Abstract: A tamper-proof fastener consists of a screw body having a flat-faced head portion and a threaded shank portion having at least one slit extending in a radial direction and located in an end of the shank opposite the head portion, the slit forming at least two legs in the end of the shank. The body defines a central bore extending from the flat face of the head portion to a point intersecting the slit at the end of the shank portion to form a squared-off shoulder in at least one of the legs and terminating in a tapered shoulder in at least one other leg. The tamper-proof screw also includes a headless pin which is sized to fit within the bore so that insertion of the pin into the bore causes an end of the pin to abut the squared-off shoulder and to engage the tapered shoulder to deflect the other leg outwardly. The pin is sized to be flush with the face of the head portion when it abuts the squared-off shoulder to eliminate a protrusion which could be grasped to remove the fastener.

Abstract: The device for fastening an object to a wall or the like by a push-in mounting, comprises an externally threaded bolt, at one end of which a nut can be threadedly advanced, and on the other end which is at least partially conical and whose maximum diameter is at most equal to the diameter of the bolt, has displaceably mounted thereon an expander element composed of two half-shell like parts. The two parts of the expander element are provided at their longitudinal edges opposite to one another in the mounted condition with integral lobes disposed transversely symmetrical and, when viewed in development, point-symmetrical, in relation to one another. The edges of the lobes are formed in such a way as to provide, when disposed on the externally threaded bolt, a form-locking connection.

Abstract: A series of adjoining cam discs are mounted on a foot having an inclined surface, with the cams surrounding a stem connecting the foot and a head of a diameter to fit within a borehole in rock. The stem extends axially between the head and the foot, while the inclined surface is spaced from the head and is inclined with respect to the axis of the anchor. The head has threads for receiving corresponding threads on a bolt which extends through the foot and stem, while the flat cam discs have a width less than, and a length greater than, the diameter of the borehole. The anchor is moved into the borehole and the cam discs are caused to engage the wall of the borehole, the bolt then being turned to thread the head against the cam discs and force the ends of the cam discs against or into the wall.

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: The invention concerns an anchoring device, more particularly a screw anchoring device, for insertion in an opening, e.g. in the end of a tube, to there form an anchor for a screw or bolt introduced into the opening. The device comprises an internally threaded locking body, preferably a conventional hexagonal nut, and a sleeve which is shaped, at least at one end thereof, to provide a tip portion, e.g. by being cut off obliquely. The device is inserted into the opening with the screw engaging the locking body and loosely accommodating the sleeve, whose tip portion is facing the body. In tightening the screw the locking body becomes wedged between the tip portion of the sleeve and an opposing portion of the wall of the opening. The union body-sleeve will then form a solidly fixed anchor for the screw, which itself can be loosened and tightened as desired.