# Elevation crane rope and cargo movement

I’m very new to UE and I need to make app, where user moves cargoes with an elevating crane. I don’t know, how to describe rope and cargo movement, when it’s lifted with the rotating crane arm. It’s obvious, that when the crane is rotating slowly with a very heavy cargo, the rope with the cargo will be near perpendicular to the horizon. And if the rotation speed is faster and the cargo’s lighter, then the angle between the rope with the cargo and the horizon will deviate more from 90 degrees. How can I describe this with the blueprints? Poorly drawn scheme related.

I think you can solve your Problem with Physics Constrains play around with them a bit. The settings are a little strange to get right but you get the hang of it when you play around a bit. Dont forget your Physics Objects themself have Mass etc. you can Adjust. In the Content Examples theres a Map that gives you some Examples you can study.

The constraint mechanics seems to be suitable for describing cargo movement, but how to make the rope now? It’s mesh have to repeat motion of the constraint’s “invisible rope” (which you can see in editor, when the constraint object is selected). How can I attach skeletal mesh actor to it?

https://docs.unrealengine.com/latest/images/Engine/Physics/Constraints/ConstraintsBlueprints/PhysConBP_Sim.jpg

hey masas glad you found my Answer suitable for your Problem. I can think of 2 ways approaching the Rope.

The first one is the Cable Component that is good for a Rope or solid continues Mesh.

The second one is to use Multiple Constrains chained together that is useful for not Continously Conected Meshes like Chains for Example.

I tried to google a Example for you and found this Video that basicly shows you exactly what I mean Unreal Engine 4 - cable and physics constraints - YouTube

Note its also Possible to use Splines but I think you would have more trouble to Manage them than its worth. Stick with one of the two methods above I would recommand you.

Have Fun with Physics =)

Thanks, the cables work fine and their physics system is completely suitable for everything I want to do. But now I have another problem. Since cargo movement is restricted with Physics Constraint and Cable is just a decoration, how can I change the Constraint length? I mean the situation, when crane’s hook is going up or down.

I’ve solved this myself, using Linear ZLimit property in Physics Constraint.

Hi, same problem here. I’ve solutioned by set reference position but it isn’t quite smooth. Can you tell me how you did it in order to get up and down the cargo?

Thanks!