Turbo Bill's couplers--question/concern

[Busdriver]

Bill/all,

Thanks for the efforts you have been putting into coupler physics. I have been playing with your PRO couplers for cushion cars. I like the effect, but they seem really "loose". I have chased a lot of real trains over Tehachapi, and I always get along side on the highway near the loco and/or the first/second car and watch as the engineer changes from power to dynamic over the summit. When he drops the power, the couplers bunch a little to get to equilibrium since everything is just rolling. Then, when I hear the dynamics kick in, you "slowly" see the couplers bunch more. In the sim, with such a low setting for your first stiffness number, they seem really sudden and quick to bunch with no resistance to the forces at all. Since you apparently do this for real, I wanted to get your opinion because you get to feel it in the seat. But, in the cab, I wonder if you have ever seen what the couplers do at 60mph a few cars back?

I have been running a test train with cars adjusted with many different settings and then running the slack in and out at speed. Here have been my results which look very much like what I physically see when "chasing" the real deal:

Stiffness ( 2e6N/m 2e6N/m )
Damping ( 1.3e6N/m/s 3.8e6N/m/s )

r0 ( 5cm 20cm )

Velocity ( 0.1m/s )

My damping line is also different from yours. I believe most of my numbers or derivitives from Dr Joe when this topic came up a long time ago before BIN.

I have also found that these settings give good showing of slack action when starting from a stop so you still have to be careful to not knock your freight around in the cars :-)

Please comment or let me know if I'm missing something in my analysis.

Bryce

[westerngy]

>Bill/all,
>
>Thanks for the efforts you have been putting into coupler
>physics. I have been playing with your PRO couplers for
>cushion cars. I like the effect, but they seem really
>"loose". I have chased a lot of real trains over Tehachapi,
>and I always get along side on the highway near the loco
>and/or the first/second car and watch as the engineer changes
>from power to dynamic over the summit. When he drops the
>power, the couplers bunch a little to get to equilibrium since
>everything is just rolling. Then, when I hear the dynamics
>kick in, you "slowly" see the couplers bunch more. In the
>sim, with such a low setting for your first stiffness number,
>they seem really sudden and quick to bunch with no resistance
>to the forces at all. Since you apparently do this for real,
>I wanted to get your opinion because you get to feel it in the
>seat. But, in the cab, I wonder if you have ever seen what
>the couplers do at 60mph a few cars back?

Bryce in real life you do feel the slack run in or when it stretches out on you.The slap can if your not ready for it knock you off your feet if standing ..of course it depends on the hogger by how much.Give you an idea in a 106 car grain train with the cars being 60ft hoppers you get around 65-70ft of slack.The in train forces when running you'll have knuckles either bunched or stretched even when running on level track but there is a time when everything goes neutral if you know what I mean.


>
>I have been running a test train with cars adjusted with many
>different settings and then running the slack in and out at
>speed. Here have been my results which look very much like
>what I physically see when "chasing" the real deal:
>
> Stiffness ( 2e6N/m 2e6N/m )
> Damping ( 1.3e6N/m/s 3.8e6N/m/s )
>
> r0 ( 5cm 20cm )
>
> Velocity ( 0.1m/s )
>
>My damping line is also different from yours. I believe most
>of my numbers or derivitives from Dr Joe when this topic came
>up a long time ago before BIN.
>
>I have also found that these settings give good showing of
>slack action when starting from a stop so you still have to be
>careful to not knock your freight around in the cars :-)
>
>Please comment or let me know if I'm missing something in my
>analysis.
>
>Bryce
>
>
>
>
>


Just Rollin Down The Tracks

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http://www.RFCHosting.com/

[Turbo Bill]

Gentle hand on that dynamic brake. It's hard in the sim and if you've never run the real deal that slack can make your ride miserable. Just ask any poor Conductor who had to ride a crummy on the end of a long mixed freight with a new hogger at the controls. Men have been carried of cabooses on stretchers. I was lucky and did my training seat time with a caboose on the rear of my train. You learn quick or you don't have many friends on your train. Just practice. The slack is very close and the cushioning is actually a little on the strong side as the loads don't all bunch up like their RW brethren. Also you need that velocity set to 0.2 or the rear couplers will not let go of the train doing the same thing as the old front couplers.

I have done a ton more testing andhave been extensively boning up on old posts, actually any posts and threads dealing with the coupler regions and bounding boxes, buffers, the whole deal. I have tested the major theories and have found that one that Joe Morris and one other gentleman brought up the notion of using one couplinghasrigidconnection on one coupler region and commented out on the other. Big difference and it works like a charm. The couplers work better and the big spring effects and problems are gone. Cars trail thru switches without jumping tracks. I will be releasing a new updated coupler pack in the next few days so stay tuned. It's been a developing process but the results are very good so far.

[Busdriver]

Thanks for the info, Dale and Bill. I'll be looking forward to your update.

Bryce