Can anyone explain why the concept of a cab forward was never carried over to all steam engines? it certainly makes sense, visibility, comfort, etc etc this concept would have been appreciated in some of the C.P.R. long tunnels in the Rockies, why it was never expounded is a mystery to me, maybe it’s the age old concept " that’s the way it’s supposed to be" And were there any other locos other than articulated that changed to this concept?
Before Western Pacific ordrerd their challengers, they asked engine crews if they wanted cab forwards. The engine crews declined. They said,because of the danger of landslides.
The biggest drawback to wider use of the concept was the rquirement that the engine be an oil burner. The only application I know of other than the SP articulateds was on a Calif. short line north on San Fran
That was something I had wondered about. Was there a viable way to move coal from the tender all the way up to the now forward firebox, perhaps using a conveyer belt under the boiler?
The other advantage of the cab forward was that it made it possible to eliminate the trailing truck (and thus put more weight on the drivers), since the usual trailing truck under the firebox was now also the lead truck. However, SP still used a two wheel trailing truck in their cab forwards, so either they could not find a way to eliminate it in the new design, or they simply did not endeavor to remove the truck from the original 2-8-8-4 design prior to reversing it.
You can bet if James Hill had adopted the cab forward, he would have eliminated the trailing truck. Of course, if he had been the genuis he was reputed to be, he’d have done it for the SP&S engines, which were all oil burners. Cab forward Challengers (4-6-6-0) and cab forward Northerns (4-8-0), 'cept would they have still been called Challengers and Northerns?
What about grade crossing incidents? Did the cab-forwards offer enough protection for the crew??
CC
Tatans, You may find this article interesting. It is fictional and deals with how CP could have made one of their Selkirks into a cab-forward.
Selkirk to Connaught
Trains, June 1987 page 34
making a 4-10-2 from a 2-10-4
( 2-10-4, CAB-FORWARD, CPR, “HOWARD, F. H.”, “JACQUIARD, MAX”, STEAM, ENGINE, LOCOMOTIVE, TRN )
I suspect that just like tunnel motors ( which had limited acceptance) most RR’s viewed CF as a novelty with limited application.
dd
The conveyer belts would have required cones that hadn’t been perfected until the Madonna era.[;)] (Inside joke from an old topic)
Can you imagine what would have arisen in terms of “styling” if some of the other railroads had built their own cab forwards?
How about the Pennsylvania? Would we have seen Sharknose cabforwards?
Or the NYC, with a Dreyfuss-style spacebar curving between the cab windows.
Or a Union Pacific cabforward with an M-10001 front.
And how many railroads would have had various themes of the slantnose cabforward?
Or, if the locomotive builders had their own off the shelf versions, would we have seen Baldwin babyface cabforwards, Alco PA cabforwards, or Fairbanks-Morse Erie-builds (all of which would have probably needed a three axle truck to support the extra forward length)?
A conveyor belt under the boiler would have caused problems with the ashpit. If you have an oil-burner, you do not need a straight pipe.
The Germans built one of their Hudsons of the class 05 as a cab forward. It was fired with coal dust, but this didn’t work. The coal-dust used to clogg to the interior of the feeder pipe, mainly at corners. Thus, less coal arrived in the firebox compared to what had been calculated before. The horse-power-output of the engine was thus much smaller than expected. After a short time, the engine was rebuilt to a conventional one.
As far as the SP&S using a cab forward it wouldn’t be needed since the few tunnels on the SP&S were pretty short. The “trailing/leading” truck under the firebox would still be neede to guide the engine into curves. Even the WM which had a seeming obsession w/ wt on drivers put 2 wheeled leading trucks on their 2-10-0s and 2-80s.
As far as the SP&S using a cab forward it wouldn’t be needed since the few tunnels on the SP&S were pretty short. The “trailing/leading” truck under the firebox would still be neede to guide the engine into curves. Even the WM which had a seeming obsession w/ wt on drivers put 2 wheeled leading trucks on their 2-10-0s and 2-80s.
It also required stronger oil and water pumps, because of the long pipes from the tender to the boiler and fire box, which would cut down on fuel effiency. On passenger service the smoke would be even closer to the passenger cars, would would not please customers.
A cab forward nose would have made it easier to place a toilet in a steam engine for the cab crew, something that didn’t catch on until Dieselss became popular.
Something amazing that I was born too late to see: standing right next to the coupler between doubleheading locomotives, both working hard, with the lead a cab-forward and the second traditional. Talk about awe inspiring sound!
Would that have been allowed in practice in the US / Canada?
I’m almost certain that I have read in old Working Instructions for our Central Wales line that coupling assisting engines “chimney to chimney” through the single track tunnels @ Sugarloaf and Llangynllo (the gradients in each were eased to 1in 74 from the ruling 1 in 60 grade) was stricly verboten as it might cause a blowback in one or the other’s firebox. If the assiting engine the “wrong way round”, it had to be attached at the rear of the train.
Similarly, the Great Western Railway’s normal operating practice for assisting Up freight trains (i.e. heading East towards London and Bristol) through the Severn Tunnel was for the assisting engine to be coupled ahead of the train engine, so that should anything untoward occur, the crews could quickly agree how to sort things out. But at Pilning, the next loop siding, the assisting engine was uncoupled and recoupled behind the brakevan (caboose) before negotiating the Patchway single bore tunnel, which was always full of smoke being on a 1 in 100 unpgrade.
The engine truck – lead truck – of the cab forwards simply had to be there; their tracking characteristics were only adequate anyway (something not really solved until the UP Challengers came along). Without the trailing truck, backing one of them would have been a nightmare, and I would believe that the trailing truck also contributed to the stability of the whole thing at speed.
As several folks have noted, the major problem with the cab-forward design is getting the fuel and water to the firebox. A conveyor would have been impractical (there isn’t a whole lot of room under a boiler, at either end); as noted the Germans tried powdered coal, which has problems of its own, etc. There is another subtle problem not mentioned, though: the most vulnerable part of a locomotive boiler is the crown sheet, over the fire box. That has to have enough water over it, or very bad things happen. The engine works hardest going up hill, which is when the water levels will be lowest. In the cab forward design, the crown sheet is the highest thing around going up hill… so the water over it is lowest going up hill, when the demand is highest. Firemen were a little jumpy about this!
Cab forwards had another very serious drawback. That is when working a grade the crew had to ber VERY diligent in keeping the water level up. When going up a hill your fire is at its hottest to keep up with the steam needed. While on an up grade the water is the highest at the back of the boiler and lowest at the front. So on a standard locomotive the crown is easily covered with water. However on a cab ahead the crown is at the water’s low point. If the crew doesn’t keep up with the water demand there will be a boiler failure. And from what I read years ago the Cab Forwards did have a higher than normal boiler explosion rate.
Two questions:
- For the cabforwards, would a six wheel lead truck have helped the tracking characteristics?
- Regarding backing without a trailing truck, how did the GN 2-8-8-0’s and other such engines accompli***hat task?
What about running a coal conveyor over the top? Since a cabforward doesn’t need a “sloping” shape of the boiler for visibility (it could have been square like an FT’s B unit for all they care), couldn’t the smokestack, sandbox, et al be split at “11 and 1 o’clock” on the upper quadrants of the boiler, and then run the conveyor right over the top?
Running a converyor over the top of the boiler would still be a clearance problem. The overall clearance diagram would come into play since the cab-forward design originated for lines that had a lot of mileage in tunnels and snowsheds.
Another design factor that affects clearances is that the boiler is on an outside tangent to the rails on curves.