Rotary actuator device having an annular piston rod

A rotary actuator device having an annular piston rod, the device comprising at least one piston head provided with sealing means and co-operating with an annular piston rod mounted so as to be capable of moving in an annular chamber, together with means for selectively applying a fluid under pressure in said annular chamber, wherein the piston head cooperates with the piston rod via a hinge having one degree of freedom in rotation and one degree of freedom in translation, said hinge comprising a piece in the form of a knife whose edge co-operates with a V-groove in a female portion of triangular profile, the knife edge and the V-groove being parallel to the axis of rotation of the piston rod;

• said rotary actuator device comprising fastening means disposed between the piston head and the piston rod to prevent the piston head coming apart from the piston rod on which it is hinged while nevertheless allowing a certain amount of motion, thereby contributing to the degrees of freedom in translation and in rotation, wherein said fastening means comprises a pin passing through the knife and the female portion of triangular profile perpendicularly to said edge.

A rotary actuator device having an annular piston rod, the device comprising at least one piston head provided with sealing means and co-operating with an annular piston rod mounted so as to be capable of moving in an annular chamber, together with means for selectively applying fluid under pressure in said annular chamber, wherein the piston head cooperates with the piston rod via a hinge having one degree of freedom in rotation and one degree of freedom in translation, said hinge comprising a piece in the form of a knife whose edge co-operates with a V-groove in a female portion of triangular profile, the knife edge and the V-groove being parallel to the axis of rotation of the piston rod;

• said rotary actuator device comprising fastening means disposed between the piston head and the piston rod to prevent the piston head coming apart from the piston rod on which it is hinged while nevertheless allowing a certain amount of motion, thereby contributing to the degrees of freedom in translation and in rotation, wherein said fastening means comprises at least one clip extending essentially perpendicularly to said knife edge, said clip being engaged in grooves formed in the knife and having curved ends themselves engaged in notches formed in the support of the female portion of the triangular profile.