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Brakes Question ? Rate Topic: -----

#1 User is offline   scottb613 

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Posted 19 February 2015 - 05:41 PM

Hi Folks,

Been running some heavy coal on pretty steep hills - it's a pair of Rick's (BLW) F-3's with 45 coal cars and a caboose in tow... I am running down a 2.4% grade and I guess F-3's don't have dynamic brakes but they seem to be self lapping... Here is my question - I can't even apply 1% brakes with completely stopping the train in less than a minute... So what I don't seem able to do is put a few pounds on the brake system to add drag to hold the train back and maintain a constant speed - it's all or nothing - I set the brakes to 1% for a few seconds - then off - if I don't it just stops me... Maybe I have a gross conceptual error - but - I would think with a heavy load on a steep grade I would need a pretty decent amount of brakes to hold me back - 1% shouldn't be stopping me in my tracks... I don't know if this is an OR issue - an engine issue - or a freight car braking system error... The F5 HUD shots follows - any input most welcome...


Attached Image: Open Rails 2015-02-19 08-27-17.jpg


Attached Image: Open Rails 2015-02-19 08-25-51.jpg

Regards,
Scott

#2 User is offline   engmod 

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Posted 19 February 2015 - 06:46 PM

You might want to look at the brakes on the coal cars first.

cheers
Derek

#3 User is offline   atsf37l 

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Posted 19 February 2015 - 06:56 PM

You might want to check to see what your MaxApplicationRate is in the .wag files on your cars.

I find that I can set up a little air and do what you're talking about when running non-self lapping brakes on steam. But in diesels with self lapping brakes I get the same problem - a 1% application will stop the train, not hold it. So I find myself fanning the brakes - apply, release, apply, release, ad nauseum - for the length of the downgrade. Or you can do the dangerous thing and apply-release-apply until you get the brakes bled off and weakened enough to just hold the train. Of course, if you go past that point it's YAAAAHAAAHAAAAHOOOOOOIE!

What you might try is going into a car's .wag file and adjusting the MaxApplicationRate - for example mine is usually set to 3.5, so I might change it down to 1.75 - then putting together a consist of 45 copies of that same car and testing it on your hill. Make adjustments and try it again, and again, until you get the braking you desire. Once you find a setting you're pleased with you can use a program like EngMod to change the setting in all your cars. While you're doing it you can check MaxReleaseRate as well to get the response you desire.

Good luck! :bigboss:

#4 User is offline   Coonskin 

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Posted 19 February 2015 - 07:05 PM

I can assure you that in the real world, two non-dynamic units on a train of around 5000 tons descending a 2.4% is NOT going to be held back, to say nothing of coming to a stop, with a minimum reduction. FWIW: Using a 26L brake valve (self-lapping), a minimum reduction results in about 6 - 8lbs of reduction.

Time to start playing with the max brake values, maximum application values, etc.

#5 User is offline   Genma Saotome 

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Posted 19 February 2015 - 08:15 PM

I was looking at a brake test the other day... hit the ' key twice and then watched what happened on the brakeline. I saw a 16psi drop the length of the train and then the label changed from apply to lap. Of course the 50 car train stopped. Doesn't seem right.

#6 User is offline   gpz 

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Posted 19 February 2015 - 11:42 PM

View PostGenma Saotome, on 19 February 2015 - 08:15 PM, said:

I was looking at a brake test the other day... hit the ' key twice and then watched what happened on the brakeline. I saw a 16psi drop the length of the train and then the label changed from apply to lap. Of course the 50 car train stopped. Doesn't seem right.

Sounds like the brake line pressures are managed correctly, and also the screenshot above assures it. Something wrong is going on with the forces here.

#7 User is offline   markus_GE 

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Posted 20 February 2015 - 04:10 AM

I see an EmergencyReservoir charged to 90 PSI, which leads me to assume, 90 PSI is your max brake line pressure. 84 PSI on your trainline means a 6 pound reduction was made, about the equivalent of what Andre said, a minimum reduction on a self lapping brake control should give you. Reducing the BP by X PSI should give you X*2.5 PSI in the BC, according to Al Krugs well-known brake page, which means your 15 PSI in the BC are OK too.

All pressure values, thus, seem OK, which only leaves one places that might cause the problems: The max brake force set for the cars. Could you please open the WAG file of the problematic car, search for "BrakeForce" and post what you find on these lines (they donĀ“t follow each other like shown here):

MaxBrakeForce(
BrakeCylinderPressureForMaxBrakeBrakeForce(

As for correct braking forces, I have just yesterday inquired about the same in another thread here on the board (please disregard the first post, it has accidentally been changed by someone of the staff, who edited it instead of replying to it).

Cheers, Markus

#8 User is offline   copperpen 

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Posted 20 February 2015 - 05:01 AM

After a long time of indecision about train brakes, I finally set up a test train using the brake physics from Bill Prieger which can be found in a couple of sub folders of RouteRiter.

Using the cast iron set, I changed some SD70Aces and a 100T test car. With three Aces and 41 cars I was able to hold my speed at around 36mph on a 2.5% grade with about 50% reduction of the air. The speed could have been lower if I had started braking sooner.

#9 User is offline   Tyler Bundy 

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Posted 20 February 2015 - 09:44 AM

Here's a good question: which physics set by Bill Prieger are you using? His ProPack 4 has normal braking physics, while the ProPack 5 has "percentage braking" physics that were recently developed for MSTS.

I set most of my cars up with the ProPack 5 percentage braking physics when I used MSTS because I liked kicking cars. There was once something said about "no noticeable change in the way trains handle overall" in regards to the ProPack 5 and I enjoyed using it very much with MSTS.

Now that I use the latest Open Rails, I find that percentage braking seems to be taken literally, like the cars have no brakes. Has anyone else noticed this or was this discussed years ago?

Tyler

#10 User is offline   Genma Saotome 

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Posted 20 February 2015 - 10:00 AM

View PostTyler Bundy, on 20 February 2015 - 09:44 AM, said:


Now that I use the latest Open Rails, I find that percentage braking seems to be taken literally, like the cars have no brakes. Has anyone else noticed this or was this discussed years ago?

Tyler



IIRC Open Rails always looks for values and ignores formulas.

If that's incorrect, I'd love to be corrected.

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