow sheds found in the SP’s main line over the Sierras (which was downright brutal during the colder months of the year). Along with Cab Forwards protecting crews from smoke and gases the locomotives were also quite powerful and had tremendous tractive effort to battle the steep grades over the Sierras.

Likely the most unique, but very effective, steam locomotive design ever conceived and built was the Southern Pacific Cab Forwards, which would go on to be one of the signature features of the “Espee”. Initially a Mallet-type steam locomotive the Cab Forwards have their beginnings around 1908 when the Southern Pacific ordered two Mallets (of the 2-8-8-2 arrangement) to negotiate the very steep Sacramento Division (with grades of 2.5% in some spots), a 150-mile stretch of main line over the Sierra Nevada mountain range.

Because this main line runs through high mountain passes it was, and still is in some areas, lined with numerous snow sheds. It quickly became apparent that these snow sheds wreaked havoc on train crews since traditional steam locomotives have cabs located at the back near the tender and they caught the brunt of the exhaust, which was very dangerous and could cause asphyxiation.

To solve this problem Southern Pacific Railroad came up with a rather unusual, but ingenious, alternative design of the Mallet type that utilized a cab located to the front of the locomotive, which would keep the crew entirely clear of smoke and exhaust. Designated class MC-2 and first operated in 1910, these Mallets were able to have a cab to the front because oil was used as a fuel source, which was piped from the tender to the firebox. The idea worked fabulously and Southern Pacific would eventually end up with a whopping 256 Cab Forwards in all different classes (with wheel arrangements including 2-8-8-2s, 4-6-6-2s, and 4-8-8-2s).

Thankfully, one of these extremely unique locomotives was preserved, #4294 where in May of 1981 it was named a National Historical Mechanical Engineering Landmark and today resides at the California State Railroad Museum in Sacramento, CA. For more information about Cab Forwards please click here.

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(A deep thanks to the Museum of the Rockies at Montana State University for allowing Ron Nixon's historic collection of the Cab Forwards to be featured here. Please note that the photos featured on this page feature their corresponding image number so that you may quickly and easily find more information about it from their website. To view Ron Nixon's entire collection please click here.)

For more information on Espee's Cab Forwards consider How a Steam Locomotive Works by author Karen Parker, which explores in great detail how exactly each component of a steam locomotive works but is also easy enough to read for anyone to understand. The book has received excellent reviews and is a great resource on steam locomotives and a fine reference tool; you should find it very useful.

Also, consider the book American Steam Locomotives from author Brian Solomon. While this publication does not include quite as much technical data as Parker's book, How a Steam Locomotive Works, it is still a very good resource with lots of information and best of all, is loaded with photographs! If you're interested in perhaps purchasing either (or both) of these books please visit the links below which will take you to ordering information through Amazon.com, the trusted online shopping network.

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