| 摘要 |
A rotary wrenching tool includes a handle and a head having an opening defined therein for receiving a polygonal head of a fastener. An inner periphery defining the opening includes a plurality of annularly spaced grooves defined therein, wherein each two adjacent grooves are connected by a connecting section. Each connecting section includes a first operative section having an end connected to one of the two adjacent grooves and forming a side of the one of the two adjacent grooves, a second operative section having an end connected to the other of the two adjacent grooves and forming a side of the other of the two adjacent grooves, and an inoperative section interconnected between the first operative section and the second operative section. The first operative sections or the second operative sections engage with the fastener to be wrenched, and each inoperative section does not engage with the fastener to be wrenched. The inoperative section may be rectilinear or convex, i.e., curved outward towards the outer periphery of the wrench head. Each inoperative section includes two ends each of which terminates at a critical point adapted to engage with a face of the fastener in which the rotary wrenching tool has been rotated through a free rotational angle.
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