Abstract A safety trenching box is provided having a pair of earthretaining wall members which are tapered at one end thereof to form a pair of vertical cutting edges. The vertical cutting edges permit the box to be dragged through trench excavations having little or no clearance between the sides of the box and the sides of the trench, since the edges shear off projecting portions of the trench walls. The bottom edge of each wall member is also tapered to form a pair of horizontal cutting edges on the box and push plates are provided on the top edge of each wall member to permit the trenching box to be driven downwardly into the trench by externally applied forces. The outer surface of each of the wall members in contact with the sides of the trench is cambered to provide the box with increased structural strength under laterally applied load conditions. Horizontally disposed beams employed in the construction of each wall member are provided with inclined cover plate to form skid paths for earth and stone accidentally dropped into the trenching box, thereby preventing any dangerous accumulation of such materials on such beams and adding to the structural strength of the box. If desired, legs may be mounted on the bottom tapered edges of the wall members to facilitate the stacking of a number of such boxes for use in deep trench excavations or for storage purposes.
A safety trenching box adapted to be disposed in an excavated trench or the like to prevent the sides of the trench from collapsing comprising a pair of earth-retaining wall members, each of said wall members having a rigid frame formed by horizontally diSposed top and bottom beam members and a plurality of vertical column members interconnecting said beam members, a sheet member mounted on and covering said frame to provide a smooth outer surface for the wall member in contact with the side of the trench, said sheet member having one edge thereof extending beyond the edge of said frame at one end of the wall member and the bottom edge thereof extending below the bottom beam member along the entire length of the wall member, first cover plate means connected between said one extended edge of the sheet member and the inner surface of the column member adjacent thereto to form a vertically extending cutting edge at said one end of the wall member, second cover plate means connected between said bottom extended edge of the sheet member and the inner surface of the bottom beam member to form a horizontally disposed cutting edge along the bottom of the wall member, and third cover plate means disposed between each of said column members, said third cover plate means connecting the inner surface of the sheet member and the upper surface of the bottom beam member along the length thereof to provide an inclined skid path on each wall member for earth and stone falling into the box; and a pair of spreader members removably connected between the column members at the ends of the frames of said wall members for separating and laterally supporting said wall members against the lateral force exerted by the sides of the trench.
Claim 2
Dependent Claim
300 words
A safety trenching box adapted to be disposed in an excavated trench or the like to prevent the sides of the trench from collapsing comprising a pair of earth-retaining wall members, each of said wall members having a rigid frame formed by horizontally diSposed top and bottom beam members and a plurality of vertical column members interconnecting said beam members, a sheet member mounted on and covering said frame to provide a smooth outer surface for the wall member in contact with the side of the trench, said sheet member having one edge thereof extending beyond the edge of said frame at one end of the wall member and the bottom edge thereof extending below the bottom beam member along the entire length of the wall member, first cover plate means connected between said one extended edge of the sheet member and the inner surface of the column member adjacent thereto to form a vertically extending cutting edge at said one end of the wall member, second cover plate means connected between said bottom extended edge of the sheet member and the inner surface of the bottom beam member to form a horizontally disposed cutting edge along the bottom of the wall member, and third cover plate means disposed between each of said column members, said third cover plate means connecting the inner surface of the sheet member and the upper surface of the bottom beam member along the length thereof to provide an inclined skid path on each wall member for earth and stone falling into the box; and a pair of spreader members removably connected between the column members at the ends of the frames of said wall members for separating and laterally supporting said wall members against the lateral force exerted by the sides of the trench.
Claim 3
Dependent Claim
111 words
A safety trenching box as claimed in claim 1, wherein push plates are mounted on the top beam member of each of said wall members in vertical alignment with the column members thereof, and at least two legs are mounted on the second cover plate means of each wall member in vertical alignment with said push plates, so that said push plates are adapted to function as load-bearing surfaces for the application of vertically applied forces to permit the box to be driven downwardly into the trench and also function as load bearing surfaces for the legs of another box when two or more boxes are employed in a stacked arrangement.