| 摘要 |
A nut member of special design is disclosed in conjunction with other elements to provide a post-tensionable mine roof support assembly. The nut member includes an upper, stem portion extending through the opening in a support plate and a lower, base portion of larger diameter than the plate opening. A through opening in the nut includes an internally threaded portion at the upper end of the stem and an internal socket for wrench engagement at the lower end of the base. Between the threaded portion and socket is an internal bore having a diameter greater than the threaded portion. Breakable means, preferably annular in form and cast integrally with the rest of the nut member, extends into the bore to a position with the cylindrical plane extending downwardly from the threaded portion. Thus, a threaded end of an elongated rod may be engaged with the threaded portion of the nut, extending into abutting engagement with the breakable means, and the other end of the rod advanced into a mine roof drill hole behind a standard resin cartridge. The cartridge is broken and the contents mixed by rotating the nut member, and thereby the rod, by a wrench engaged with the socket. By stopping rotation for a few seconds and allowing the resin to harden sufficiently to prevent further rotation of the rod, excess torque applied to the nut member will cause the threaded rod end to break through the breakable means, permitting the nut to be tightened against the support plate and the rod tensioned with the end of the rod extending into the bore area between the breakable means and the socket.
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