[Genma Saotome]

copperpen, on 10 May 2019 - 02:34 AM, said:

As the main part of the object by definition of its name is invisible, I don't think you would need a major offset.

How about the 25m gap I have between the track and the surface of the water? My point is not all routes are alike.

[copperpen]

As that part of the wag/model is invisible, what does it matter how big the gap is. I am not talking about putting a stonking great 86 foot boxcar complete with skin in midair, just a small cube with all sides alphaed out. While it is clear that not all routes are alike they all have one common denominator, a TDB. To my mind all that is needed is a shape that is far enough below the tdb level to avoid crash detection that can be placed and not collected.

[Genma Saotome]

Ahhh, I did not realize what you intended for the shape... nevermind!
:give_rose:

[steamer_ctn]

A working version for Advanced Coupler operation has been added to MG.

A demonstration activity has been created and is available from here.

The key parameters required to configure the advanced coupler are as follows:
ORTSTensionStiffness ( a b ) - coupler forces, where a = coupler force at end of Zone 2, and b = coupler force at end of Zone 3.
ORTSTensionR0 ( a b ) - coupler displacement distances, where a = zero length (adjusts distance between cars), and b = displacement distance of Zone 1.
ORTSTensionSlack ( a b ) - coupler displacement distances, where a = displacement distance of Zone 2, and b = displacement distance of Zone 3.
ORTSCompressionStiffness ( a b ) - coupler forces, where a = coupler force at end of Zone 2, and b = coupler force at end of Zone 3.
ORTSCompressionR0 ( a b ) - coupler displacement distances, where a = zero length (same as value above), and b = displacement distance of Zone 1.
ORTSCompressionSlack ( a b ) - coupler forces, where a = coupler force at end of Zone 2, and b = coupler force at end of Zone 3.

ORTSBreak ( a b ) - Coupler breaking force, where a = force at end of Zone 2, and b = force at end of Zone 3.
CouplingHasRigidConnection ( a ) - defines coupler as rigid (very small amount of slack), where 0 = flexible coupler, and 1 = rigid.

For more information on setting up Advanced Couplers see here.

[Traindude]

Something else to think about while we're rewriting the coupling code...

http://www.elvastowe...-front-coupler/

[Lamplighter]

Hello!
I tried this new feature.
I used the same two trains. One with advanced cuplers and the other with standard couplers.
I tried it on the simulator OR MG and standard OR.

Here's my code for advanced couplers:

Comment ( "Open Rails Advanced Couplers" )	
Coupling (
Type ( Chain ) 
Spring ( 
ORTSTensionStiffness ( 4e5N 2.64e7N )
ORTSTensionR0 ( 0cm 1.0cm )               
ORTSTensionSlack ( 0.5cm 1.5cm )           

ORTSCompressionStiffness ( 4e5N 2.64e7N ) 
ORTSCompressionR0 ( 0cm 1.0cm )     
ORTSCompressionSlack ( 0.5cm 1.5cm )   

ORTSBreak ( 8.5e5N 8.5e5N ) 
) 
CouplingHasRigidConnection ( 0 )
Velocity ( 0.01m/s ) 
)

I found out that the advanced couplers function partially. He can only tension, but no longer compression (with braking or without power and so on).
Here's an overview:

https://1iq.cz/img/C9a2k/66XPz.png

And here video (OR MG + Advanced Couplers):
https://youtu.be/ZmdmhDLkqXo

and video (OR MG + Standard Couplers):
https://youtu.be/vSNesJuoAZo

I'm not sure I'm doing something wrong.

[steamer_ctn]

Lamplighter, on 07 July 2019 - 03:32 AM, said:

I tried this new feature.

Thanks for the feedback.

Firstly a couple of comments.

This feature is still a WiP (work in progress) as the code is closely entwined with the basic code for train movement in OR, and I am still trying to integrate the features without breaking basic train movement.

Lamplighter, on 07 July 2019 - 03:32 AM, said:

I tried it on the simulator OR MG and standard OR.

The advanced coupler code has not presently been integrated into the mainstream (standard) OR program. So apart from comparing "standard" coupler features between the standard OR and OR MG, there is no value in looking at advanced couplers in standard OR.

Lamplighter, on 07 July 2019 - 03:32 AM, said:

I found out that the advanced couplers function partially. He can only tension, but no longer compression (with braking or without power and so on).

The activity demonstrating this feature shows one scenario where compression does happen, ie when traveling over an undulating section of track. Also reversing the train will cause the couplers to compress and the train to "bunch" up.

Compression may not automatically happen in all the scenarios suggested (eg braking, without power, etc). For example turning power off on a train may not cause compression if all the cars continue to move at the same speed with respect to each other, and slow down at the same rate. Similarly braking the train (using the train brake) may not cause compression either as the cars may not change speed relative to each other, and thus all slow down at the same rate.

I notice that you have appeared to brake the train with the locomotive brake only, and in this situation there may be some form of compression introduced to the train, and perhaps this is not showing up correctly at the moment.

So whilst compression is still present, it may not be fully functional for the advanced couplers in all valid instances where it makes sense to appear. Hopefully this will be corrected in the foreseeable future with a further patch.
You may also wish to review your R0 and Slack statements as the values do not appear to "increment" correctly across the various zone boundaries for the coupler.

Thanks again for the feedback.

[darwins]

Here is an interesting thought. Not really on the technical side, but on the practical. Just as dual braked vehicles were common on UK so were vehicles with two types of coupling for many years.

I refer of course to passenger carriages ( LNER / SR / BR ) with Pullman gangways and buckeye (knuckle) couplers. Carriages were joined within sets (carriage to carriage) by knuckle couplers with the Pullman gangways providing a part of the required strength. The couplers were drop head type with a draw hook underneath. Such rakes were always coupled to locomotives (and to vehicles without Pullman gangways) by dropping the knuckle, extending the side buffers and using the locomotive (screw) coupling.

Presuming that the two types of coupler would have different properties, which one would the modeller choose to use in an OpenRails wag file?

[Lamplighter]

steamer_ctn, on 07 July 2019 - 11:59 PM, said:

Compression may not automatically happen in all the scenarios suggested (eg braking, without power, etc). For example turning power off on a train may not cause compression if all the cars continue to move at the same speed with respect to each other, and slow down at the same rate. Similarly braking the train (using the train brake) may not cause compression either as the cars may not change speed relative to each other, and thus all slow down at the same rate.

I notice that you have appeared to brake the train with the locomotive brake only, and in this situation there may be some form of compression introduced to the train, and perhaps this is not showing up correctly at the moment.

I brake the locomotive therefore to point out on inertia forces.
But the HUD (and display) only shows a "pull". Even if the train stops.

Thank you for the explanation and I wish you much success to complete this feature.

[Lamplighter]

I would add an my opinion.
My English is not worth anything. I'll try to describe it best:

Longitudinal movements occur whenever the tensile force changes. Change force tensile occurs when: Descent and ascent railway track, power unit acceleration and deceleration, etc.
Pulling and pushing devices (eg couplings and buffers in Europe) or automatic couplings (eg in the USA or Russia) eliminate these movements.
When driving, there is always a longitudinal movement of the vehicle within the entire train.
How much coupling springiness allows (plus in Europe with the springiness of buffers).

[copperpen]

steamer_ctn, on 07 July 2019 - 11:59 PM, said:

braking the train (using the train brake) may not cause compression either as the cars may not change speed relative to each other, and thus all slow down at the same rate.

This may well be the case if running a short train as the propogation time along the brakepipe will be minimal. A long train will behave differently, propogation along the brakepipe will take longer so the cars at the front of the train will be slowing down before those at the rear start to brake, thus there will be varying degrees of compression along the length of the train.


Modern trains will behave differently where fitted with an EOT device that can activate braking from the rear of the train as well. Not currently modelled in OR.

[steamer_ctn]

Advanced coupler functionality has now been added to the Unstable version of OR (from 05-03-2020).

The functionality allows slack movement of couplers, and also animation of couplers (big thanks to Chris Jakeman for his assistance in working out the world co-ordinate positions for placement of the coupler shapes).

A demonstration activity has been created and is available from here.

This activity and associated tasks demonstrates the following:

i) Operation of slack movement on a train (The test train is over 200 cars long, and each set of couplers can expand up to approx 8 inches). The couplers will expand to a slack distance consistent with the force on the coupler and the stiffness of the coupler
ii) The interaction between slack and starting resistance can be seen. In other words a train with "sufficient" slack movement requires less starting effort then one without.
iii) Poor driving when starting a long heavy train may cause coupler failures, so some added realism is now in play.

For more information on setting up Advanced Couplers see here.

Any issues identified should be referenced back to the test models as this will assist in any code fault finding.

Over time it would be good to establish a small set of standard coupler configurations as this would make settings consistent within OR.

[darwins]

Sounds good. Let me know when someone has worked out the correct numbers for three link couplings.

First of course as the links go from drooping to stretched - the force needed to stretch them would be very minimal. No force at all passed on to the next wagon.

Second as they reach the point of being stretched there is the 'snatch' when force begins to be transmitted through the three links to the next vehicle.

At this point force is also on the leaf springs (if any) at either end of the draw hooks on each wagon - so there may be some coupler stretch depending on train load and springs.

With no train brakes then when the locomotive brakes the wagons are retarded by colliding with the vehicle in front.

At this point there is no compression force as the coupling links can freely change from being stretched to being in various stages of not stretched at all.

As the chain coupling reaches the not stretched at all state then the side buffers collide and start to bear the retarding force.

The side buffer may have springs that can absorb the impact and compress - or on very old wagons could be just blocks of wood with no more ability to absorb compression forces than a block of wood!

[steamer_ctn]

darwins, on 04 March 2020 - 10:14 PM, said:

Sounds good. Let me know when someone has worked out the correct numbers for three link couplings. .............................................................

The description you have described I believe can be modeled with the Advanced coupler features added to OR.

If you look at the introduction section for couplers on my website you will see a force/displacement diagram for two coupler types. One is a drawhook/buffer type of coupler so perhaps the figures suggested on this diagram can be used to construct a coupler as you suggest.

I would be interested in looking at this type of coupler if you are interested. If so please contact me.


Thanks

[darwins]

I have been able to get dimensions from RCH drawings.
The amount of slack with totally free movement in either direction (where no force is passed on to the next wagon) is 4.125 inches (105 mm).
With the chain extended and tension force being passed on to the next wagon the distance between headstocks is 40.125 inches.
With buffers touching and compression force being passed on to the next wagon the distance between headstocks is 36 inches.
I am going to estimate from the drawings that buffers will compress up to about 6 inches maximum (150 mm)
The draw hook and buffer diagram you have on your website seems to be for a screw coupling with buffers (UIC standard).
It seems reasonable to assume that the forces and distances for a three link coupling with buffers will be the same as for the screw coupling, but with the extra 105 mm of free movement on the tension side.
** That adds up to about 26 feet (8m) of slack in an 80 wagon mineral train (or about 2% of train length) **

https://i.imgur.com/Zb6eCJa.jpg