Abstract: An improved quick action keyless drill chuck having a single one-piece outer body which encloses all the other components within its interior, a thrust screw in the form of a hollow cylindrical body divided by a division wall into two cavities, a central body with a central longitudinal bore in two sections screwcut such that the rear section accepts the correspondingly threaded spindle of the drilling machine and the front section, of which the diameter is greater than that of the rear section, accepts the screwthread of the thrust screw, this same central body being provided also with two salient cylinder forms on its outer face which fit precisely into the interior of the single outer body; the drill chuck also having the optional complementary device for operation in percussion with a hammer drill consisting of a helicoidal spring which exerts a continuous pressure on the thrust screw, the force being applied against the division wall.