Abstract: A precast roof bearing block, such as a mine roof bearing block, may have a substantially solid molded body provided with reinforcement. The body has an upper bearing surface and a generally parallel lower bearing surface. A lateral surface connects the upper and lower bearing surfaces. A hole passes through the body member extending from one bearing surface to the other and may be located at the central axis of the body. A first reinforcing member may take the form of an annular ring which is disposed close to the upper bearing surface and a second reinforcing member may take the form of an annular ring which is disposed close to the lower bearing surface. The body member may have a substantially frustoconical or dome shaped configuration. A modified embodiment facilitates angular positioning of the roof bolt.

Abstract: A resin or grout anchored rock or mine roof nut and anchor assembly including an elongated cylindrical anchor to be inserted in a bore hole in assembled relation with a nut after insertion of a destructible adhesive resin or grout containing cartridge. The anchor includes an elongated threaded rod to be received in threaded portions of the nut and the nut includes a frangible disc normally held by crimped lip portions forming a stop wall to stop rotation of the nut relative to the anchor when the nut and anchor are assembled at a first relative axial position and operative when the anchor is restrained against rotation in the bore hole by setting of the adhesive resin and torque above a selected threshold is applied to the nut to dilate the crimping and expel the disc to accommodate further threaded insertion of the nut onto the anchor.

Abstract: A resin anchored rock or mine roof bolt anchor assembly including an elongated cylindrical anchor member to be inserted in a bore hole in assembled relation with a bolt after insertion of a destructible adhesive-resin-containing cartridge. The anchor member has an elongated bore to receive threaded portions of the bolt and includes a threaded entrance throat having distorted thread portions providing controlled interference with the threads of the bolt to induce resistance to rotation of the bolt relative to the anchor member when the bolt and throat threads are assembled at a first relative axial position and operative when the anchor member is restrained against rotation in the bore hole by setting of the adhesive resin and torque above a selected threshold is applied to the bolt to accommodate further threaded insertion of the bolt into the anchor member bore.

Abstract: A bail type expansion anchor for mine roofs and the like including a threaded bolt, and expander cone nut, and an expansible shell assembled together, with the shell formed from an integral blank of sheet metal having a pair of initially flat rectangular leaves bent to semi-cylindrical configuration with side edges thereof in abutment with each other to define a complete cylinder and having a bail strap of U-shaped configuration extending upwardly from the leaves and along side the cone nut. The bolt is threaded through the cone nut with the cone nut extending between the leaves of the shell, and the bail portion of the shell includes a circular top portion having a pop-out center having an interrupted circular periphery of slightly larger diameter than the bolt aligned with the bolt and connected to the remainder of the bail by frangible uncut attachment sections, designed to be broken out from the bail upon predetermined rotation of the bolt and form an aperture for passage of the bolt therethrough.