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

[Kozzie]

After looking at pictures of those SP cab forwards, I've ended up with another Kozzie Question. [:I] [;)] [:)]

Was the cab forward design used by a lot of other RRs? Haven't seen many images of that principle being used extensively across other RRs.

Maybe the design, although possibly a good idea, was over taken by the advent of the diesel loco? hmmmmm....

What's the thoughts from the Forum Folk? [;)] [;)] [;)]

Dave [:)]

[edblysard]

Exclusivly a SP design, due to the smoke inside tunnels and snow sheds, of which SP had many.

Due to the nature and location of the tunnels on the SP, proper venting was not the rule, so putting the cab up was the easiest(cheapest) solution.

Other railroads had tunnels, of course, but also had the ability to use power venting, fresh air blowers ect...

The need for the design became moot with the advent of the FT and the GP diesel, but they lasted for quite some time, there are several photos of the SP fleet, mixed first generation diesels and AC Cabforwards in the tie up and fuel racks, side by side.

An informed source has provided 1910 as the beginning of the cabforward use on the SP, with a MC-1 Mallet Consolidation as the first cabforward.


Ed

[eastside]

1. Cab forwards would have required switching to oil firing
2. For crash survivability, many engineers wanted all that iron in front them, not behind. Witness the insistence of some railroads up until recently to order road diesels with the cab in the rear

I also heard that the SP CFs were limited to low speeds. I'm not certain if that was characteristic of CF designs in general or only in this particular case.

[Kozzie]

[tup] Thanks very much Ed and eastside [;)]

Very interesting stuff.

Since it was what one could call a 'line requirement, they could have hauled passenger as well as freight?

Dave

[Anonymous]

QUOTE: 2. For crash survivability, many engineers wanted all that iron in front them, not behind. Witness the insistence of some railroads up until recently to order road diesels with the cab in the rear

That was one of the things that I could never understand....

Why would the engineers run their diesels long hood forward......why why why.....

And as you said it turned out to be because of safety reasons, it makes sense to me.

Apparently there were a lot of RTEs complaining when the newer diesels started arriving that could really only be operated in the one direction with the cab up front.

[Modelcar]

...I understand about the long hoods forward for safety, etc....and the C F's but as some engineers stated...long part of the steam engine forward made them feel safer...but what about a hard hit with a steamer....Wouldn't that have put them in much danger with all the coal slamming forward from the tender....? And worse yet the tender being mashed right into the back of the engine cab, etc....Often wondered about all of this...I'm talking about a hard hit to brake metal, etc...

[eastside]

I've never seen any serious statistics in support of rear-end cabs. I agree it seems mostly psychological when it came to cab forwards. The engineers must have been uncomfortable with the imagery going through their minds. It must have been something like that they're the nut between the hammer (the locomotive or whatever else is coming at them) and the anvil (their locomotive), conveniently ignoring the many thousands of tons of the following consist [:)]. My hunch would be that the benefits of better visibility of front-end cabs outweighed the potential increased survivability of rear-end cabs, but that's easy to say in hindsight after decades of experience with mostly front-end cab diesels.

[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.

The Italian State Railways, Ferrovie della Stata, (FS) had some coal burning four cylinder compound 4-6-0 locomotives which were cab forwards, and had coal carried in a bunker above and around the firebox. The shape of the cab front was a sharp vee, even sharper than the later SP AC-9 to AC-11. The bogie was under the cab and firebox, and the four cylinders were reasonably accessible all at the back end under the smokebox. My memory is that they were class 670 locomotives in the FS system. These were high speed (for the day) passenger engines. One was rebuilt in the 1920s with a Crosti feedwater heater on the tender, and was fully streamlined, retaining the pointed cab.

The FS also had four cylinder compound 0-10-0s which had bunkers around the firebox and very small water tanks. They were used as pusher locomotives in the Alps, and ran with a six wheeled auxiliary tender with a cylindrical tank! This allowed them to uncouple from the tender, so that the engine was always leading, whether cab or boiler was leading. At least some of these were rebuilt as conventional 0-10-0s with normal tenders carrying both water and coal at the cab end.

The German State Railways, Deutsche Reichsbahn Gesellschaft (DRG) ordered a cab forward version of the 05 4-6-4 (the real world steam record holder- remember the "Mallard" was unserviceable after its run downhill in which it beat the 05, running on the level, by only ONE mph) in 1935. This loco, 05 003 used pulverised coal which was blown by compressed air up a tube under the boiler and directly into a burner in the throatplate of the firebox. It too was fully streamlined, with a curved cab reminiscent of the E18 and E19 electric locomotives and the later "Flying Hamburger" diesel electric railcars. It didn't actually enter service, and was rebuilt as a non streamlined version of the other 05s in the early 1940s. Liliput make a model, but not (so far) in cab forward form (that I know of).

So while Southern Pacific had the best known "Cab Forwards", they weren't the first nor were they the fastest, but they were the last in service.

Peter

[CSSHEGEWISCH]

According to Dan Ranger's article about cab-forwards in TRAINS in about 1968, Western Pacific also considered a cab-forward design but it was voted down in a poll of engineers in the operating district in which they would have been used.

The same article includes a photo of a cab-forward on the "Overland Limited" at Dutch Flat, CA, with a 2-8-0 as a helper.

Kozzie, it's interesting that you would bring up the cab-forward question when you consider the cab-forward design of the latest Australian diesels compared to the North American designs with which I'm familiar.

Paul

[Modelcar]

....In the basic question of cab forward designs...that of safety, I consider the fact all large railroad engines are large in size including their height...I realize it would be a nasty experience to be an engineer in one of the SP units back then and see a non preventable accident looming ahead....With exception of hitting a fuel tanker of some kind, wouldn't the engineer [and fireman], still have a good chance of survival being up high off the rails and of course massive steel structure underneath and right in front of them....

[WDGF]

I recall reading somewhere that there was also some trouble keeping them steamed properly on grades. With a normal locomotive, the water in the boiler is highest over the firebox when going uphill, where with the CFs, the water is lowest over the firebox going uphill.

[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.

[espeefoamer]

QUOTE: Originally posted by eastside

1. Cab forwards would have required switching to oil firing
2. For crash survivability, many engineers wanted all that iron in front them, not behind. Witness the insistence of some railroads up until recently to order road diesels with the cab in the rear

I also heard that the SP CFs were limited to low speeds. I'm not certain if that was characteristic of CF designs in general or only in this particular case.

I always found it quite interesting, that the two railroads (Southern & N&W) that bought high hood diesels,also ran them long hood forward.They ordered high hoods for crew safety,then ran them long hood forward for the same reason.

[kenneo]

FIRST --- These are NOT CF engines. They are Class AC-1 through AC-12 for the 4-8-8-2's and MC-1 through (at least) MC-6 for the 2-8-8-2's. That is, the 4-8-8-2's are. All but one class ran Cab Forward. This class was used between El Paso and Tucumcarrie and burnt coal, not oil.

AC = Articulated Consolidation, and were originally 2-8-8-2 cab to the rear, converted to cab-forward 2-8-8-2. The single axel lead truck did not track well (what was originally the trailing truck), and all 2 wheel lead trucks were replaced with 4 wheel.

AC's were passenger engines as well as freight and pulled all the passenger trains between Sacramento and Reno and, when not used as the "order engine", were helpers for passenger trains between Dunsmuir and Eugene. They pulled passenger trains elsewhere on the SP, as well. The SP had a fleet of 12 2-6-6-2's with 63" drivers that were designed especially for Sierra passenger service to end double-heading these trains. These engines were cab-forwards, also.

When I went to work for the SP, steam was not that far in the past, and I never heard any remarks about not liking riding up front. They did say, however, it was a bit of a strange feeling until you got used to it.

The originals, MC1's 4000 and 4001, built by Baldwin as conventional 2-8-8-2's. They hadn't made many runs out of Roseville before funerals were being held for the enginemen that were being asphyxiated. They were withdrawn from service, and sat rusting away on "flat land runs" for quite a while until Baldwin re-designed them with the oil and water feed lines moved to the front , the tender put there, and a "front put on the back" of the cab. Thus was born the cab-forward. Baldwin built 51 total Class-MC 2-8-8-2's (4000's) and 12 2-6-6-2's (4200's) (later converted, like their bigger brothers, with a 4 wheel lead truck) between about 1911and 1922. The first 10 AC's (4100's) (4-8-8-2) were built in 1928 (AC-1) and the 16 AC-2's were built in 1929, and 25 AC-3's in 1930. The conventional AC's were built in 1939 as 2-8-8-4's and were semi-streamlined, and built by Lima. Memory tells me the class was AC-9.

The SP had about 250 cab-forwards of various designs and classes.

[Anonymous]

Before CF was the engineer going through 37 miles of snow sheds blind? If conventional 2-8-8-2s asphyxiated crews, how bad was it for crews of less powerful predecessors. Did passengers feel like they were in a chimney?

[Modelcar]

....From reading of the cab forward operations with SP over the years I did not realize the operation was so large to have had that many of these engines...The problem must have really been critical for them to change their operation like that with completely different design engines. Even with the CF units I suppose that limited a train to one engine on the front and then I wonder about the pusher operation.....ANY pusher would have been subjected to the gasses from the lead engine....?? What did they do...limit the length of trains to just one engine...? Were special instructions in force to keep all passenger car windows closed passing through all the sheds and tunnels...? When one really digs into this situation you wonder how the operation was sustained without really getting the company in trouble with asphyxiated passengers, etc....and at that time each freight train had...what, a crew of probably 4 or 5 men...plus more if an additional engine was included in the consist. Compare that to OSHA today...!

[M636C]

Since the problem was snowsheds rather than tunnels, spacing the pusher locomotives at the half way point or at the rear would allow the exhaust gases to disperse (through the open downhill side) enough to allow an acceptable (if not desirable) concentration of smoke in the air.

Photos I've seen suggest that ACs often ran just ahead of the caboose.

Peter

[UPTRAIN]

Espee thought it all up when they had to run those huge smoke belching locos through their long tunnels. No other railroad that I can think of embraced this design.

[Anonymous]

Some railroads did permit heavy steam power to push behind the caboose, though I wonder if anyone was foolish enough to actually ride in a wood caboose with a 2-8-8-2 hammering at the rear. In the diesel era, most railroads restricted the use of pushers behind cabooses, even though they were all-steel by that point -- D&RGW allowed two GP40s or one SD40T-2 or SD45 behind a caboose; anything more had to be cut in ahead of the caboose, or the excess units isolated.

I can't imagine that a cab-forward rode very well. Must have been pretty bouncy.

[UPTRAIN]

Hey, wasn't there a picture of a crew coupling onto the rear of a D&RGW train as a photo finish in TRAINS a few years ago? The locos were behind the caboose if I recall.

[Anonymous]

Zach: That's right. Try the August 2001 issue, with the articles on helpers. It shows two GP40s (allowable by rule, see above) coupling up behind a lumber drag at Thistle, Utah -- now a ghost town buried in mud.

[Modelcar]

....It's my understanding they did have long tunnels to deal with besides the many miles of snow sheds....

[GMS-AU]

Could it be said that any tank engine could be seen as a cab forward. Many British designs of tank engines had running lights on both ends and were used on branch lines or passenger service where they couldn't always be turned on a wye.

[Modelcar]

...Concerning the massive flood at Thistle some years ago...and requiring the boring of a tunnel to support the revised routing through that area....Did the flood waters ever drain or has it become a permenant dam behind all the debris.....?

[kenneo]

The comments about venting are correct. The snow sheds (and rock sheds, too) were vented out the top and also out the open sides. Mid-train helpers had a fairly well vented location. Helpers located in front of or close to a caboose usually had the rear-end crew in the locomotive.

Their ride took some getting used to. The cab was at the far end of a rigid frame balanced by the rear set of drivers. Take your school ruler, grab ahold of one end and notice how the free far end reacts to the inputs from your hand. Bouncy is about as kind as you will get, I think.

The cab-forwards were designed for and assigned to the Ogden-Roseville, Roseville-Eugene (Siskiyou (as far as Ashland) as well as the Natron Cutoff) and used extensivly also between Bakersfield and Taylor. The coal-burning AC's were used out of El Paso, generally towards the CRIP. Due to their large numbers they tended to wander about the system some, but were concentrated as described above.

You may also want to know, that just 10 years after the first cab-forwards were being introduced, SP and Baldwin designed a replacement for them for "flat-land" and mountain service that did not have the enclosure problems north and east of Roseville. These were the 2-10-2's (Prosperity Special) of which a large number were made and used, and the much slower 4-10-2's, which were the 5000 series 3-cylinder compounds.

[Anonymous]

Thistle "Lake" was drained by a tunnel specifically bored for that purpose at the same time the railroad tunnels were bored; otherwise, the water would have eventually overtopped the mudslide, caused it to fail, and obliterated most of the town of Spanish Fork at the canyon's mouth. There is no lake, but the new ground level is about four feet higher because so much silt washed into the lake while it was there.

[Modelcar]

....Thanks Mark, for your comments....I've wondered about that situation for some time now having not seen any photos of the location since all that had happened and the line was rerouted. That must have been a tricky tunnel boring...Knowing their goal was to get to the water for it to drain...and not take the sand hogs with it.

[Kozzie]

Thnaks to everyone for all their comments. It has been very informative.

Apreciate it very much [:)][:)]

Dave

[broncoman]

Wasn't there an article about what UP's steam team went through, going through the snow sheds a couple of years ago when they brought both 3985 and 844 out. I was waiting in person at Soda Springs to watch them come by. Apparently the two SD70s that were helping dropped out forcing them to pu***he two loco's harder. It was amazaing how they looked by the time they made it to soda springs. I think one of the Steam team personel wrote the article, it was pretty cool.

[mike-65]

Cal State Rail Museum has one of these beasts - she's magnificent and massive.

Here's an interesting link, with a little more background info, and an 'odd' phrase:
"...the first California cab-forward..." apparently wasn't built by the SP...

http://www.csrmf.org/doc.asp?id=162