CLUTCH MECHANISM COUPLABLE TO DOOR LOCKS WITH LOCKING BOLT OPERATED BY HANDLES OR KNOBS, with which a pulling movement manages to be transferred or not to the bolt for the lock and of the type of those that are mounted in a casing superimposed on the door and whose square-section shaft operated by the handles is formed from two aligned elements able to become locked in rotation, comprising: a protector cover integral with an interior body which houses the mechanisms for the actuation of the lock; a first clutch element and a second clutch element respectively connected to the outside and inside handles of the lock, the second clutch element acting on the locking bolt of the lock, the first clutch element offering a square-section spike connected to the outside handle and a head or disc fitted with an eccentric and axial tab which turns on the spike part and on which there rests one end of the spring for recovery of the handles (5, 6), the other end being fixed to a projection of the interior body, said head or disc having diametrically opposite to the tab a prismatic extension with an orifice, and the second clutch element having a slot; a pulling pin dimensioned to fit through said orifice of said prismatic extension of the first clutch element and through said slot of the second clutch element, the pulling pin being radial to that head or disc and pushed radially outwards by a spring; in such a way that the pulling pin is at all times in contact with an arched guide of the interior body when it is outside of the slot; and a thruster rocker arm oscillating at a point of the interior body and assisted by a spring which pushes it against the pulling pin when a worm-screw turns by means of a drive unit such a motor; in such a manner that the engagement of the clutch is caused by said pulling pin being introduced into said slot of the second clutch element once the thruster rocker arm is actuated by the worm-screw. a protector cover integral with an interior body which houses the mechanisms for the actuation of the lock; a first clutch element and a second clutch element respectively connected to the outside and inside handles of the lock, the second clutch element acting on the locking bolt of the lock, the first clutch element offering a square-section spike connected to the outside handle and a head or disc fitted with an eccentric and axial tab which turns on the spike part and on which there rests one end of the spring for recovery of the handles (5, 6), the other end being fixed to a projection of the interior body, said head or disc having diametrically opposite to the tab a prismatic extension with an orifice, and the second clutch element having a slot; a pulling pin dimensioned to fit through said orifice of said prismatic extension of the first clutch element and through said slot of the second clutch element, the pulling pin being radial to that head or disc and pushed radially outwards by a spring; in such a way that the pulling pin is at all times in contact with an arched guide of the interior body when it is outside of the slot; and a thruster rocker arm oscillating at a point of the interior body and assisted by a spring which pushes it against the pulling pin when a worm-screw turns by means of a drive unit such a motor; in such a manner that the engagement of the clutch is caused by said pulling pin being introduced into said slot of the second clutch element once the thruster rocker arm is actuated by the worm-screw.