Dodgy physics

[Bart35]

Kali.... I just took 5 modified sd 40-2 and 50 modified coal (loaded) from monument to castle rock and all i can say

[Kali]

Kali.... I just took 5 modified sd 40-2 and 50 modified coal (loaded) from monument to castle rock and all i can say

Thanks :) with respect to modding other engines this is mostly about getting principles and guidelines right rather than specifics at the moment. I picked the SD40 because everyone has one, it has dynamic brakes and the RW3 one doesn't need all the rest of it's physics redoing as well, which would just complicate matters. Once a) people who'd know are happy with the handling, and b) general gamers are happy it isn't impossible to drive, then there's condensed knowledge and practical examples for anyone who's building or setting up engines ( and rollingstock! ).

I have a working version that picks up the train length and uses it to adjust brake release - looks a bit funny but 3 mins brake release time makes quite a difference when you're thinking ahead :p ( that's 3 mins from full service, if you're only at min app that's not that long ).

[Rich_S]

Okay let's clear up a couple of items.

#1 In the real world Independent brakes only apply on the first locomotive. Some games may have figured out how to get them to go to all the locos. That is not prototype. So if you want to run right...first loco only.

Nick

Hi Nick, that is not correct. If the A+R MU hoses are connected in a consist and all trailing units have they mu value set to trail, the independent brakes will work on all units when the independent brake handle is moved from release toward the applied position. If the EQ MU hoses are also connect on all units in a consist, when a brake pipe reduction is made, all locomotive brake can be bailed off by pressing down on the independent brake handle. This is something that is not modeled in Rail Works. Many months ago Mike Simpson added my updated brake handle settings to RW_Tools. This update represents the real world handle movement of 26L and newer brake equipment, with the minimum reduction of 7 lps (if you can hit 8% handle movement) And Full reduction is at 50% handle movement.

Regards,
Rich S.

[TrainMaster1]

Rich: If you look at a subsequent post I have already correct that. Was info provided by several actual BNSF employees (do not stand too close to the crossing!!!) They apply equally to all engines in the consist. Should have known better myself but since I was not in the cab now almost 15+ years thought maybe that changed. Should have known better and researched it better. In the simulators out there pretty sure it is first engine only...not sure how RW handles that....I know MSTS only applies to the first engine right now (unless a patch for that changed that as well but I do not think so.)


Nick

[GaryG]

Hi

One more item to consider. Do not know if this applies to RW or not.

Keeep in mind that when Dynamics are used, the brakes (loco or train) on the locos are normally never used to avoid wheel lockups.

With MSTS locos MU'd, most trailing locos will apply the loco brakes when the train brakes are applied which really upsets the simulation of real world braking. The way I got around this with MSTS was to define a trail .eng file which had the braking force set to one Newton or so and use these loco definitions for any trailing units. This way, the Dynamics and brake settings of the train came fairly close to letting a train react properly except at speeds where dynamics would not be used.

As I started out, I do not know if this applies to RW or not but it might be a reason why the Dynamics appear to be so strong.

GaryG

[Kali]

It ( thankfully ) isn't, the dynamics really are that strong in some setups, so much so that the F7 can jackknife trains...

You don't appear to be able to remove brakeforce from the driven engine; I tried and the trainbrakes still stopped it, I just lost use of the independent brakes! I guess I might have found a bug there. So there's seemingly no way of bailing the engine brakes off unless the I find the right combination there. My idea was to zero out the trainbrake force for the engines and script the independent brake to work in it's place, but that is a rather large hurdle to overcome.

So, I have my train-length dependent brakes now, and I'm not sure many people are going to like this at all; waiting for 3 mins for the brakes to come off isn't much fun. Thoughts? a step too far?

[PapaXpress]

I am all for a bit more realism.

perhaps have two scripts?

[Rich_S]

It ( thankfully ) isn't, the dynamics really are that strong in some setups, so much so that the F7 can jackknife trains...

You don't appear to be able to remove brakeforce from the driven engine; I tried and the trainbrakes still stopped it, I just lost use of the independent brakes! I guess I might have found a bug there. So there's seemingly no way of bailing the engine brakes off unless the I find the right combination there. My idea was to zero out the trainbrake force for the engines and script the independent brake to work in it's place, but that is a rather large hurdle to overcome.

So, I have my train-length dependent brakes now, and I'm not sure many people are going to like this at all; waiting for 3 mins for the brakes to come off isn't much fun. Thoughts? a step too far?

Hi Kali,
Not sure if this was covered earlier in this thread? but on modern North American diesel electric locomotives, you have automatic bail-off for locomotive brakes when using the dynamics. From what you mentioned in a previous thread, I believe all the brakes on the train including the locomotive brakes apply as on English stock and there does not seem to be a way of bailing off the Independent, also automatic bail off also does not seem to be modeled. As for Dynamic's, I believe most of the engines have their DynamicBrakesSystem MaxForce value in the Engine Simulation file set extremely too high. Some of us found, that if you took the original MaxForce value and divided it by 4.45, the lower value provided a more realistic train handling. I just checked the F7 that ships with the Horseshoe curve route and it's DynamicBrakesSystem MaxForce value is indeed still set to 267, should be in the 50 to 60 range.

Regards,
Rich S.

[Kali]

Yes, I tried really hard to bail the engine brakes off ( I still have something really daft to try ) and no joy yet. The default SD40 was set to 60kN iirc which isn't that bad, but was still a bit effective... the one in my rwp from a couple of pages back is at 45kN I think which seems fairly nice, a number arrived at by pure guesswork :p

I'll get the quirks out of this script & post a new version so people can try the new trainbrakes. I will note I set up a loaded coal train to go down Tori's Alleghany route and actually had to keep the throttle open most of the time to keep moving - extra friction in corners is fine, but I'd have thought an 0.6% grade would have kept them moving at least...

[TrainMaster1]

Okay couple of points...I am unaware that the loco brakes apply to anything but the first loco in MSTS or any other sim. Most sims are set up to treat trailing units like cars and apply only automatics. In the real world they all apply and generally are used only in switching or other low speed operations. They are not a primary braking system when your train is moving at anything over restricted speed. You tend to avoid them at higher speeds unless you are headed for trouble and then you need every brake shoe you have. I have been in situations where an emergency application was all that stood between me and killing a Darwin Award candidate at a grade crossing or trespassing.

You can indeed apply air while the dynamics are engaged and I have done that many times in 1:1. On a downgrade like Horseshoe or Sand Patch you set a minimum application (some roads 6 lbs and others 7lbs) and have the dynamics on. You can even pull against an application after returning to power from dynamics if the grade only levels out briefly and you will not have a chance to recover your air before it is needed again. By the way a 6 lbs reduction, if your brakes are working properly applies 15 lbs of force to the wheels (2.5x the reduction in the pipe). That is usually enough to control a train down Horseshoe where the NS TOB rule is 8 mph at the top of the grade.

When you apply automatics (which control the cars) they also apply to the locos and need to be bailed off. Most newer engines do have the ability to do this when the dynamics are engaged to prevent excessive heat build up. Older Locos, well we have many tricks to create auto bail offs especially on older geeps and alcos where a taped stack of coins wedged just right on the brake handle kept it depressed and in "automatic" bail while you tended to other things during the run. (Did I just say that out loud?)

I admire you guys for getting inside the game and making these kinds of adjustments. My programming skills are limited to where's the "on" button on this thing. This has been one of the best discussions I have seen anywhere and I moderate in multiple forums. Keep up the good work.

Nick

[Kali]

Loco brakes aren't propogated in RW, I'm sure I tried that earlier in the thread ( there's scripting in the SD40 to make it work if RSC ever flipped a switch to let it happen ). If you did it in core to let US stock work it'd break european behaviour, so, interesting problem there. On UK - and I assume European - engines all the brake systems feed into the distributor, so there's no way you even could bail them off without having a totally seperate brake control system to do it; and there's no operational need for it anyway.

I need a small behavioural issue cleared up.

* Automatics are on to some value, call it 10lbs
* You move the handle to Release to get them to start releasing
* You move the handle to the lowest point in advance of the release position you can.
* Is the resulting pipe pressure minimum app, or can you release the brakes to below min app?

Thanks to wanting to change the timing in script I have to script all this behaviour too. So much more complicated than our systems :P

[Dan]

Has anyone tried running prototypical consists and power? For example in a lot of the Cajon scenarios the trains are often quite short but have quite a lot of power on them and seem to me to be somewhat overpowered but then sometimes they seem somewhat under-powered.

Does anyone have any thoughts or comments?

[Rich_S]

Loco brakes aren't propogated in RW, I'm sure I tried that earlier in the thread ( there's scripting in the SD40 to make it work if RSC ever flipped a switch to let it happen ). If you did it in core to let US stock work it'd break european behaviour, so, interesting problem there. On UK - and I assume European - engines all the brake systems feed into the distributor, so there's no way you even could bail them off without having a totally separate brake control system to do it; and there's no operational need for it anyway.

I need a small behavioural issue cleared up.

* Automatics are on to some value, call it 10lbs
* You move the handle to Release to get them to start releasing
* You move the handle to the lowest point in advance of the release position you can.
* Is the resulting pipe pressure minimum app, or can you release the brakes to below min app?

Thanks to wanting to change the timing in script I have to script all this behaviour too. So much more complicated than our systems :P

Hello Kali,
I hope I can explain this to give you a better understanding and eliminate a little bit of the confusion When you move the handle all the way to the left, that is the full release position. At the full release position the brake pipe should charge to 90 lbs. (Unless it is set to another value with the feed valve, but that's another topic) When you move the handle from the full release position to the first bump on the valve, that is the minimum reduction position



There literly is a bump that causes some resistance while moving the brake handle. When you hit that bump you have made a minimum reduction, usually 5 - 7 lbs depending on the railroad. Moving the handle just beyond that bump, you are now in the service zone. The Service zone ends at the full service bump which at full service is about a 25 lbs brake pipe reduction. The next zone is suppression, used for recovering a PCS penalty brake pipe application, then comes handle off and finally Emergency.



*** Note the white handle in the above drawing is the Automatic (Train Brake) handle. The Gray handle is the independent (Locomotive brake) handle ***

The only difference in the above drawing is terminolgy. Some railroads call minimum reduction, initial reduction and some call the service zone the application zone. It's that old you say "tomato" I say, you know what I mean I hope this clears up some of the confusion? The update I sent Mike Simpson that has been included with RW_Tools, trys to model the 26L brake stand. Here are the settings I used in the Engine.bin file

Code: Select all

                           <Notch>
                              <cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData d:id="34354912">
                                 <Identifier d:type="cDeltaString">Release</Identifier>
                                 <Value d:type="sFloat32" d:alt_encoding="0000000000000000" d:precision="string">0.0000</Value>
                              </cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData>
                              <cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData d:id="34364256">
                                 <Identifier d:type="cDeltaString">GraduatedSelfLapLimitedHolding</Identifier>
                                 <Value d:type="sFloat32" d:alt_encoding="000000403333D33F" d:precision="string">0.0800</Value>
                              </cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData>
                              <cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData d:id="34365664">
                                 <Identifier d:type="cDeltaString">Suppression</Identifier>
                                 <Value d:type="sFloat32" d:alt_encoding="000000403333EB3F" d:precision="string">0.5100</Value>
                              </cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData>
                              <cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData d:id="34361056">
                                 <Identifier d:type="cDeltaString">ContinuousService</Identifier>
                                 <Value d:type="sFloat32" d:alt_encoding="000000C0CCCCEC3F" d:precision="string">0.6500</Value>
                              </cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData>
                              <cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData d:id="34359520">
                                 <Identifier d:type="cDeltaString">Emergency</Identifier>
                                 <Value d:type="sFloat32" d:alt_encoding="000000606666EE3F" d:precision="string">0.9500</Value>
                              </cControlContainerBlueprint-cInteriorIrregularNotchedLever-cNotchData>
                           </Notch>


I hope this all helps some?

Regards,
Rich S.

[TrainMaster1]

Excellent stuff Rich...almost made me want to get back in the cab and run again....but then again....

I think I saw something in here about if you grab too much air can you give a piece of it back. In general once you make a reduction there is no way to only release a part of it. That is why when you make you minimum reduction you hold on the downgrade because there is no way that I know off to give a piece of it back.

Then you get in trouble because now speed picks up and you make another application. At some point the reservoir will not have enough air and you can end up out of control and on the evening news. I have trained guys to run on lots of different brake systems and equipment. Know what application you need and stick with it.

There are a bunch of railroad rules and guidelines that go with train handling and braking systems such as what to do when you exceed speed on a downgrade and much more. You literally can spend many evenings getting all the situational rules handled.

To answer your question Dan yes I know people who operate Cajon according to the book. I also have access to consist info and we use the BNSF SSI (Special Systems Instructions) to guide everything from assembling the train to power sets and more. This also specifies weight and length of trains allowed on certain tracks. The train described at the beginning of this thread would cost the DS14 a major fine at least if not their jobs for routing a heavy intermodal down track 3. That train would more than likely be on 1 or 2 where it would not face an automatic 10 mph speed restriction all the way down the hill.

A BNSF Q or Z train would need to maintain the best speed possible. An S class train may show up on three if 1 and 2 are parking lots but that is not how the ops plan is generally arranged.

Can't wait until someone figures out how to get a sim to run in "picket fence" mode. That will show you how to control a train on Cajon. This is where you can have the DPUs operate a different throttle setting and/or brake setting to bunch slack or hold a train back as you negotiate a downgrade. All controlled from the friendly confines of the lead loco with the DPUs dialed in.

Nick

[Kali]

Nick, are you saying that once you've released you can't do anything at all until the train pipe pressure has rebuilt to fully off? I was understanding the sequence to reduce your current brake app ( not to release it all the way ) was something like this - assuming the controller has a self-lapping range anyway:

1: Currently 35lbs in the pipe, decide that's too much, want 20lbs
2: Move automatic handle to Release to initiate a reduction. Once that's started
3: Move automatic handle to wherever you think 20lbs would be, and the pipe pressure will stop rising when it reaches there.

if step 2.5 is "Wait for full release" then that changes matters considerably ( not least because a full release can take up to several minutes ).

So there's a detenté for what I'll call minimum application and you can't ever really make a smaller application ( without leaning on the handle I guess! ). I like simplifications like that :). RW has significant issues with partially notched controls, the scripting tends to make them unusuable with the mouse, but if I think of a simple solution I'll throw that in.

DPUs: can do the dyna brakes on those already ( if someone set a cab up to control them with ). That's it with the current state of play though. I was thinking of maybe having DPUs not turn their DB on if they're going uphill ( so you can just brake the front of the train ) but what happens if you really want to stop the whole thing?