More Realistic Brake Force Settings on Freight Cars?

[Kali]

Hi G_Nash,
Are you using the braking ratio for the loaded weight or empty weight? Also has anyone verified that when you do load a car in Rail works, does it actually change the cars weight or is loading just a visual effect only?

Regards,
Rich S.

It does, provided the load mass is set right. Most definitely makes a difference to braking distance.

Problem is there *are* loading points in RW - what cars do you use when you want to use one if yours are all fixed?

[g_nash]

It's not problem at all , I don't bother with loading points other than fuel . Could post a long rant WRT loading/unloading and the method choice we get to use for what load (full/part) on which cars , cars which can in fact have a dozen or more load types with varying mass/weight , could also comment on the animation side of things as well , I'll just let it go though . I found a method that suites me , others can do the same .

.

[GreatNortherner]

Hi,

Wow, this is a great reading! And unlike in the "dodgy physics" thread I'm even still somewhat able to keep up with my limited understanding of how a real railroad actually works. So, THANK YOU!!! This is very enlightening indeed and great food for thought.

Kali, you say you ended up using a value of 45% for the brake% value? This is incidentally only a bit more than what Bill Prieger uses on his MSTS freight cars (100t weight car -- 35kN max brake force). 45% would mean 45kN on a 100t car, about 12kN on an mt one? That looks like some nice "in-between" values in comparison with the MSTS settings.

BTW, empty / loaded weight on freight cars does work, very well so actually.

For example, if you have a boxcar -- set its mass (MT) to say 27t. Then add a cargo component for "bulk freight", enter say 50t in the "capacity" line of the cargo component. And that's how much your car will heavier when ticking the cargo checkbox in the scenario editor. The only difference to the cargo setup of a hopper or other open-top car is that you don't need to attach a shape file and/or animation to the cargo component group in the BIN file.

FWIW, most of the default freight cars (except the open and covered hoppers) do not have this feature. They have an approximated LD weight as basic mass, and do not even have a cargo component at all. So in effect, most of the default cars (tank cars, boxcars, autoracks, coil cars, ...) are always fully loaded -- which is one of the reasons why so many RW trains run around so heavily overpowered. (Another reason is the often quite heavy loads, sometimes even more than their CAPY would allow, see the HSC 70t hopper with a 100t load, for example).

Cheers,
Michael

[Kali]

No, I'm using 45% on an empty hopper of iirc about 25 tons. When it's loaded and over 100t - I don't remember the exact number - that is still 45% of 25 tons ( or whatever it was empty ), which ends up at effectively around 13% or so when loaded. I decided it was more important to get the feel right when the train is full. If I was doing a permanently loaded version I'd set it to 12-13%.

There is ( as usual ) a not particularily brilliant scripting tweak which I will try and incorporate into the brakes I'm working on to deal with loaded/empty consists - unfortunately a) it needs the wagon knowing how much it weighs empty, and b) is only really any good for a whole consist.

[_o_OOOO_oo-Kanawha]

Kali, how is this coming along?

I really would like to incorporate such braking characteristics in the COARW coal drag scenarios. The trains really do "feel" like 10000-14000 tons while accelerating, but they brake still very much the same as any other train.

Your SD40 physics and "stiff" couplers already made a huge difference. I believe I haven't tried your brake pipe flow hack yet on the SD40.

I might try and modify the ES44 and SD70 models in likewise fashion. Am now busy sort of comparing them in time needed to make it from Alderson to Alleghany with a 100 car train of those aluminiun bathtub gondolas. The cars are marked "LD LMT 243600" and "LT WT 42400". That means they weigh 122 US tons loaded and 21 tons empty? I am not familiar with imperial units. So a 100 cars is 12200 tons, a typical 6-axle Diesel is 180-200 tons?

[Kali]

Well, I'd have to do special wagons set up as powerless diesel electrics to do it properly - I might do that one day but that is some serious work for a train that wouldn't be much more than a self-contained demo, if it doesn't cripple the game. The engine brake stuff with a virtual air tank I'm writing as a proof of some new script framework, so that's slow and steady. Don't bank on anything that soon though, lots of distractions this time of year!

An imperial ton ( long ton anyway ) is practially the same as a tonne, as far as we're concerned they're interchangeable.

[_o_OOOO_oo-Kanawha]

There is no need to rush as Tori hasn't scenicked and signalled the Virginia portion of her COARW yet. All of the loaded eastbound coal drags climb uphill before passing the summit and stateline near Alleghany, VA, the current end of all scenarios. So braking and holding back 14000 ton trains is for the next revision of her route. One can drive the train all the way down to Covington and beyond, but the landscape is mostly bare tabletop and hardly fun.

Reminds me of the brown wrapping paper mountains and valleys of my once model railroad. Took ages to make proper scenery so I just spray painted it. Just looked like the "decals" most of us use in laying out a route.

[Kali]

Thought I'd bump this since I found a little doc I'd read a while ago and forgot the link to: http://www.standardsteel.com/rdpapers/freightcar.pdf

[_o_OOOO_oo-Kanawha]

Thanks, Kali. That was an interesting if technical read. Probably applies to US mostly given the axle loadings and brake characteristics.
The only of these problems I remember being a problem overhere in the Netherlands is polygonisation of passenger stock's wheels, but since they are all disc braked it must have a different cause.
Freight cars used in pan-European container and TOFC servce which travel over the Alps and/or attain speeds of up to 120 km/h are regularly monitored for said wheel defects. Domestic and lower service class usage cars probably not.

US freight cars mostly use one-piece solid wheels, instead of separate wheel disc and cramped on tire, like most European stock?
Do US freight cars still mostly use the simple three piece trucks of Bettendorf's and related designs?

[simer4]

US freight cars mostly use one-piece solid wheels, instead of separate wheel disc and cramped on tire, like most European stock?
Do US freight cars still mostly use the simple three piece trucks of Bettendorf's and related designs?

Most European stock don't use friction disks. Passenger yes, freight no. A lot of the "bogies" employed on their freight cars are Barber S-2 style.
Yes freight car here do still use a three piece (excluding brakes and bearings), but use roller instead of journal bearings. They are called Barber S-2, Ride Control, and Motion Control (ASF) trucks. They are made ASF, Buckeye, and Dofasco.
The different types are seen here:
http://trainiax.net/drawings/36-part/36 ... uck-fc.GIF

[Kali]

The UIC standard bogie is the Y25 ( google "Y25 bogie", you'll get way more info than you ever wanted ), which is clasp brakes - however even with clasp brakes we tend to have twice as many shoes per wheel as US trucks ( other than the odd wagon - seemingly mostly built in Wabtec UK - which uses US pattern trucks ). Higher speed freight stock - anything expected to run over 60mph loaded - will probably have disk brakes though, like container wagons. I dug up the UK operations manual yesterday for someone else's query, our brakeforce calculations allow for a minimum 50% train weight ( without the engine ). US, as you can see from that doc, is more like 13%.

[simer4]

Ah, ok.

[_o_OOOO_oo-Kanawha]

The different types are seen here:
http://trainiax.net/drawings/36-part/36 ... uck-fc.GIF

That's like a "spot the difference" game!

The journal boxes are still held in place by gravity alone? In pictures of US derailments you always see axles lying strewn around.
Do our VR trucks have those distinctive rotating roller bearing end caps? I always think they are a nice touch.

[NDORFN]

If I may daydream a little: if a sort of "realistic brake physics consensus" could be reached in the community, maybe it would even be possible to create a tool that could automatically edit a big number of cars' BIN files in one go? (If such a tool is even possible, my programming skills are on par with my maths skills
[/code]

So what is the general consenus on creating a set of standardised physics for the community? Is anyone else interested? I'm dead keen on it as my route is a bit of a roller-coaster and requires realistic physics to operate trains over it. I was planning to package custom repaints specific to the route with patched physics... but if there is a common physics set available I could release the route before the repaints (months earlier!).

[_o_OOOO_oo-Kanawha]

I am all for realistic physics, both traction and brake.

Yes, you are right, someone needs to take the lead and apply the hacks into his route and rolling stock.

That leaves perhaps only you, Bob Artim and Tori Morgan, i.e. authors of substantial routes with an interest in prototype operations and which routes which offer sufficient challenge.
Hacking track, signals and rolling stock pretty much makes that route an isolated island as the hacked assets are incompatible with other "standard" routes.
Everything has to be adapted to the desired prototype operation and all scenarios have to be written anew. Everything will be quite a bit slower and one doesn't know if the general player wants this and subsequently dumps the route into which so much effort has been invested.

Doing everything double, for the casual player and for the discriminating prototype user, is something no author is really looking forward to, I presume.