SP Cab Forwards - an idea not that widely used[?]

[Anonymous]

> This class was used between El Paso and Tucumcarrie and burnt coal, not oil.

By necessity, a Cab Forward was an oil burner (no way to move the coal from the tender at the rear to the front of the engine easily. The only engines that weren't rear cab that burned coal were the camel back's, prodominantly used on eastern lines that burned anthracite (hard) coal. This was due to the massive size of firebox needed as hard coal burns much slower than soft (bituminous) coal. As for helpers pushing on the rear, many states had laws banning helpers behind the caboose (unless the caboose was unnoccupied-easily done by having the occupants ride in the cab of the helper). The roads that did couple after, however, required the caboose to have a steel underframe (irregardless of steel or wood body). If the caboose had a wood underframe, in order to prevent crushing it, it had to be dropped, and the helpers inserted between the last car and caboose.

[Anonymous]

The genesis of the Cab Forward is a bit complicated but here's a quick rundown.
*The first two units, 4000 and 4001 were built as conventional 2-8-8-2s and then turned around with the cab in front. These were built in 1909 and classed as MC-1.
*The next fifteen were built as cab forwards and with the engineer on the left as the reversed first two were built. They were erected in 1909 and numbered 4002-4016 in class MC-2.
*MC-4 consisted of 12 more built in 1911 and numbered 4017-4028.
*MC-6 (there was no MC-3 or MC-5; the MC stood for Mallet Consolidation) were 20 more constructed 1912-1913. That ended the Mallet Consolidation program.
•MM-3 which stood for Mallet Mogul (2-6-6-2) comprised 12 units constructed in 1911 supposedly for passenger service. Their front trucks were totally unsatisfactory and were soon replaced with four wheel high speed trucks, making them into 4-6-6-2. These were the only Mallet Mogul cab forwards built.
In the twenties, all of the MCs and MM were rebuilt from mallet compounds to simple expansion locos, turning the MCs into ACs, but they never had their two wheel front trucks replaced and remained 2-8-8-2s, though the rebuilding saw the engineer's controls moved to the right side. The MMs were rebuilt into AMs and renumbered into the 3900s.
*Class AC-4 was constructed in 1928 with 10 "flat face" units.
*AC-5 was built in 1929 with 16 machines, and AC-6 saw 25 units in 1930. These numbered 4100 - 4150 and no more of this design were built.
*AC-7s were built in 1937 and had the new cab design on the 26 members of this class.
*From 1937 to 1944, AC-8 saw 28 units, AC-10 saw 40, AC-11 saw 30, and AC-12 saw 20. All had more or less the same cab design as the AC-7. See Kalmbach's wonderful "Guide to North American Steam Locomotives" for more.
*Of all the cab forwards built, only 4294 survives, and it may be visited at the California Railroad Museum in Sacramento, CA. All the rest were scrapped.
*Very few cab forwards were involved in collisions or mishaps. #4107 exploded on the Siskiyou Pass in 1929 when the water injector failed and the crown sheet was exposed. The engineer was killed and CFs never ran over the Siskiyou Pass again. This same engine in 1951 ran into some flatcars on the Modoc Line, kicking the first one up and into the cab, killing the crew. Also on the Modoc in June 1942, 4038 ran off the tracks and rolled on its side. The engineer survived but the fireman was killed. In 1951 on the Modoc, sabotage of the track put 4147 on its side in the ditch, but the crew walked away unharmed. All that happened in these wrecks would have likely been similar in a traditional back-cab locomotive. AC crews claimed their rides were cooler in the summer than sitting behind a backhead would produce.
*In the end, cab foward won because all the diesel locos today are built with their cabs on the front. It just takes a while for a good idea to catch on :-)

John Sipple, editor
Model Railroad News Magazine

[vsmith]

QUOTE: Originally posted by M636C

Apart from Southern Pacific, I believe, in the USA only one short line ever built a cab forward, and it was a strange 4-4-0.

Yes, it was for the North Pacific Coast RR, a 36" narrow guage line that ran north from Saulsalito to Peteluma and up into the Pacific Coastline. It was oil fired and used a unique Marine type boiler. Heres a photo link:

http://narrowmind.railfan.net/440NPC21L.jpg

This was a 19th century engine and was way ahead of its time.

[Anonymous]

CF's were used on almost all SP lines west of the Sierras. With the exception of the San Francisco commutes, CF's were used on the SF,SJ,&LA line until almost 1960. The CFs Were used extensivly for passenger service in the S.J. Valley and the Donner line. I never saw a CF adhere to a speed restriction except the ones placed due to general track restriction orders. If you check the records, a cab forward was never involved in a head-end collision that injured an engineer or fireman.

[Anonymous]

These comments remind me of a few years back when someone asked Trains how the fuel was fed to these engines. Trains asked if anyone knew, which I thought was rather silly comming from the editors of TRAINS! Several of us joked about how many firemen it would take to carry scoops of coal to the firebox to keep the fire going. Oh, well.

[jchnhtfd]

QUOTE: Originally posted by Modelcar

...In theory I suppose that could be a factor...but I'm sure the fireman had to keep the crown sheet covered above the firebox or the boiler wouldn't have stayed in assembled condition very long. Don't know what kind of compensation was made [if one was needed], to make sure all that area was water covered in an up hill attitude. I would think it would have been a critical factor but maybe the grades they operated on didn't make that much difference in keeping the water level above all the critical parts.

This was a real problem. Keeping the crown sheet covered with water on an upgrade -- even a relatively flat one (consider: your boiler is 60 feet long. On a 2 per cent grade the water level will be over a foot higher at the downhill end than at the uphill end. If you are steaming hard, the water level is down anyway... and if the crown sheet is the uphill end... [xx(]). There were a good few cab forwards which disassembled themselves because the water got too low; a considerably higher proportion of the fleet than for conventional engines.
Another slightly nasty problem was trouble with the oil feed on upgrades; again, you are using the most oil going uphill, and you have to pump the oil up from the tender. Quite a good ways. If the pump wasn't quite up to it, or the oil a little cold, or... you could lose your fire, albeit briefly. That wasn't the problem. The problem was when the durn thing relit, having gotten enough oil. Could be REAL scary[:0] -- as in BOOM!

[Modelcar]

...Jamie, understand what you are saying....If it was that critical for the water situation I wonder how they kept from blowing up many of them because we all know things don't always go as planned on daily routines...
I saw a large steam engine that had a boller explosion many years ago and it was total devistation....Nothing but the equipment below the frame was all that survived.

[jchnhtfd]

QUOTE: Originally posted by Modelcar

...Jamie, understand what you are saying....If it was that critical for the water situation I wonder how they kept from blowing up many of them because we all know things don't always go as planned on daily routines...
I saw a large steam engine that had a boller explosion many years ago and it was total devistation....Nothing but the equipment below the frame was all that survived.

you'd be surprised how many steam engines did blow up[xx(]. While hardly a daily occurence, it was not exactly unheard of. Usually something silly like a water gauge not functioning right -- and there were lots of reasons why they didn't. Sometimes the injectors or feed water pump would pack it in, too. There was (and is!) astonishingly little margin between everything being just wonderful, and too little water and boom[:D]. The fireman had a lot more to do than just heave coal into the engine; he was a very important guy -- he watched the water!
Thing is, the cab forwards had a good bit less margin that the conventional arrangement, and so they did it more often...[:(]
But no steam engine is easy to operate correctly, and the penalty for error is pretty severe.
And you are right -- a steam engine which has had a boiler explosion doesn't have much left above the frame[:D]

[Anonymous]

SP sure spent a lot of money on their locomotives working with environmental conditions rather than fix the problem. Why didn't they vent the tunnels? Would that not have been cheaper? Seems also that they continued building "specialised" locomotives for tunnel operations- the so called "tunnel motors" -right up to when UP merged with them. Did UP "fix" the tunnels- or just give up on using them?

Erik

[Philcal]

Subject has been pretty well covered,the SP cab forwards were unique to the SP,and were used in passenger service.Have at least one photo of a cab-forward powering the "Owl",SP's San Francisco-Los Angeles night time train.Probably no where near as speedy as the GS-4s,the cab-forwards could produce respectable speed,and were truly dual service locomotives.

[Anonymous]

This entire discussion has been very interesting. I happen to have a book, "Cab Forward," by Robert J. Church, DDS, self-published, printed by Central Valley Railroad Publications, copyright 1982, with no dabframmit ISBN, that seems to tell the entire story of the cab forwards very authoritatively. Dr. Church even mentions the odd-pot 4-4-0. This exercise proves to me that no matter how much you know about anything, there is always more to be learned. Thanks to all who contributed, I enjoyed reading it. CWT

[Kozzie]

QUOTE: Originally posted by tebo41

This entire discussion has been very interesting. I happen to have a book, "Cab Forward," by Robert J. Church, DDS, self-published, printed by Central Valley Railroad Publications, copyright 1982, with no dabframmit ISBN, that seems to tell the entire story of the cab forwards very authoritatively. Dr. Church even mentions the odd-pot 4-4-0. This exercise proves to me that no matter how much you know about anything, there is always more to be learned. Thanks to all who contributed, I enjoyed reading it. CWT

tebo41 - thanks for those comments. [;)][:)]
I'm glad this post has been interesting for others as well as answering one of those questions that I have wondered about. [;)] [:)]

Dave