Abstract: A bore hole rotary reamer includes a body having cutters rotatably mounted by one or more respective spindles. A bearing region is formed on the spindle. At least one annular seal prevents ingress of contaminant to the bearing region. A circumferential void is formed adjacent the seal. At least one passageway extends in an axial direction of the spindle to the circumferential void and a piston movable in the passageway in response to supply of pressure to an outer side of the piston from the environment which surrounds the reamer. The piston transfers pressure to fluid in the cylindrical passage on an inner side of the piston to supply pressure to the circumferential void and thereby to the seal. The pressure is substantially determined by the pressure of the environment surrounding the reamer.

Abstract: A bore hole rotary reamer includes a body having cutters rotatably mounted by one or more respective spindles. A bearing region is formed on the spindle. At least one annular seal prevents ingress of contaminant to the bearing region. A circumferential void is formed adjacent the seal. At least one passageway extends in an axial direction of the spindle to the circumferential void and a piston movable in the passageway in response to supply of pressure to an outer side of the piston from the environment which surrounds the reamer. The piston transfers pressure to fluid in the cylindrical passage on an inner side of the piston to supply pressure to the circumferential void and thereby to the seal. The pressure is substantially determined by the pressure of the environment surrounding the reamer.

Abstract: A bore hole rotary reamer (1) includes a body (2) having cutters (4) contained in respective recesses (3) formed in the body (2). Each cutter (4) is rotatably mounted by one or more respective spindles (5). A bearing region (10) is formed by an inner bearing surface (11) rotatable on an outer surface of the spindle (5). At least one annular seal (12) about the spindle (5) prevents ingress of contaminant to the bearing region (b 10). A circumferential void (13) is formed between the inner bearing surface (11) and the outer bearing surface of the spindle (5) adjacent the seal (12). At least one passageway (17) extends in an axial direction of the spindle (5) to the circumferential void (13) and a piston (19) movable in the passageway (17) in response to supply of pressure to an outer side (19a) of the piston (19) from the environment which surrounds the reamer (1).

Abstract: A stabilizer tool (15) for a drill string (10) has a circular body (16) with recesses (17) containing projecting pad assemblies (18) arranged in a spaced helical configuration, each pad assembly (18) having at least one projecting wear block (20) maintained in abutment with an undercut recess surface by a wedge block (21) the outer wear surface (30) being of harder material than the remainder of the blocks (20, 21).