The air brake results are in

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Trainman4602
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The air brake results are in

Post by Trainman4602 » Fri May 30, 2008 8:43 pm

Last week at the PLS spring meet we were finally able to test the air brake system.

The first day we had a major leak on the second car so we cut it out. Cutting it out means to shout off the triple valve and then dump the auxiliary reservoir. There was no time to check it out. That evening we found the leak in the air hose between the cars. Just a tightening of the hose clamp did the trick.

The first day I found that the electric pump ran after two or three applications. Not expectable. This meant that we had too many leaks. The brakes still worked great but the battery ran down to quickly.

After I fixed all the leaks I could apply the brakes approximately 20 times before the compressor would run. That’s great. The one thing about that test is that the train was not moving. The next day was a different story from the first test. The compressor would run every 15 minutes. That’s after several applications. I thing the hoses are leaking and the glad hands are leaking as well. It seams that when standing still they don’t leak but as soon s the train starts to swing and sway the gland hands and hoses start to leak.

I can fix the hoses leaks but the glad hands are a different story. I think if I can’t fix the expensive ones I’ll make my own non-leaking type.

Upon leaving the station there is a 4% down grade. With a four car train and 10 passengers I can stop the train dead on in the center of the down grade. That’s a lot of weight. The Locomotive ways 1500 lbs. The average weight of the passengers lets says 100 lbs. (kids and adults mixed). That’s 1000 lbs. The cars weigh another 1000 lbs for a total of 3500 plus lbs.

I’m currently working on a Mercer gondola. It has roller bearing truck pictured in an earlier post. I have fitted the trucks with brake rigging.

The next run for us will be at Pioneer Valley Live Steamers in Southwick MA.

Rwilliams
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Post by Rwilliams » Sat May 31, 2008 1:45 pm

Dave,

Even the full size railroads have issues with brake pipe leakage. It has been a major trouble spot in air brakes systems since they were invented. With improvements in materials and brake systems including maintaining air, brake pipe leakage is not the problem it used to be.

I can remember cars being air tested for service and how they went over all joints and connections in the car with a strong batch of tide and a brush to slop it on. The car was pressurized with air and immediately any large leak was visible where all the humongous Tide bubbles were present. These were tightened down and the test run again. Soon the smaller leaks would make themselves known with smaller bubbles. Again they were fixed until all the bubbles were eliminated. Some cars were more trouble than others.

The bigger problem was all the movement around curves, over rough crossings with low hanging hoses where the glad hand connections were stressed beyond any normal testing situation. That was where the leakage could never be completely cured. Cold weather was also a bigger problem as the gasket material was unable to remain flexible enough to keep leaks to a minimum.

When worse came to worse, and we did not even have a spare air hose gasket with us many cars from the caboose or locomotive, on the spot repairs were attended to. We would carefully spit on the offending gasket or gaskets of both glad hands, and carefully put them back together hoping the biological sealer would get us over the road to the next terminal. The leak would be tight or at least much reduced in volume. Many times this on the spot repair made the difference in keeping the brake pipe leakage under the 5 PSI per minute requirement.

Perhaps all that is needed to cure the model leakage is some silicone sealer on the glad hand gaskets. It is worth a try.

Robert

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Trainman4602
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Post by Trainman4602 » Sat May 31, 2008 2:23 pm

I though of the use of silicone to seal the gaskets. I still think Barrys gasket is two narrow. There is only 1/16 to seal the two together. I would like to see more land aera.

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Bill Shields
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Thoughts

Post by Bill Shields » Sat May 31, 2008 5:32 pm

Your brakes seem to work very well - except for the leaks.

Something to think about as an auxiliary pressure source.

A 5000 PSI paintball compressed air tank, hidden somewhere on the train, regulated down to whatever PSI you need, should run even a leaky system for a week or so - no batteries, no compressor. You could even toss it in the water tank - they are all composite wrapped / stainless - water won't hurt them.

These tanks, some about the size of a softball, cost something like $4.00 to fill at a paintball store.

Yes, they are safe...

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Trainman4602
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Post by Trainman4602 » Sat May 31, 2008 6:53 pm

Thanks bill i'll look into that. I like the idea of the compressor but for the noize and vibration.

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bcody
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AIR SUPPLY

Post by bcody » Sat May 31, 2008 8:28 pm

If you have the steaming capacity why not use a steam driven air compressor? They just sit there and do their thing, no regulation required. Bill

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Trainman4602
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Post by Trainman4602 » Sat May 31, 2008 9:07 pm

Not enough air supply from a 1/1/2 scale compressor.

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Fender
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Post by Fender » Sat May 31, 2008 9:12 pm

I think Dave said in an earlier thread that his engine has a steam-driven air compressor installed, but it doesn't have enough capacity to keep up with the train brake system.
By the way, Dave, very impressive system you have there!
Dan Watson

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LivingLegend
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Post by LivingLegend » Sat May 31, 2008 9:45 pm

Bill Cody:

The capacity of a working steam powered cross-compound air compressor model is safe enough for engine and tender brakes alone.

For train brakes, the model cross compounds don't put out enough (especially for reserve air) for safe operation. You also have to factor in the reliability of the miniature air pumps.

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Rwilliams
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Post by Rwilliams » Sun Jun 01, 2008 12:25 am

Having had some time to consider a few more issues with air leaks and Glad hand seals, I am including the following items.

Car length can be critical for proper hose length alignment. On sharp curves, longer cars have greater overhang from the center line of the curve and put excess stress on the air hoses and glad hands. In full size operation, I observed many times where a certain combination of long and short cars coupled together on sharp curves was guaranteed to give an air hose separation every time. We even kept a short 12 inch dummy hose with us to insert after the train went into emergency. This was the only way to solve the problem.

Sometimes just the result of an accident and a poor air line alignment in the RIP track could cause enough misalignment to cause air hose separation on sharp curves. Sometimes we would be just waiting at the sharp point of the curve and listen for the air to start hissing knowing the next moment might bring the rupture of the air hose glad hands. If lucky, the hiss noise remained just a hissing noise and once around the sharp curve, things aligned themselves again and the hiss of air diminished and we dodged another trip to the locomotive to fetch the dummy hose.

I remember speaking to Barry about the design of his air brake system and one of the primary requirements was that the mounting of the air lines to the equipment had to be just right for everything to stay in alignment.

With the sharp curves in our club tracks, and the longer 8-10 foot long heavy weight passenger equipment out there, it would seem that we have also built in a stressful situation for our scale air brake systems, just as in the full size equipment. I believe this needs to be addressed before judging a well researched and designed glad hand gasket. Based on my experience, it would seem that questionable length equipment in our hobby needs to be coupled up and carefully observed around all the tight curves and reverse curves without much straight track between, them to check for stressful alignment of air hoses. It could be that special accommodations will need to be made for trackage and equipment when the stress on the hoses alignment is too great.

I can remember speaking with Barry in regards to the Superscale gasket design which was one of the important parts of the entire system. It was mentioned that the size of the gasket sealing surface was a compromise even in 2.5 scale to get the right contact surface for the pressure being used. To make the surface any larger would result in more leakage instead of less leakage. The secret to his system was to insure no leaks and to make the brake pipe alignment and locations as accurately as possible. A perfect tight trainline just will never exist. A reasonably tight trainline with minor acceptable leakage is all we can hope for under the best of operating conditions.

This brings to question just how much leakage is acceptable in our hobby?

How are we going to measure this leakage without going to excessive cost?

For many years full size equipment air leakage was simply measured in pounds per minute with the brake valve placed in lap position and watching the train line air gage needle fall from 90 PSI. As the technology of air brakes improved, some roads began to include a nice brake pipe leakage gage or meter that would show the amount of air flow or leakage in pounds per minute. The air flow gage was a luxury item and the crews quickly adapted to the device that gave them a direct indication of their air flow problems or lack thereof.

A good reliable scale air brake system is only going to work well if all the parts are in place and working correctly. With the issues of safety being a primary requirement, it would seem that attention to all the details is going to be required before judging a few small glad hand gaskets.

Robert

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Trainman4602
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Post by Trainman4602 » Sun Jun 01, 2008 11:18 am

All the details of the system have been considered. The one thing that I knew would be the weak link would be the hoses. I have absolutely no problem with all the other components. They all work as expected. Until this point I have only been able to make a non running test. So I have already fixed all the problems except for the connections between the cars.

As mentioned, in the static test I could apply the brake 20 times before the compressor would start. While running, the compressor would run after 3 applications indicating leaks in the hoses and glad-hands. I should mention that the compressor cuts out at 150lbs and restarts at 110lbs. The system works on 70lbs so we always had air for brakes. I just don’t like the compressor running every 15 minutes. 30 minuets would be acceptable.

I’ll make new larger that’s to say gaskets with a wider land. If that doesn’t work I’ll go to straight hoses and eliminate the glade hand until I can make an acceptable glad-hand gasket.

The glade hand pictured was used on the Centerville and Southwestern RR. It was a 2 ½ inch scale 9 7/16 ga. railroad. As you can see from the quarter they are big. I have also used them on 3” and 5 “scales. Take not of the gasket, larger and with a wider land then scale. These gland hands do not leak at all. Even with the wider gasket they are still able to separate if the coupler should disengage.

I think that’s what Barry was referring to when he said that the gasket was a important part of the system. He wanted them to break apart in an emergency.

My theory is that I would rather the glade hands be air tight. If the train should part, I would rather see the hose pull of the fittings and go into emergency. The glade hand is really there for conveyance when uncoupling.

I will look into using small quick disconnects. That would require a special fitting to go between the two disconnects. In this manner I don’t have to worry which end is with which end. The cars can be turned any way.
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ccvstmr
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Post by ccvstmr » Sun Jun 01, 2008 5:44 pm

Many of the northern iron ore railroads ran into the same problem with air leaks and leaky glad hands. They couldn't afford the time that it took to pump up the entire train when temps were low...or even below zero. So, in a fit of yankee ingenuity, they solved the problem by process of elimination...and eliminated some of the glad hands between cars. They installed drawbars to semi-permanently couple (4) ore jennies into (1) car set. As such, the four cars had only (2) glad hands...one at either end of the quad car sets. This cut the number of potential leaks considerably. Once again, the model follow prototypic practice...and problems. Carl B.

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