What system is the air brakes modeled after?

[Maniac]

The only 2 train brake systems I am familiar with are the Westinghouse Air Braking system and an old Vacuum braking system (of which I do not know the name).
The brakes in Derail valley seem to be air, not vacuum, but they behave more like vacuum brakes, with the braking strength directly responding to the air pressure, both on application and release.

With the Westinghouse system, there is no partial release, as soon as you raise the pressure, the brakes are off.

Is it modeled after a real life system, or is it just something "similar" to real life, but simplified?

[Altfuture]

It's not entirely modeled after a real system, although isn't this how a triple-valve brake system would operate?

We'd like to have a more traditional brake model with lapping too, for the older locos, but haven't had time to work on that so far.

[LeadCatcher]

On air brakes you do have a propagation delay with the releasing of brakes, it takes a while for the pressure to travel the train line. Of course I am sure the brakes are greatly simplified for the game.

[Maniac]

Originally posted by LeadCatcher:

On air brakes you do have a propagation delay with the releasing of brakes, it takes a while for the pressure to travel the train line. Of course I am sure the brakes are greatly simplified for the game.

On a real train, it would take longer to fill the brake pipe with air, the longer it is. This does not appear to be the case.
I do think that the brakes are simplified for the game.
On a real life train, the brake reservoir is going to be set to a significantly higher pressure than the brake pipe. So a small reduction (application) can be quickly released and returned to full pressure, compared a large reduction, which will use up the air in the reservoir and you will be stuck waiting for the compressor to fill the pipe.

Originally posted by Altfuture:

It's not entirely modeled after a real system, although isn't this how a triple-valve brake system would operate?

On a Triple Valve (Westinghouse) Brake system, you have 3 states. Hold, Apply, and Release.
Hold and apply work as you would expect, but release is all or nothing. You can't get a little less braking, unless you release and apply them again.

Brake pipe pressure is usually 90psi, but it can be lower or higher. A full service brake application is a reduction of 26 psi. So with 90psi, you can apply and release the brakes a few times before you're out of air. The brake reservoirs only recharge when the brakes are in the released state.

You have a separate air reservoir for emergencies. This is activated when there is a rapid drop in brake pipe pressure, as well as causing each car to dump brake pipe air, to increase the propagation down the train.

The loco brake is really nice, as it doesn't have this limitation.

As far as I understand it, the reason it is this way is to allow a long train to release its brakes quickly. As soon as the increase of air pressure reaches the last car, the brakes will be released.

The current system functions like the old vacuum brakes, and on a long train (especially with a diesel locomotive at idle, since the ejector was run off the motor), it could take a long time sitting there waiting for the brakes to release. Like the current state of the game, but probably a lot longer. (The train length limit in Derail valley means this wouldn't be as much of a problem, compared to real life)

With the Steam loco having 2 more bars of pressure, it wouldn't have stronger brakes, but it would have more available applications, before it doesn't have enough air left to fully apply the brakes.

[JazzGuru]

Originally posted by Altfuture:

It's not entirely modeled after a real system, although isn't this how a triple-valve brake system would operate?

We'd like to have a more traditional brake model with lapping too, for the older locos, but haven't had time to work on that so far.

Glad to hear that you may add a break-lapping system to the game at some point. This is something that I miss having at the moment...

[Newtown71]

I hope we can see a development in the braking system and its physics, get close to the real thing will add more immersion and will be a challenge to master it.

[Lanthan O'Ide]

Originally posted by Altfuture:

It's not entirely modeled after a real system, although isn't this how a triple-valve brake system would operate?

Huh, I'd have thought the same thing as Altfuture.
Air brakes that can be released step by step, and don't have to be released completely to be reapplied, are pretty much standard equipment nowadays in Europe.
Except for some minor details, the DV system seems to be quite consistent with the Knorr brakes my DB textbook.

Which is not to say the DV system could not be changed to something more challenging.
I'd just hesitate before calling it "unrealistic". ;-)

[Maniac]

I'd say with it's smaller spaces, european trains require more responsive brakes than what north american trains can get away with. Maybe that explains the differences?

This is why I asked.

Originally posted by CRS1435:

Originally posted by Altfuture:

It's not entirely modeled after a real system, although isn't this how a triple-valve brake system would operate?

Except for some minor details, the DV system seems to be quite consistent with the Knorr brakes my DB textbook.

Is there an online version I could check out?
(I suspect these systems would require either electronic control, or a second brake hose)

[Metallos]

Originally posted by Maniac:

On a Triple Valve (Westinghouse) Brake system, you have 3 states. Hold, Apply, and Release.
Hold and apply work as you would expect, but release is all or nothing. You can't get a little less braking, unless you release and apply them again.

Brake pipe pressure is usually 90psi, but it can be lower or higher. A full service brake application is a reduction of 26 psi. So with 90psi, you can apply and release the brakes a few times before you're out of air. The brake reservoirs only recharge when the brakes are in the released state.

Westinghouse brakes are historical, actual Knorr brakes or electropneumatic brakes are used and also the pressure is in bar, not psi (the game is based on European rail systems).

[Enichelle ^_^]

Well on European Rails, you won't see a system like Westinghouse, not even decades ago you'd see this :)

[Lanthan O'Ide]

Originally posted by Maniac:

Originally posted by CRS1435:

Except for some minor details, the DV system seems to be quite consistent with the Knorr brakes my DB textbook.

Is there an online version I could check out?
(I suspect these systems would require either electronic control, or a second brake hose)

Well, it's a book from the DB (Deutsche Bahn), so it will only help you if you understand German.
There doesn't seem to be an online version from what I can tell, but here's a link, in case it helps anyways:
https://www.bahn-fachverlag.de/shop/fachbuecher/schienenfahrzeugtechnik/


First brake systems with these property go back to 1883, invented by Jesse Fairfield Carpenter.
So it's definitely not (neccesarily) electronic.
The system has been developed over and over again, with various respective names (Kunze-Knorr, Hildebrand-Knorr,...).
It get's really hard to track what variants are or have been used where and when.

The system also doesn't require a second brake pipe: I'm still trying to figure out the details, but they somehow managed to get around this need by the use of pressure controlled valves (?) and reserve pressure tanks.
Also, there is a special reservoir charged with 10 bars (twice the normal brake pipe pressure), that can be used to quickly restore pressure in the brake pipe.
Again, I know I'm just throwing claims at you, without any proper explanation. I'm obviously not an expert on this.


Unfortunately, the only decent description I could find is in German.
I've been searching the web for an hour now, I'm afraid this is the best there is.
I'm putting it in here, in case you can decipher the schematics, or want to auto-translate something.
Especially the section "Stufenweises Lösen", meaning "stepped releasing", will probably be of interest to you.
https://de.wikipedia.org/wiki/Steuerventil_(Eisenbahn)#Steuerventile_der_mehrl%C3%B6sigen_Druckluftbremse


Nevertheless, to give you at least something in English, I've tracked down an english wikipedia article for one of the variants, in the hope that it can clear something up:
https://en.wikipedia.org/wiki/Kunze-Knorr_brake
However, keep in mind that this is a historic system, and not exactly how the current brake system works. (And I think that one needs indeed a second pipe? Not sure)