| 摘要 |
There are disclosed two embodiments of a trench shoring device of the type having rails which are forced against the sides of the trench by one or more fluid actuated, extendible and retractible braces connected to and extending between the rails. In one embodiment, the rails extend vertically within the trench, and the opposite ends of the braces are so connected to the vertical rails that they may be swung folded positions during lowering into and raising from the trench. In another embodiment of the invention, the rails extend horizontally of the trench, and the ends of the braces are connected thereto in such a manner as to prevent substantial movement of the braces out of perpendicular positions with respect to the rails. In each embodiment, the rails are of "I"-beam shape including a relatively wide outer flange and a relatively narrow inner flange connecting the web, and the connections of the ends of the braces to the rails are of such construction as to transfer the load of the brace to the inner flange of each rail, and thus through the web of the rail to the outer flange, as well as directly to the outer flange.
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