Mine roof bolt assembly

A mine roof bolt assembly for insertion in a bore in a mine roof, said roof bolt assembly including

• (a) a shank
• (b) anchor means for securing one end of said shank in said mine roof at the back end of the bore
• (c) the opposite end of said shank being threaded
• (d) a bolt head having a central bore
• (e) said bolt head bore having a first threaded portion threadedly engaged with the threaded end of said shank
• (f) a second threaded portion adjacent said first threaded portion
• (g) a stop plug threadedly engaged with said second threaded portion and in abutting engagement with said opposite end of said shank for initially limiting penetration of the shank into the bolt head
• (h) said stop plug gravitating from the bolt head upon application of a predetermined torque to said bolt head, causing the stop plug to strip the second threaded portion of the bolt head, whereby said bolt head moves upwardly toward the face of the mine roof as the threaded end of said shank advances through the bolt head bore, and
• (i) a support plate positioned on said shank between said bolt head and the face of said mine roof, said support plate being forced upwardly against the face of the mine roof upon movement of the bolt head towards the face of the mine roof.

A mine roof bolt assembly for insertion in a bore in a mine roof, said bolt assembly including:

• (a) a shank
• (b) a first means for anchoring an end of said shank in said mine roof at the back end of the bore
• (c) the opposite end of said shank being threaded
• (d) a head member having a threaded bore in threaded engagement with said opposite end of said shank for permitting rotational movement of said member with respect to said shank and relative longitudinal movement of the head member with respect to said shank in the direction of the face of the mine roof
• (e) stop means in the bore of said head member for initially limiting penetration of said shank into said head member
• (f) a second means for retaining said stop means in the bore of the head member
• (g) said shank exerting a force on said stop means to overcome said second means and causing said stop means to gravitate from the bore of said head member when a predetermined torque is applied to said head member, thereby allowing unimpeded travel of said shank through said head member, and permitting said head member to move longitudinally of said shank in the direction of the mine roof, and
• (h) a third means positioned on said shank between said head member and the face of the mine roof, said third means being forced upwardly against the face of the mine roof upon movement of the head member towards the face of the mine roof.