Mechanism of the arm type articulated and sonar antenna equipped with such a mechanism

The invention relates to a mechanism having an articulated arm 2 of a connecting rod 1, from a translational movement in two opposite directions XX, choose between positions decreased arm and arm extended which are substantially mutually orthogonal. the invention has been to take against the foot of the vector solution at an obtuse angle, and not acute, between the connecting rod and the arm in position and arm down by inverting the axes roles rotation other than the common axis B to the connecting rod and the arm: the A of the connecting rod becomes fixed and the C arm is subjected to translational movement. The free end of arm position arriving by decreased arm follows a path with sliding downward and passing through a "hard point" which ensures a good position retention arm lowered. Application in particular the sonar antenna.