Drilling apparatus

Claim 2

Drilling apparatus comprising a subassembly adapted to be connected at one end to one end of a conduit a bit, means mounting said bit at the other end of said subassembly and allowing movement of said bit along the axis of drilling, a hammer within said subassembly adapted to impart a blow to said bit to move said bit sharply in the direction of drilling, a first means urging said hammer in the direction of drilling, a second means for pulling said hammer against the force of said first means and for releasing said first means tO cause said hammer to impart a blow to said bit, wherein said second means comprises a linear fluid actuator, a cable having one end connected to said hammer, means for fastening the other end of the cable to the conduit and a reciprocable sheave movable by said actuator, said cable being wound around said sheave between said fastening means and said hammer.

Claim 3

Drilling apparatus comprising a subassembly adapted to be connected at one end to one end of a conduit, a bit, means mounting said bit at the other end of said subassembly and allowing movement of said bit along the axis of drilling, a hammer within said subassembly adapted to impart a blow to said bit to move said bit sharply in the direction of drilling, a first means urging said hammer in the direction of drilling, a second means for pulling said hammer against the force of said first means, and for releasing said first means to cause said hammer to impart a blow to said bit, wherein said second means includes a fluid actuator, means for pivotally mounting a first part of said actuator, cam release means mounted adjacent to said fluid actuator for releasing said second means, a follower on a second part of said actuator which is movable relative to said first part, said follower being engageable with said cam release means, and said follower and cam means being so related that said second part moves angularly about said pivotally mounting means as a result of interaction between said cam means and said follower through at least part of the range of operation of said actuator, and means engageable by said second part of said actuator for effecting withdrawal of said cable against the force of said spring means, the last-mentioned means being arranged to be disengaged by said second part of said actuator when said second part moves about said pivoting means through a predetermined angle.

Claim 4

Drilling apparatus comprising a subassembly adapted to be connected at one end to one end of a conduit, a bit, means mounting said bit at the other end of said subassembly and allowing movement of said bit along the axis of drilling, a hammer within said subassembly adapted to impart a blow to said bit to move said bit sharply in the direction of drilling, a first means urging said hammer in the direction of drilling, a second means for pulling said hammer against the force of said first means, and for releasing said first means to cause said hammer to impart a blow to said bit, wherein said second means includes a fluid actuator, means for pivotally mounting a first part of said actuator, cam release means mounted adjacent to said fluid actuator for releasing said second means, a follower on a second part of said actuator which is movable relative to said first part, said follower being engageable with said cam release means, and said follower and cam means being so related that said second part moves angularly about said pivotally mounting means as a result of interaction between said cam means and said follower through at least part of the range of operation of said actuator, and means engageable by said second part of said actuator for effecting withdrawal of said cable against the force of said spring means, the last-mentioned means being arranged to be disengaged by said second part of said actuator when said second part moves about said pivoting means through a predetermined angle.

Claim 5

Drilling apparatus comprising a subassembly adapted to be connected at one end to one end of a conduit, a bit, means mounting said bit at the other end of said subassembly and allowing movement of said bit along the axis of drilling, a hammer within said subassembly adapted to impart a blow to said bit to move said bit sharply in the direction of drilling, a first means urging said hammer in the direction of drilling, a second means for pulling said hammer against the force of said first means, and for releasing said first means to cause said hammer to impart a blow to said bit, wherein said first means comprises a spring located within said subassembly, and said second means includes a linear fluid actuator comprising piston and cylinder element one of which elements is adapted to be connected at the other end of the conduit opposite said subassembly and the other element being movable with respect to said connected element through a range of positions, a cable connected to said hammer, means engageable by said movable element for pulling said cable in response to operation of said actuator to withdraw said hammer against the force of said spring, and triggering means for automatically and instantaneously releasing said cable and allowing movement of said hammer by said spring when the movable element of said actuator reaches a predetermined position in said range.

Claim 6

Drilling apparatus comprising a subassembly adapted to be connected at one end to one end of a conduit, a bit, means mounting said bit at the other end of said subassembly and allowing movement of said bit along the axis of drilling, a hammer within said subassembly adapted to impart a blow to said bit to move said bit sharply in the direction of drilling, a first means urging said hammer in the direction of drilling, a second means for pulling said hammer against the force of said first means, and for releasing said first means to cause said hammer to impart a blow to said bit, wherein said first means comprises a spring located within said subassembly, and said second means includes a linear fluid actuator comprising piston and cylinder element one of which elements is adapted to be connected at the other end of the conduit opposite said subassembly and the other element being movable with respect to said connected element through a range of positions, a cable connected to said hammer, means engageable by said movable element for pulling said cable in response to operation of said actuator to withdraw said hammer against the force of said spring, and triggering means for automatically and instantaneously releasing said cable and allowing movement of said hammer by said spring when the movable element of said actuator reaches a predetermined position in said range.

Claim 7

Drilling apparatus according to claim 3 in which said triggering means comprises means for effecting disengagement of said movable element and said means engageable by said movable element.

Claim 8

Drilling apparatus according to claim 3 in which said triggering means comprises means for effecting disengagement of said movable element and said means engageable by said movable element, and including means for automatically effecting reengagement of said movable element and said means engageable by said movable element when said movable element reaches a second predetermined position in its range of movement.