GB929818A - Hydraulic actuated borehole drilling apparatus - Google Patents

Abstract

929,818. Boring earth &c. JERSEY PRODUCTION RESEARCH CO. Aug. 4, 1961 [Sept. 13, 1960], No. 28384/61. Class 85. [Also in Group XXIX] An hydraulically actuated drill collar 26 has resiliently mounted anchors 74 engageable with the wall of the hole, and encloses means by which the drill bit 21 carried by a rotary member 20 fixed to the drill string may be forced against the bottom of the hole. Drilling fluid is pumped down a bore 23 in the member to the bit and through nozzles 24 so that the fluid pressure in the bore is greater than that in the annulus 25 outside the bit. Some of the fluid from the bore passes through ports 96 and is directed by an annular slide 84 (having an initial position as shown in Fig. 6) into a duct 100 to a chamber 68 to force the anchors into engagement with the wall. Pistons 40, 49 on the member, initially at the tops of their strokes in the chambers 38, 46, are moved downwardly with the member by fluid from the duct 100 passing through ports 106, 104 after the anchors engage the wall. As drilling proceeds the slide follows the member and a cage 80 fixed to the slide by a resilient sleeve 90 engages a shoulder 120 on the collar so that after further drilling the spring fingers 94 on the slide are released from a projection 116 on the member by a surface 83 on the cage. The latter part of the downward movement of the slide distorts the sleeve so that the slide snaps upwardly on release of the fingers 94 to engage its fingers 92 with a projection 114 on the member. The duct 100 is then vented to the annulus through openings 82, 63 to release the anchors 74, and fluid from the bore passing through port 96 is directed by the slide into a duct 110 and through a port 112 into the chamber 46 to move the collar downwardly until the cage engages the upper part of the chamber 62 and the latch fingers 92 are released from the projection 114 (see Fig. 9) to permit the slide to snap downwardly to return to the position shown in Fig. 6 at the beginning of a cycle.