"Bottling the Air"

[NW Mailing List]

Gordon,
 
Thanks for a better and detailed explanation. I know basically how they work, but not the Techno aspect, as you mention.

One more thing. I did get confirmation for your Bluefield question regarding getting a train started east. Although there was nothing in the rules specifically instructing, nor prohibiting, pulling against the air brakes to start a train, that is exactly what was done. 
 
The idea, and what happened most of the time, is that when the engine brake was released (with the holding brake still on the train) the train would normally start moving. If not, you had to pull against the holding brakes. You DID NOT release the air, or you would most likely find yourself derailed at Jug Neck, if not before. 
 
Jeff Sanders
 
--- On Mon, 11/1/10, NW Mailing List <nw-mailing-list at nwhs.org> wrote:


From: NW Mailing List <nw-mailing-list at nwhs.org>
Subject: Re: "Bottling the Air"
To: "NW Mailing List" <nw-mailing-list at nwhs.org>
Date: Monday, November 1, 2010, 9:49 AM





Dave,
 
I don't know whether a little Techno Talk as a follow up to Jeff's fine remarks will help or hinder, but assuming the former, here goes.
 
There is an "L" shaped bleed rod (or Release Rod) on both sides of a car so that the brakes can be released or bled from either side of the car.  After the ABD control valve superceded the AB control valve in new applications, a loop was formed into the end of the Release Rod handle to indicate that the car was equipped with the newer ABD control valve instead of the older AB valve (no loop on the handle).  The inner ends of the rods are attached to a Duplex  Release Valve on the Control Valve (The latter is frequently termed a "triple valve" although triple valves were superseded for new freight car applications by the AB Control Valve effective September 1, 1933, and were prohibited on interchange freight cars after December 31, 1951--old railroad terms such as "triple valve" tend to linger on!  The "AB" designation indicates that the control valve is comprised of a service portion (A) and an emergency portion (B), whereas the triple
 valve was all in one housing.).
 
When the Release Rod is pulled to the first position for two or three seconds, auxilliary reservoir air is reduced enough to exhaust brake cylinder pressure provided the brake pipe is pressurized.  This could be the situation if an inspector needs to replace a brake shoe in a train with a charged brake pipe.  He would close the cutout cock in the branch pipe between the brake pipe and the control valve to insure that the brakes do not reapply if something should reduce the brake pipe pressure, and he would then pull the Release Rod handle for a couple of seconds to exhaust brake cylinder pressure and release the pressure of the shoe against the wheel.  The brake shoe could then be replaced.
 
If there is no pressure in the brake pipe, the Release Rod would have to be pulled to the second position and held there longer to exhaust both auxilliary and emergency reservoir, which would exhaust the air in the brake cylinder also.  Some cars were/are equipped with a Brake Cylinder Release valve which will exhaust brake cylinder pressure when the Release Rod is pulled for a couple of seconds even if there is no air in the brake pipe.
 
Although the auxilliary and emergency reservoirs are spoken of as two separate reservoirs, they are actually combined into the one reservoir commonly seen near the control valve.  The combined reservoir is fitted with a dished partition in the middle of the reservoir that divides the combined reservoir into the auxilliary and emergency reservoirs.  The convex side of the partition forms the service reservoir with a 2,500 cu. in. volume, and the concave side of the partition forms the emergency reservoir with a 3,500 cu. in. volume.  In a full service application of the brakes from a 70 psi brake pipe (the value commonly used in technical manuals), the pressure in the auxilliary reservoir equalizes with the pressure in the brake cylinder, giving a nominal 50 psi cylinder pressure (with 8" standard piston travel) because of the relative volumes, but in an emergency application the pressure of both reservoirs equalizes with the pressure in the brake
 cylinder, giving a nominal 60 psi cylinder pressure, again because of the relative volumes.  This 20 percent increase in brake cylinder pressure will shorten the stopping distance in an emergency application of the brakes.
 
I know there are some good air brake people among us, so I would appreciate any comments to correct anything I set forth above, or to update my comments to apply to present equipment or practices.
 
Gordon Hamilton
 
 
----- Original Message ----- 

From: NW Mailing List 
To: NW Mailing List 
Sent: Monday, October 25, 2010 2:58 PM
Subject: Re: "Bottling the Air"






Dave,
 
You are exactly right. That is called a "bleed rod". That is how the air is bled out of the brake cylinder. When you bleed off the air from the brake cylinder, the air still remains in the air reservoir, which speeds up the train line charging process. If you "bleed the car dry", that means that you hold the bleed rod until all air has stopped blowing. That drains the air from the reservoir, which means it will take longer to charge the air system.

Jeff Sanders

--- On Mon, 10/25/10, NW Mailing List <nw-mailing-list at nwhs.org> wrote:


From: NW Mailing List <nw-mailing-list at nwhs.org>
Subject: Re: "Bottling the Air"
To: nw-mailing-list at nwhs.org
Date: Monday, October 25, 2010, 1:35 PM



When I was a teenager watching the LIRR crews on the Babylon Freight switch the team track in Massapequa, they showed us a little "L" shaped rod that stuck out to the side of the car from the triple valve.  If you pulled it out, the air was bled out of the brake cylinder.  You experienced operating folks will have to tell us whether that was the universal way to prepare a cut for humping or "kicking."
 
Dave Phelps
 

In a message dated 10/25/2010 1:13:25 P.M. Eastern Daylight Time, nw-mailing-list at nwhs.org writes:


What was done at Bluefield was simply a variation of what they still do in "hump" yards (where retarders are used instead of riders). Which makes me wonder - how do they go about releasing the brakes on cars that are humped? I can see the men working the cut levers at the Radnor hump in Nashville, but I don't see them doing anything with the angle cocks. In Bluefield there were riders in proportion to the length of the cut to do the braking, and there was a big motor car which brought the riders back up to the scale house. Once in awhile, not enough riders would get on a cut, and there would be a big derailment when the cut got down to the cars already at the east end.
     As to the length of time to pump up an entire train, that is why N&W put the second air pump on the S1a's and retrofitted the S1's. I can remember a railroader saying that the first S1's assigned to Williamson took a long time to pump up the train. (they were accustomed to the two pumps on a Z1a) Shortly afterward, the 200 came out of Roanoke with two pumps. How C&O got by with one pump all those years is a mystery. They obviously had a different operating philosophy from N&W.    Jim Nichols





From: NW Mailing List <nw-mailing-list at nwhs.org>
To: NW Mailing List <nw-mailing-list at nwhs.org>
Sent: Mon, October 25, 2010 10:12:46 AM
Subject: Re: "Bottling the Air"

Gene 


Technically I would seriously doubt that.


What was done on what you saw, and someone who actually was a brakeman/conductor like Jeff could confirm. In Bluefield yard, and other places, the cars were set out on tracks, and a certain number of cars had hand brakes tied down. That would depend on the size of the cut as to how many brakes were tied down. Once hand brakes were tied down, the switch engine would cut off, the air on the cut was dumped, causing an emergency application, but hand brakes had already been applied. Over time, the air system would leak off, depending on how long they had sat.


Once the yard shifter came in and coupled on to the cut, and applied its independent brake (for the locomotive) to hold it all in place. The brake systems on the cars had probably sat long enough that most if not all the air had bleed off the system, but the brakemen would walk along the cut to the triple valve on each car, and bleed off the remaining air, to release all air brakes. The brakemen did not couple the air line, therefore the hand brakes were all that would hold the cut. The hand brakes would still be on, once the air had been bleed, the brakemen would go along and release the hand brakes, the switch engine would pull back out, with the cut, into the clear, then shove the cut towards where they were to be put, if they were sorting cars, one man would pull the cut lever between the cars, and a brakeman would ride the cut, if needed for controlling the speed with the hand brake, while the cars rolled down into its track and couple with the
 other cars in that track, the brakeman would tie down the hand brakes, and the go back and do it again with another cut, etc.


Generally handing rolling cars, not coupled to a locomotive, was rarely done with air in the system. As Harry reported, air pumping can take some time to fill the entire train line. You used to see with the diesels, running at high RPMs while standing, the engineer, is running the diesel up to run the compressor faster, and pump air through the train quicker. A number of factors can determine how long it takes to pump a train, including, of course, train length, cold weather, how many leaks are in the system and how much initial terminal time that crew wants to report on their time sheet! I've heard of occasions where it would take several hours of pumping time to release all the brakes in a coal train.


In my younger days, when I was riding my bicycle down to the track, I'd sit and watch, and see eastbound coal trains get stopped by the signal at VN before going into South Yard, once the signal cleared, it might take them 30-45 minutes to pump air before they moved, and that was in good weather. They were great days, and I wish I had the interest and time to do that today, but alas, I have neither today.


Ken Miller



On Oct 25, 2010, at 9:12 AM, NW Mailing List wrote:


Ken;
 

Bluefield had a natural grade in both the East and West yard with the high point being in the area of the Round House. I remember as a young fellow in the East End of Bluefield, watching the "yard shifters" sorting the cars. There would be a number of cars released to freely roll to an appointed switch to make up trains. The Yard brakeman with his brake stick would control the speed until making couple with the other cars. I remember watching the men try to time the coupling just right and jump up in the air so as to miss the coming jolt of the sudden stop. I assume that free roll had to be done by "bottling the air", which was a common practice even in the late 50's. Also I remember watching "road shifters" push cars up to a speed and then stopping the locomotive allowing the cars to run freely though a switch, either coming to a stop on their own, or making couple with other cars.
 
Gene Arnold 
 
 
"Bottling the air" which I think, is now prohibited by most rule  
books, means to close the angle cock (air line) on both ends of the  
car or cut of cars before separating them from the train. That way,  
air stays in the system, and does not dump the air to emergency on  
that car or cut of cars. It is, among other things, made to speed up  
operations, as with air already in the train line of those cars, it  
means that the locomotive air compressor, does not have to run as long  
to pump air back into the system, which can be a considerable amount  
of time, meaning the crew can get underway sooner.

If the air is dumped from the car or cars, it sets those brake systems  
into emergency, and to release those brakes, the air system has to be  
pumped up again from the locomotive. By bottling the air, it means  
that only hand brakes, or chocks may be holding the cut of cars in  
place, which can lead to a drift off, or runaway, or difficulty  
coupling if the brakes are not holding well.

Ken Miller


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