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Locating air leaks...

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Posted by coborn35 on Sunday, May 8, 2011 12:01 AM

Interesting take on the I.T.A.B.T...

Mechanical Department  "No no that's fine shove that 20 pound set all around the yard... those shoes aren't hell and a half to change..."

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Posted by edblysard on Saturday, May 7, 2011 10:34 PM

A little clairifacation to the original question...

If your on the road, the conductor walks the train till he finds the leak...if its a gasket in the glad hands, he changes it out with one of the spares on his key ring, if its a hose that was not laced up, he laces it up, rear anglecock left open, he closes it, air hose damaged beyond repair you close the anglecock on the car ahead and set the car out, if there is no where or way to set the car out you button up the train ahead of the problem car and proceeded at restricted speed to the nearest location where the car can be set out.

Both GCOR and NORAC have specific rules regarding this.

If you in the yard picking up a track that has been worked already and is ready to depart, you call the car department, they will ride the train on thier scooter and find/fix the problem.

If its is a outlieing yard with no car department, you walk it and find/fix the problem.

As for finding the actual leak, with 90 psi of air blowing through a 1" opening in a glad hand/hose that was not laced up, well its pretty loud, you can hear it from 10, 15 or 20 cars away, it is a very distinct sound.

As for the handheld gauges we carry them with us so when we have to pick up cars that have no ground air supply we can do a initial terminal air test.

I have my engineer charge the line as I walk to the rear, laceing the cars as I go and doing a visual check of the cars, (if your lucky they are already laced up by the industry) then we use the hand gauge to check train line pressure and to compare the rear train line pressure against the locomotive gauge, minimun pressure is 85 pis and the rear has to be withing 5pis of the head end, we then do a leak down test, allowable for us is 1pis per minute, the locomotives's compressor can easily over come that small leakage.

Once we confirm that, we perform a set and release to make sure the rear car's brakes function properly, then I have my engineer set the brakes and I walk the cars back to the head end, checking eack car to make sure the brakes have set, and doing a visual once over for broken safety appliances and any obvious bad order cars.

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Posted by kolechovski on Saturday, May 7, 2011 12:34 PM

IF there's good communication, and one knows as a result that this type of load will be picked up, simply venting some or all of the air first before connecting to the main trainline would avoid this, right?  Then again, with leakage being quite common in small amounts everywhere, combined with this kind of thing being possible anywhere really, wouldn't this be best as a common practice?

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Posted by BaltACD on Saturday, May 7, 2011 12:16 PM

A occasional problem when a train makes a rear end pickup (done to maintain blocking integrity at times) is having the pickup that has been on ground air or handled by another crew having that cuts train line charged to a higher pressure than the train that is making the pick up....after the pick up is made the road power is unable to pump off the initial brake application.  Sometimes it can be quite a experience in finding out that the rear end pickup has been overcharged (at least in relation to the through trains brake pipe pressure).  Placing the entire train in emergency a time or two and then pumping off the emergency applications will normally cure the condition.

kolechovski

Would it ever be feasable to overcharge the air a bit more to try to produce a more discernable hiss?  You clearly wouldn't want to take it too high, and only keep it raised as long as necessary to avoid unnecessary wear and tear.

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Posted by kolechovski on Saturday, May 7, 2011 11:19 AM

Would it ever be feasable to overcharge the air a bit more to try to produce a more discernable hiss?  You clearly wouldn't want to take it too high, and only keep it raised as long as necessary to avoid unnecessary wear and tear.

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Posted by Paul_D_North_Jr on Saturday, May 7, 2011 8:50 AM

I believe the car people have portable gages that they use to test individual cars after working on their brake systems - "Single Car Test" or "SCT"; also Single Car Test Device or SCTD; also Automated Single Car Test Device or ASCTD; and also Computerized Single Car Test Device or CSCTD.   

Some are pretty big and need a wheeled cart, such as this Wabtec / WABCO one (2 pages, approx. 185 KB in size):

http://techinfo.wabtec.com/DataFiles/Leaflets/ASCTD%20Quick%20Start%20Guide%20A.pdf

But others are more portable, such as this New York Air Brake Co. one:

 http://nyab.thomasnet.com/viewitems/test-devices/freight-single-car-testing-device-complete

And the smaller brake cylinder test gages from Pittsburgh Air Brake Co.:

http://www.pabco.biz/shopsales.htm 

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Posted by Paul_D_North_Jr on Saturday, May 7, 2011 8:25 AM

OK - thanks, Ed.  "Ground pounder" I knew from the military, and "daily constitutional" from various references in literature.  In his novel The Great Train Robbery, the late Michael Crichton referred to the many people who walked to work in London, England as "taking the Marrowbone Express", so I would have recognized that variation.  But the others are all new to me.  <Checks off "Learn something new today" from daily "to-do' list . . .  Smile, Wink & Grin >

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Posted by Rader Sidetrack on Saturday, May 7, 2011 7:06 AM
Paul_D_North_Jr

Ed - What's a "Mares shank"

"Mares shank" is slang for walking. From Wikipedia: More obscure terms for walking include "to go by Marrow-bone stage", "to take one's daily constitutional", "to ride Shanks' pony", "to ride Shanks' mare", or "to go by Walker's bus". Among search and rescue responders, those responders who walk (rather than ride, drive, fly, climb, or sit in a communications trailer) often are known as "ground pounders". http://en.wikipedia.org/wiki/Walking
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Posted by coborn35 on Saturday, May 7, 2011 1:12 AM

tree68

Ah, the old "half split" method I learned in USAF electronics school.

You just want to make sure you've tied down that part of the train...

If your not breaking the joint you shouldn't need to tie it down, the engines independents should hold it, mountain grades notwithstanding.

Mechanical Department  "No no that's fine shove that 20 pound set all around the yard... those shoes aren't hell and a half to change..."

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Posted by Paul_D_North_Jr on Friday, May 6, 2011 10:37 PM

Someplace I read that when there's a "dynamiter" = a car with a triple-valve that's either defective or too quick-acting, so that it goes into emergency upon a small or no brake application, etc. - and a DPU or EOT on the back, then the approximate location of the suspect car can supposedly be determined by comparing the times when the pressure drop arrives at the front and rear ends, and then by proportions figuring about where that car is.

It might be possible to do something similar with a leaky trainline, by comparing the flow rates into the air line from the front and rear units - likely, more air is coming from the air compressor on the unit(s) that is closer to the leak, all other things being equal.  But I've never tried it, and it would be only a rough approximation.

Ed - What's a "Mares shank" ?      

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Posted by tree68 on Friday, May 6, 2011 9:28 PM

Ah, the old "half split" method I learned in USAF electronics school.

You just want to make sure you've tied down that part of the train...

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Posted by Paul of Covington on Friday, May 6, 2011 9:10 PM

   Sorry, I meant to say "angle rooster"

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Posted by Paul of Covington on Friday, May 6, 2011 9:06 PM

    Just thinking,    in a case like Jeff mentioned where the leak is not obvious, would it be worthwhile to narrow it down by going about halfway down the train, cutting off an angle$1****$2and seeing what the pressure does, then depending on the result go forward or back a quarter of the way and repeat, etc?    Once narrowed down to a few cars, you concentrate on inspecting them.   Would this be impractical?   It would probably be time-consuming, but as a last resort?

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Posted by jeffhergert on Friday, May 6, 2011 8:15 PM

Sometimes it's not one large leak, but many smaller ones.  Especially during really cold weather.  When I was a condr, I was fortunate never to have had major air problems like this.  The few times I had to find a leak it was easily found and corrected.

I've heard a few horror stories trying to find air leaks.  One condr said that he and a yard utility man walked the train twice and couldn't find the leak.  He said they found a couple of small ones and changed out the airhose gaskets, but still couldn't get the flow down to do the air test.  They heard some air blowing at the EOT, but it wasn't near has bad has the leaks they had found and corrected.  Finally, they changed EOTs and that fixed it. 

Jeff

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Posted by zugmann on Friday, May 6, 2011 7:37 PM

henry6

Backwoods of Maine on a blistering cold winter night or the make up track in an innercity yard on a hot summer night or across a 200 foot high bridge anytime.  Ten cars, not too bad.  One hundred and ten cars....eh, you do the math.

 

 

Spending all day shifting cars in a downpour... soaked way past your underbritches... couplings not making...cars not rolling when you kick them...remote engine refusing to respond...radio becoming useless due to being soaked...LOL..those are the fun days!

It's been fun.  But it isn't much fun anymore.   Signing off for now. 


  

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Posted by henry6 on Friday, May 6, 2011 7:23 PM

Backwoods of Maine on a blistering cold winter night or the make up track in an innercity yard on a hot summer night or across a 200 foot high bridge anytime.  Ten cars, not too bad.  One hundred and ten cars....eh, you do the math.

 

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Posted by zugmann on Friday, May 6, 2011 7:22 PM

Ulrich

Surprising in this day and age there wouldn't be a tool that could pinpoint the location of the leak from the locomotive cab.. ..maybe I'll invent one and sell it to the railroads. Stick out tongue 

So the conductor would walk the length of the train to listen for the telltale sound of escaping air... sounds like alot of fun on a blistering cold winter night in the backwoods of Maine. 

 

That's called railroading!

 

Now I don't know how the ECP brakes work in all of this... I know you can cut out individual cars from the head end.    (just takes all the fun out of it!)

It's been fun.  But it isn't much fun anymore.   Signing off for now. 


  

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Posted by Ulrich on Friday, May 6, 2011 7:14 PM

Surprising in this day and age there wouldn't be a tool that could pinpoint the location of the leak from the locomotive cab.. ..maybe I'll invent one and sell it to the railroads. Stick out tongue 

So the conductor would walk the length of the train to listen for the telltale sound of escaping air... sounds like alot of fun on a blistering cold winter night in the backwoods of Maine. 

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Posted by ChuckCobleigh on Friday, May 6, 2011 5:22 PM

zugmann

Just gotta open your ears...

 

hisssssssssssssssssssssssssssssssssss

Just be sure there isn't an accompanying rattle! Surprise

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Posted by edblysard on Friday, May 6, 2011 4:58 PM

Mares shank.......

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Posted by zugmann on Friday, May 6, 2011 3:46 PM

Just gotta open your ears...

 

hisssssssssssssssssssssssssssssssssss

It's been fun.  But it isn't much fun anymore.   Signing off for now. 


  

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Posted by henry6 on Friday, May 6, 2011 3:43 PM

The Conductor walks the train until he/she finds it.

 

RIDEWITHMEHENRY is the name for our almost monthly day of riding trains and transit in either the NYCity or Philadelphia areas including all commuter lines, Amtrak, subways, light rail and trolleys, bus and ferries when warranted. No fees, just let us know you want to join the ride and pay your fares. Ask to be on our email list or find us on FB as RIDEWITHMEHENRY (all caps) to get descriptions of each outing.

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Locating air leaks...
Posted by Ulrich on Friday, May 6, 2011 3:23 PM

Let's say an engineer is charging the train  air system prior to departure... the compressors are working but the pressure will not rise to 90 psi (or whatever it is) and the brakes therefore won't release. He/she determines that there's probably a leak in the system. How does the crew determine where the leak is? Is there a quick way to determine where in the train the leak is located? ..or does the crew have  to walk the length of the train to find the leak... 

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