Cab Forwards were a very distinct locomotive found only on the Southern Pacific, in use over the Sierra Nevada mountain range. 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 affixation.
To solve this problem Southern Pacific 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 on Espee's Cab Forwards consider one (or both) of the books below. Guide to North American Steam Locomotives by author George Drury includes nearly 500 pages of information on virtually all of the steam locomotive wheel arrangements and designs (including streamlined steamers) ever developed. The book 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 Guide to North American Steam Locomotives it is still a very good resource with lots of information and best of all, is loaded with photographs!
