Twist-lock connection and tool utilizing same

Claim 1

Means for attaching a drill bit or the like to a power tool, said means comprising a first member having a longitudinal bore extending at least partially therethrough; protrusion means extending laterally into said bore at a first location, resilient spring means projecting into said bore at a second location spaced from the first location; a second member having a longitudinally extending shank which is received in the bore of said first member; said shank having a first groove extending longitudinally from a first end thereof and forming two generally radially extending walls disposed generally perpendicular to one another; a second groove extending laterally of, and intersecting one of said walls of said first groove at a point spaced from the first shank end; whereby the second groove creating a wall which is arcuate in configuration and having a portion inner most from the periphery of the shank generally located in the plane of the other of said two first groove walls, said first shank end may be inserted axially into said bore such that said protrusion means is received in said first groove, said second member rotated with respect to said first member to bring said protrusion means into engagement with said second groove to thereby prevent axial displacement between the first and second members and creating torque transmission mating bearing surfaces between the innermost wall portion of the second groove and the protrusion means, said resilient spring means frictionally engaging a portion of the surface of the shank to prevent undesired counter-rotation of the second member relative to said first member.