| 摘要 |
A pushing tool adapted to grip a joist and exert pushing force on a board located immediately above the joist. The tool comprises a block having a threaded bore, a screw which threads into the bore, and a clamp fixed to the block. Four arms forming dual parallelogram linkages are pivotally mounted to the block and to the jaws of the clamp such that when the block is drawn along the screw by screw action, the arms fold in the direction of parallel orientation relative to the screw. This draws the jaws of the clamp towards one another such that they engage and grip the joist. The jaws of the clamp have cleats preventing the jaws from slipping ineffectually along the joist. Continued rotation of the screw advances the screw against the board located above the joist. Pitch of the threading of the bore and the screw enable great pressure to be exerted on the board when the screw is turned by a wrench.
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