Device to position a device in a cylindrical cavity comprising perforation disposed along a regular network

Device to selectively position a member in a cylindrical cavity, said cylindrical cavity being defined within an inner cylindrical wall, and having a given longitudinal axis and providing an access opening at one of its extremities, said inner cylindrical wall providing perforations disposed along a network which radially open into said cavity, said perforations being generally directed towards said longitudinal axis of said cavity, this device including a seating provided to be secured to said opening and supporting a pole by means of positioning means, said positioning means enabling the pole to be moved in rotation and in translation between various pre-established indexing positions, the pole being orientated parallel to the axis of the cavity and supporting inside the latter a support block and an active head connected to the support block by means of an extensible cladding arm provided with extension means which, when implemented, have the effect of simultaneously cladding the support block and the active head against the inner cylindrical wall of the cavity, the active head being equipped with retractable fingers adapted to be introduced into the perforations, means for controlling a movement of the active head in a given working zone of said wall, this zone being different for each of the pole indexing positions, and at least one support suitable for receiving said member to be positioned.