Motion and Buffering Mechanism for Magentic rings

[COLOR=#333333]I am trying to create the motion mechanism and the beffuring mechanism for the magnetic rings. Any advice and help will be appreciated. Like what kind of buffer can be used and in which position it will be best effective. The 3D model is only a rough model the structure is just ideal, any new ideas will be a help. Please comment on the structure on how it may be improved.

[/COLOR][IMG]http://www.engineersedge.com/engineering-forum/attachment.php?attachmentid=1844&stc=1[/IMG][COLOR=#333333]

[/COLOR]