Train separation with buckeye_type_e

[ttjph]

Hi all,

Long time UKTS resident, first time RWA poster here. Hoping someone here will know something about this one...

There seems to be a recognised issue (from posts on the Steam community, and others) with trains separating, particularly on Sherman Hill although I've had it on Norfolk Southern Coal District too. It seems to be linked to the buckeye_type_e_coupling.

Does anyone have an edit for this coupling which fixes the problem? I've tried increasing the Strength line to no avail, and in any case the Sherman Hill version already had higher strength than the Kuju default. There are spring and damping coefficients which I suspect may influence this; and there's a Max Force with the rather specific value of 2.89134e+6.

If anyone's found values which work (ideally including slack, which is missing from the default ones) then I'd love to hear them; otherwise I'll just have to try occasional edits and see what happens.

Thanks!

[JohnS]

Welcome to RWA! Unfortunately, I don't have an answer to this. I have both routes mentioned and haven't had a pull apart on either route. Do you have a specific scenario this is happening in or is it a quick drive type scenario? Do you have specific location it happens or is it random? The more information you can give the better someone might be able to address the issue. Again welcome to the forum.

John

[AmericanSteam]

The only issues I have had with break-aparts is when I ran these routes were the first few times due to my rough train handling. After passing the learning curve I have had none on either route. The secret is learning on how to properly balance both dynamic and train brakes. Are you the poster in Steam Forums?

[ttjph]

Hi, and thanks for the replies.

I don't have a specific scenario, although it's happened two runs out of two in the Sherman Hill Scenario Pack SH1.07 UP Extra 3200 West Part 1. Unfortunately it occurs some time in (I think I was about ten minutes from the end of a 1-hour scenario last time) so it takes a long time to reproduce and test.

I don't think it's related to train handling - I'm not an expert in handling long US freights, but I've been playing RW/TS for many years and like to think I have a reasonably sympathetic driving style. I don't believe I usually experience these breaks immediately after a brake application - they generally seem to be when the train state has been constant for some time.

I'm not the main poster in any Steam threads (I use the same username across Steam and TS forums) but one poster here has reproduced the problem and video'd it, and insists that it's not related to train handling:
https://steamcommunity.com/app/24010/discussions/3/358415103479358061/?ctp=2#c2295094230833527041
In his first video the break happens just after 43 minutes; it looks like he's been in Notch 1 for the preceding ten minutes.

https://steamcommunity.com/app/24010/discussions/3/364041517013329056/
Some more discussion, with at least one other poster supporting that it's a semi-random bug.

I've also just noticed that user 'Cyclone' has responded to my request for his fix (in the upper linked thread) by suggesting a dramatic reduction in stiffness and damping - this makes sense if it's a numerical simulation issue, as excessive stiffness tends to cause issues in this kind of thing. However I don't really want to take too much spring stiffness out and go back to the original Kuju 'Slinky' trains... I'll probably test reduced damping at the next chance I get.

[dphorton]

You might try this. Be sure o back up old Buckeye_type_e first just in case.

Replacement Buckeye.zip

[ttjph]

Thanks... Looks like it's mostly a cosmetic replacement, though. Both versions of the .bin file have damping set to zero, but no entries at all for slack or stiffness.

[ttjph]

Results of some experiments:

'Strength' seems to do nothing. I set it to 1 with no issues.
'MaxForce' does seem to determine couplers separating. It need to be at least about 20 to withstand 4x SD40-2. 50 seems fine (compare to the default 2.9 million!)

I've increased the stiffness purely as I thought the couplers looked like they were extending too far at high tractive efforts.

I've decreased the damping significantly. I'm not sure how much or little damping there should really be - can anyone advise? At 1000, with 20000 spring stiffness, the speedometer needle can rise in surges after pulling away and notching up.

I've added slack (0.07, or a little under 3") because it should be there. It makes driving more interesting!

With all that, I've just completed SH 1.07 successfully (after two failed runs with the default coupler). Maybe I'll try Midnight Magnet next - it looks like I've never completed it, but then it is 100 minutes long so it might not be any time soon...

This is my current Sherman Hill coupler, then. It could easily be edited for other routes or as the Kuju default.

Code: Select all

<?xml version="1.0" encoding="utf-8"?>
<cBlueprintLoader xmlns:d="http://www.kuju.com/TnT/2003/Delta" d:version="1.0">
   <Blueprint>
      <cCouplingTypeBlueprint>
         <UncoupledGeometry d:type="cDeltaString">RSC\ShermanHill\RailVehicles\Couplings\Buckeye\Type-E\[00]buckeye_type-e_uncoupled</UncoupledGeometry>
         <Bogey d:type="cDeltaString"></Bogey>
         <Strength d:type="sFloat32" d:alt_encoding="0000000000C06240" d:precision="string">1</Strength>
         <CouplingConnection>
            <cCouplingConnectionBlueprint d:id="9457">
               <Type d:type="cDeltaString">buckeye</Type>
               <CoupledGeometry d:type="cDeltaString">RSC\ShermanHill\RailVehicles\Couplings\Buckeye\Type-E\[00]buckeye_type-e_coupled</CoupledGeometry>
               <ReceivingGeometry d:type="cDeltaString"></ReceivingGeometry>
               <PivotType d:type="cDeltaString">eMidPoint</PivotType>
               <MinDistance d:type="sFloat32" d:alt_encoding="0000000000000000" d:precision="string">0</MinDistance>
               <MaxDistance d:type="sFloat32" d:alt_encoding="0000002085EBB13F" d:precision="string">0.07</MaxDistance>
               <TargetDistance d:type="sFloat32" d:alt_encoding="0000002085EBA13F" d:precision="string">0.035</TargetDistance>
               <SpringCoefficient d:type="sFloat32" d:alt_encoding="00000000004CCD40" d:precision="string">20000</SpringCoefficient>
               <Damping d:type="sFloat32" d:alt_encoding="0000000000C09240" d:precision="string">1000</Damping>
               <MaxForce d:type="sFloat32" d:alt_encoding="0000000000006940" d:precision="string">50</MaxForce>
               <ManualCoupling d:type="bool">0</ManualCoupling>
            </cCouplingConnectionBlueprint>
         </CouplingConnection>
      </cCouplingTypeBlueprint>
   </Blueprint>
</cBlueprintLoader>


[ttjph]

I've now completed Midnight Magnet as well... looks promising!

[torfmeister]

Hi, I posted a fix concerning this on the DTG forums.

https://forums.dovetailgames.com/thread ... ues.50579/

Many consist breaks on Sherman Hill were reported and I looked into the coupler blueprints. Zero slack is the issue, leave strength at 150 that's OK. Found problematic couplers on Norfolk Southern Coal District, Donner Pass, Kansas Topeka, Cajon Pass (US Loco & Asset Pack) and provided fixes.

I found the best values to use for the Type-E are

Strength: 150
MinDistance: 0
MaxDistance: 0.1
TargetDistance: 0.05
SpringCoefficient: 15000
Damping: 12000
MaxForce: 2.89134e+006

Those parameters are already in use in many DLCs. (Marias Pass, CSX Hanover...)

I had a conversation with Mike Rennie (Smokebox) who proposed even more realistic values but those require adjustment on the engine/cars' blueprints.