Hey folks, I'm detailing an old BLI Blueline USRA light Mike for UP. I have specific photos of a prototype I'm modeling, and they show this piping going up and behind the smokestack that goes down the left side of the smokebox. Any idea what this is? I'm looking for more photos on other engines that also show this piping in detail, but I'd probably be having more luck if I knew exactly what I was looking at, and I'd like to add this detail.
Here's a photo of a USRA Mike for UP from Brasstrains to illustrate. It's that pipe behind the stack and just under behind the numberboards. What is this doo-hicky? I've read the page on Sweeny stacks from Utahrails and looked at the blueprints, but this still eludes me.
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Looks like a light on the stack so the engineer and fireman could monitor the color of the smoke to tell how the engine is running.
Dave H. Painted side goes up. My website : wnbranch.com
I think you're looking at two things simultaneously.
No question in my mind that's right about the stack light. These were hooded to throw a beam at the back of the exhaust column, to aid the fireman in getting the 'fine gray haze' that was best compromise for that era of oil firing.
The thing behind the stack might be a junction box to the light, but it is in just the right spot to be a drifting throttle arrangement, a valve providing low-pressure steam to exclude air and 'not pull a vacuum' to suck soot and hot gases into the cylinders when running downhill with the throttle closed. Key for this would be if there is a similar 'downpipe' on the other side of the locomotive.
This is too far forward in the extended smokebox to be a top check for an injector, but that part of the convection section would probably be one of the best places to introduce feedwater for least shock and better early settling of scale minerals...
Besides the stack illumination, which, I might be wrong here, seems to be a feature found on more oil fired locomotives than coal, there was also the exhaust for the stoker engine and air pumps sometimes piped to that location.
Some booster-equipped engines had a larger exhaust pipe (maybe 2" pipe) and in some cases, look similar to the NYC Hudson, actually looked like a small, additional "stack".
Seems like 99.9% of the photographers in the past loved the 3/4 frontal shot which hides the detail of the behind-the-stack appliances.
Good Luck, Ed
I was not aware that lights were mounted under the stacks to monitor the exhaust. Thank you all so much for the information! I think I have a better idea of what to look and search for. I've found a few more shots that sort of show the set up but...
gmpullman Seems like 99.9% of the photographers in the past loved the 3/4 frontal shot which hides the detail of the behind-the-stack appliances.
...yeah. There is one USRA UP 2-8-2 in Walla Walla, and it has this hardware behind the stack, but no one has taken detailed pictures of that area of the locomotive.
I may pick up a copy of some of those class photo books from the UP Historical Society, maybe I'll get lucky.
There is something of an untold story about that booster exhaust 'piped to the stack'. I think if you carefully put the thing together, including the lawsuit between the Ingersoll/Franklin and Bethlehem people (and checked Fryer) the actual development might be clear. As I recall, the Ingersoll NYC original piped the booster exhaust INTO the stack -- logical, to boost the fire quick at starting with the extra steam demand of the booster motor. That seems to have introduced just the sort of problems you'd predict, and by the time of the Lima A-1 you have a great long restrictive tract running from the booster exhaust, with more fancy swing joints, all the way up to the stack (to vent the exhaust where it blows along with the existing steam exhaust) but not INTO the stack. (Or in a nozzled ring around it, which is a different 'thing' Ed can mention...)
The final version involved routing the booster exhaust somewhere on the tender, realizing at last that boosters were supposed to be run so little they wouldn't heat the cistern dangerously high for injectors. I think there were some other things on Bethlehem engines, acting like 'scape-pipes, but would have to go back and look at notes I don't have at hand.
Do not be fooled by some designs that have a little stack, sometimes with a cap just like the bigger one, just ahead of the stack. I thought that was a booster exhaust for years. It is not -- as I recall it's a feedwater-heater vent.
The stoker engine exhaust is another of those classical fun topics; it certainly made little sense to equip it with an enormous angled pipe with mandatory but freezable condensate traps up to the top of the smokebox. Ed can gainfully list the different exhaust strategies for the pumps, some of which IIRC were integrated with exhaust-steam use for feedwater heaters and exhaust-steam injector setups.
Routing low-restriction exhaust from some of the auxiliaries was also an interesting topic. Ed will have the flow diagram for the ill-starred Hancock Turbo-Inspirator that combined some of the stuff. I do not now remember where Peter Lewty actually recommended exhausting his original booster design -- someone better look that up.
There was a little article in Trains many years ago that depicted a stack light in use, I think on the MKT, and they described what the engineer and fireman looked for when using it.
OvermodThere was a little article in Trains many years ago that depicted a stack light in use, I think on the MKT, and they described what the engineer and fireman looked for when using it.
I believe the stack lights were in front of the stack so the fireman was looking at the lamp through the exhaust.
Here is a capture from a film I made at the California State Railroad Museum's Cab Forward:
SP_cabforward_stack by Edmund, on Flickr
gmpullmanI believe the stack lights were in front of the stack so the fireman was looking at the lamp through the exhaust.
It also seems evident in the picture that the view of the plume using a conventionally-mounted, hooded light would be blocked by the air reservoirs... could that be part of it?
OvermodI have never seen one (until your picture) that shows the lamp anywhere but behind the stack, with a hood over the entire part of the lamp visible from the cab on either side,
140928_84_union by lmyers83, on Flickr
I attribute the J-3a Hudson "Booster Stack" to Al Stauffer, who made several references to it in his multiple volumes covering NYC steam. Seems like once an "authority" proclaims a fact it becomes incontrovertable.
Regards, Ed
Amusingly, Frisco 1522 at NTM in St. Louis prominently has one of those front-mounted lights ... and I never noticed its position.
Someone who can get onto the O Gauge Forum 'full-size trains' board, where Jack Wheelihan and others are chronic participants, and ask in detail how the light was used on 1522 and whether it was preferable to a rear-mounted type, perhaps depending on time of year or weather condition.