I know why they made the C.F.s, but how? I have read and been told, that they took a the boiler and turned it around on the chassis to put the cab forward. Or did they just put the tender in the back and run it backwards? I have my ideas but love to hear others…
Thanks.
From what I have heard and read, the SP cab forwards simply were turned around locomotives with the cabs and tenders modified. If I recall correctly, the locomotive had a large “porch” (platform) built on to the back end away from the cab. The cab was modified to close it off, and I believe the controls were modified somewhat to allow the engineer and fireman to face “forward”.
Erik
Erikthered is pretty much on the mark. Lionel Wiener, in “Articulated Locomotives”, also viewed the MC’s, which were the compound cab-forwards, as 2-8-8-4’s running backwards, and classified them as such.
There was one other significant change – the Walschaerts valve gear was modified (cranks moved relative to side rods) so that when the engine was moving ‘forward’ (cab leading) the linkage was in the more direct geometry.
Ok. Well, that what I was thinking. The other day I was looking at my model and it struck me the running gear looked “backwards” compared to anytoher steam engine I could find. Which, made me think, well they just turned it around. You gus helped settle a small debate I was haveing with some others. Thank you.
Note that Cab Forwards were ALL oil-burners. SP did have some conventional 2-8-8-4’s. These were coal-burners originally but some were converted to oil and some back to coal again before retirement.
Did they have to do anything special (different from a normal oil fired engine) to keep the oil warm enough to flow from the tender to the firebox? I
I’m not sure they did much different to keep the oil warm but I’ve read somewhere that that the oil bunker was pressurized with air from the main reservoir to help the oil flow to the atomizer.
Most of the oil burners of that day were run on Bunker C oil, which is, at room temperature, slightly more runny than tar. There was a steam line back to the oil bunker to heat the oil enough to let it flow.
Considering the fact that the Cab Forwards were designed for the long tunnels and snow sheds, they also spent some time in the higher elevations with the colder weather.
There’s a good book out on the SP Cab Forwards by Robert Church.
It’s probably out of print, but you should be able to find it through some of the used book sellers.
It’ll tell you all you want to know about these unusual engines.
Old Timer
I won’t pretend to be an expert on this, but looking at some photos it appears that they were a fairly standard steam locomotive just set up to run in “reverse”. No doubt some modifications facilitated that operation, such as the gear modification mentioned above, but if you put the tender on the cab end of the engine, you would have to take a second look to make it out as a cab forward type.
Still very interesting.
My 3.8 year-old son has recently become fascinated with cab-forwards since I started telling him about them. We’ve looked at books, websites, and videos about them. A couple weeks back, we went to the Cal State RR Museum and sat in the cab of the last of them. He was in awe. He now runs all his Thomas the Tank Engine locomotive characters in “cab-forward’” mode.
Cab forwards ran on oil, which made it possible to run cab forward – oil flows, does not have to be shoveled or screwed. The AC-9s however were not cab forward, since they originally burned coal.
The oil is heated with an oil heater, such as the casting available from CalScale.
In addition to everything else mentioned, the lead truck, which normally would have been the trailing truck, had to be modified to do more than support the cab and firebox – lead trucks play an important role in guiding the locomotive smoothly into curves at speed. This a regular trailing truck won’t do.
One other thing that you can see on the one in Sacremento is that there is an exhaust splitter above the chimney so that the exhaust went partually sideways. Apparently this was becasue the blast was so strong when the locos were working hard uphill that it started to blast rock out of the tunnel roofs.
Gadzooks! The sky is falling!
Here is a link to a web site that discusses the Southern Pacific Cab Forward
http://www.steamlocomotive.com/cabforward/
Bob Church’s book on Cab Forwards is certainly the ‘bible’ on this locomotive - long out of print and used usually goes for pretty big $$ ($200-300).
The original SP cab forwards were in fact existing conventional articulated designs from Baldwin that SP had Baldwin modify to run ‘cab forward’. Ultimately 256 were built (a very large number for such a big, unique and single road locomotive). Only 4294 (the last one built in March 1944) escaped the scrap torch and is on display at the CA State RR Museum in Old Sacramento.
Speaking of the lead truck - the original were 2 wheel and soon changed to 4 wheel to provide better tracking into curves (the 2 wheel experienced a number of derailments).
The oil was heated in the tender with internal steam piping and the oil bunker was pressurized with 5 lbs air to force flow to the firebox. If a cab forward lost fires and steam pressure in cold weather I don’t believe there was a way of bootstrapping startup without an external steam source.
From my understanding, the stack splitter was to prevent the exhaust from blowing the top off the snowsheld over Donner Pass (at one point totaling some 37 miles). The rocks from tunnels could also be a possibility but I hadn’t heard that one.
I can’t find the fool thing now (you’d think I would have at least filed my annual indexes) but TRAINS, of course, had an atricle some years ago covering some of the details involved in “turning” the locomotive around to run cab forward. Some things that spring to mind: moving the throttle/brakestand to the normal lefthand side, extending the throttle from the backhead and moving gauges, etc.
I bet there are (were) a lot of hoggers who wished the had cab-forwards when hauling a long drag through the spiral tunnels in the rockies, I remember going in the tunnels on our way to Air Cadet camp in coaches that you could open the windows, we told all the other cadets you had to open all the windows when in the tunnels and they did, soot and cinders and steam for about an hour after exiting the tunnels, AHHH the good old days eh ?
Trains, April '41, April '56, Jan’58, Aug '68, Feb '69 (From the Index of Magazines link above.)