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sniper297 (1096 posts)
Dec-19-01, 04:10 PM (EST) "Front coupler test results" Here's what I did so far. I took the same test conditions Craig used, 1 GP-38 with 17 US2Graincars at Cadman docks in Newcastle. Most of Newcastle is relatively flat for the PO&N, so it's as good a place as any to test this kind of thing. I coupled on with the front coupler, dragged the 17 cars out, and shoved them onto the main line by the station platform. All this was using only notch 1, 13% power. I had a difficult time uncoupling, since my usual trick when working with the front coupler is to set the handbrake on a few cars, then back away slowly while clicking on the loco's front coupler. Without any brakes at all it's hard to draw out any slack, so I ended up pushing to get the train rolling forward, then reversing while clicking on the couplers. I turned the engine on the wye, coupled up to the other end of the 17 grain cars, again pushing and pulling using only notch 1. It takes a while for it to start moving without goosing the controller up to 50%, but it's the same friction as with the back coupler. Uncoupling again, I ran around to the other end to use the rear coupler, due to the difficulty of uncoupling making it still hard to switch with the front, and broke the train up into four cuts. I then reassembled it with the cars that were previously on the ends in the middle now. No change, either end moves with notch 1, front coupler or back, and will coast with the throttle off.
I had been using the "Oil Cars", not the 13 oil cars consist but the other one further down the menu with 16 US2Chemicars, for my testing. The "Grain Car Cut" Craig was using is 17 US2Graincars. The US2Graincar has a Mass of 106.747t, X 17 cars = 1809.99t. The US2Chemicar's Mass is 117.57t X 16 cars = 1881.12t, so the weight is pretty close.
So for my next Mad Scientist experiment I applied only the portion of Craig's hack that changed the maxbrakeforce to 0kN on the US2Chemicar.wag, leaving everything else unmodified. I then added the 16 car string to the activity. With the handbrakes available on the tankers uncoupling was easier, and the friction was identical to the graincars, so I don't think any of the other modifications have to be made to get the current results, only the MaxBrakeForce. I broke up both trains, reassembled into a mixed consist, pulled it with the front coupler. Notch 1 with 33 heavy cars takes about 10 seconds or so, but it will get it moving, up to 2 mph after about 30 seconds. This is not a problem, again, it's identical to the back coupler.
Well. With all this playing with tank cars, plus the fact that the mainline out of Newcastle is on a slight grade, I decided to take these long trains down to Texas Tea for further testing. I think I oughtta reinstall the Flatlands route if I'm gonna keep doing this, it's hard to find zero grade track on my route. I put two strings of 16 tankers on the main at Texas Tea, again BNSF 2081, and push pull 32 cars no problem.
I should mention, when you push one string of cars into another, if the couplers don't engage it's the drag sled story again, so it needs to be moved back and forth until the couplers engage, then it moves easy. This is a definite clue that there is something somewhere else holding a loose consist when it's uncoupled, the brakes can't be set when there are no brakes. But when the coupler engages, that bails off the phantom non-brakes that were holding it in place, so why does it make a difference when the maxbrakeforce is set to zero? I dunno, all I do know is that whatever kind of holding brakes the sim uses are normally released with the back coupler and not the front, and this part of Craig's hack makes them release when the front coupler is engaged too.
So now what? Obviously, this is only part of it, I tried Brinch's hack for the minimum coupling speed, but it's hard to measure whether it's easier or not when it never was consistent in the first place. So that's two things that need to be addressed, making the coupler actually couple and uncouple, having it show up in the coupler window consistently would be nice too. And altho this is a key to why all the drag with the front coupler, it's not a fix until you have train brakes that are on when you want them and off when you don't.The loco I used for this was the unmodified GP38 #2081 with a MaxForce of 300kN (2000HP), I also did some tests with a less powerful engine, John Fowlis' Alco RS-2 with 221.7kN (1500HP).
Unless the coupler is actually engaged, the consist pretty much has it's axles welded to the journals.
Coupling on releases the "brakes", or maybe a bunch of invisible guys come along and put new bearings in the cars real fast. 1st notch, 13% power, gets 17 cars moving in a few seconds.
Turning the train inside-out. And it coasts with the throttle off.
Altho it's a step in the right direction, it's only part of the solution. AI trains aren't bothered by the lack of brakes going down a steep grade, the Dash-9 with 38 grain cars is creeping down at 10mph or so, but I got a runaway train.
Now where did I put that broom, spilled grain all over the place.
Well, I'll leave somebody else to clean that up, maybe I'll put Dugan on it. Pulling and pushing 32 US2Chemicars, 3762.24t total train weight in notch 1.
Even this little guy gets it moving after a while.No pooping at this party allowed boys, if he don't cool his jets a little I'm gonna change his nickname from "TopDog" to "I GOT IT!!!!!!!!!", but he has the right to crow a little, it's progress where there has been no progress before.
So how about all you physics geniuses picking up on this? Maybe fool around with a second maxbrakeforce entry or something? Alert Edit | Reply | Reply With Quote | Top
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Subject Author Message Date ID RE: Front coupler test results DKlemm Dec-19-01 1 RE: Front coupler test results Would71 Dec-19-01 2 RE: Front coupler test results Would71 Dec-19-01 3 RE: Front coupler test results sniper297 Dec-19-01 4

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DKlemm (848 posts)
Dec-19-01, 04:47 PM (EST) 1. "RE: Front coupler test results" Sniper;I've been following this closely because of my desire to use the IC yards for more than static consists!!!!I agree that TopDog has some energy, but didn't we all in our younger days!!!!!!!!!!!!! It could be tempered down some, but hey, at least he is trying to fix this and appears to be making headway. I'd rather he be spastic and come up with an answer than toned down and give up!Keep it up TopDog. Great job so far : ) Maybe Sniper should be your agent though! : )David Klemm
Illinois Central Route
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Would71 (104 posts)
Dec-19-01, 05:09 PM (EST) 2. "RE: Front coupler test results" I thought maybe he was onto something with the double entries bit. (one positive number, one negative) Perhaps a check to see which lines have single entries by default but could take a second (negative) number. Remove | Alert Edit | Reply | Reply With Quote | Top
Would71 (104 posts)
Dec-19-01, 05:24 PM (EST) 3. "RE: Front coupler test results" Mmkay, now I'm poking around in .eng and .wag files too. Perhaps someone should make a list of settings they've checked on a test engine and a test car.. and check off items on this centralized list when they've been tested.. along with listing the effects or lack thereof. Cuts down on duplication of effort. Yes, I see everyone doing the testing is listing their results in this post and that post.. but there's no single spot (thread) where all updates are recorded.Perhaps include a list of working theories that need to be checked out, as well as just the raw numbers in the files. Remove | Alert Edit | Reply | Reply With Quote | Top
sniper297 (1096 posts)
Dec-19-01, 11:57 PM (EST) 4. "RE: Front coupler test results" Single spot would71 be difficult at best, it would71 rapidly fill up and become so slow to load you couldn't read it anymore. Even without pictures, check out some of the old archived threads that grew to 200+ replies, or even any one of the current ones that have the view all attached. And all the other posts I've seen so far are like this;

"Look, I fixed the front coupler bug! I can move these 3 empty woodchipper cars easy as pie with only 2 SD-40s and 4 DD-40s!" Of course you can do that without any hack at all, but some people have trouble being objective in there testing, and it's natural to want to try something new every time, so keeping the conditions consistent from one test to the next is an important step that a lot of people are missing. One thing we could do is use "TopDog" as a keyword in the title, but with different people trying totally different hacks somebody may come up with something unrelated. The important thing is to get the blasted thing fixed, it's been sitting static with nobody really working on it since day one.
Yeah, Dave, I admire his enthusiasm and exuberance, I just want to slow down the speed of his bouncing off the walls a little, he's made an important discovery here IMAO, he really thought outside the box on this one. It's a long way from the cure tho, we not only need to stay focused, we need to get some programmers and physics gurus involved in this. I don't see a total fix for quite a while yet, but who knows, it may be something as stupid as adding two forward slahes instead of one someplace. I still think there's something in another file, it don't affect AI trains, which pretty much ignore physics limitations anyway, it really only affects the player engine, any helpers can face backwards as long as they're coupled behind the lead engine instead of in front, and there is some kind of additional holding brake working to keep loose consists from rolling when they're uncoupled. Hacking the wag file to eliminate all the brakes from the car, you can uncouple them on a 4% grade and they'll stay put instead of rolling downhill.
This is encouraging, it's kind of like the old joke about 1000 lawyers at the bottom of the ocean; it's a good start. Remove | Alert Edit | Reply | Reply With Quote | Top

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