  In this paper, we derive a "hamiltonian formalism" for a wide class of
mechanical systems, including classical hamiltonian systems, nonholonomic
systems, some classes of servomechanism... This construction strongly relies in
the geometry characterizing the different systems. In particular, we obtain
that the class of the so-called algebroids covers a great variety of mechanical
systems. Finally, as the main result, a hamiltonian symplectic realization of
systems defined on algebroids is obtained.
