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A Caveat: Input Desired


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#1 laming

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Posted 08 May 2004 - 08:47 PM

MSTS'ers:

I was a bit hasty in my assessment in the Front Coupler Discovery thread. After further use of the front coupler with the last version of definitions, I experienced a random lock.

SO... I continued experiementing and have further deduced that the steam eng files also have difficulty with interpreting engine brakes when switching with the front coupler. I don't fully understand all the confusion within the steam eng files and/or steam engine hard coding, as a diesel doesn't seem to have such tendencies. But the problem is there.

Anyway, the long and short of it is:

I now have a front coupler that works fine. On two separate occassions I've switched for 20-30 minutes each session using nothing but the front coupler. Cuts, joints, shuffling and juxtaposing cars, run-arounds, etc. All is fine. No lock ups. Hit the cars at 3-4 MPH: They couple no problem. Truly hassle free front coupling (provided you still back slowly away when uncoupling.)

But there IS a caveat:

I had to disable the Engine Brakes and remove all references to those values in order to get such stability.

This means you're faced with two options:

1. Have a steam engine that handles more prototypically via use of the engine brake when switching... but you can NOT use the front coupler without high risk of locking.

2. Have an engine that you will have to use the train brake when switching... BUT... you can use the front coupler at will.

What's your pleasure?

Andre Ming

#2 Joe Morris

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Posted 08 May 2004 - 09:05 PM

All the experimental work I did with the front coupler was with diesels. When I did try it on a Steamer, I may have used the train brakes instead of the engine brakes. I had a couple people test a steam loco .eng file for me, and I don't know how they were braking. I will look into this as soon as I can. Have you installed the change to the default.wag file, changing the Collision Threshold Velocity? This is very curious that it would have this effect with the engine brakes on a steamer. It does not seem to do this with diesel locomotives. MSTS is a strange beast indeed. If I find an answer, I will let you know Andre.

#3 laming

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Posted 08 May 2004 - 09:22 PM

Joe:

No. The default.wag file is just that: default. My reasoning is to optimize everything possible without altering any files the end user would also have to alter in order to see the same results. I prefer to limit any alterations to only files delivered with the route and equipment intended for the route.

Of further note: The lock would NOT occur when coupling. It would couple fine. The lock would happen once the SHOVING move commenced.

With handbrakes on all equipment and engine brakes active such a lock was 100%. With engine brakes and no handbrakes it is random. With no engine brakes and no handbrakes: It appears gone (on my installation/system).

The more minds on this the better. Steamers have traditionally been tougher on the front coupler than diesels, perhaps I'm beginning to unravel the "why's".

BTW: Spent some time tonight with a Canton Geep with the collective input "fixes" installed developed in the Physics thread: Seemed to be able to switch with the front coupler at will. No brake release problems or any such oddities. Switched like a dream. Good work guys!

BTW2: The lower throttle steps simulate the slower load time of an EMD quite nicely! Seemed quite natural to hear Runs 3-4 having to be used while switching!

Note to self: Hurry up and get the North Arkansas finished so I can play MSTS.

Andre

#4 Joe Morris

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Posted 08 May 2004 - 09:53 PM

Andre,
The change in the default.wag file is possibly crucial to the front coupler solution. It is as easy to open as any other .wag file. It is also as easy to install a replacement as it is to install an updated .eng or .wag file. The change "matches" the collision threshhold velocity to the coupler velocity settings ( 0.1m/s ) and ( -0.1m/s ). If you don't want to change it, then change your .eng velocity line ( only single one in steamer, two in diesel ) to

Velocity ( -0.05m/s )

Then your coupler velocity will "match" the velocity in default.wag. Let me know if changing one or the other improves things for you.

Edit: If you install the Canton Realistic Physics upgrade, the default.wag file is changed automatically.

#5 laming

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Posted 08 May 2004 - 10:03 PM

> The change in the default.wag file is possibly crucial to the front coupler solution.
> It is as easy to open as any other .wag file.

Understand about the ease of editing. I've hacked around in the default.wag file many, many moons ago in various ways. I was in reference to being hesitant to institute a change in the end users system files.

So you feel the Velocity statement would have an impact on the brakes values? That is, removing of the hand/eng brakes = no front coupler problems. Adjusting the Velocity value will help this to where I can reinstall engine brakes?

Mind pointing me to the correct thread so I can read exactly what you're in reference to? (There were a BUNCH of physics threads/posts! smile.gif )

Thanks for the input.

Andre

#6 Joe Morris

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Posted 08 May 2004 - 10:20 PM

I don't know if "matching" the values will correct the problem you are referring to, but I do know that even with diesels, the front coupler is more stable when the velocities match in the .eng file and the default.wag file. Perhaps the problem is that the engine brake is more sensitive and quicker than the train brake, so it demands more of the velocity matching than does the train brake. Actually, I wanted you to test. If you get stability with the values matching, then we would know that they MUST match. If you don't get stability, then further research is necessary. You are the first person to report this problem ( not much done with steamers yet ), and you found a unique solution to it! I am hoping that matching the values works, otherwise a new "fly is in the ointment".

#7 laming

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Posted 08 May 2004 - 10:26 PM

Understood.

It's certainly worth a try.

Post here what default.wag value you want installed as well as eng/wag Velocity values, and I will modify the files, reinstall engine brakes, and test.

I would really prefer to have operative engine brakes as to the current "work around". However, between the two, I prefer the freedom to use the front coupler over the engine brakes.

Andre

#8 Joe Morris

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Posted 08 May 2004 - 10:54 PM

Andre,

In the default.wag file there is a section that looks like this

ExtraParameters (
"0.01 # Default coefficent of restitution"
"1 # Floor contact ratio friction scaling factor"
"5e4N/m/s # Linear water friction"
"5e4N/rad/s # Angular water friction"
"0.05m/s # Collision threshold velocity"

The section needing to be changed is in bold. Change it to this:

ExtraParameters (
"0.01 # Default coefficent of restitution"
"1 # Floor contact ratio friction scaling factor"
"5e4N/m/s # Linear water friction"
"5e4N/rad/s # Angular water friction"
"0.1m/s # Collision threshold velocity"

Then "reinstall" your engine brakes and test.

#9 zhivago47

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Posted 08 May 2004 - 11:31 PM

Andre, if Joe doesn't solve your problem (and I hope it will as it will probably help us out in the other areas he is working on) then I opt for version two of your opening remarks. I would rather have the train brakes and coupler working than than engine brakes and no coupler working. I don't think the speed that these trains are going to run will cause major problems with just a train brake working and not an engine brake.
However, I do hope Joe's solution works so you don't have to choose.

Anyway, will be looking for your reply to testing of this fix. I hope he is right. Of course if you are doubling the collision threshold velocity, I would think that would help a lot. Would this also affect the uncoupling? Probably not, perhaps a dumb question anyway.

Hope it works for you Andre so you can get the route out the door. I know you are looking forward to that anyway! And even if you have to compromise on the brakes, I don't think it is a major problem that we will have to deal with. The reason I vote for the coupler over the engine brake is the fact that I believe you are going to need the front coupler much more in your route and activities than you are the engine brake. Food for thought!

Good luck anyway. Nice work as always Joe!

Tim

#10 Joe Morris

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Posted 08 May 2004 - 11:57 PM

Unfortunately, I have to report that I was able to duplicate Andre's problem. I had to push quite a ways, but then the darn thing phoned home. The loco I was using is aliased to the Scotsman cab, and doesn't seem to show an engine brake. The engine brake function does not appear in the "little white box" near the bottom of the screen either, but it is there, because I can stop the thing using them. Quite quickly too. I am sure that the engine brakes on this little 0-6-0 are possibly too powerful, but I am not sure what that has to do with it. Maybe I am just getting used to the more realistic brakes on the upgraded Canton equipment! Now I have to find out why this affects steamers and not diesels. My head is starting to hurt again.

#11 laming

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Posted 09 May 2004 - 06:40 AM

Tim:

My feelings too.

Joe:

So, do I still need to modify and test? If so, it will be later today or tonight.

Andre

#12 Joe Morris

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Posted 09 May 2004 - 06:41 AM

Andre,

Could you email the the .eng file of the engine you were using, as well as the .wag file of its tender. I am trying to make comparisons with diesels to see the difference. I still think it may be in the coupler section values, but it would help to have another engine file that we know has this problem. Thanks!

#13 Joe Morris

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Posted 09 May 2004 - 08:41 AM

Andre,

I have been somewhat successful in fixing my steamer. I was able to front couple to two different consists ( one was a default Ohio Rail group of boxcars with a caboose and the other was seven of the upgraded Canton 40 ft. boxcars ). I was able to successfully push them over 10 miles of Ohio Rail track. The only "problem" was that on exit from TS, I got a Send/Don't Send message. NO problem exiting the activity, no problem going back to the 1st menu screen, but it did phone home on exit. Don't know what this means. Later I am going to repeat the test, and see if I still have the exiting error. If so, I will remove the engine brake from the steamer and see what happens.

Send me the .eng file and the .wag file for the tender, and I will change the couplers for you. I really do want to study the files to see why this problem exists. I am not completely sure that I have the answer since I got the exiting error.

#14 Joe Morris

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Posted 09 May 2004 - 01:31 PM

Another report: This may be a bounding box issue. Try this, take your steamer and make your coupling with the front coupler. After you are coupled use view 2 to look at the assembled train. Press <CTRL> + to show the bounding boxes. In my tests, the loco's bounding box disappeared. The car coupled to the front has a bounding box, the tender has a bounding box, but none on the loco. If you save the activity, exit and then restart, the loco now has its bounding box. I now recommend that everyone check the bounding boxes right after using the front coupler, even with diesels. If none shows for the loco, then you will have a potential crash of MSTS.

#15 laming

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Posted 09 May 2004 - 02:08 PM

Hi Joe:

First, here's a zip containing the current eng file (no hand/engine brakes), a back up of the engine file WITH engine brakes, the tender file I (no handbrakes), an example of the wag files (sans handbrakes), and a copy of the default.wag file.

I'll go look at the bounding box issue after I'm off the net.

Andre

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#16 laming

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Posted 09 May 2004 - 03:37 PM

Looks like with the eng/wag file values I'm now using, the bounding box issues are not apparent. To wit: The pic below!

smile.gif

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#17 Joe Morris

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Posted 10 May 2004 - 06:17 AM

Thanks Andre,

You have helped in tracking down this mystery. I wish I could afford to have forty differently configured systems for testing. There is a severe bounding box issue with the steam loco I am testing. I needed to be able to rule out bounding boxes as the problem since "bad" things happen when bounding boxes aren't right.

I am analyzing the files you got ready, and I will see if I can figure out why this is affecting steamers, and not diesels. I am trying to look at what is different about the two ( other than the obvious smile.gif ). I even tested with a diesel and a car, since a steamer has something on both ends when using the front coupler. No problem with the diesel. I am going to have to find a steamer that works correctly without the engine brake, and then see what happens as I add in some things, I guess.

A couple of questions: In the bounding box pic above, is that loco one with the engine brake removed? Is that the loco that goes with the .eng files you sent?

Thanks again for testing!

#18 laming

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Posted 10 May 2004 - 06:42 AM

That's a yepper on that being a pic of the loco with engine w/brakes removed. That file will be the StLNA3.eng file. The file WITH the brakes is StNA3eng.bak. The StLNA3tw.wag is the tender's wag file. All the wag files in that picture are represented by the basic wag file sent.

If you want to download the basic model for yourself, it is the "Jessica" Ten Wheeler engine by John Fowlis, available at Train-sim.com. The "TenWheel" cabview by John Pratorious has had the cvf file modified to point toward common folders, as well as having been modified to read in US units of measurement. Of course, both the engine and cabview have been reskinned/modified... but still the basic engine would be available to you through Train-sim.

As it is, I'm going forward with release as the eng file currently is as I've invested a lot of time chasing the problem to the point that I have. IF I/we figure out a way to make engine/handbrakes work for steam engines and still be as stable with the front coupler as my modified eng/wags are, I will issue an updated set of eng/wag files.

Good luck!

Andre Ming

#19 laming

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Posted 10 May 2004 - 06:58 AM

Joe:

On your note about possible success with the eng brake and nose coupling, be advised there are two ways the problems arise (when engine brakes are installed):

1. The infamous lock upon shoving with the nose coupler. This is random. You MAY be able to do it, in your case, up to 10 miles. However, you still have to face problem 2...

2. The train brakes won't release after recoupling to the FRONT of the train for departure/whatever.


Your tests of the front nose coupler must ALWAYS include:


1. Uncoupling from the front of the train and making a runaround to the rear.

2. Once at the rear of the train, multiple uses of the front coupler off the rear of the train. (I typically will set cuts from the train off on sidings and spurs, then regather them back up and reassemble the train.)

3. Run around back to the FRONT of the train, recouple and proceed.


The above procedure really needs to be used to test ANY modifications aimed at the front coupler, diesel or steam. Figure about 20 minutes of shuffling per test.


Andre Ming

#20 zhivago47

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Posted 11 May 2004 - 12:49 AM

At this point Andre, I would have to agree with you. You can test til the cows come home, so to speak, and never get the route out the door. I think that what you have is good enough to make it out the door, and then if Joe or you come up with a fix then just issue an update. That is the only reasonable thing to do for you I think at this point. I know I won't complain. I really don't think we are going to need those breaks on this route anyway, at least for running the activities you have created.

I say go for it! I know I am looking forward to it!

Tim

PS, saw a boxcar on a consist today go by the house, with an Arkansas Midland boxcar in it. Was that a railroad at one time in Arkansas? Really just curious. Was being pulled by two UP engines! Seeing a lot of UP and BNSF stuff go by here lately.