Physics question

Got a question for those familiar with engine physics files. I and a few other people have posted about not having train brakes on some GE's and some EMD locomotives. If I were to take an '.eng' file where the brakes work and edit it for the GE with appropriate mass, HP, compressor ratings, etc. would that be enough. I'm worried that there are subtle things about these files that I don't understand and would rather not overlook. The major data items are obvious, but I suspect there are things that affect acceleration and other items that are unique to a locomotive type. I'd rather do it right the first time, and if waiting for the fix to be found is the proper thing, then so be it. Lyle

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RE: physics question, baldwin, Jun-08-03, 03:49 PM, (1) RE: physics question, slyone, Jun-08-03, 04:23 PM, (2) RE: physics question, plainsman, Jun-08-03, 05:12 PM, (3) RE: physics question, slyone, Jun-08-03, 07:05 PM, (6) RE: physics question, chucksc, Jun-08-03, 05:14 PM, (4) RE: physics question, slyone, Jun-08-03, 06:59 PM, (5) RE: physics question, plainsman, Jun-08-03, 10:43 PM, (9) RE: physics question, slyone, Jun-09-03, 11:12 AM, (11) RE: physics question, GaryG, Jul-16-03, 04:09 AM, (13) RE: physics question, robertreedy, Jun-08-03, 08:45 PM, (7) RE: physics question, chucksc, Jun-08-03, 09:12 PM, (8) RE: physics question, kevarc, Jun-08-03, 10:56 PM, (10) RE: physics question, xlspecial261, Jul-16-03, 03:42 AM, (12)

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Have you tried this file from the library - phyv45.zip -. If not, go get it and read the instructions for use. Most engine types are covered, and most things that you are asking about.mervyn@madasafish.com

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yes I have, and it has the ineffecive train brake and emergency brake as well. Paraphrasing the author, he said that the part of the file that carries this data is not a part his physics changes impact. When you splice his data into the original in theory you're not touching this brake data. He's never needed to change anything there, so apparently the 'flaw' was in the original file and has been carried into the updated one. I've looked at a working file beside a nonworking file, and I don't know enough about them to recognize the subtle differences. The impatient part of me is looking for a way to make them work, but I'm probably going to be patient and wait for the fix to be found. I have a couple of locos I'm repainting that will be used as switchers, and not having effective brakes when shoving and pulling cars is a hazard to one's health.

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This is actually a little more complex than you make it sound. For example, you could do as you say, but then all your lights and exhaust would be misplaced. I suspect part of the problem is not in the braking parameter section as such, but may have an item out of order or a parenthesis misplaced. This will likely be in the sections outside the physics parameters as such.
Bob

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Thanks, but I do realize that there is a lot of this type of info' in the .eng file and that transferring it would be a major pain in the tukas. I'm more inclined to take a wait & see attitude. I'm usually very patient, but I'm getting a bit antsy on this one for some reason.

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>yes I have, and it has the ineffective train brake and
>emergency brake as well. Paraphrasing the author, he said
>that the part of the file that carries this data is not a
>part his physics changes impact. When you splice his data
>into the original in theory you're not touching this brake
>data. He's never needed to change anything there, so
>apparently the 'flaw' was in the original file and has been
>carried into the updated one. I've looked at a working file
>beside a nonworking file, and I don't know enough about them
>to recognize the subtle differences. The impatient part of
>me is looking for a way to make them work, but I'm probably
>going to be patient and wait for the fix to be found. I have
>a couple of locos I'm repainting that will be used as
>switchers, and not having effective brakes when shoving and
>pulling cars is a hazard to one's health. OK one possible quick and dirty fix if your locomotive physics has dynamic brakes based on the Kuju Dash 9....find the line in your physics (ENG file) that says.... DynamicBrakeHasAutoBailOff( 1 )and change that to..... DynamicBrakeHasAutoBailOff( 0 )That will prevent automatic bailing off ( Releasing ) of the locomotive brakes when the automatics are set on a light engine.....More "quality code" from the world class physicists at Kuju (Oops that was DIV) You should be aware that total braking of your locomotive when running "light" is much lower that when attached to a train...
12" to the foot scale railroads have speed restrictions for engines running light due to this phenomenon. Usually this is something like 25 or 30 mph IIRC.The other problem is with the physics engine (again) the independent brakes are not modeled correctly (shock horror!) and if the values are set approx. correct (say like 80kn for a B-B Diesel) you get this problem... There does not seem to be an easy way to "take a 10 lb set" on the independents and then watch it stop....If you are running light and want to stop then use the "Loco Brakes" (AKA independent Brakes) and be prepared to set them hard! Forget about the automatics (Train Brakes) on a light engine!
Chuck Schneider
(Virtual) CEO
North American (Virtual) Locomotive Works

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LAST EDITED ON Jun-08-03 AT 07:07 PM (EDT)

>OK one possible quick and dirty fix if your locomotive physics has dynamic brakes based on the Kuju Dash 9....the ones I've been trying to fix are GE C30-7 & similar, and B32-7 (U33B) files. I'll look and see how closely they resemble the dash-9. Anything is possible. Its been other parties who have found sd40-2's that apparently have a similar problem. I haven't encountered that one yet.>The other problem is with the physics engine (again) the independent brakes are not modeled correctly (shock horror!) and if the values are set approx. correct (say like 80kn for a B-B Diesel) you get this problem... There does not seem to be an easy way to "take a 10 lb set" on the independents and then watch it stop....Is there something then in the original and/or updated EMD files, like the GP38, that forces an appearance of correct behavior? When I 1st started using MSTS, I immediately went for the switching jobs, my personal preference. I got use to using the train brake to alter speed of a light loco right from the beginning. Its an automatic response by me now. I can apply a few % (5-10 lbs equivalent) and get a speed reduction. In these flawed ones, I get no speed reduction whatsoever with a full application. There was a fix found that enabled emergency brakes at least. And, BTW, that fix involved a bailoffbutton value not being present, so perhaps there's some connection to what you suggest. I'll probably go ahead with these loco repaints, I just don't like doing stuff where I know there to be flaws. I'll see if your info' leads to anything.

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Have you checked all the parenthesis to see that all are paired and close properly. There are also several other switches that could have unintended effects much like the wipers have on dynamics?? The actual physics seems to be fine, but there are a lot of other things in the file that may be causing a glitch.
Bob

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I don't know how complete they are in their checking, but all the locos get a clear bill of health when checked in eng-mod, conbuilder, AND routeriter. EngMod does a bracket check, but I don't know if all it does is count left-paren's and right-paren's and says they're equal or not. It spits out a list of other problem files, but the locos in question are not in that list. And I'm not familiar enough yet with the files that I recognize problems by examining them, and need people who do to help me. If there's another tool that accomplishes this better, I'm all ears! :) Even a document that explains the format so I have something to compare to. I have come across a tutorial on the variables in the eng file, but it doesn't do much for formatting the file. Lyle

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HiI spotted a problem a week or so ago with parenthesis in the Lights section that could impact other sections possibly. This is MSTS so who knows how well these types of errors are handled.Easiest way to find the files with this error. Move to the end of the Lights section and count parenthesis between the last light and the Sound definition. Every eng file I've looked at that does not have this problem will have four, all the ones with three seem to have an error earlier in the file.To fix, while at the end of the Lights, add a fourth parenthesis. Now start moving towards the start of the file. Each Light description should end with three parenthesis. Eventually you will find one with four, delete the last of these leaving three. I think all the bad files I saw had a comment about the start of the AI lighting section.One more thing to watch for if you find and fix one of these files; confirm the number of Lights at the start is not less that the number of Light descriptions. This is very important. Too big a number is ok (otherwise these locos would have caused other problems), but too small a number will cause a note to Billy to be written.I guess that way back, someone made the error and used the file as a master template propogating this error. Will it fix brakes, I don't know... The parenthesis couting programs won't find this error 'cuz the quantities are correct, just one is misplaced. I do have a feeling that a certain engine modification program might be able to look for this error one of these days but not yet.GaryG

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Chuck, you said "You should be aware that total braking of your locomotive when running "light" is much lower that when attached to a train...
12" to the foot scale railroads have speed restrictions for engines running light due to this phenomenon. Usually this is something like 25 or 30 mph IIRC."What is the reason for this? It's something I was not aware of and seems to go against logic, and was just wondering what caused it

RobertR .. ADF-M&RM at http://www.adfrr.com

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Robert it is because most of the time the brakes on a locomotive are minimal tread designs especialy on drivers...
No room to hang anything big under there with traction motors et al...
On Steamers all wheels/axels may not even have brakes....
FWIW the AEM7 was one of the 1st Road Engines (Motors) to have both Tread and Disk brakes and has excellent stopping power compared to your generic diesel or motor....
Chuck Schneider
(Virtual) CEO
North American (Virtual) Locomotive Works

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I have seen this mentioned before and I think it is because of the total weight/number of axles with brakes. Kevin Arceneaux
DEFAULT IS FOR DUMMIES
Lone Wolf Activities Forum on www.3DTrains.com

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Found this while looking for something else.We have a 40MPH restriction for light power on CP/Soo. Near as I can tell, this is due to the reason Keven mentioned. I've stopped a pair of AC4400's from 40 pretty quickly, around 6-800 feet or so, with little drama, but you could really smell the brake shoes. The faster you go, the more heat you generate in the brake shoes. Get too much heat, and you lose braking power.By comparison, BNSF has no speed restriction on light power. (At least not 2-3 years ago.) I've seen them running along at 60+.Todd

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