Screw, screwdriver and screw-holding attachment therefor

A screw-holding screwdriver, comprising:

• (a) an elongated driver shank having a longitudinal axis, a handle end region, and an opposite blade end region,
• (b) a driver blade of one-piece with the blade end region of the shank;
• (c) means for holding a screw to be turned by the driver blade, said holding means including
• (1) a pair of movable elongated resilient arms at opposite sides of the driver shank, said arms being separated by two slots which extend lengthwise along the arms, each arm including
• (A) a screw-gripping end portion having a plurality of curved fingers which extend in smooth, continuous arcuate manner, both longitudinally away from the handle end region and radially inwardly towards the longitudinal axis to thereby form a generally semi-dome-shaped configuration, said fingers of both arms terminating at tips which define a circular periphery which surrounds the stem of the screw to be turned, said fingers of both arms engaging substantially the entire underside of the head of the screw to be turned to thereby hold the screw in a positive locking manner, said fingers of both arms being successively separated by radially-extending slits all of which have generally the same cross-sectional area along their lengths,
• (B) a semi-cylindrical body portion adjacent to each screw-gripping end portion, both of the semi-cylindrical portions extending circumferentially about the shank for partially enclosing the latter, each slot extending lengthwise along the semi-cylindrical body portions and having generally the same cross-sectional area along the lengths of the latter,
• (C) a generally flattened body portion adjacent to each semi-cylindrical body portion, both flattened body portions being located at opposite sides of the shank and having arcuate side edge regions which extend radially inwardly towards the longitudinal axis such that each slot has an enlarged cross-sectional area in the region of the flattened body portions, and
• (D) a semi-cylindrical collar end portion adjacent to each flattened body portion for partially enclosing the shank, and
• (2) means for moving the resilient arms between a non-gripping position in which the arms are spaced apart of each other, and a gripping position in which the screw-gripping end portions form a dome-shaped configuration and substantially enclose the screw head of the screw to be turned,
• said moving means constituting a cylindrical locking sleeve slidably mounted over the resilient arms for movement lengthwise of the latter, said locking sleeve having an interior passage formed with a leading axial end, a trailing axial end and an annular cam-type projection intermediate said axial ends of the passage, said projection being an annular ridge which extends radially inwardly from the inner circumferential wall of the passage, said ridge being in sliding frictional engagement with the body and end portions of the arms;
• and
• (d) means for finely and continuously adjusting the position of the holding means in longitudinal direction relative to the shank, said fine-adjusting means including
• (1) a mounting collar surrounding the arms and being fixedly connected to the collar end region of the arms for longitudinal movement with the same, said collar having a longitudinally-extending internally threaded collar portion adjacent to the handle end region, and a polygonally-shaped flange portion to facilitate manual gripping, and
• (2) a longitudinally-extending mating externally threaded shank portion of one-piece with the shank in the near vicinity of the handle end region for turning movement with the shank, said mating shank portion being in constant threaded engagement with the threaded collar portion during the entire turning movement of the driver shank for shifting the shank relative to the holding means with infinitely variable displacement.