"Train Air Brake Animation" / Simulation - from Trackmobile

[miniwyo]

I have been looking for this for quite a while. I looked it up when I first started using the trackmobile at work and wanted a little better understanding of the operations. The guy that trained me just used the emergency brakes to stop the cars, which I knew was obviously wrong. I have been looking for this because now that it is my turn to train someone new, I knew it would be a good resource to help them understand it.

[petitnj]

The 3 CFM orifices provide two functions:

 

1) When charging a train, all of the cars charge together. If charging were unlimited, the first car would take all of the flow until it were nearly charged, then the next car, and so on. This is not important for the first charge of the day but when the brakes are released in operation we want all cars to see the release (increase in brake pipe pressure) at nearly the same time. With unlimited recharging flow cars would release in sequence and give very uneven brake application. 

 

2) When the brake pipe pressure is reduced (to apply the brakes) the orifice flow reverses and could potentially keep the brake pipe pressure up (again from front to back of the train) and cause uneven application. Actually, the reversed orifice flow causes an differential pressure across the piston of the triple valve and that is what moves the valve into the normal apply position, putting reservoir air into the brake cylinder. 

 

And yes, the triple valve needs much more detail to see its multiple functions. The little demo is great to give folks a first view of how the system works. 

[wabash1]

Bucyrus

Paul_D_North_Jr

Also, I don't quite understand the symbolism or intent of the 'air arrows' going back to the locomotive when there's a brake application, as the air does not flow that way, unless that is intended to depict the exhaust from the trainline pressure when an application is made.

 

Paul,

 

I don’t see a problem with the arrows going out of the trainline and out of the triple valve and back to the engine when the brakes are set.  I would assume that is exhaust from the trainline being reduced by venting back to the control valve on the engine.  And as the trainline exhausts, the triple valves would exhaust into the trainline.  Wouldn’t that be the normal occurrence?

 

What would be interesting is animating the action of the brakes being triggered to dynamite as happens when the rate of trainline reduction exceeds a certain rate of decrease, and each triple valve responds by directly dumping its portion of the trainline to the atmosphere. 

 

I could not get the “scenarios” button in the animation to open anything.  Maybe they show the dynamiting or “emergency” function under scenarios.  If not, it seems like they are leaving out an important and most interesting facet of air brake operation.

Hit the senareo and then to the right is sentences of what will happen click on them to see the play

[Anonymous]

Paul_D_North_Jr

Also, I don't quite understand the symbolism or intent of the 'air arrows' going back to the locomotive when there's a brake application, as the air does not flow that way, unless that is intended to depict the exhaust from the trainline pressure when an application is made.

 

Paul,

 

I don’t see a problem with the arrows going out of the trainline and out of the triple valve and back to the engine when the brakes are set.  I would assume that is exhaust from the trainline being reduced by venting back to the control valve on the engine.  And as the trainline exhausts, the triple valves would exhaust into the trainline.  Wouldn’t that be the normal occurrence?

 

What would be interesting is animating the action of the brakes being triggered to dynamite as happens when the rate of trainline reduction exceeds a certain rate of decrease, and each triple valve responds by directly dumping its portion of the trainline to the atmosphere. 

 

I could not get the “scenarios” button in the animation to open anything.  Maybe they show the dynamiting or “emergency” function under scenarios.  If not, it seems like they are leaving out an important and most interesting facet of air brake operation.

[Rodney Beck]

Their is a major problem with the reservoir the emergency reservoir is about 33% larger than the auxilary, for this reason when I have a 10psi reduction when I realese the brakes a small ammoont of air goes in the brake pipe to kick in accelarated service release.

 

Rodney

[Anonymous]

Paul,

I think that is an interesting and informative animation.  But I wonder why air is intentionally restricted by the 3 cfm orifices when charging the service and emergency reservoirs of each car.  Would the reason be to spread out the release of brakes by getting the trainline up to pressure before the reservoirs are charged, so the trainline can charge the reservoirs in a closer-to-simultaneous manner, rather than sequentially from front to rear of the train? 

[Paul_D_North_Jr]

Hey, thanks for those 'real-world' insights, wabash1 - I was hoping you'd take a look at it. Over 100 'views' and yours is the 1st response, too.

Your explanation of the arrows makes more sense than mine, too. Have you seen anything like this anyplace else - even at 'engineer school' ? ;-)

- Paul North.

[wabash1]

Paul pretty much on target the arrows going to the engine is reading brake pipe pressure and the slight differance your seeing in the gauge is about what a trainline does it wont read 90psi right away takes time to air up, and in emergency dealing with air hose seperation  the eqaulizer would stay at 90 and brake pipe at 0.

[Paul_D_North_Jr]

While looking for something else, I stumbled across the above.  It's pretty neat -I'd been wishing for something similar 'on-line' so a user could see how a real air brake system operates at various points in the locomotive's air system and the trainline - although it won't be confused with the MicroSoft Train Simulator or other sophisticated application or simulation software.  If you make the small jump in your imagination from "Trackmobile" to a real locomotive, you'll be close - and I'd say this has about 80 percent of what I'd like to see, which is plenty good enough for now.

The 1st link below takes you to a little 1-paragraph explanation from Trackmobile, from which you can then click on the link to go to the "Train Airbrake Animation", or you can just click on the 2nd link and go to it directly:

  http://www.trackmobile.com/trainairbrakeexpert.htm 

 http://www.trackmobile.com/trainairani.htm 

The initial screen is a little confusing - don't start with the left-most 'button' for "Detailed Brake Operation", but instead click on the middle button for "Basic Brake Application"; next go the Detailed one, and then go to one of the 4 "Scenarios" at the right side.  Once it 'loads' - which can take a minute or so - it asks you to click to Start, then it mostly runs itself. 

I like how the red needle for the main reservoir pressure drops about 20 lbs. when there's a major flow into the train line, then gradually recovers back up to the nominal 90 PSI operating pressure.  But I think the diagram for the triple valve is poor/ lacking, especially when compared to the details of the brake cylinder's reservoirs.  Also, I don't quite understand the symbolism or intent of the 'air arrows' going back to the locomotive when there's a brake application, as the air does not flow that way, unless that is intended to depict the exhaust from the trainline pressure when an application is made.  Finally, see if you can spot the minor discrepancy between the air brake handle setting and the pressure gage for some of the applications/ situations . . .  

- Enjoy ! have fun, and maybe learn something, too. 

- Paul North.