Abstract: In a reversible power tool, such as an electric drill, a clutch mechanism is coupled to selectively connect and disconnect a chuck jaw reciprocating means to advance and retract the jaws of a chuck or to allow the chuck jaw reciprocating means to be carried in rotation with the chuck jaws. According to the improvement the clutch mechanism is decoupled as the chuck jaws approach a position of complete retraction, despite actuation of a coupling mechanism which would otherwise prevent the chuck jaw reciprocating means and the chuck jaws from turning together in rotation. The decoupling mechanism prevents damage to the chuck which occurs in prior devices when the chuck jaws are driven longitudinally beyond the designed limit for complete chuck jaw retraction. Also, an annular workpiece holder is releasably secured to the chuck to hold a workpiece in axial alignment with the tool drive shaft to safeguard against accidental injury to the fingers of an individual operating the tool.

Abstract: A reversible drill, equipped with a chuck having a jaw guide, chuck jaws constrained by the jaw guide for radial advancement and retraction, and chuck jaw propulsion means for driving the chuck jaws in advancement and retraction, is equipped with a manually actuable clutch for easing the chuck jaw propulsion means into and out of engagement with the drill housing to, respectively, prevent and allow relative rotation between the jaw guide and the chuck jaw propulsion means. When the drill motor is driven in one direction of rotation, the chuck jaw propulsion means is immobilized relative to the drill housing and the chuck jaws are advanced radially toward each other to grip a drill bit. When the housing and chuck jaw propulsion means are eased together and the drill motor is driven in the opposite direction, the chuck jaw propulsion means is immobilized and draws the chuck jaws apart as the jaw guide rotates to release a drill bit.