Was the only reason the cab was at the front was to preserve the crew in tunnels??? They are some sweet looking locos, I could never understand why the cab HAD to be 60 feet away from the front, and were they only to be found in the western U.S. ? ?
Tatans:
It wasn't tunnels as much as it was Snowsheds.
The original Central Pacific (later Southern Pacific) route from Sacramento to Reno over Donner Pass went through one of the heaviest snowfall areas in the entire United States. And since the route was constructed on a series of ridge-tops instead of the bottom of canyons, the route was subjected to HUGE snowfalls during the rather long Sierra winters. It was these snowsheds that proved the undoing of early Mallet articulateds. By turning the locomotive around, the exhaust was behind the crew, instead of in front of it.
Since the SP burned oil instead of coal, it was a relatively easy thing to get the oil to the firebox from the tender by a series of heat-pumps. The original AC's were of a 2-8-8-2 design, but in the late 1920's early 'thirties, SP needed a faster, more powerful 'Mallet' for the steep grades and snowsheds of the Sierra. They went back to Baldwin and with the company designed a locomotive with a four-wheel leading truck, larger drivers and one HELL of a lot more tractive effort. The AC 4 was the first of several classes of powerful, fast, simple articulateds, all with the cab in front. Later classes simply improved upon this design. SP ended up with almost 250 of these 'Backward Yellowstones' as they are called (by everyone except SP men, they simply referred to them as "Malleys" or "Wamps" because of their very soft chuff). SP was the only railroad to ever run their articulateds 'backward' and it was originally because of the Sierra crossing. But the design was so successful that SP used them systemwide, and only used one class (the Lima-built AC-9 2-8-8-4's) in a conventionally cab-backward configuration.
When Western Pacific approached Baldwin in the late 'twenties about powerful 2-8-8-2 simple articulateds for their Feather River canyon route, Baldwin suggested a cab-forward design, but WP opted for the more traditional cab-backward design for their 251 series, since WP's Sierra crossing was at a much lower elevation than Donner Pass, and did not have near the snow depth problem (nor the extensive snowsheds). So SP remained the only railroad to have the cab-forward design.
As a side-note: The WP 251 2-8-8-2's were the design basis for probably the most powerful (and handsome, IMO) Yellowstones ever built, the Missabe M3/4 class.
But SP's Cab-forwards were designed with a specific geographical locale in mind--the California Sierra Nevada--however they were soon running all over the system, and could be seen all the way from rainy Oregon to sunny Southern Cal and into Arizona. They were incredibly versatile, powerful, smooth-running, fast (when need be) and unique.
Great lokies. I used to watch them all the time when I was a kid.
Tom
Tom View my layout photos! http://s299.photobucket.com/albums/mm310/TWhite-014/Rio%20Grande%20Yuba%20River%20Sub One can NEVER have too many Articulateds!
the first cab forwards were "forney" 4-4-0T s (0-4-4T s running backwards) built in the 1870s. later there was a cab fwd 4-4-0 with tender on (i think) the South Pacific Coast. i'm sure there were others. the biggest user was of course Espee, and yes they were designed for tunnel and snowshed running. Espee was the only to own articulated cab forwards and owned them in a variety of wheel arrangements.