Coupling problem- uncontrolled acceleration

[sswgp60]

Hello everyone,

I'm testing a railcar that I've recently created and I've noticed that upon coupling engines to a lose consist made up of my railcars that the train will then uncontrollably accelerate to 10-20mph. Atthaced are screenshots of the wagon blueprint.

Any ideas on what the problem could be?



Thank you,

Aaron

[GreatNortherner]

Hi,

Two values in your coupling BP look quite big to me, try Spring Coeff. 15000, Damping 12000.

Important is also the relation of CollisionLength, Front/BackPivot and Front/BackCouplingPivot to each other. They all largely depend on where the center/pivot points are in your two coupler geometry files. For the Kuju coupler, the coupled/uncoupled shape have their pivots 0.75m offset from each other, which ideally is then also the difference between the two pivots in the rail car blueprint on both ends of the car.

One other thing to check is the CargoComponent. Don't set the mass too high there -- keep it below 40t to be safe, there may be a physics bug in there somewhere that causes weird car coupling behaviour when using heavy car loads in the cargo component. This is just speculative, but based on some testing we did on the RWA route equipment. (A setting around or below 40t here also helps prevent the 'leaning cars' issue on loaded unit trains).

[sswgp60]

GreatNortherner,

Thank you for your reply and your assistance. I was very careful with inputting the collision box values in addition to the coupling bp and mass but still no joy. I'm using custom couplers so I'm thinking the problem might have to do with that. But I'm still not sure as I've tried multiple values to no avail..

[buzz456]

If you don't mind me butting in here what custom couplers are you using?

[JerryC]

This is an issue that recently ran into. Mine had to do with a coupler matrix position value that was -1 instead of 1. The issue affected only one end of the car, but when compounded by 30 cars it caused quite a springload affect.

Also, i've found that it's a good idea to actually model your collsion box so you can get exact values to input into the BP. The bottom of the collision box should be on the top of the rail head, not on the ground, as this will cause jumping and flipping and all other sorts of weird gymnastic stunts that a freight car should not be capable of.

[sswgp60]

Thanks for the help. I think I figured it out thanks to everyones input.

The custom couplers were some new E-Type couplers. My intentions are to add more details to the couplers.
Regards,