Nose of a tool for motorized pulling of an expanded element head, comprising: - a catching system which is movable in an axial direction (X-X'), in front of which an axial passage is provided for the element head and which is elastically returned from a retracted catching configuration for the element head to a loading configuration in which the axial passage is transversely expanded relative to the retracted configuration, - a sliding sheath comprising an internal constriction for switching the catching system into its retracted configuration through an axial stroke of said sheath, - a device for coupling the sheath to an actuator (7, 22, 25) for deriving in the axial direction (X-X'), - a device (9, 28, 29) for detecting an engagement of the element head by a predetermined amount within the catching system, and for controlling a drive of the sheath along its axial stroke, characterized in that - the sheath has a rearward axial stroke relative to the catching system so as to retract the catching system, upon detection of the engagement of the element head by the predetermined amount within the catching system by the device (9, 28, 29) for detecting and controlling the drive of the sheath, - the detecting device (9, 28, 29) comprises an axial pusher sliding axially relative to the catching system and which is forwardly returned toward a waiting position in which one front end of said pusher forms a push-button protruding inside the catching system toward the axial passage, the pusher being part of an axially movable slide (26, 27, 30) which comprises the sheath and which is forwardly returned relative to a fixed frame of the nose, - in its waiting position, the pusher protrudes by a lower amount, in the axial direction, than the axial stroke of the sheath so that the detecting and controlling device (9, 28, 29) can detect a engagement of an element head inside the catching system before an inertia of said drive brings the sheath to the rear limit of travel relative to the catching system. - a catching system which is movable in an axial direction (X-X'), in front of which an axial passage is provided for the element head and which is elastically returned from a retracted catching configuration for the element head to a loading configuration in which the axial passage is transversely expanded relative to the retracted configuration, - a sliding sheath comprising an internal constriction for switching the catching system into its retracted configuration through an axial stroke of said sheath, - a device for coupling the sheath to an actuator (7, 22, 25) for deriving in the axial direction (X-X'), - a device (9, 28, 29) for detecting an engagement of the element head by a predetermined amount within the catching system, and for controlling a drive of the sheath along its axial stroke, characterized in that - the sheath has a rearward axial stroke relative to the catching system so as to retract the catching system, upon detection of the engagement of the element head by the predetermined amount within the catching system by the device (9, 28, 29) for detecting and controlling the drive of the sheath, - the detecting device (9, 28, 29) comprises an axial pusher sliding axially relative to the catching system and which is forwardly returned toward a waiting position in which one front end of said pusher forms a push-button protruding inside the catching system toward the axial passage, the pusher being part of an axially movable slide (26, 27, 30) which comprises the sheath and which is forwardly returned relative to a fixed frame of the nose, - in its waiting position, the pusher protrudes by a lower amount, in the axial direction, than the axial stroke of the sheath so that the detecting and controlling device (9, 28, 29) can detect a engagement of an element head inside the catching system before an inertia of said drive brings the sheath to the rear limit of travel relative to the catching system.