Abstract: An expansion bolt, particularly adapted for supporting the roof of a mine tunnel, includes an elongate stud having distal and proximal threaded ends. Coaxially mounted on the stud near the distal end is an expansion sleeve that is axially divided into a plurality of circumferentially-spaced sleeve segments. A cam element is threadedly attached to the distal stud end. The cam element is formed of a sheet metal stamping; and includes an annular collar with a plurality of circumferentially-spaced fingers extending proximally from the periphery of the collar. The fingers also taper radially outwardly to give the cam element a frusto-conical configuration. The proximal ends of the fingers engage the interior surface of the sleeve near the distal end of the sleeve. The sleeve is constrained from axial movement on the stud, and the stud is rotatable independently of the cam element and the sleeve. The proximal end of the sleeve has a nut adapted for the application of a torque thereto.

Abstract: A roof bolt for use in a predrilled hole in a mine has an elongated stud on which is mounted a cylindrical sleeve. The first or inner end of the stud is threaded and carries a wedge adapted to enter one end of the sleeve and forcefully expand it in response to the rotation of the stud. The second or outer end of the stud is threaded in a like direction and carries a nut, held in a fixed position of rotation on the stud by a shear pin engaged in a common hole through part of the nut and stud. A shoulder plate is carried on the stud between the nut and sleeve, and the second end of the stud has a backing plate attached.