Screw driver for gripping screw head - has blade with axial oval section rod rotated to wedge blade in screw head slot

摘要

The screwdriver grips the screw head, and is used to locate small screws in inaccessible positions. It has a rotatable cam-shape chamber-ended blade which wedges in the screw slot. The longitudinal axis of the blade is traversed by an aperture, of uniform cross-section, and houses a rotatable rod (4). The rod (4) is of oval cross-section and terminates flush with the blade head (2). The lesser dimension of the rod (4) cross-section is equal to screw head slot width. The rod (4) is housed within the blade head. After the blade is inserted in the screw head slot, the rod (4) is rotated until it wedges in the slot.