Abstract: A trench box wherein there are spaced, parallel side wall panels between which there are spacer panels and wherein the upper longitudinal edges of the side wall panels and spacer panels are transversely inclined.

Abstract: An excavator for use in tunneling operations wherein there is minimal head room, comprising a boom mounted to a mobile carriage for rectilinear movement in a horizontal plane and angular movement in a vertical plane. A rigid arm is pivotally mounted at one end to the distal end of the boom for angular movement relative thereto and a slide is supported by the arm for rectilinear movement thereon. The backhoe is fixed to the slide and there is linkage for manipulating the backhoe.

Abstract: An air filter for combustion engines used in motorized heavy equipment so structured as to be restored to full usage without replacement of the filter elements.

Abstract: An excavator for use in tunneling operations wherein there is minimal head room, comprising a boom mounted to a mobile carriage for rectilinear movement in a horizontal plane and angular movement in a vertical plane. A rigid arm is pivotally mounted at one end to the distal end of the boom for angular movement relative thereto and a slide is supported by the arm for rectilinear movement thereon. The backhoe is fixed to the slide and there is linkage for manipulating the backhoe.

Abstract: A filter module for removing metallic sludge from lubricating oil used in automobile engine crankcases and transmissions embodying permanent magnets for intercepting and retaining magnetizable sludge and a filter cloth for intercepting and retaining non-magnetizable sludge.

Abstract: An excavator comprising a beam pivotally supported at its proximal end to the platform of a mobile support for movement about a horizontal axis, telescopically interengaged upper and lower arms at the distal end of the beam, an excavator pivotally mounted to the distal end of the lower arm and hydraulic cylinders coupling the distal end of the lower arm to the distal end of the beam and the excavator to the distal end of the upper arm. The distal end of the lower arm is structured to mount a backhoe or shovel as may be required for a given operation.

Abstract: A magnetic filter module and system embodying the same for removing magnetic materials from lubricating oils used in hydraulic systems such as supplying oil to hydraulic excavators. The filter module includes one or more filter elements each having an elongate cartridge, a plurality of permanent magnets disposed about the cartridge and a plurality of non-magnetic spacers disposed about the cartridge between the permanent magnets.

Abstract: A trench box of the kind comprising spaced, parallel side walls held in spaced, parallel relation by end plates characterized in that the side walls are comprised of relatively light gauge sheet metal, reinforced at the opposed sides by sheet metal ribs and braces such as to prevent buckling of the side walls.