| 摘要 |
A screwdriver tool provides positive engagement with screw having a head with a straight slot. An end portion is substantially flat, but is wider at its midpoint than at its ends. A tapering segment extends from the end portion and an engagement area is defined on the side of the segment. Engagement initially occurs at a location intermediate to the ends and midpoint of the end portion. As torque on the screwdriver is increased the engagement extends toward the midpoint and up the side of the segment.
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