Abstract: A core drill bit segment (10) comprises an elongated member (12) having an upper end (14), a lower end (16), first side (18) and opposite second side (20). Attached to the lower end (16) is matrix (22). The matrix (22), while depending from the lower end (16) also extends upwardly toward the upper end (14) along first and second sides (18, 20) of the member (12). The lower end (16) is provided with a lip (24) that is turned upwardly to extend in front of the first side (18) to define a recess (26) for seating a lower edge of a drive sub (25).

Abstract: A retrieval head (14) coupled to a downhole tool that is used for retrieving a drill bit composed of individual drill bit segments (14). The down hole tool is adapted to travel through a drill sting and a drive sub (12) attached to the drill string. The tool also releases segments (14) which are clamped between the drive sub (12) and a bit locking sleeve (16). The retrieval head (10) includes a body (30) having a first length (32) and a contiguous second length (34). The first length (32) is of constant diameter. The second length (34) has a portion (42) of reduced diameter relative to that of the first length (32). The diameter of the first length (32) is dimensioned so that the bit segments (14) can initially collapse radially inwardly wholly onto an outer circumferential surface (38) of the length (32). The reduced diameter portion (42) is dimensioned so that when the bit segments (14) are disposed thereon, the bit segments (14) can pass through the drive sub (12) and bit locking sleeve (16).

Abstract: A sleeve (10) comprises a cylindrical member (12) provided at one end (14) with a pair of opposing tapered peaks (16) and (18). Peak (16) is higher (longer) than peak (18). Sleeve (10) is retained within a drive sub (26) of a ground drill and is constrained to move linearly along the drive sub (26). The peaks (16) and (18) cooperate with latch dogs (20) and (22) which are evenly spaced about and extend radially from a running tool (24). When the running tool (24) travels down the drive sub (26) and enters the sleeve (10), one of the latch dogs (20, 22) will strike one of the peaks (16) and (18) causing the tool (24) to rotate toward a predetermined rotational position. Because the peaks (16) and (18) are at different heights, latch dogs (20) and (22) cannot simultaneously contact the very top of each peak (16) and (18). If latch dog (20) strikes the top of peak (16), it will then slide down one of the sides of that peak causing the tool (24) to rotate.

Abstract: A spear head assembly (10) comprises a main body portion (14) with axially opposite first and second ends (16 and 18) respectively. The first end (16) is adapted for threaded connection with a down hole tool (12). The tool, which does not form part of the invention, is provided with an internal fluid flow path (13). Passage (20) is formed in the main body portion (14) and extends between first and second spaced apart openings O.sub.1 and O.sub.2 which are coincident with the first end and the second end (16 and 18) respectively of the main body portion (14). Spear point (22) is coupled to the main body portion (14) at, and extends from, the second end (18). In use, when the spear head assembly (10) is coupled to tool (12), to facilitate connection of the tool to a wireline and overshot via the spear point (22), the passage (20) is in fluid communication with the path (13). Therefore, fluid such as drilling mud can go through the path (13) in a substantially unimpeded manner.