| 摘要 |
A body is provided defining a center axis and having at least four adjacent sides equally spaced from and about the center axis and disposed normal to adjacent 60 DEG relatively angularly displaced radii of the center axis. Each of the sides includes opposite ends and at least the center two sides of the four adjacent sides are interrupted centrally intermediate their opposite ends by a pair of spaced torque transfer surfaces spaced apart generally one-third the length of the corresponding side and equally from the opposite ends thereof. The surfaces are disposed on radii of the center axis. In a first form of the invention only four of the adjacent sides are provided and the end two or remote sides of the four adjacent sides are free of the aforementioned transverse surfaces and the sides face inwardly toward the center axis of the body. In second and third forms of the invention, the sides equal six in number and comprise outwardly and inwardly facing sides, respectively, and each of the sides includes the side interrupting surfaces with the surfaces extending from the sides inwardly toward the center axis. Each pair of surface inner ends are interconnected by an edge extending therebetween disposed generally normal to a radius of the center axis bisecting the edge.
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