sroll a rope

[coolface man]

Hello everyone, I am a new inventor user.
Could someone explain to me how to get a rope (or a crotch) that can roll up and unroll like in this video?
Thank you very much
http://www.youtube.com/watch?v=sg7x8j6wz6a

 

[laura888]

animates the parameters in inventor study.
But I think I've already seen a request like this a few years ago...

 

[laura888]

the parameter would be the num revolutions of the rope