Self-gradually locking chuck

A gradual self-locking chuck comprising:

• a sleeve adapted to be fixed to a rotating shaft;
• a ferrule having a frusto-conical portion, a small diameter cylindrical portion and a large diameter cylindrical portion at each end of the frusto-conical portion respectively, the end of the sleeve opposite the rotating shaft being received within the larger diameter cylindrical portion of the ferrule;
• a mounting having a longitudinal axis and located at least partially within the ferrule and having a longitudinal passage running therethrough, the mounting having at least two holes therein, locking jaws located between the mounting and the ferrule at the holes, the locking jaws movable between a first unlocked condition in a radially outer position relative to the longitudinal axis of the mounting, and a second locked condition in a radially inner position relative to the longitudinal axis of the mounting, the locking jaws being adapted to engage a tool located in the longitudinal passage when in the locked position, the mounting having a central portion, an anterior portion which projects through the smaller diameter cylindrical portion of the ferrule, and a posterior portion located at least partially within the larger diameter cylindrical portion of the ferrule, the holes through which the jaws move being located in the central portion of the mounting;
• means for permitting relative movement between the mounting and the ferrule, such relative movement moving the locking jaws between the radially outer and radially inner positions;
• and
• an annular ring located coaxially with and adjacent the smaller diameter cylindrical portion of the ferrule, and means for securing the annular ring to the anterior portion of the mounting projecting beyond the smaller diameter cylindrical portion of the ferrule, and retaining means between the annular ring and the ferrule for releasably securing the annular ring and the ferrule to each other, the annular ring when firmly secured to the small diameter portion of the ferrule engages the tool in the second locked condition preventing accidental release of the tool by the chuck.