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 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.