Engagement head for tensioning assembly

Abstract

An engagement head for a rock bolt tensioning assembly is disclosed that is profiled to include at least one key surface to inhibit rotation of the engagement head relative to a rock surface, either by direct engagement with the rock surface or through abutment with a plate-like member that is engageable with the rock surface.

1 . A tensioning assembly for a rock bolt, the tensioning assembly comprising an engagement head that in use is forced into either direct or indirect engagement with a rock surface, wherein the engagement head is profiled to include at least one key surface to inhibit rotation of the engagement head relative to the rock surface. 
     
     
         2 . A tensioning assembly according to  claim 1 , wherein the engagement head is arranged to engage the rock surface through abutment with a plate-like member and wherein rotation of the engagement head relative to the plate-like member is inhibited by the at least one key surface. 
     
     
         3 . A tensioning assembly according to  claim 2 , wherein the at least one key surface is formed as one or more flattened surfaces formed on the engagement head. 
     
     
         4 . A tensioning assembly according to  claim 2 , wherein the at least one key surface comprises one or more lateral surfaces that project radially from an axis of the engagement head. 
     
     
         5 . A tensioning assembly according to  claim 4 , wherein the one or more lateral surfaces project radially from a central zone towards the circumference of the engagement head. 
     
     
         6 . A tensioning assembly according to  claim 2 , wherein the at least one key surface is located on a projection extending outwardly from the circumference of the head. 
     
     
         7 . A tensioning assembly according to  claim 2 , wherein the at least one key surface is located in a slot extending into the head. 
     
     
         8 . A tensioning assembly according to  claim 2 , wherein the engagement head forms part of a bearer member incorporating a passage through which the rock bolt extends. 
     
     
         9 . A tensioning assembly according to  claim 8 , wherein the bearer member includes an inner surface that defines said passage and which incorporates a surface that cooperates with an abutment mounted to, or formed in, the rock bolt to provide a positive engagement therebetween that inhibits rotation of the bearer member relative to the abutment about the bolt in at least one direction. 
     
     
         10 . A combination comprising a tensioning assembly according to  claim 2  and a plate-like member arranged to directly engage the rock surface, the plate like member including at least one plate key surface that cooperates with the at least one key surface of the engagement head to inhibit rotation therebetween. 
     
     
         11 . An engagement assembly for engagement between a rock surface and a tensioning assembly, the engagement assembly comprising:
 a plate-like member arranged to directly engage the rock surface, the plate like member including at least one plate key surface; and   a bearer member arranged to engage with, or form part of, the tensioning assembly, the bearer member having a head including at least one head key surface, wherein the head key surface and the plate key surface are adapted to engage such that rotation of the head relative to the rock surface is inhibited.   
     
     
         12 . An engagement assembly according to  claim 11 , wherein the at least one head key surface is formed as one or more flattened surfaces formed on the bearer member head. 
     
     
         13 . An engagement assembly according to  claim 11 , wherein the at least one head key surface comprises one or more lateral surfaces that project radially from an axis of the bearer member head. 
     
     
         14 . An engagement assembly according to  claim 13 , wherein the one or more lateral surfaces project radially from a central zone towards the circumference of the bearer member. 
     
     
         15 . An engagement assembly according to  claim 13 , wherein the at least one head key surface is located on a projection extending outwardly from the circumference of the head. 
     
     
         16 . An engagement assembly according to  claim 13 , wherein the at least one head key surface is located in a slot extending into the head. 
     
     
         17 . A rock bolt assembly comprising a rock bolt having an axis, a bearer member for facing and urging against rock strata, the rock bolt being arranged to extend through the bearer member, and an abutment mounted to, or formed in the rock bolt, wherein the abutment and the bearer member incorporate cooperating surfaces that provide positive engagement therebetween that inhibit rotation of the abutment relative to the bearer member about the bolt axis in a least one direction. 
     
     
         18 . A rock bolt assembly according to  claim 17 , further comprising an engagement assembly according to  claim 11 , wherein the bearer member forms part of the engagement assembly. 
     
     
         19 . A method of inhibiting rotation of a tensioning assembly with respect to a rock surface, the tensioning assembly including a bearer member, the method comprising:
 positioning a plate-like member in contact with the rock surface;   positioning a bearer member in contact with the plate like member; and   causing a key surface in the bearer member to abut a corresponding key surface in the plate-like member.