is possible to simulate mechanisms in code-aster?

I wholly agree with RichardS, that you should find dedicated software for such a simulation, but there aren't many good or at least easy to use multi-body dynamics for Linux (that I know about)
Code_Aster isn't one either, but depending on what you want to simulate, it is principally possible.

That said, by substituting much of the 3D geometry with discrete elements you could probably create a reasonable simulation. If you are a beginner with Code_Aster, forget about it for now, and learn how to do each step individually first.
You cannot plug this model into Salome/Code_Aster, assign boundary conditions and hit 'simulate'. It would be a difficult (but not impossible) project to simulate this.

/C