| 摘要 |
PURPOSE: A screw driver is provided to use conveniently in the narrow space by horizontally inserting the tip of the screw driver into the groove of the head part of the bolt or the screw and contracting the variable length unit of the tip supporting bar. CONSTITUTION: A screw driver(10) is composed of a tip(11) inserted to a groove(23) formed in a head part(21) of a bolt or screw(20), a tip supporting bar(15) connected to the end of the tip, a grip part(17) installed in the end of the tip supporting bar, and a variable length unit(13) mounted in the middle of the tip supporting bar. The variable length unit is formed of a coil spring. The length of the screw driver is decreased by contracting the variable length unit mounted in the tip supporting bar for using the screw driver in the narrow space, and the tip of the screw driver is leveled with the groove of the head part of the screw. The tip of the screw driver is inserted to the groove of the head part of the screw, and the screw is tightened or loosened by turning the grip part.
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