Southern Pacific’s Cab Forwards

These pages follow the restoration of a pair of old brass Akane Cab Forwards.


The Cab Forward

From the opening of the transcontinental line, the Central Pacific and later the Southern Pacific railroad built increasing larger locomotives in the quest to move freight over the Sierra mountain range.  The narrow curves of the mountain district limited the length of a locomotive’s wheelbase, and hence limited the size of conventional locomotives.  Southern Pacific’s solution was a new articulated locomotive based on a design by the French engineer M. Anatole Mallet.   With the Mallet locomotive Southern Pacific found it’s solution to getting the freight over “the hill”.


But with these new locomotives the railroad quickly discovered that they had a new problem to overcome.  The “Hill” was lined with miles and miles of wooden snow sheds to keep the line open through the high Sierra winters.  When the first Mallets were run through the snow sheds the crews were almost asphyxiated by the locomotive’s exhaust.  The exhaust just bounced off of the top of the snow sheds and came right back down into the cab.  The cabs were later fitted with respirators to help the crews breath, but they couldn’t help relieve the crews from the intense heat coming from the exhaust.


As an experiment one of the conventional Mallet’s was run tender first (backwards) through the snow sheds.  With the exhaust stack running behind cab the crews had no problems with the exhaust.  The idea of a Cab Forward came about as a result of these experiments.  Early Cab Forwards were Mallet locomotives that were modified into run in reverse.  The oil and water connections were extended the length of the locomotive so that the tenders could be coupled behind the smokebox end of the locomotive.  These locomotives were so successful that they led to a whole series of different Cab Forward designs.


By the AC-8 series the design of the Cab Forward had reached its pinnacle, all the further orders of the AC-10 through AC-12 series were nearly identical to the AC-8 design.  The AC-10 through AC-12 series consisted of 90 locomotives numbered from 4205 to 4294, all were built between the years of 1942 and 1944.  These big Cab Forwards were built in the twilight years for new steam locomotives and number 4294 was the last new steam locomotive delivered to Southern Pacific.


 Here is Dick Kuelbs photo of AC-11 #4271 taken in 1956.



Page 1 - Last updated April 25, 2004


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