Abstract: An off-center rock bolt anchor includes a wedge nut having a modified frusto-conical lower end portion having a first surface portion with an enlarged radius of curvature matching that of the mine roof bolt hole. A threaded hole for receiving the shaft of a roof bolt extends longitudinally through the wedge nut parallel to and close to the first surface. A locking cam with outwardly oriented teeth is pivotally connected to an off-center portion of the top surface of the wedge nut. A plurality of expansion wings are positioned around the lower conical portion of the wedge nut and expand outwardly to engage the walls of the bolt hole as the wedge nut is tightened onto the roof bolt. Initial rotation of the bolt causes eccentric rotation of the wedge nut that urges the teeth of the locking cam to engage the side of the bolt hole.

Abstract: Base thrust anchor assembly for use with roof bolts and base plate having means to provide deep penetration of the rock strata and provide large areal distribution of the longitudinal load in order to prevent overstressing the rock strata. The assembly employs anchor wings having a small longitudinal cross-sectional area that is applied in a transverse (radial) direction to permit deep penetration of the strata of a bolt hole wall, and a large transverse cross-sectional area to better support the longitudinal load imposed on the rock strata.

Abstract: A dual thrust anchor shell assembly for use with mine roof bolts or rock bolts include first and second opposed pivotal upper wing elements and first and second opposed, pivotal lower wing elements disposed about a mine roof bolt between a movable upper nut and a fixed lower nut so that tightening of the roof bolt forces the upper wing elements downward toward the lower wing elements. The upper wing elements each have a plurality of sloped camming surfaces. The lower wing elements also each have a plurality of sloped camming surfaces that engage camming surfaces of the upper wing elements as the roof bolt is tightened. Tightening of the roof bolt first causes the upper wing elements to pivot outward and dig into the walls of a roof bolt hole, anchoring the upper wing elements. Further tightening of the roof bolt causes a roof plate to be drawn tightly against the mine roof, binding strata of the mine roof and reinforcing the mine roof.

Abstract: A bushing/seal assembly for providing an airtight seal between the shaft of a mine roof bolt and a roof bolt hole includes a body having first and second flexible skirts extending outwardly from the body, the diameter of the first skirt being less than the diameter of the second skirt in order to facilitate adequate sealing with both standard size and slightly overside roof bolt holes. A rigid stabilizing washer engages the flexible body, the roof bolt shaft and the wall of the roof bolt hole in order to prevent excessive tilting of the roof bolt assembly after anchoring thereof in the roof bolt hole.

Abstract: A pick arm anchor assembly for use as a rock or mine roof bolt hole anchor characterized by an arrangement of components into an assembly which can be either used in conjunction with conventional expansion type rock anchors or it can be used independently with a mine roof bolt (without the expansion type anchor) to reinforce tunnel rock strata or mine roof strata. For a given hole diameter the assembly provides deeper penetration of the rock strata than conventional anchors. It also uses a greater concentration of transverse thrust in a small area to overcome rock stress resistance, to aid in penetration of the rock strata of a bolt hole. By deeper penetration of the rock strata of the bolt hole, the rock stress resistance to longitudinal forces is utilized in addition to the rock stress resistance to transverse forces employed in conventional expansion shell type anchors.

Abstract: A mine roof bolt hole seal characterized by an arrangement of components which seal the bolt hole from the mine atmosphere at the time the roof bolt is installed and which, thereafter, provides for the removal of moisture and excess oxygen from within the bolt hole, through use of a desiccant and an oxidant. In the preferred invention form, the desiccant and the oxidant are automatically exposed during installation of the roof bolt.

Abstract: An expansion type mine roof bolt assembly is shown that is to be installed in a roof bolt hole in a mine roof. The roof bolt has a stem that is fitted on a base plate, and it includes an expansion shell unit that expands when the bolt is tightened. A chemical dispenser assembly is fitted onto the bolt stem. The chemical dispenser assembly includes a base flange unit with an elongated sleeve that is threaded to the bolt stem. A hollow cylindrical chemical container is supported on the base flange unit. An elongated pressure sleeve unit is interposed between the expansion shell unit and the top portion of the chemical container so that when the bolt is tightened the pressure sleeve transmits a rupture force to the bottom portion of the chemical container to cause the contents of the container to be expelled into the roof bolt hole for sealing the base of the roof bolt hole. The base flange unit may include perforations and spike members for piercing the bottom portion of the chemical container.

Abstract: An improved method and mine roof bolt assembly for sealing a roof bolt hole in a mine to reliably prevent ambient mine air from entering the roof bolt hole. The roof bolt assembly includes a support plate, a roof bolt extending through a hole in the support plate, a flexible washer/gasket for providing a reliable seal between the support plate and a portion of the mine roof surrounding the roof bolt hole and also providing a reliable seal to the roof bolt shaft. An expansion shell is attached to a threaded end of the mine roof bolt to anchor the mine roof bolt assembly in the roof bolt hole. The washer/gasket includes an outer annular portion for providing a reliable seal between the mine roof and the support plate. The washer/gasket also includes a flexible inner annular portion for providing a reliable seal to the roof bolt shaft. The inner annular portion includes a relatively thin sphincter annulus which grips the roof bolt shaft to produce the seal therewith.