How to stop curve deforming?

i have made a chain of my snowmobile and when i move up my snowmobile chain deforming.How to stop ? i used nurbs curve.

why is noone replying to this, I have same question

Perhaps the user name is an issue.
Mostly the origin is messed up or the parenting is wrong.
Post your .blend file in an new topic so we can look at the problem.