Hello Everyone,

I'm looking for some help and advice on a project.
I have just started helping restore Illinois Railway Museum's former Milwaukee Road Dynamometer car X-5000. At the present time, we are working to bring the car's onboard systems back to operational status while waiting for the next barn to be built, at which point the X-5000 can then go indoors. Before I joined the project, focus was on sealing the roof and getting the car's Waukesha Enginator functioning. Both have been achieved, and a great example of the success of the latter was seen at IRM's museum showcase, when the dynamometer car powered not just its own lights, but those of three trailing coaches during IRM's night operations. During the same event, the Dynamometer itself (measuring forces through the center sill) was made functional after a lot of head scratching and pipe-tracing.

Last Sunday, The focus was on getting more anti-freeze into the heating pipes, as when the car was donated, the system was left full, and incredibly, all 50 gallons of water/anti freeze remained in the system over the 20+ years it has sat outside at IRM. The system was partially drained, and the anti-freeze was filtered and returned to the system along with fresh antifreeze to replace that which was to bad to be reused and lower the freezing point further. As a part of filling the system, we had to ensure all hot water lines were closed. While tracing pipe connections inside the car, I noticed an air valve, and traced it to a line that parallels the train brake pipe the length of the center sill. Based on my own knowledge, I guessed it was an air signal line. The project manager has asked me to research and confirm my guess, as well as determine the method of usage and how we should go about testing the system. (This will teach me not to find new things on the Dynamometer!)

Based on the research I have done so far, I can confirm it is an air signal/communication system that would have been used when the Dynamometer was cut in to a passenger train. Despite difficulties finding relevant information, I have located a online copy of a Milwaukee Road rule book dictating use of the system. I have also located a Penn Central rule book that mentions it. Today I located a text on Google Books covering the System's operation, function, and troubleshooting maintenance: http://books.google.com/books/about/Air ... hWAAAAMAAJ (if you click on the link, scroll down and you can click on the table of contents section "Air Signal System"). This is pretty heavy material, complete with diagrams of the various components. My biggest hesitation in saying, "Okay I've found what I need, lets start working on this" is that the book is dated 1906.

So hear is what I would like to know:

#1. Is the material in the book accurate? If not, where can I find the current information?

#2. Current intention is to attach shop air to the system (if that succeeds, we hope to test the system with a locomotive this coming spring): are there any precautions we should take before charging the system (Note: This car has sat outside since arriving at IRM, but did arrive fully operational) EDIT: The primary purpose of this question is to make sure that I don't test it in a way that damages the system

#3. This text covers regulators and whistles in a steam engine; what, If any changes were made when the switch was made to diesel?

#4. What precautions should be taken for testing the system with a (diesel) locomotive attached? EDIT: see edit to #2 above

#5. Is standard practice to have a valve on the (diesel) locomotives that would have to be opened to allow this system to function? If so, where would it typically be?

#6. Information from someone in IRM's Diesel department indicates that the pipe should be charged to 90 psi, however the text linked above says 40 psi; which is accurate to post 1930? What about after steam was retired, but before passenger service ended on the Milwaukee Road?

#7. In keeping with its role as a test unit; would it be conceivable for the car to be fitted with a signal whistle like what was fitted to the locomotives for the purpose of listening to the signals? If so, where should I look for this? How would I go about testing it?

I hope this make sense, an questions, feel free to ask me. If I don't know the answer, I will find it.

Thanks in advance for the help.
I'm looking forward to the insight members of this board may be able to provide

You kinda clopped my brain about this. I think you have to recall certain railroad technologies stuck around between steam and diesel. Early diesels had steam generators for the steam heating lines of the passenger cars, since the dynamometer car is modded to work with passenger equipment it would have to be fitted with the required systems to function in the passenger train.
I'm sure the air signal lines were in place long into the 60's as I recall watching a passenger train trainwatching hearing the squealing pea whistle in the diesel as the conductor signals train ready..lets go (2 long toots). For compatibilities, I don't see any changes from steam to diesel for the air signal system.


I don't know how the air was powered but it would make sense simply borrow the brake system air.

I was thinking about testing the air line, this is only a suggestion, nkp 765's superheaters were tested filling with water and looking for leaks under pressure, maybe this could be done on the air system, or perhaps charge it with a low amount of air pressure and spray childs bubble water all around the air line watching for bubbly leaks (or dishwashing soap)

just a few thoughts

My main thought with differences between steam and diesel was the operating pressure, as the 40 pounds mentioned in the text is a lot different than 90 pounds of pressure that was indicated by an IRM Diesel Dept. member. Personally I doubt that much changed with the valves, but I really want to be thorough and not damage anything.

My research to this point has indicated that this system was used until Amtrak's Superliners and Amfleets arrived on scene.

From the text linked in my earlier post, the air would have been charged off the locomotive's main reservoir through a reducing valve. I'm suspecting that there is a shut off somewhere so that this system is only online when in a passenger train, I'm just not sure where it would be if it actually exists.

Thank you for the suggestion on the soapy water; I've used that trick on large dual-burner camping stoves, but wouldn't have thought of using it on an train air line.

Air signal components were supplied by the air brake companies. I would check with whoever is your best knowledgeable air brake person.

The signal line pipe was smaller than the air brake trainline pipe. The glad hands were smaller in size to avoid making a wrong connection between cars. They also had cut-off valves similar to the trainline.

The system used in the 20th century would have been compatable from at least the teens on through to the change to Amtrak

I saw the Union Pacific using air signals here in Los Angeles area in 1969-70 era to signal that the last car was off the bridge and on the platform at the East Los Angeles depot. This when the company took back the portable (lunch box size) radios.

I have several railroad published books that may have some air signal information along with the air brake information. I have a full schedule and may not have time to research for several days.

This edition of Locomotive Fireman's magazine states that the pressure for the signal line should be 45 psi. It seems there was some variation in signal line pressure, but I would guess that it's not built for 90. Perhaps you test it it on 40? If it works on 40, no need to go higher, right?

http://books.google.com/books?id=jUUYAAAAYAAJ&pg=RA7-PA21&lpg=RA7-PA21&dq=air+signal+line+railroad&source=bl&ots=6ma1uu5OpD&sig=KoUKXAZp87_0uicsaeOddZUtJ0I&hl=en&sa=X&ei=4ZiFUrHLEY7oiALMt4HgAw&ved=0CEEQ6AEwBjgK#v=onepage&q=air%20signal%20line%20railroad&f=false

We have a functioning air signal system on a 3-car electric interurban train at the Western Railway Museum. I've done quite a bit of restoration and servicing on it.

The book is quite accurate as it relates to our system (thanks for the link to it!).
It's quite consistent with our equipment, which was current to about 1940.


Our system was specified for 40 psi - I suggest regulating to that pressure (at least for a start). Aside from that, the system is pretty robust.


As others have noted, probably not many changes since both steam and diesel worked together for many years.


Just start with 40 psi air.


There should definitely be shutoff cocks on the train line at both ends of the locomotive, also one between the main air reservoir and the feed valve which regulates the signal line pressure. There would also be one before the car discharge valve, and possibly one before the signal valve. Lastly, there is usually a shutoff cock between the signal valve and the signal whistle. The piping diagrams in the Westinghouse book you found on Google are good.

As a general rule, probably a shutoff valve to isolate any component which might fail and thus disable the signal system on the entire train.


40 psi would be good - even after the steam locos were retired the diesels were still pulling steam-era equipment so the change in locomotives would not have affected the equipment on the cars they were pulling.


It's possible (I guess) - maybe the engine crew might want to pass a signal back to the dynamometer car? You would have to follow the signal train line on the car and follow every tee you find to see what it was used for. It could be that the signal valve was under the car with a small (1/4") pipe leading to the signal whistle, but that is just a guess.

Good luck!

It's been a while since I looked at that system.

My understanding is;

1) There is a continuous "pipe/hose" connection between all the locos/cars in a passenger train. Passenger cars in a freight train cannot make use of the signal line. The presence of this signal line is is one of the distinguishing features of some "head-end" cars and passenger train equipped cabooses.

2) It had smaller "glad hands" so you couldn't "goof up" the signal line with the air brake line.

3) Locos and some cars like your dyno car and observation cars had a whistle and an operating valve.

4) The signal line is not usually charged with air.

5) To make the whistle "toot" in the loco a valve in the dyno car would apply reduced train-line air (at about 40 psi) to the signal line and also close off the local whistle while "tooting" the whistle in the loco.

6) A valve in the loco could do the same thing to make other whistles on the signal line "toot" when you pulled the valve.

7) The pressure only needed to be 40 psi or so to make a loud enough noise at the whistles elsewhere in the train.

8) The pipe and fittings are probably 1/2" (about 3/4" outside diameter) schedule 80 (good for about 250 psi) simply because they routinely used schedule 80 (instead of the weaker schedule 40 (old fashioned house water pipe)) for all the other piping on railroad equipment.

9) The observation cars used on the 20th Century Limited have a small door in the floor at the back end. By opening the door and using the enclosed hoses and valve/whistle it was possible to communicate to the loco when to stop the train when backing it into GCT or Chicago before a departure. That's how they spotted the train inside the underground areas of GCT before radios.

10) It was a simple and robust system, the only flaw was users at both ends could not signal at exactly the same time.

11) All that was needed was a pass through pipe/hose/glad hands on all passenger train equipment and valves and whistles on locos/cars that might need them.

If there is no extreme corrosion I would think that a leak test at 50 psi (or so) and cleaning the valves / whistles is all that would be needed.

Kevin

Not correct.

The signal pipe system is always charged with 40 psi air.

The reduction in air pressure caused by opening a car discharge valve anywhere on the train causes a small volume of air in each signal valve to force that signal valve's diaphragm upward, which lifts a valve stem connected to the diaphragm; this opens a valve which allows the remaining air in the signal valve to pass out through the whistle.

The feed valve which keeps the signal system charged has a choke in it to slow the recharge rate a little bit so that the pressure reduction is "seen" the whole length of the train.

See Section 9 ("Operation of signal valve") on page 52 of that Google reference.

Also see the sectional view of the improved feed valve on page 49 (fig. 5) which shows the choke.

Al, thanks for the correction. As I said I have not looked at that system in a while. I thought I remembered it without any additional fancy valves.

Seems like it is more fail safe if it is pressurized (and you have a gauge to make sure pressure is there).

Of course, if there is a break in the line you can't use it either way. But if it is pressurized you at least know it's broken.

Thanks Kevin

I guess there are different views of fail safe.

If a train were to break in two (which would depressurize the signal line), it would cause a single whistle blast (stop signal) in the locomotive.

Of course it would also put the train into emergency so the signal would be redundant.

On our restored Sacramento Northern interurban, there is no gauge monitoring signal line pressure.

When a train break in two occurs, the signal whistle blows for a long time. I think in the cab the whistle is not blowing off of line air, so it could blow indefinitely. It is useful information because of course the brake could be the result of a passenger emergency brake cord, and not a train separation.

I experienced this back when the Strasburg still maintained air signals. We had a worn coupling that kept popping open on the curve exiting Leaman.

On a quiet day, you could hear the escaping air from the conductor's cord pull, and there was a time delay between that and the whistle blow in the cab.

The conductor's air signal system was more or less passive, on the car. The valves, which bled the signal air to atmosphere, were usually in the vestibule's, and many times with a clothesline-type rope went thru the vestibule wall into the end of the passenger compartment. There was usually a safety cut-off angle cock on the line coming up from under the floor to the vent valve. The line under the car was 3/4" schedule 80 pipe, if I remember correctly. The end-hose glad hands faced the same way the air brake hose did, and I believe carried about 40 pounds of air pressure. Today, the second hose on Amtrak and most commuter cars is not for the signal, but for main reservoir air (up to 140 lbs pressure), and the glad hand on the MR hoses are the other hand, and won't make up with the air brake hoses. Electric train-lined buzzers, sounding in each car and the locomotive, have replaced the conductor's air signal, at least since the mid 1970s, perhaps a little earlier.

The current standard for testing passenger car air brakes or testing Conductor’s Air Signal Equipment refers to the following publication: Conductor’s Air Signal Instruction Leaflet No. 2377-2, July 1942. The publication is obsolete, but probably could be found in libraries or museum collections. I've seen them occasionally on E-bay.

There was no whistle in the cars, as I remember. The source of air and signal whistle was on the locomotive. There are probably some passenger locomotives, either diesel or steam, in the IRM collection, which are equipped with the signal equipment, and there is no reason it couldn't be made functional.

G.F.Payne
Baltimore, MD

For those of us old enough to have ridden pre-Amtrak passenger trains, this is one of those aspects of restoration or re-creation that gets lost to history - like steam heat, friction bearing journals, Spicer drives, and axle generators. Some would say good riddance, some of us think that any operation that can recreate those things adds to the historic experience. I clearly remember as a child being in a vestibule of a passenger train (probably either B&O or EL), watching a conductor reach up and tug on a cord to give the engineer "two to go" after a station stop. I had a chance to see inside the cab of RDG 2102 when it was being kept in Akron in the late '60's, and I saw the signal whistle behind the engineer's seat (probably no longer there?). If your museum or tourist operation is totally off the national system, there might be no legal reason it couldn't have a train set with those archaic systems functioning (other than the maintenance issues - I know, I know, I'm not the one who has to work on them) to give visitors a real sense of what it was like to be a passenger "back then" (probably should also ditch the crew radios and cell phones, except in emergencies).

The shrill "peep" of the whistle in the cab can be heard on an O. Winston Link CD recording of a J-class starting from a passenger stop-- then as the second "peep" is sounding, the cylinder "snifter" valves pop closed and the engine starts out of the station.

To those of us of a certain age, that signal whistle sound meant they were off-- heading for the far horizon, for the next town. Very much a part, as Paul says, of old-school railroading.

I see no reason that this system couldn't be used on a "captive" line, as long as the equipment is maintained and serviced in accordance with accepted railroad practices. Much easier to use that radio, though!

Howard P.

If anyone would like a copy of Conductor’s Air Signal Instruction Leaflet No. 2377-2, July 1942 that George Payne mentioned in a previous post, I have it as a PDF and will email it to those who contact me via RYPN PM.
Mike Tillger