Abstract: An expansion bolt including an anchor bolt having an expansion section, and further including an expansion sleeve which surrounds the anchor bolt and which can be expanded by retracting the expansion section, and a spring element arranged on the anchor bolt. The spring element can be tensioned by inserting the anchor bolt into a bore hole and can retract the expansion section of the anchor bolt into the expansion sleeve when it is released. An indicator element indicates when a rated tension of the spring element is reached.

Abstract: The present invention relates to a rock bolt comprising first and second ends, a shaft extending between the ends, and an anchoring device extending along a first part of the shaft adjacent the first end. The anchoring device comprises a mandrel, and at least one expansion element overlaying the mandrel. The expansion element is displaced radially outwardly on a predetermined relative movement between the mandrel and the expansion element. The expansion element is joined to a connector to form an anchor assembly. The anchor assembly is keyed to the mandrel. The anchor assembly comprises relative rotation actuator means active during rotation of the anchoring device. The invention further relates to an anchoring device per se.

Abstract: An expansion wedge anchor (80) for insertion in a hole (H) delimited by a wall comprises an expander member (32) and an expansion number (34), the expander member being provided at a leading end of the expander member, the expander member comprising a flaring end (40), the expansion member being expandable at a trailing end (48) thereof and being adapted to engage the wall of the hole when the expander member is positioned in the hole, wherein upon longitudinal withdrawal of the expander member from the hole, the expander member displaces longitudinally relative to the expansion member with the flaring end thereof gradually causing the trailing end of the expansion member to expand, whereby a trailing edge of the expansion member engages the wall of the hole. The trailing end is adapted, when expanded by the flaring member, to extend at an angle with respect to a longitudinal axis of said expander member.

Abstract: A mine roof bolt expansion anchor is formed from a plurality of identical shell segments. Each shell segment has a first end, a second end, and an end section at the first end. A first finger extends from the end section to the second end of the shell segment. A second finger extends from the end section toward the second end of the shell segment and terminates at a distal edge spaced from the second end of the shell segment. The end section, the first finger and the second finger each include an inner surface and an outer surface. A deformable coupling couples a plurality of shell segments together to form a multi-piece shell. The inside surfaces of the end sections, the first fingers and the second fingers of the multi-piece shell define a central aperture in which a wedge, adapted to coact with the plurality of shell segments, is received in the central aperture. Movement of the wedge from the second end to the first end of the shell segments forces the fingers to move in an outwardly direction.

Abstract: A bail element (10) having a medial portion (12) with a pair of legs (14, 16) extending integrally therefrom and a mechanical expansion anchor having a pair of shell halves (68, 70) and tapered plug (80) held in assembled relation by the bail. The bail legs are identical to one another and, prior to assembly with the shell halves and plug, have three distinct, linear portions (46, 48, 50) respectively extending at preferred angles of about 10.degree., 36.degree. and 12.5.degree. with respect to lines parallel to the bail centerline (A--A). The bail medial portion includes a pair of upstanding portions shown in a first embodiment (34, 36) and a second embodiment (54, 56) for puncturing a resin cartridge which may be installed with the anchor.

Abstract: A mine roof expansion anchor having a conventional tapered camming plug and radially expansible shell having associated therewith an element which resiliently engages the wall of a bore hole as a roof bolt carrying the anchor is inserted in the hole. The resilient element may be incorporated in the structure of a bail having bore wall engagement portions position in a plane closer to the lower end of the expansion shell than the lowest position of the tapered plug after full expansion. The engagement portions may comprise outwardly and downwardly extending portions of the bail legs, either at the terminal ends or pierced from the bail material slightly above the ends. In another embodiment, the engagement portions extend from a support nut positioned on the bolt below the lower end of the shell.

Abstract: An expandable mine bolt assembly having a shell and wedge unit threaded upon the shank of an elongated bolt. The shell contains at least one or more leaf sections. The arms of a U-shaped metal strap are joined to the shell and the strap is arranged to pass over the wedge and the distal end of the bolt. At least one arm of the strap is provided with a wrapped section containing folded legs. The distal end of the bolt applies pressure against the strap as the bolt is threaded through the wedge which, in turn, causes the legs of the wrapped section to unfold into holding contact against the wall of a receiving hole thereby preventing the assembly from spinning in the hole as the shell is being expanded by the wedge.

Abstract: An improved expansion assembly for a mine roof bolt has a tapered plug, two expansion leaves that bear against the tapered plug, a bail that connects the expansion leaves and extends over the end of the mine roof bolt, and a breakable holding ring to keep the expansion assembly assmebled until after it is placed into the bore hole. The tapered plug has a threaded bore therethrough for threading onto the mine roof bolt. The tapered plug also has tapered surfaces that have an angle of taper of 8.degree. to the axis of the mine roof bolt. The expansion leaves each have nine serrations formed on the surface such that the serrations are formed by the intersection of a planar surface perpendicular to the axis of the mine roof bolt and a frusto-conical surface. The frusto-conical surface is at an angle of 69.degree. to the planar surface. The serrations are equally spaced from each other and have a peak to peak distance of 0.25". The expansion leaves each have a maximum length of 3".

Abstract: A mine roof bolt expansion anchor utilizes a plurality of transversely bent elongated leaves which are compressed within a bail by the rotation of the roof bolt. The compression results in movement of the leaves toward a flattened position whereby the outer edges of the leaves engage the bore hole walls to anchor the bolt. Downwardly extending flanges on each end of the leaves increase the bearing surface which engages the bore hole wall, while spacers near the center of the leaves act as a spine to evenly distribute the compression to all the leaves so that they all engage the bore hole wall simultaneously and with the same pressure.

Abstract: An expansion anchor including an expansible shell and tapered nut for insertion into a drill hole in a rock formation and adapted for outward expansion of the shell into gripping engagement with the drill hole wall to support a rock bolt and bearing plate engaging the rock formation surface around the hole. The invention resides in a novel arrangement of dimensional and structural relationships of the expansion shell and tapered nut which allow the same anchor to be used in drill holes over a range of diameters approximately three times that of conventional prior art anchors of the same general type.

Abstract: The invention relates to an expansion bolt of a type having an expansible shell arranged on an elongated stud, with a tapered plug being provided to expand the shell in use. In order to render the bolt more versatile, a spacer is provided between the plug and the expansible shell, the spacer being in the form of finger elements which engage the inner surface of the shell to expand it.

Abstract: This invention relates to an anchor bolt expansion unit and the bolt assembly using such a unit. The unit consists of a plurality of leaves connected together by a bail having a flat cap and fingers secured one to each leaf. The flat cap is dimpled to ensure an even distribution of tension applied to the fingers before the bail yields in use and also has a line of weakness to ensure that it will yield at a predetermined axial pressure. The fingers of the bail are also weakened at points in their length to a strength slightly greater than that resulting at the peripheral line of weakness.