[JLChauvin]

Genma Saotome, on 04 July 2014 - 02:39 PM, said:

I'm familiar w/ the one over at TS.com... I participated in it but the one at 3dtrains was new to me. I read it this morning and noted one of the posts you made had a table for maxhandbrakeforce(). I took down the numbers and w/ a few minutes in excel concluded your numbers were almost equal to Mass() * .425; I found that very interesting as some years ago Leland suggested using mass() * .4 and I've been using that ever since.

It is not at all clear to me that that formula should apply to a value of mass() that is less than 50t, which was the low limit in your table. Do you think it should?

The less than 50t "limit" is not a real limit, this is only because most of modern US loaded wagons are weighting more than 50t in general case... and I am a little lazy. :sign_rockon:

There was a discussion here, long time ago, about trains brake:
http://www.elvastowe...2-train-brakes/
including UIC brake study:
http://www.elvastowe...dpost__p__46550

I made a more recent paper with more "optimized" values for MSTS, since that time.
We all knew that values used for MSTS are tweaked values, sometimes seaming aberrant, to correct the awful KUJU code.

For ORTS I think it's better to use real values, like accurate seconds for application and release time or recharging time as an example.

As you can read, I have accurate values for UIC brake performance (braked mass/stopping distance) but I didn't found enough reference about AAR performance (brake ratio/stopping distance).

[Genma Saotome]

JLChauvin, on 05 July 2014 - 04:46 AM, said:

There was a discussion here, long time ago, about trains brake:
http://www.elvastowe...2-train-brakes/
including UIC brake study:
http://www.elvastowe...dpost__p__46550

On re-reading the first one I recall now how complex this issue and how much more needs to be done to get realistic braking.

For positive air pressure brakes it seems to me that EmergencyBrakeResMaxPressure( ) means the maximum air pressure available to a car's braking equipment... for freight cars built before 1950 that would be 70PSI, between 1950 and some future date... 60's, 70's, 80's... I dunno when, 80PSI would be correct, and for modern freight cars 90PSI... with passenger equipment being higher... perhaps 110-120PSI.

That creates the question of whether that value belongs in the each .wag (where it is now) or somewhere else, such as the activity or the route that specifically dates things. For example, in <routename>.trk I believe there is a parameter there called Era(). I don't know if that is being used but what I'm getting at is if something like that could be used to set the expected-for-the-era maximum pressure on each car, allowing the parameter to be removed from the .wags. I don't know if that would be correct tho... perhaps older cars retained their lesser max pressure ability while newer cars were built to hold more, in which case it would be better to keep the parameter in the .wag.

The other thing that struck me while re-reading that thread is the different effects produced by the material used in the brake shoes as well as the differences between disk brakes and non-disk brakes... how cast iron shoes increased their effectiveness as train speed slowed. I also recall reading (elsewhere) that the old cast iron shoes lost effectiveness as their temperature increased. No data but since they worked by friction it makes sense that considerable heat would be produced, enough so that they smoked.

I know some freight cars carried what was called clasp brakes. AFAIK these were applied to open top cars with very heavy loads that would normally be passing over routes with steep or long descending grades. The B&LE put them on every hopper car... the DRGW on some of their coal cars. I do not know how such brakes might be characterized as data for use in OR... or how OR might make use of that data. Any thoughts?

And so candidate parameters for wags (should we come to understand how to code given the differences):
BrakeApplicationMethod ( Shoe | Disk ) or perhaps ( Clasp | Shoe | Disk | any others that make sense )
BrakeShoeMaterial ( Iron | Composition | any others that make sense )

Last I noted that both Wayne and Bill were of the opinion that lading weight belonged somewhere besides the .wag... Activity based. I agree. Let the .wag describe the mesh itself... the car "as built" by the modeler and move the variables like lading and its effects somewhere else.