CA1138419A

CA1138419A - Retractable bit system

Info

Publication number: CA1138419A
Application number: CA000350532A
Authority: CA
Inventors: Robert A. Kaiser; Ronald E. Cozad; John D. Tucker
Original assignee: Longyear Co
Current assignee: Longyear Co
Priority date: 1979-05-15
Filing date: 1980-04-24
Publication date: 1982-12-28
Also published as: AU542985B2; US4281722A; ZA802880B; AU5821580A; JPS5628992A

Abstract

RETRACTABLE BIT SYSTEM
ABSTRACT OF THE DISCLOSURE

A retractable bit system that includes a single piece annular core bit that is movable through a drill string (drill stem), had an outer diameter about the same as that of the drill stem, and can be releasably locked to the drill string, an outer barrel assembly for the drill stem that is operable for lockingly engaging the core bit and driving the core bit, bit replacement tools for moving the core bit through the drill string and operable for operating the outer barrel assembly and replacing the bit on the drill string without removing the drill string from a drill hole, a manually oper-ated surface tool removably mounted on the drill string for clampingly engaging a wire line and retracting the wire line to operate the respective one of the bit installation tool and bit retraction tool when the respective tool extends into the outer barrel assembly, and a safety release tool for op-erating and withdrawing the replacement tools which will un-couple from the replacement tool when more than a predeter-mined force is applied.

Description

~ 9 This invention relates to a core bit that is retract-able through a drill string and tools for replacing the bit on the drill string withou~ removal of the drill string from a drill hole. More particularly this invention relates to an annular core bit having an outer diameter about the same as that of the drill string, and tools used for removing the bit from the inner end of drill string and replacing another bit of the same construction on the drill string while the drill string remains in a drill hole.
T,he U. S. Government has rights in this invention pur-suant to Contract No. H0272004 awarded by the Bureau of Mines, U. S. Department of the Interior.
During drilling operations, for example exploring for minerals, the drill bit wears and has to be replaced in order to carry out an efficient operation. Withdrawing the drill string to remove, inspect and/or replace the drill bit is a time consuming task and leaves the drill hole subject to cav-ing by unstable formations along the hole path. Drill bits have been made in the past that are replaceable on the drill string without withdrawing the drill string, but such past atttempts have not been commercially successful.
Two general categories of prior art systems have been evolved to eliminate having to pull the entire drill string to replace a worn or damaged bit as follows: (1) collapsible bits and (2) pilot bit with retractable reamer. Collapsible bits are made of many segments which may travel through the drill string as a group and unfold or spread out upon reach-ing the axial inner end of the drill string, for example see U. S. Patent 3,603,413; or in line one above the other through the drill string and guided into position at the axial inner --1-- , 1 1 3~ 4 ~
end of the drill strlng where they are locked in place for drilling, for example see U. S. Patent 3,437,159. Such seg-mented bits must be machined into intricate shapes, which is costly, and the drill operator is not always sure the bit seg-ments are locked in place for drilling. Further, grit from the drilling operation can interfere with the proper exchange of bits.
An example of a pilot bit with an expandable reamer are U. S. Patent Nos. 3,894,590 and 474,080. This type of system is subject to probLems such as mentioned with reference to collapsible bit systems.
U. S. Patent 3,965,996 discloses a bit assembly that is lowered through a drill string with its drill axis transverse to the longitudinal axis of the drill string and when locked in a drilling position has its drill axis generally aligned with the drill string axis. However, such a bit is not suit-able for taking a core sample.
U. S. Patent 3,545,553 discloses coupling apparatus for mounting and moving bits through a drill string, the coup-ling apparatus being hydraulically operated to latchingly engage the drill string. The coupling apparatus includes cam mechanism to angularly align its coupling members with drill string slots. The coupling apparatus remains latched to the drill stem while the hole is being drilled.
In order to provide a commercially feasible retract-able bit system for replacing a drill bit without removing the drill string from the drill hole, and that can be used for core drilling, this invention has been made.
The retractable bit system disclosed herein includes a single piece annular drill bit having axially opposite 11 3~
transverse surfaces, opposite outer peripheral circular sur-face portions axially between the transverse surfaces, op-posed outer peripheral surface portions circumferential be-tween the circular portions that are of a minimum spacing that is substantially less than that of the circular surface portions, and lock key recesses.
An operative transverse outer barrel assembly is pro-vided for being mounted on the axial inner end of a drill string, the outer barrel assembly having drive surfaces for drivingly rotating a drill bit, lock keys for lockingly en-gaging the drill bit, a transverse outer tube, and an annu-lar member that mounts the lock keys and is rotatably mount-ed in the outer tube for moving the lock keys between a bit locking position and a bit release position.
An annular bit replacement tool has a bit mounting mem-ber, operative detents for releasably holding a bit on the bit mounting member, latches mounted for movement between a drill string release position and a drill string latched position and operating mechanism for moving the latches to a drill string latching position and thence the bit mounting member between a drill string bit mounted position and a position the drill bit may be moved through the drill string, and if a bit is being installed on the drill string, move the detents to their release position after the mount-ing member has been moved to a drill string bit mounted posi-- tion and locking mechanism on the drill string has been oper-a~ed to a drill bit locking position; and if a bit is being removed from the drill string, move the detents to their locking position when the mounting member is in a bit in-stalled position and thence operate locking mechanism on 1~l3~
the drill string to release the drill bit.
One of the objects of this invention is to provide a new and novel drill bit for being replaced on a drill string without removal of drill string from the drill hole.
Another object of this invention is to provide a drill bit of a novel one piece construction that may be moved axially through a drill string and that when mounted on the drill string, will cut a drill hole of a diameter that is about the same as the outer diameter of the driIl string. A fur-ther object of this invention is to provide an annular drill bit having new and novel surface portions retainingly engag-able by a bit replacement tool for moving the bit through a drill string and additional novel surface portions that are retainably engagable with the drill string to mount the bit to the drill string. Another object of this invention is to provide a new and novel core bit that can be replaced without removing the drill stem from a drill hole, that is easy to manufacture and that can be used in conjunction with a standard wire line inner tube assembly.
A different object of this invention is to provide a new and novel tool for replacing a drill bit on a drill string without having to remove the drill string from a drill hole. In furtherance of the last mentioned object, it is another object of this invention to provide a tool with new and novel means for operating bit mounting mechan-ism on the axial inner end of a drill string between a drill bit locking position and a drill bit release position.
Still another object of this invention is to provide a new and novel bit replacement tool that is hydraulically and mechanically actuatable between a drill string latching engagemen~ position and a drill string release position.
A different object of this invention is to provide a min-eral explorator drilling tool having new and novel means for operating detent mechanism between a drill string latch-ing position and a drill string release position.
Another object of this invention is to provide a new and outer barrel assembly that is mountable on the axial inner end of a drill string. A further object of this inven-tion is to provide a core barrel outer tube assembly with new and novel means for releasably mounting a drill bit and drivingly rotating a drill bit. Another object of this in-vention is to provide an outer tube assembly mountable on the axial inner end of a drill string that has new and novel means operable between a drill bit lockingly engaging posi-tion and a release position while the outer tube assembly remains in the axial inner end of a drill hole.
Another object of this invention is to provide a new and novel manually operated surface tool for being mounted on a drill string and retracting a wire line. A further object of this invention is to provide a surface tool mount-able on a drill string that has new and novel clamp means for clampingly engaging a wire line. In furtherance of the last mentioned object, it is another object of this inven-tion to provide a pair of new and novel clamps and clamp moving mechanism for moving one clamp relative the other.
Another object of this invention is to provide a new and novel safety release tool for releasably engaging a dril-ling tool that is to be moved through a drill string. A
further objective of this invention is to provide a safety release tool having new and novel means for latchingly _~_ 1~ 3~ ~19 engaging a tool that is to be moved through a drill string.
In furtherance of the last mentioned object an adcitional ob-ject of this invention is to provide new and novel means for holding a latch in a latched position and upon more than a predetermined withdrawal force being applied, allow the latch to move to a release position.
Conventional wire line inner tube assemblies can be used in the drill stem for collecting core samples with the bit of this invention on the inner end of the drill stem and the same overshot assembly that is used for withdrawing the inner tube assembly can be used for lowering, or with-drawing the combination of the safety release tool and bit replacement tool of this invention. Further the bit of this invention can be withdrawn through the drill stem, is of a single piece unitary construction, has opposed circumfer ential surface positions that are of about the same radius of curvature as that of the drill stem outer peripheral sur-face and that each extend angularly through an angle of at least 60, and opposite drill stem drivingly engagable sur-faces that angularly extend through angles of at least 60. In the preferred embodiment described herein each of the circumferential surfaces extend through an angle of about 90.
Even though the bit replacement tools disclosed herein are of relatively complex construction, it is to be remem-bered that these tools can be used over and over again for replacing a drill bit on the axial inner end of drill string without having to remove the drill string from the drill hole.

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For purposes of facilitating the description of the in-vention, the term "inner" refers to that portion of the drill stem, or of the assembly, or an element of the assembly being -described which in its position "for use" in, or on, the drill stem is located closer to the drill bit on the drill stem (or bottom of hole being drilled).than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumferential, direction, or dia-meter of the drill stem or other apparatus being described.
The term "outer" refers to that portion of the drill stem, or of the assembly, or an element being described which in its position "for use" in or on the drill stem is located axially more remote from bit on drill stem than any other portion of the apparatus being described, except where the term clearly refers to a transverse circumferential, direction, or dia-meter of the apparatus being described-.
The invention is illustrated with reference to the ac-companying drawing wherein:
Figure 1 is a plan view of the bit of this invention, said view being generally taken along the line and in the direction of the arrows 1-1 of Figure 2;
Figure 2 is in part a transverse cross sectional view and in part a side view of the bit, said view being gener-ally taken along the line and in the direction of the arrows

2-2 of Figure l;
Figure 3 is in part a transverse cross sectional view and in part an end view of the bit, said view being gener-ally taken along the line and in the direction of the arrows

3-3 of Figure l;

113~41~

Figures 4-8 with one arranged above the other with the axial center lines aligned and lines A-A of Figures 4 and 5 aligned, and lines B-B of Figures 5 and 6 aligned, and lines C-C of Figures 6 and 7 aligned, and lines D-D of Figures 7 and 8 aligned, form a composite longitudinal section through the drill bit, the bit retraction tool, the safety release assem-bly, and the axial inner end portion of the drili stem; the cam sleeve and landing ring engaging balls being shown out of their relatively rotated positions in Figure 5; Figure 7appearing on sheet 2 and Figure 8 appearing on sheet 3;
Figure 8 shows the bit retraction tool in position for re-moving the bit from the outer tube assembly of the drill stem;
Figure 9 which appears on sheet 3 is a fragmentary longi-tudinal sectional view of the inner end of the bit retraction tool, said view being generally taken along the line and in the direction of the arrows 9-9 of Figure 8;
Figure 10 which appears on sheet 4 is a fragmentary longi-tudinal sectional view of the inner end of the bit retraction tool showing the bit removed from the outer tube assembly and rotated 90 about the central axis of the drill stem and 90 about an axis perpendicular to the central axis and trans-versely spaced therefrom;
Figure 11 which appears on sheet 1 is a transverse cross sectional view in part generally taken along the line and in the direction of the arrows 11-11 of Figure 12 showing the bit locked on the drill stem in a position for drilling and the radially adjacent part of the floater subassembly in a posi-tion to lockingly engage the bit, and in part along the line and in the direction of arrows 11-11 of Figure 3 to show the adaptor ring flanges extended into the bit adaptor ring flange recesses;

1~L3~'~19 Figure 12 which appears on sheet 1 is a fragmentary lon-gitudinal sectional view generally taken along the line and in the direction of the arrows 12-12 of Figure 11;
Figure 13 is a longitudinal sectional view of the outer barrel assembly of the drill stem with a drill bit mounted thereon with axial intermediate portions of the assembly being broken away; said view being generally taken along the line and in the direction of the arrows 13-13 of Figure 15 other than only one of the locking pins of the bit retraction tool is 10 shown, and the pin is shown in its radially extended position;
Figure 14 is a fragmentary cross sectional view showing the mounting of the detent spring that releasably retains the locking sleeve in either a bit unlocked or locked position, said view being generally taken along the line and in the di-rection of the arrows 14-14 of Figure 13 and showing the spring in its bit locked position;
Figure 15 which appears on sheet 5 is a transverse cross sectional view generally taken along the line and in the di-rection of the arrows 15-15 of Figure 13 to in part show the 20 relationship of the inner and outer sleeves relative the outer barrel of the outerbarrel assembly and the axial outer drive slug;
Figure 16 is a view of the adjacent end portions of the stationary sleeve and locking sleeve when rolled out flat and looking at the inner surface thereof with circumferential in-termediate portions broken away, said view also showing the locking pins of the axial outer drive slug assembly in an ex-tended position with the sleeves in a bit locked position;
Figure 17 is a transverse cross sectional view generally taken along the line and in the direction of the arrows 17-17 of Figures 7 and 13, the left hand half of the view showing _g_ ~3 :

one locking pin in an extended position and the right hand half of said view showing a second locking pin in a retracted position;
Figure 18 is a fragmentary longitudinal cross sectional view generally taken along the line and in the direction of the arrows 18-18 of Figure 17, said view showing the locking pin in solid lines in a retracted position and showing two other positions of the locking pin relative to the cam por-tions in dotted lines;
Figure 19 is a view of a fragmentary portion of the cam tube showing one of the locking pins in a retracted position in solid lines and two other positions of the locking pin rel-ative to the cam portions in dotted lines, said view being gen-erally taken along the line and in the direction of arrows 19-19 of Figure 18;
Figure 20 which appears on sheet 5 is a transverse cross sectional view generally taken along the line and in the di-rection of the arrows 20-20 of Figures 7 and 13 to in part il-lustrate the orienting pin subassemblies;
Figure 21 which appears on sheet 5 is a fragmentary lon-gitudinal cross sectional view generally taken along the line and in the direction of the arrows 21-21 of Figure 20 to further illustrate one of the orienting pin subassemblies, Figure 22 is a side elevational view of the camming tube with axial intermediate portions broken away;
Figure 23 is a view showing the interior surface of the camming tube with the camming tube being rolled out flat, axial intermediate portions being broken away;
Figure 24 which appears on sheet 6 is a transverse cross sectional view of the drive slug assembly, said view being generally taken along the line and in the direction of the arrows 24-24 of Figure 8;
Figure 25 which appears on sheet 8 is a transverse cross sectional view of the drive slug assembly, said view being gen-erally taken along the line and in the direction of the arrows 25-25 of Figure 8;
Figure 26 which appears on sheet 8 is a transverse cross sectional view of the drive slug subassembly generally taken along the line and in the direction of the arrows 26-26 of 10 Figure 8;
Figure 27 is a transverse cross sectional view showing the lift rod retaining disk in the center outer tube; said view being generally taken along the line and in the direction of the arrows 27-27 of Figure 6;
Figure 28 is a transverse cross sectional view generally taken along the line and in the direction of the arrows 28-28 of Figure 6 to show the set screw for retaining the transverse outer lift inner tube in the same angular relationship to the axially inner outer tube as the lift tube moves axially rela-20 tive thereto;
Figure 29 which appears on sheet 3 is a transverse cross sectional view generally taken along the line and in the di-rection of the arrows 29-29 of Figures 5 and 30 to show the structure for operating the detent balls between a landing ring release position and a landing ring latching position;
Figure 30 which appears on sheet 6 is a side elevational view of the piston tube with an axial intermediate portion and the end portions broken away to more clearly show the camming track and camming grooves thereon;
Figure 31 which appears on sheet is a side view of the drive slug (pivot rod);

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Figure 32 which appears on sheet 10 is an exterior view of the piston tube rolled out flat with an axial intermediate por-tion broken away, said view also showing the relative positions of the cam sleeve recesses and cam set screws, said view also showing different positions of one of the cammlng set screws and the latch ball relative to the piston tube during a cycle of operation;
Figure 33 which appears on sheet 7 is a fragmentary trans-verse cross sectional view generally taken along the line and in the direction of the arrow 33-33 of Figure 5 to more clearly illustrate the structure adjacent the landing ring;
Figure 34 which appears on sheet 2 is a transverse cross sectional view generally taken along the line and in the direc-tion of the arrows 34-34 of Figure 5 showing the mounting of a pin for moving the lift rod axially outwardly relative the head tube and the piston tube;
Figure 35 which appears on sheet 2 is a transverse cross sectional view generally taken along the line and in the direc-tion of the arrows 35-35 of Figure 4 to show a portion of the stopper subassembly and the mounting thereof;
Figure 36 which appears on sheet 2 of the transverse cross sectional view generally taken along the line and in the direc-tion of the arrows 36-36 of Figure 4 to further illustrate the construction and mounting of the stopper subassembly;
Figure 37 which appears on sheet 7 is a transverse cross : :
sectional view generally taken along the line and in tne direc-tion of the arrows 37-37 of the latching mechanism of the safety release assembly of Figure 4 to illustrate the latching relationship to the bit retraction tool;
Figure 38 which appears on sheet 7 is a fragmentary lon-gitudinal sectional view generally taken along the line and in the direction of the arrows 38-38 of Figure 37 to further ~13~ 3 illustrate the construction of a latch and the latch latchingly engaging a retaining ring of the bit retraction tool;
~ igure 39 which appears on sheet 7 is a fragmentary longi-tudinal cross sectional view generally taken along the line and in the direction of the arrows 39-39 of Figure 38 to further illustrate the construction of a latch, a portion of the acti-vating shank being broken away;
Figure 40 is a fragmentary view of the bit retraction tool adjacent the stopper subassembly mounting pin, part of the outer lift tube being broken away;
Figure 41 is a front view of the surface tool mounted on an axial outer end of the drill stem, with an axial intermedi-ate portion broken away, said view being generally taken along the line and in the direction of the arrows 41-41 of Figure 42;
Figure 42 is in part a transverse cross sectional view generally taken along the line and in the direction of the arrows 42-42 of Figure 41, and in part a side view of the structure of Figure 41, an axial intermediate portion of the surface tool being broken away;
Figure 43 which appears on sheet 11 is a transverse cross sectional view of the stationary clamp block subassembly, said view being generally taken along the line and in the direction of the arrows 43-43 of Figure 41;
Figure 44 which appears on sheet 11 is a fragmentary longitudinal view generally taken along the line and in the direction of the arrows 44-44 of Figure 43;
Figure 45 which appears on sheet 11 is a fragmentary front view of the stationary c~mp subassembly, said view being generally taken along the line and in the direction of the arrows 45-45 of Figure 43;
Figure 46 which appears on sheet 11 is a transverse cross sectional view of the lift clamp subassembly, said view being generally taken along the line and in the direction of the arrows 46-46 of Figure 41;

~ ~ 3Y ~ ~

Figure 47 is a longitudinal view somewhat diagrammatic-ally showing the bit installation tool in latching engagement with the drill stem prior to starting retraction of the safe-ty release tool for installing the bit on the drill stem, an axially intermediate part being broken away;
Figure 48 is a view similar to Figure 47 other than the safety release tool has been retracted to a position the bit is locked to the drill stem;
Figure 49 is a longitudinal view somewhat diagram-lO matically showing the bit removal tool in latching engagement with the drill stem prior to starting retraction of the safe-ty release tool for removing the bit from the drill stem, an axially intermediate part being broken away; and J Figure 50 is a view similar to Figure 49 other than the safety release tool has been returned to a position the bit is in a position to be retracted through the drill stem.
Referring now in particular to Figures 1-3, the drill bit of this invention, generally designated 10, has generally planar side surfaces 11, 12 that are diametrically opposite 2~ one another and are inclined to be nearly parallel to the central axis R-R of the bit to converge in an axial outer direction. For example, the angle of one of the planar sur-faces is about 3 relative the central axis. The planar sur-faces extend axially between the transverse outer surface 13 and the transverse inner bottom surface 14. Further, the bit has generally cylindrical outer surface portions 15 that are diametrically opposite one another and extend between the planar surfaces 11 and 12. Extending between the axial inner edges of surfaces 15 and the bottom surface 14 are generally frustoconical surface portions 16. Industrial diamonds (not shown) are set on the surfaces 14, :16.
The bit has a central bore 19 that extends axially there-through, the axial outer bore portion l9c being beveled axially and radially inwardly to in~tersect the axial inter-mediate bore portion l9b which is of a larger diameter than the axial inner bore portion 19a whereby an annular axially outwardly facing shoulder 20 is formed. Opening through the inner wall that defines bore portion l9b are four equally circumferientally spaced detent recesses 21.
l'he planar faces 11 and 12 are respectively provided with lock key recesses 24 and 25 that are circumferentially elongated. Further, in transverse cross section the recesses are ~enerally triangular shaped, the recesses in transverse opposite directions extending progressively closer to a plane 26-26 of the central axis of the bit that is midway between planar surfaces 11, 12. Thus in the angular direction of arrow 54, the recesses are of progressively greater depths, the minimum depth portion of the recesses being adjacent, but on transverse opposite sides of a plane Y-Y of the bit central. axis that is perpendicular to plane 26-26.
The axially outer surface portion of the bit is provided with arcuatly elongated flange orienting recesses 23 that are diametrically opposite one another and are centered with reference to planar surfaces 11, 12 of the bit. The axial outer part of recesses 23 are beveled to be convergingly in-clined in an inward direction. Other than for the aforemen-tioned recesses, the axial outer surface 13 of the bit is planar and is generally parallel to the axially inner surface 14.
In order to mount the bit for drilling a bore hole, ~ 1 3~
there is provided a drill stem (drill string) having an outer barrel assembly, generally ~esignated 30, at its inner axial end tsee Figures 8 and 13). The outer barrel assembly 30 includes a reaming sheet subassembly 30A, a locking sleeve subassembly 30B, a stationary sleeve subassembly 30C, and an orienting pin subassembly 30D, each being respectively gener-ally designated.
The reaming shell subassembly includes an axially elonga-ted shell tube 31 that has circumferentially adjacent axially elongated lock grooves 32 and 33 respectively that open to the interior thereof and open through the inner annular edge of the tube. Welded to the inner annular edge of the shell tube is an adapter ring 34, the adapter ring having diametri-cally opposite, arcuately elongated flanges 34a that extend axially away from the tube 31 and are extendable into the orienting recesses 23 of the bit. The arcuate length of each of the flanges is substantially less than that of a recess 34. Further the adapter ring is provided with a pair of arcu-ately elongated recesses 35 that open toward one another, and are centered between the flanges 34a.
Welded to the adaptor ring to extend axially inwardly thereof are a pair of diametrically opposed drive lugs 36 and 37 respectively (see Figures 11, 12 and 13). Since each of the drive lugs is of the same size and shape, other that they are oppositely faced, primarily only drive lug 36 will be described. Drive lug 36 includes a generally planar face 36a that in axial direction is inclined at an angle sub-stantially equal but opposite the angle of inclination of the adjacent planar side surface of the bit 10 when it is mounted on the drill stem. Further, the drive lug includes a 1 1 3~

cylindrical outer surface 36b that is curved to form a con-tinuation o surfaces 15, and frustoconical surface 36c which is shaped from a continuation of surfaces 16. Additionally the drive lug includes an axial inner surface 36d that is shaped to form a continuation of the inner surface 14. The drive lugs 36, 37 are mounted by the adaptor ring to have the planar surfaces 11, 12 of the bit received between the planar surfaces of the drive lugs and the surface 14 of the bit to be a general planar continuation of the drive lug axial inner transverse surfaces. At this time the combination of drive lugs and bit pr~vide a circular annular axial inner surface.
The drive lugs are provided with diametrically opposite arcu-ately elongated key lock receiving recesses 39 that open axi-ally to the adjacent adapter ring recess and radially to the bit recesses 24 and 25, respectively when the bit is locked - to the outer barrel assembly 30.
Located in the shell tube is the locking sleeve sub-assembly 30B which includes an axially elongated locking sleeve 44. The locking sleeve has an axial inner annular edge 45 that is in rotatable abutting relationship to the outer edge of the adapter ring, diametrically opposed ex-tensions 46 of the sleeve extending through the adaptor ring recesses and mounting lock keys 47 that are extendable into the bit recesses 24, 25 for releasably retaining the bit in driven relationship to the drive lugs.
Mounted on the transverse inner surface of the locking sleeve adjacent the axial inner end thereof are a plurality of stabilizing pads 49. Axially outwardly of the stabilizing pads, the locking tube is provided with a general rectangular -30 opening 50. A circumferentially elongated detent spring 51 1 1 ~8~ ~9 has one axial edge Sla welded to an axial edge that in partdefines the opening 50 (see Figure 14). Circumferentially remote from edge 51a, the detent spring has an axially elong-ated dimpled portion 52 that extends radially outwardly. In one angular position of the locking sleeve relative the shell tube, the dimple 52 extends into groove 33 and in a second angular position, the dimple 52 extends into groove 32. Thus the spring 51 serves to resiliently retain the locking sleeve in one of two angular positions relative to the shell tube.
Referring now in particular to Figure 16, it is to be noted that the locking sleeve includes an axial outer tran-sverse edge 58 and axial intermediate transverse edge 59.
From one circumferential end of the transverse edge 58, the locking shell has an axial edge 60 that at the inner end thereof intersects the edge 61 that is inclined inwardly in the angular direction represented by arrows 54. The inner edge of 61 intersects an axial edge 62 which in turn inter-sects one end of edge 59, the opposite end of edge 59 inter-secting one end of axial edge 66. The outer end of axial end - 20 66 intersects one end of an edge 65 that is inclined axially outwardly in the angular direction represented by arrow 53.
The outer end of edge 65 intersects the one end of axial edge 64, the edge 64 intersecting the transverse edge 58 circum-ferentially remote from edge 60. The circumferential spacing of edge of 66 from edge 62 is substantially the same as the - circumferential spacing of edge 60 from edge 64, however, edge 65 is located further axially outwardly than edge 61.
The stationary sleeve 70 of the stationary sleeve sub-assembly 30C has an extension 70a that extends into the cut-out defined by edges 59-62, 64-66; the sleeve having an axial 1 ~ 3~ 3 inter~ediate edge 72 abutable agalnst edge 58 and an axial inner edge 71 that is closely adjacent to or in abutting re-lationship to edge 59. Extending between one end of edge 72 and transverse edge 71 is an axial edge 73 while an axial edge 74 extends between the opposite ends of transverse edges 71, 72. The minimum circumferential spacing between edges 60, 73 is sufficiently great to have the locking pin 75 ex-tend radially therebetween while the minimum circumferential spacing of edges 64, 74 is sufficiently great to have the locking pin 76 extend therebetween. In order to prevent the sleeve 70 from rotating when the locking pins extend between the aforementioned edges and are moved axially relative there-to, a set screw 69 is threaded through the shell tube and into the stationary tube extension 70a.
Referring now in particular to Figures 13, 20 and 21, the stationary tube 70 has diametrically opposed, axially elongated openings 82 adjacent its transverse outer edge 78.
For each opening 82, an axially elongated leaf spring 83 has its axial opposite edges retained in grooved portions 83a of the stationary tube that opens to the shell tube while the intermediate portion thereof resiliently extends through open-ing 82 and a short distance into the interior of the station-ary tube. The axially intermediate portion of the leaf spring mounts a radially inwardly extending button 84 to be diametrically opposite the button of the other leaf spring.
Further, a plurality of circumferentially spaced stabilizing pads 85 are mounted on the inner surface of the stationary tube adjacent its transverse outer edge 78.
In order to remove the bit 10 that is being retained between the drive lugs 36, 37, there is provided the bit ~ ~ 3~ ~*~

retraction tool, generally designated 77. Referring now in particular to Figure 8-12, the tool 77 includes a floater subassembly F that has an annular floater 90. The floater 90 has an outer enlarged diametric portion 90a, an intermediate portion 90b that in conjunction with portion 90a provides a shoulder seatable on the axial outer surface of the bit, and a reduced diameter portion 90c that in conjunction with por-tion 90b forms a shoulder. Additionally, the floater has a bore 91~extending axially therethrough, the bore being de-fined by diametrically opposed parallel planar wall portions91b of the floater and diametrically opposed cylindrical wall portions 91a that extends between planar wall portions. The axial inner end of the bore is closed by a plug 97 other than for a central bore that extends through the plug.
Circumferential spaced apertures 92 extend radially through the intermediate portion of the floater for mount-ing lock balls 103 in a position to be moved into the detent recesses 21 of the bit. Circumferentially between a pair of apertures 92 of the floater is provided with a slot 94 that extends radially therethrough and opens through the trans-verse outer surface thereof. Diametrically opposite slot 94 the floater is provided with an axially elongated slot 9S
that opens to bore 91 and through the transverse inner sur-face of the floater, the inner end of slot 95 opening to a plunger recess 96 which in turn opens to bore 91.
Mounted for axially movement in the floater bore 91 is a floater plunger 101 that has diametrically opposite cylin-dricaL surface portions lOla that form a close sliding fit with cylindrical wall portions 91a and diametrically opposed - 30 planar wall portions lOlb that form close sliding fit with ~ 4 ~

wall portions 91b. Further, the plunger has circu~ferential spaced recesses 102 that when radially ali~ned with cylin-drical apertures g2 permit the lock balls 103 moving radially - relative the drill bit; but when the plunger is moving axi-ally inwardly, the cylindrical surface portions force the balls into recesses 21 as will be more fully explained herein-after.
Mounted within a radial aperture 106 in the floater plunger is a ball plunger 104 that is resiliently urged radi-ally outwardly by a spring 105. At the time the finger 99 of the cam tube 98 of the cam tube subassembly, generally desig-nated C, extends through slot 95 and the part thereof axially outwardly of its beveled inner end abutting against the ball plunger, the ball plunger is retained within the confines of the plunger aperture 106. However, when the finger 99 is axi-ally outwardly of the recess and the ball plunger is radially adjacent recess 96, spring 105 moves the ball plunger into the recess 96 to prevent relative axial movement between the plunger 101 and the floater 90.
The plunger 101 is provided with a pair of axial aper-tures 109, springs 110 being located within the apertures and bearing against the head portions of screws 111 and shoulders on the plunger 101 to resiliently urge the plunger 101 axi-ally toward the floater plug 97. The screws 111 are threaded into the floater plug. The plunger 101 has a slot 113 extend-ing diametrically thereacross to open outwardly and provide outwardly extending ears lOlc. A transverse pivot 115 is mounted by one radially outer end portion of the plunger ears for pivotally mounting a pivot member 117 that extends across the slot 113. The slot 94 is of a size to have the pivot ~3l34~L~3 member extend thereinto when the plunger 101 is-moved to be closer adjacent the floater i)lug 97.
The pivot member 117 forms part of the drive slug sub-assembly D and is welded to the inner end of the extension 118a of the drive slug (pivot rod) 118 (See Figure 8, 24 and 31). A cylindrical opening 119 extends axially through a transverse outer portion of the drive slug and continues the axial length of the extension to open radially inwardly. The inner part of the cylindrical portion 118c of the pivot rod 118 has an axially elongated bore 120 that opens through the inner transverse surface 118b of the cylindrical portion and opens to the cylindrical opening 119. Also cylindrical por-tion 118c has an arcuate recess 124 that opens to the cylin-drical opening 119 just outwardly of the bore 120 and is pro-vided for receiving a portion of the latch disk 123. On the radial opposite side of the cylindrical opening from the arcu-ate recess, the cylindrical portion 118c is provided with an axially elongated slot 125 that opens to the cylindrical re-cess and through the outer circumferential surface portion 118cj the slot being of a size to receive a portion of the latch disk and extending axially outwardly a greater distance than the arcuate recess. The diameter of the latch disk is greater than the maximum transverse dimension of the arcuate slot plus the diameter of the cylindrical opening and also is greater than the combination of the transverse dimensions of opening 119 and slot l25. Axially aligned with slot 125 and axially outwardly thereof the cylindrical portion has an ax-ially elongated transfer pin slot 128 that opens through the transverse outer surface of the portion 118c to the cylin-drical opening. Axially intermediate slots 125, 128 the ~3~4~3 cylindrical portion is provided with a transverse aperture 112 that opens to the cylindrical opening and to the trans-verse outer surface thereof on the diametrically opposite side from slots 125, 128 for mounting a rotation pin 127. An axially elongated spring shaft 129 has its inner end mounted by the outer end of the drive slug.
The axially inn'er end portion of the cylindrically por-tion 118c is provided with a transverse outer arcuate cutout that provides a recess 122 of a size to have the finger 99 extended thereinto and at the same time permit the drive slug to be rotated through an angle of approximately 90 relative the finger.
Mounted in the cylindrical opening of the drive slug for slideable movement relative thereto is an axially elon-gated cylindrical actuating rod 131, the clevised inner end of the actuating rod being pivotally connected at 134 to the outer end of a pivot arm 135. The inner end of the pivot arm is pivotally connected by a pivot member 136 to the ears of the plunger 101. As may be noted in Figure 8, pivot 136 is transversely opposite pivot 115 and is parallel thereto.
Outwardly of the pivot 134, the actuating rod has a disk slot 137 for rotatably receiving a latch disk 1~3 while permitting very limited axial movement of the latch disk relative the actuating rod. Outwardly, of the disk slot, the actuating rod has an axially elongated rotation pin slot 138 for having one end of the rotation pin 127 extended thereinto. The out-er end of slot 138 limits the axial inward movement of the actuating rod relative the drive slug. Outwardly of slot 138 the actuating rod has an aperture 140 for mounting the trans-fer pin 139 to extend into the transfer pin slot 128. The ~ ~ 3~

relative position of the rotation pin and transfer pin and th~ir slots are such that the actuating rod cannot move to a position that the latch disk can move into the transfer pin slot 128.
Referring to Figures 7 and 8, the spring shaft 129 slid-ably extends through the reduced diameter bore portion of the spring cap 126, there being provided a spring 130 having one end abutting against the spring cap and an opposite end abut-ting against a washer 132 that in turn abuts against a thrust bearing 133 which abuts against the drive slug. This struc-ture permits limited axial movement of the drive slug rela-tive the spring cap and the drive slug rotating relative the spring cap. On the outer end of the spring shaft there is provided a snap ring 147 abutting against a washer which in turn abuts against a thrust bearing 133 that is on the axial opposite side of the reduced diameter bore portion from spring 130. This structure limits the axial inward movement of the drive slug relative the spring cap. An axial outer drive slug 148 is threaded into the spring cap bore and has a recess 149 into which the spring shaft may be extended to per-mit limited axial movement of the spring shaft relative there-to. The axial outward movement of the drive slug 148 rela-tive the cam tube 98 is limited by abutting against a snap ring 150 that is mounted in a groove in the cam tube.
The drive slug 148 has a bore i52 extending diametric-ally therethrough (see Figure 17), an annular locking pin body 153 being mounted at each end of the bore and having a transverse outer, enlarged diametric flange seated against the adjacent enlarged bore portion shoulder 152a.
. . .
In each of the locking pin bodies there is mounted one of ~ 9 the locking pins 75, 76 for radial movement, a snap ring 157 bein~ provided in body to limi~ the radial inward movement of the respective pins. A spring 155 at one end bears against the inner enlarged flange 75a of the pin 75 and at opposite end abuts against shoulder 153a of the body for resiliently urging pin 75 radially inwardly. Pin 75 also has a trans-verse outer enlarged annular flange 75b and a head portion 75c extending transversely outwardly of flange 75b. Spring 155 resiliently retains pin 75 in a position that head 75c does not extend radially outwardly of the outer peripheral wall of the cam tube 98, and flange 75b is located trans-versely between the inner and outer peripheral walls of the cam tube as will be more fully set forth hereinafter. Lock-ing pin 76 is of the same construction and mounted in the same manner as pin 75 but is oppositely faced.
The axial inner ball screw assembly B includes a ball nut 161 that is secured to a flange 162 that is bolted by - bolts 163 to the outer end of the drive slug 148 to prevent rotation of the ball screw nut relative the drive slug. An axial inner ball screw 164 is threadedly extended through the ball 161 and into the bore 156 of the drive slug 148 whereby as the ball nut screw is rotated relative the ball nut 161, the drive slug 148 is moved axially relative to it. The out-er end of the ball screw is mounted by bearing shaft 167 to be rotated thereby, the bearing shaft rotatably extending axially through a coupling 168. A bushing 170 is provided between part of the coupling and the outer end portion of the bearing shaft. Thrust bearings 171 are provided on either axially side of the enlarged diametric flange 168a of the bearing shaft. The coupling cap 172 is bolted at 173 to the ~31~4~-3 coupling 168 for removably retaining the bearing shaft in a fixed axial position relative the coupling. The outer end of the cam tube 98 is threadably mounted on the coupling 168.
Referring now to Figure 22 and 23, the cam tube in-cludes a palr of axially elongated diametrically opposite orienting pin grooves 175 in the transverse outer surface portion thereof. The outer ends 175a of the grooves are lo-cated a short distance inwardly of the coupling 168, the grooves including outer linear portions 175b that at their lower ends are joined to groove portions 175c. Groove por-tions 175c, as they extend axially inwardly, are curved around the circumference of the cam tube in the angular dir-ection of arrow 178, the groove portions 175c extend angu-larly through an angle of 188. Just axially outwardly of groove portions 175c, groove portions 175b open to an annular groove 179.
Diametrically opposed locking pin slots 176 are located between groove portions 175c and have enlarged outer slotted end portions 176a, axially elongated linear portions 176b, and inner ends 176b that are located axially outwardly of the inner ends 175d of the orienting pin grooves. Referring to Figures 18, 19, a short distance inwardly of the slotted por-tion l76a, on each wall defining the respected slotted por-tion 176c has a generally trapezoidal cam portion 177, which is of an altitude substantially the same as the radial thick-ness of the cam tube and has its minor base 177a substan-tially coextensive with the outer periphery of the cam tube.
The outer edges 177d of the cam portions 177 are inclined transversely outwardly in an axial inward direction while the opposite edges 177c of the cam portions are inclined axially inwardly in the transverse inward direction. As the locking pins 75, 76 are moved in the slots 176 to a posit:on that their flanges 75b, 76b engage surfaces 177d, the locking pins are cammed transversely away from one another to positions to extend between the circumferentially spaced, axially extend-ing edges of the locking sleeve 44 and the outer sleeve 70 such as shown in Figure 16. As the locking pin flanges 75b, 76b moveover surfaces 177c, the locking pins are resiliently urged toward one another to be retracted from extending be-1-0 tween sleeves 44, 70.
A generally L-shaped transfer pin slot 180 is provided in the cam tube, the slot 180 having an axially extending leg 180a, that has its outer end located circumferentially be-tween the inner ends of the orienting pin grooves 175. Fur-ther, the transfer pin slot has a circumferentially extending leg 180b that extends arcuately through an angle of about 122 and arcuately in a direction opposite arrow 178 from the inner end of leg 180a.
Additionally, the cam tube is provided with a rotation pin slot 181 that has an axially extending leg 181a with an upper end circumferentially between orienting pin groove ends 175d and on the diametrically opposite side of the tube from leg 180a. Leg 181a extends a substantial dis-tance axially inwardly of leg 180b, and at its inner end in-tersects an arcuately curved, axially inwardly extending leg 181b. Leg 181b extends arcuately through an angle of about 90 (in a direction opposite arrow 178) and at its inner end intersects the short axial leg portion 181c.
Inwardly of the inner slot portion 181c, the cam tube is provided with a roller (latch disk) slot 182. The slot 1~3~4~t has a circu~ferentially elongated slotted portion 182a that extends arcuately through an angle of about 120, one end portion of slot portion 182a opening to an axial slotted por-tion 182b. The axial dimension of the transverse inner peri-pheral wall portion of the slot is greater than the axial dimension of the outer wall portion whereby the wall portions that in part define the slot are somewhat dished-shaped at 182c.
Referring now in particular to Figures 6 and 7, the lift tube subassembly X includes an axial inner, transverse outer tube 197 having its inner end threadedly mounted on coupling 168. The inner end of the axial outer ball screw 192 is con-nected to the bearing shaft 167 to rotate the bearing shaft therewith. The ball screw 192 extends through the axial out-er ball nut 193 whereby as the ball nut is moved axially, the ball screw is caused to rotate. Located within the trans-verse outer lift tube 197 is a transverse inner lift tube 191 that has its inner end attached to the ball nut 193 to move the ball nut therewith. A set screw 196 is threadedly mount-ed by the outer lift tube and extended into the axially elon-gated groove 195 of the inner lift tube to prevent the inner lift tube rotating relative the outer lift tube as the inner lift tube is moved axially relative the outer lift tube.
The axial outer end of the transverse outer lift tube 197 is threadedly connected to the inner one of the coupling half section 200 of the swivel subassembly S. A swivel con-nector 201 connects the swivel half section 200 to the outer swivel half section 202 which in turn is threadedly connected to the inner end of the axial center, transverse outer tube 211 of the axial center, transverse outer tube subassembly G.

~ 3~

The inner lift tube 191 is axially movable in the swiv-el subassembly, the ~uter end of the lift tube 191 being threadedly connected to the lift cap 203. A lift stud 207 is extended through the lift cap, there being provided snap rings 206, washers 205 and thrust bearings 204 on either side of the outer portion of the lift cap to prevent the lift cap moving axially relative the stud but to permit rotation of the lift cap relative to the stud.
The outer end of the lift stud 207 is threadedly connec-ted to the axially elongated lift rod 212 that is rectangu-lar in transverse cross section. The lift rod extends axia-lly outwardly through a rectangular aperture 214 in the plate (shaft retaining disk) 213 that is welded in a fixed position in the tube 211 (also see Figure 27). The disk has a plurality of fluid bypass apertures 215 that open to the rod aperture 214.
The lift rod extends axially outwardly of the retain--ing disk 213 and axially slideably through a piston 218 that is threadedly secured to the lower end of a piston tube 223 to be moved therewith (see Figure 5). The piston has an 0-ring 219 for forming a fluid seal with the head tube 217.
The inner end of the head tube is threadedly connected to the center outer tube 211, a lock ring 220 being threaded on the head tube and abutting against the outer tube to re-tain the outer tube in an adjusted threaded position on the head tube.
An axial intermediate portion of the piston tube is rotatably and axially slidably extended through a cam sleeve 224, the outer transverse edge of the cam sleeve abutting against a retainer ring 225 that is mounted by the head tube 1 ~ 3~ 3 to prevent the cam sleeve moving axially outwardly relative the head tube. The inner end of the cam sleeve abuts against an annular shoulder 221 of the head tube, the cam sleeve being rotatable relative the head tube but not axially movable relative thereto. Three pins 226 are mounted in equal circumferentially spaced relationship by the cam sleeve to respectively extend into one of the equally circumferen-tially spaced, transversely outwardly opening, axially elon-gated grooves 232-234 of the piston tube to prevent relative rotation between the cam sleeve and the piston tube (see Fig-ure 33). Axially inwardly of the pins 226, the cam sleeve is provided with three latch recesses 227 that are circumferen-tially equally spaced from one another and three latch reces-ses 228 that are equally circumferentially spaced from one another (see Figures 30 and 33). With the pins 226 extended into the axially elongated portion of 223a of groove 232-234, the recesses 227, 228 are located such that one recess 227 is located on one side of groove portion 223a and one recess 228 is located on the circumferential opposite side and closely adjacent the same groove portion. With reference thereto, the relative positions of the recesses 227, 228 and the pins 226 are illustrated in dotted lines in Figure 32 to show their positions relative the grooves.
The inner end of each groove portion 223a opens to the inclined groove portion 223b that extends circumferentially in a direction of the arrow 231 in an inward direction, the inner end of groove portions 223b opening to the short axial groove portions 223c.
The outer end of each groove 232-234 opens to the cam trac~ T. For each of the aforementioned grooves, the cam ~ 3 track includes an axial edge 239 and an inclined edge 240 that at their inner ends open to the respective groove, por-tion 223a, edge 240 being inclined to diverge away from edge 239 in an outward direction. The outer end of edge 240 is joined to an inclined edge 241 which extends outwardly about the same distance from the respective groove as edge 239 but diverges at an angle that is substantially smaller than the angle of divergence of edge 240. The outer end of edge 241 is joined to the outer end of an axial edge 242 while the inner end of edge 242 is joined to the inner end of an in-clined edge 243, which in turn is joined to the inner end of inclined edge 244. The angle of divergence of edges 243 and 244 relative edge 242 is the same as that of edges 241 and 240 to edge 239. The outer end of edge 244 is joined to the edge 239 of the next adjacent one of groove portions 223a.
Approximately midway between the edges 239, 242, for each groove, the cam track has an axial edge of 247 that at its upper end is joined through a reversely curved edge por-tion 250 to an inclined edge portion 249. Edge portion 249at its inner end is joined to an edge portion 248, edge por--tion 249 in an inward direction diverging from edge 247 at a substantially greater angle than the angle of divergence of edge portion 248 from edge 247. The inner end of edge por-tion 248 is approximately midway between the circum-ferentially adjacent parts of edges 244, 242. The inner end of edge 247 is joined to an edge 245 which, in turn, is joined through edge portions 246 and 253 to the outer end of axial edge portion 254. The shape of edge portion 245, 246, 253 and 254 is the same as that of edge portions 248, 249, 250 and 247, respectively. Mounted by the head tube to ex-tend into the cam track groove T are three equally circum-ferentially spaced set screws 252, screws 252 being axially outwardly of the cam sleeve 224.
Just axially outwardly of the cam tract T, the piston tube has an enlarged diametric portion 223d in which there is provided a groove that mounts an 0-ring 256 to form a fluid seal with the head tube axially outwardly of the aper-tures 229.
The reduced diameter inner end portion of an adjust-ment sleeve 257 is threadedly mounted in the outer end of the piston tube, a locking sleeve 258 being threaded on the adjustment sleeve in abutting relationship to the piston tube to hold it in an adjusted axial position relative the adjust-ment sleeve. The reduced diameter end portion of an axial outer sleeve 261 is threaded into the enlarged diameter por-tion of the adjustment sleeve 257 and bears against a thrust collar 262 that abuts the outwardly facing annular shoulder 260 of the adjustment sleeve. The inner diameter of collar 262 is substantially less than the minimum inner diameters of each of sleeves 257 and 261, the lift rod 212 extending through the thrust collar in spaced relationship to the inner peripheral wall thereof.
A spring washer 263 is retained in abutting relation-ship with the inner transverse edge of the adjustment sleeve 257 by spring 264, the inner end of spring 264 abutting against the spring collar 265 that is welded to the lift rod 212.
Axially between the spring washer 263 and the thrust collar 262, axially spaced pins 266 and 267 are mounted by the lift rod. The axial length of each of the pins is greater than the inner diameters of the washer and ~ollar, pin 266 serving to abut against the washer 263 for retain-ing the spring in compression during assembly. Pin 267 pro-vides an indication of proper adjustment of the threading of the adjustment sleeve in the piston tube and the head tube in the outer tube 211. Axially outwardly of the thrust col-lar, the lift rod mounts a pin 268 that is of a greater axial length than the inner diameter of the thrust collar.
Axially outwardly of the lift rod 212 and in the outer end portion of the outer sleeve 261, there is welded a plug 270 that has a central aperture 278 therethrough (see Fig-ures 4, 36 and 40). Outwardly of the plug, the sleeve has diametrically opposed slots 272, a spring pin 271 being ex-tended through the slots and movable a limited amount in the slots in an axial direction. The spring pin is mounted by a stopper 273 which slidably extends through the central aper-ture in a retainer plate 275. The retainer plate is bolted at 276 to the inner circumferential wall portions of diamet-rically opposed retainer plate slots 277 of sleeve 261. As may be noted in Figure 4, the retainer plate is axially be-tween the plug 270 and the spring pin 271. A coi~ spring 274 has one end abutting against the retainer plate and an oppo-site end abutting against the annular flange at the base of the,generally frustoconical head portion of the stopper for resiliently urging the stopper to a position to block fluid flow through the plug aperture 278 when pin 271 is in the inner end portions of slots 272.
The transverse outer end portions of pin 271 slidably extends into axially elongated slots 281 that are provided ~ 3 in the axial outer lift tube 269. Transverse slots 282 open to the slots 281 at a slight distan~e above the inner ends thereof whereby the tube 269 can be rotated relative the pin 271 a limited amount in a transverse plane. Slots 281 are of a substantially greater axial length than that of slots 272.
Referring to Figures 4, 37 and 38, axially outwardly of the lift tube slots 281, the lift tube is provided with a transverse inner, angular recess 287, a wire snap ring 284 being mounted in the recess to resiliently retain the two retainer ring half sections 285, 286 with their ends closely adjacent or in abutting relationship whereby the retainer ring has a smaller inner diameter than the inner diameter of the adjacent part of the inner peripheral wall of the lift tube 269.
A reduced diameter portion 302c of a latch mounting cylinder 302 is extended axially through the retaining ring 285, 286, the latch mounting cylinder being part of a safe-ty release assembly, generally designated 290. The inner end of portion 302c of the cylinder is joined to the major base end of a frustoconical tapered portion 302d which has its inner end close by a wall 302e. The outer end of por-tion 302c is joined to an intermediate diameter cylindrical portion 302b to form a shoulder 303 therewith that abuts against the retaining ring 285, 286 to limit the inward move-ment of the safety release tool relative the bit retraction tool. The outer end of cylindrical portion 302b is joined to enlarged diametric flange 302a that has a greater outside diameter than the inner diameter of the adjacent end of the lift tube 269.
The axial outer reduced diameter end portion of an ~ 4 ~-~

activating shank 291 extends through a compression spring cylinder 292 that has its inner end welded to the latch mount-ing cylinder 302. Adjustment member 293 i5 threadedly mount-ed by the outer end of the compression spring cylinder, the activating shank being slideably extended through the adjust-ment member and at its outer end having a spear point head 2-97 mounted thereto by a pin 296. A spring 294 is provided on the activating shank and has one end abutting against the adjustment member and an opposite end abutting against a com-pression collar 295 that is welded to the shank whereby the activating shank is resiliently urged inwardly. A set screw 316 is mounted by the spring cylinder to extend into a posi-tion to limit movement of the compression collar in the event an axial outer force of greater than a preselected value is exerted on the spear point head while the spring cylinder is prevented from moving axially outwardly. Prior to the com-pression collar abutting against screw 316, the latches L
will have moved to a retainer release position as will be set forth hereinafter. The movement of the activating shank in an axial inward direction is limited by the shank abutting against the transverse wall 302e of the latch mounting cylin-der.
The latch mounting cylinder has four circumferentially spaced latch slots 304, a latch pin 305 mounting a latch L in each of the slots. In a retainer ring latching position, each latch has a transverse outer axial edge 306 that.at its inner end intersects with the transversely extending edge 307 to provide a shoulder for abutting against the inner surface of the retainer ring. Edge 307 is inclined transversely out-wardly and slightly axially inwardly; and is transversely outwardly and axially inwardly of the pivot axis of pivot pin305 whereby the latch can pivot in the direction of the arrow 310 as will be set forth hereinafter. Inwardly of the edge 307, the latch has edge 308 that is inclined both axially and transversely inwardly to provide a camming surface for expand-ing the retainer ring 285, 286 and snap ring 284 transversely outwardly further into recess 287 when the activating shank is abutting against wall 302e and the safety release tool is moved axially inwardly relative the lift tube to a position to latchingly engage the retainer ring such as shown in Fig-ures 4 and 38. Further, each latch has a transversely and axially outwardly tapered edge 309 that is abuttable against adjacent edge 304a that in part defines latch slot 304 for limiting the pivotal movement of the latch about latch pin 305 in a direction opposite arrow 310. Transversely opposite - from edges 306, 307, the latch is provided with a rounded transverse inner, axially outwardly facing shoulder 312 for abutting against a roller 315 whereby the roller is retained adjacent the transverse outer and axial inner portion of the activating shank that in part is defined by the axially elon-gated roller groove 314. The groove opens through the trans-verse inner surface of the activating shank. Latch edges 309 and slot edges 304a limit the movement of the latches in the direction opposite of the arrow 310 whereby shoulders 312 abut against the rollers to retain the rollers in the roller grooves.
Axially outwardly of shoulder 312, each latch has a rounded transverse inner shoulder 311 that is curved to face transversely inwardly in an axial outward direction. A gen-erally axially extending edge 310 extends between shoulders ~3R~

311, 312. When the pull on the act:ivating shank exceeds a preselected value, the shank 291 moves axially outwardly rela-tive the cylinder 302. As a result the axial outer trans-verse wall portions 314a of grooves 314 move outwardly and the rollers roll outwardly between edges 310 and the axial wall portions 314b that in part define grooves 314 to a pos-ition to abut against shoulders 311. At this time the latches can pivot in the direction of arrow 310 to release the tool 290 from latching engagement with the retainer ring 285, 286.
In order to mount a surface tool, generally designated 325, on the outer end of the drill stem rod 327 that extends above the surface from which the drilling operation is carried out, there is provided a mounting tube subassembly M (see Figures 41 and 42). The mounting tube subassembly includes a tube 326 that is threadedly connected to drill stem rod 327, a lock ring 328 being threaded on tube to abut against the drill stem rod. Diametrically opposed inner studs 330 and outer studs 329 are mounted in axial alignment on tube 326 to extend transversely outwardly of the tube for mounting the surface tool. The outer end of the tube 326 on diametrically opposite sides thereof has a pair of ears 327 for mounting a pivot 340 which mounts the inner end of a swing bolt 338 for pivotal movement between a position ex-tending into the slot 346 of a plate 345 and a position out of the slot. A washer 342 and a wing nut 341 are threaded on a swing bolt to releasably retain plate 345 and the fustroconical plug 344 thereon in a position to close the axial outer end of tube 326. The plug is bolted to the plate by bolts 348. An inclined slot (not shown) opens to the plug 1~ 3~
axial aperture 351 and a slot (not shown) is provided in the plate to permit a wire line 352 being extended through the center portions of the plug and plate and.at the same time prevent any substantial loss of fluid through the plug and plate when the wire line 352 is moved axially relative said plug and .plate. A fluid inlet 349 is provided on a tube for being connected to a source of fluid under pressure (not shown).
The surface tool 325 includes a vertical channel sub-assembly (housing) V that is axially elongated and includes a rear plate 359 and opposite side plates 360 that are se-cured together to be open at the front. The front portions of the side plates are cut out to provide axially inwardly opening stud slots 362 and 363 for having the studs 329 and 330 extended therethrough to mount the subassembly V on the tube 326 such as shown in Figure 42. With this type of mount-ing, the surface tool may be removed from tube 326 by being initially moving axially outwardly and then transversely away from the tube. Reinforcing gussets 361 are provided on the side walls adjacent the slots 362, 363.
A transverse plate 366 is secured to the outer ends of plate 359, 360 while the inner ends of rear plate 367 and side plates 368 are secured to the transverse plate. The plates 367, 368 are joined so that they are generally U-shaped in transverse cross section to provide a front open-ing. To the outer end of plates 367, 368 there is attached an end plate 369, the end plate 369 mounting a bearing mount 375 that in turn rotatably mounts the axial outer end of a screw shaft 376. The inner end portion of screw shaft 376 is rotatably mounted by a thrust bearing 377 that in turn extends through and is mounted by the transverse plate 366.
The reduced diameter inner end portion of the sc-ew shaft has a pinion gear 378 fixed thereto in driven relation-ship to a bevel gear 379. The beveled gear is keyed to a transverse shaft 380 that extends through wall 359 and is rotatably mounted by a shaft mount 381 that is welded to said wall. A handle 382 is keyed to shaft 380 for manually rotat-ing the shaft.
Referring now to Figures 41-45, a stationary clamp block ~o subassembly J includes a clamp block 389 secured to mount-ing blocks 388 that in turn are bolted to side walls 360 and 368 by bolts 390. The clamp block has a front opening re-cess 391, the recess being defined by opposite walls 391a, 391b that diverge in an axial outward direction and walls 391c, 391d that converge in an outward axial direction.
As may be noted in Figure 44, walls 391c, 391d, extend primarily in a transverse direction while walls 391a, 391b ~-extend predominently in an axial outward direction. The in-ner end of the recess opens through the transverse inner sur-face of the block 389 while the other end of the recess opens to a slot 392 that is generally U-shaped in transverse cross section and opens through both the transverse outer surface and the front surface of the clamp block.
A left hand front cover plate 393 and a right hand front cover plate 394 are bolted at 395 to the clamp block, the cover plates having diverging edges 393a, 394a that diverge at the same angles as walls 391b, 391a, but are substantially transversely more closely adjacent one another. Further, the cover plates have edges 393c, 394c, that coverage in an outward direction at the same angles as walls 391c,391d, and ~ 3~ 3 are located at the same elevations. Further, the cover plates have spaced axial edges 393d, 394d that are spaced the same as the transverse width of slot 392 to permit the wire line being moved into notch 392. A plate 396 is welded to the transverse inner edges of the cover plates and has a notch 396a that opens to the inner end of the recess 391 and is axially aligned with slot 392.
The stationary clamp block assembly J also includes a right hand lift lug RH and a left hand lift lug LH. The left hand lift lug includes a jar portion 400 having a surface (edge) 400a transversely and axially outwardly inclined at an angle opposite that of recess wall portion 391b but is of substantially smaller axial length as may be seen in Fig-ure 45. Opposite edge 400a, the jaw portion has an axial planar surface 400b and an axial, semi-circular recess 401.
Jointed to the jaw portion to extend outwardly between the cover plate edges 393a, 394a is a neck portion 407, the oppos-ite end of the neck portion being joined to a transversely extending arm portion 408. The arm portion mounts a spring actuated plunger device 409 that resiliently urges its plung-er member 409a into engagement with the cover plate 393.
An aperture 410 is provided in the cover plate 393 for re-ceiving the plunger member and thereby retaining the jaw por-tion in a wire line released position.
To mount the left-hand lug for movement in a direction parallel to that of wall 391b, there is provided a guide rod 403 that is extended through the jaw portion aperture 402, the inner end of the rod being mounted in the aperture 405 of plate 396 and the outer end of the rod being mounted in the aperture 406 of the block 389. A spring 404 is provided ~ 3 on the rod and has its inner end abutting against Jaw portion 400 and its outer end abutting the shoulder 406a of the en-larged diametric part of aperture 406 to resiliently urge the jaw member in the direction of arrow 411 to its wire line clamping position that is shown in Figure 44.
The right hand lift lug is of the same construction as the left hand lift lug other than being oppositely faced.
That is the right hand lift lug includes a jaw portion 414 having a surface tapered at an angle opposite that of recess wall 391a to slideably abut thereagainst, a transversely oppo-site surface 414b that is planar to the surface 400b of the jaw portion 400 and contains a semi-circular recess 415 that opens to recess 401, a neck portion 419 that extends out-wardly between the cover plate edges 393a, 394a, and an arm portion 420 joined to the neck portion to extend trans-versely away from the arm portion 408. Arm portion 420 mounts a spring actuated plunger device 409 that resiliently urges its plunger member into engagement with the cover plate 394, and when the plunger is extended into aperture 421 of cover plate 394, it retains the right hand lift lug in a wire line release position. The jaw portion 414 is mounted for slideable movement in a direction parallel to recess wall 391a by a guide rod 403 that has its inner end extended into aperture 417 of plate 396 and its outer end into block aper-ture 418. A spring 404 is provided on the rod to resiliently urge the right hand lift lug in the direction of arrow 422 to its wire line rod clamping position as shown in Figure 44.
When the right hand and left hand lift lugs are respectively moved in the direction opposite arrows 411, 422, their planar faces are moved apart, and when the lugs are moved in the opposite direction their planar faces are progressively more closely adjacent one another.
Referring to Figures 41, 42 and 46, the movable clamp subassembly K includes a left hand lift lug 429, a right hand lift lug 430, and a clamp block 431 having a clamp recess 432, left and right hand cover plates 433 and 434 respect-ively that have cover apertures 435 to receive the plungers of spring actuated plunger devices 436 whereby the lugs 429 and 430 are releasably retained in a wire line nonclamping position. Since members 429-436 are of the same con-struction, including size and shape and are in the same rela-tionship to one another as described with reference to the corresponding elements of the stationary clamp assembly J, they will not be further described.
Welded to the rear of clamp block 431 (transversely o~po-site the side to which its recess 432 opens) is a nut 440 that has internal threads forming a mating fit with the screw shaft 376. To prevent the nut rotating with the shaft as it is rotated, stop plates 441 are welded to the clamp block to extend transversely outwardly from one another and abut against the front edge of the adjacent side plate 368. Ac-cordingly, as the screw shaft is rotated, the nut, the clamp block 431 and the structure mounted thereon is moved axi-ally, the direction of axial movement depending on the direc-tion of rotation of the screw shaft.
Referring to Figures 1, 2 and 11, the maximum dimension A of the bit that is taken midway between the transverse oppo-site end of the planar surfaces 11 and 12 is about three-quarters of the outer diameter E of the cylindrical outer surface 15 of the bit. Further, the height (axial dimension) ~ 9 H in conjunction with the dimension A of the bit is such that when the bit is rotated about its central axis R-R approxi-mately 90 and ap~roximately 90 about a transverse axis that is parallel to axis Y-Y relative its position of use, the bit will pass through the adaptor ring 34 which has a minimum inner diameter N (see Figure 8) and will pass through all portions of the drill stem thereabove. Axis Y-Y passes through the central axis R-R and transversely is midway be-tween cylindrical surfaces 15.
For purposes of facilitating the d~scription of the use of the invention, it will be assumed that the bit is locked in a position of use on the lower end of the drill stem (posi-tion shown in Figures 8, 9, 12 and 13). At this time, keys 47 extend into recesses 24, 25 to retain the bit transversely between the planar faces of the drive lugs 36, 37 and the adapter ring orienting flanges 34a extend into the bit orient-ing recesses 23. Due to the relative dimensions of the parts, and in particular the axial height of the keys rela-tive the recesses 24, 25, the driving force imparted to the bit is from the planar surfaces-of the drive lugs to the planar surfaces of the bit and the axial inward force is transmitted from the inner transverse surface of the adapter ring between the orienting flanges to the planar surface 13 of the bit. In this connection, at the time the bit is cut-ting the core, the inner and outer transverse surfaces of the keys are axially spaced from the axially inner and outer transverse walls that in part define recesses 24, 25 whereby the cutting force is transmitted other than through the keys.
At the time the lock keys are in their locking position, the dimple 52 of the detent spring 51 extends into groove 33 to prevent the locking sleeve rotating relative the shell tube 31 (Figure 14) When it is desired to remove the bit while retaining the drill stem in the drill hole, the drill stem is moved axially outwardly a short distance, and if core is being taken, the core barrel inner tube assembly is withdrawn.
Thereafter, with the surface tool 325, plug 344 and plate 345 removed fro~ the drill stem, and tube 326 mounted on the drill stem, the bit retraction tool 77 has a conventional wire line overshot assembly (not shown) coupled to the spear point plug 297 of the safety release device, with the wire line extended through plug 344 and plate 345 and the coupled overshot assembly, safety release assembly and retraction tool is lowered in the drill stem by use of conventional hoist mechanism. Plate 345 with plug 344 are secured to tube 326. At this time the plunger 101 is in the position rela-tive the annular floater 90 shown in Figure 12 whereby the recesses 102 are aligned with the cylindrical apertures 92 so that balls 103 either do not extend radially outwardly of the outer circumference of the annular floater or they freely move to a position inwardly of the outer circumferential sur-face of floater portion 90b. Further, due to the weight of the tool, the pin 271 abuts against the inner axial ends of slots 281 whereby the adjacent transverse annular surfaces of the axial outer lift tube 269 and the head tube 217 are sub-stantially axially spaced from one another; the amount of axially spacing being limited by the set screws (cam pins) 252 abutting against the rounded shoulders formed at the intersection of cam track edges 242, 243 such as shown by the solid line positions Pl of the pins in Figure 32. The above - ~.3R~!3 separation also results in pin 271 moving axially outwardly in slots 272 whereby stopper 274 is moved away from aperture 278.
As the retraction tool moves axially inwardly, the inner beveled surface of the cam tube 98 comes into abutting rela-tionship with orienting pins 84 and moves the orienting pins radially outwardly. Further inward movement of the cam tube results in the cam tube moving to a position that the orient-ing pins are in radial alignment with the cam tube slots 175, and thereupon the orienting pins are resiliently urged into the cam tube slots. The amount of axial inward movement of the cam tube relative the outer tube before the pins 84 snap into the cam slots 175 depends upon the angular relationship of the cam tube relative to the stationary upper sleeve 70.
Continued inward axial movement of the cam tube relative the orienting pins results in the cam tube being rotated in the direction of arrow 178 relative the drill stem, it being as-sumed that the oriented pins initially extended into the groove portions 175c. The inward movement of the cam tube with the orienting pins extending into grooves 175 results in the pins moving from groove portions 175c to groove portions 175b whereupon no further rotation of the cam tube relative the upper sleeve or drill stem takes place. Thus, due to the position of the orienting pins and the grooves 175, the cam tube is rotated so that balls 103 will be radially aligned with floater recesses 21 when the retraction tool has been moved sufficiently axially inwardly; and the locking pins 75, 76 will be angularly aligned to be moved radially between cam edges 60 and 73, and 64 and 74 ~Figure 16).
At the time the tool 77 has been lowered so that the g shoulder 31g of the lift tube seats on the landing ring 317, the annular floater extends through the bit with the shoulder defined by floater portions 90a, 90b axially adjacent to out-er bit surface 13, and the floater recesses 92 radially align-ed with the bit recesses 21. The head tube shoulder 319 in seating on the landing ring provides a high pressure signal at the surface that indicates the tool 77 is in position to be latched to the drill stem. Due to the weight of the axial outer lift tube 269, the safety release tool and the overshot assembly; the lift tube moves axially inwardly relative the lift rod to abut against the head tube whereby pin 271 is located axially outwardly of the inner ends of slots 281 and stopper 273 is resiliently urged to block aperture 278.
With plug 344 and plate 345 in place about the wire line, fluid under pressure is pumped through inlet 319 to exert an inward force on the stopper and plug 270, which pro-vide a piston surface. It is noted that if 0-ring 256 is not presently in fluid sealing relationship with the head tube, there is a fluid seal between the head tube and piston tube that is provided by O-ring 219 and piston 218. The amount of fluid that can escape through apertures 229 prior to 0-ring 256 moving into fluid sealing relationship with the head tube, if not in such relationship, is not sufficient to pre-clude the fluid under pressure acting against the stopper and plug to move the piston tube 223 and the axial outer sleeve 261 axially inwardly relative the lift rod and the head tube.
An opening tnot shown) is provided in tube 211 inwardly of retainer disk 213 to permit the escape of fluid from within the tube that is below the piston. The lift rod can not move axially inwardly with the piston tube since the drive slug 148 abuts against snap ring 150 (Figure 7), and the axial movement of the piston tube from pin position Pl to Fin posi-tion P2 is not sufficiently great that the thrust collar abuts against either of pins 267, 268.
Since the cam screws 252 are fixed to the head tube, as the piston tube 223 moves axially inwardly relative the head tube, the cam screws are moved in the cam tract T from the position Pl shown in Figure 32 to abut against cam trac~
edges 248 and thence edges 249 to a position P2 abutting against the rounded track portion 250. Due to the inclina-tion of edges 248 and 249, this also results in the piston tube 223 rotating in the direction of the arrow 231 relative the head tube 217, the cam sleeve rotating with the piston tube due to pins 226 extending into grooves 232-34.
During the time the tool 77 was being lowered, the head tube apertures 229 were aligned with the cam sleeve recesses 227 so that the latch balls 230 extended thereinto. As the piston tube moved axially inwardly relative the head tube so that the pins 252 moved from position Pl to position P2, the cam sleeve was rotated so that the recesses 227 are moved out of radially alignment with head tube apertures 229. As a result, the latch balls 230 are forced to extend into the landing ring recess 318 to prevent axial movement of the head tube relative the drill stem (tool 77 being in a drill stem - latched condition at this time). That is, when the piston tube is in position Pl, the latch ball extending into cam sleeve recess 227a is at position P10, and when;the piston tube is at pin position P2 the location of the latch ball relative the piston tube is indicated by position P20.
Now the safety release tool is moved axially outwardly, preferably by using the surface tool in the manner such as described hereinafter. The axial outward movement of the safety release tool results in the inner ends of slots 281 again moving to engage pin 271, and thence the resulting move-ment of the pin moves the stopper 273 away from plug 270.
Pin 271 in engaging the outer ends of slots 272 moves the outer sleeve 261 outwardly and thereby the piston tube axi-ally outwardly relative to pins 252. This movement of the piston tube results in pins 252 being relatively moved from their position P2 (Figure 32) so that first edges 241 abuts against the pins 252 and thence edges 240 whereby the piston tube and cam sleeve are again rotated in the direction of arrow 231 relative the head tube. As the piston tube rotates from pin position P2 to pin position P3, the cam sleeve is rotated relative the latch balls and the piston tube moves relative the latch ball that was in recess 227a from posi-tion P20 to a position P30 that indicates the position of the latch ball relative the piston tube. At this time the latch balls are still out of radial alignment with cam sleeve reces--20 ses 227. Thus the latch balls are retained in their landing ring latching position.
At the time the cam screws have moved to the cam screw position P3, the ends of that cam screws that extended into cam track T are in direct axial alignment with cam grooves 232-234.
The continued axial outward movement of the piston tube ~oves the thrust collar 262 to abut against pin 268 and there-by move the lift rod 212 axially outwardly. The axial move-ment of the lift rod moves the outer lift tube 191 and there-by the axial outer ball nut 193 in the same direction. Since pin 196 that is mounted by the outer tube 197 extends into slot 195 of the transversely inner lift tube 191, tube 191 cannot rot-ate relative to tube 197 as it is moved axially relative thereto. Further, since the outer ball screw is prevented from moving axially relative the outer tube 197, the axial outward movement of the ball nut 193 drivingly ro-tates the outer ball screw. The rotary movement of the outer ball screw is transmitted through bearing shaft 167 to driv-ingly rotate the inner ball screw 164. Due to the threading of the inner ball screw being opposite of the outer ball screw, the rotation of the inner ball screw results in the inner ball nut 161 being moved axially inwardly. The thread-ing on the ball screws is such that every rotation of the outer ball screw results in the outer ball nut being moved a greater axial distance than the inner ball nut.
Since the outer drive slug 148 mounts the locking pins 75, 76 to extend into the linear cam tube slot portions 176c, the cam tube cannot rotate relative the drive slug 148. Fur-ther, the orienting pins 84 now prevent the cam tube rotating relative the drill stem. As a result the cam tube cannot now rotate with the lower ball screw, and thus the drive slug 148 moves axially inwardly as the lower ball screw is rotated As the drive slug is moved axially inwardly by the inner ball nut relative the inner ball screw, the structure mounted in the cam tube from the ball nut axially inwardly is moved in the same axial direction. During the initial inward axial movement of the outer drive slug 148 relative the cam tube, the transfer pin 139 extends into the linear portion 180a of the transfer pin slot and the rotation pin 127 extends in the axial linear portion 181a, thus preventing pivot rod ~ 3 118 and the actuatin~ rod 131 from rotating relative one an-other and relative the cam tube as they move axially relative the cam tube. As a result the plunger 101 is translatory moved axially inwardly relative the floater to move the plung-er recesses 102 out of radial alignment with the floater aper-tures 92. This forces the lock ba:Lls 103 to extend into the bit recesses 21 to prevent any substantial movement of the bit relative the floater. Since the bit is still lockingly retained on the reaming shell subassembly by keys 47, the floater at this time cannot move further inwardly as the drive slug 148 is continually moved inwardly, and accordingly the continued inward movement of the spring cap 126 com-presses spring 130.
After the floater plunger 101 is moved relative the floater to force the lock balls out of the plunger recesses, the plunger 101 has been moved axially inwardly sufficiently relative to the floater so that the plunger 104 is radially aligned with floater recess 96. At the time the lock keys are moved to their unlocked position, springs 110 resiliently retain the floater wall 97 in abutting relationship to the plunger 101.
After the bit has been latchingly engaged to the floater by the lock balls, but prior to the inward movement of the drive slug 148 being blocked by abutting against shaft 129 or the spring cap abutting against washer 132, the lock keys have been moved out of the bit lock key recesses 24, 25.
The above mentioned movement of the lock key takes place due to the locking pins 75 and 76 in moving axially in lock-ing pin slots 176 are moved to bring their transverse outer annular flanges (flange 75b for pin 75) into abutting relationship with the downwardly and transversely outwardlyinclined surfaces 177d of cam portions 177. This cams the pin radially outwardly to position P70 of Figure 18 such that as said flanges ride over the axial surface 177 of the cams 177, the pin 75 is extended between edges 60 and 73 of the locking sleeve 44 and the stationary sleeve 70, respectively (see Figure 16), and pin 76 extends between edges 64 and 74.
Now, as the inward movement of the pins continues with the drive slug 148, first pin 76 moves axially inwardly of the inclined edge 65 and thereafter pin 75 moves into abutting relationship to the inclined edge of the locking sleeve.
Since the stationary sleeve is pinned to the reaming shell tube 31, the locking sleeve 44 is forced to rotate in the direction of the arrows 53 (for example, angularly about 10). This rotation of the locking sleeve rotates the lock keys in the same direction to move the lock keys out of the bit recesses 24, 25 whereby the bit is free to move axially with the floater. After pin i5~has moved axially inwardly of edge 61,-the transverse outer flanges of the locking pins move into engagement with the axial and transverse inward surfaces 177c of the cam plates whereby the locking pins are resiliently retracted from between the edges of sleeves 44, 70.
Upon the lock keys being moved out of the bit recesses,-the bit and floater can move axially relative the cam tube and the above mentioned compression of sprin~ 130 results in the pivot member 118, the floater and the bit moving axial-ly inwardly relative drive slug 148; but plunger 101 does not move relative the floater, initially since springs 110 resiliently retain the plunger in abutting relationship to ~ 3 floater waLl 97, and a~ter the floater has moved to locate its recess 96 inwardly of finger 99, the plunger lG'I extends into the recess 96 to prevent plunger 101 and the floater moving relative one another. Thence further inward movement of the drive slug also moves the floater and bit axially in-wardly.
After the bit is freed to move axially with the floater, and the outer drive slug 148 has been moved sufficiently ax-ially inwardly that the transverse inner surface of the bit is adjacent or axially inwardly of the transverse inner sur-faces of the drive lugs, the transfer pin 139 moves to the inner end of the axial slot portion 180a and the latch disk 123 is moved axially adjacent slot portion 182. As a result the actuating rod 131 cannot move further inwardly with the inward movement of the outer drive lug 148 and pivot member 118, slightly further inward movement of the pivot rod 118 forcing the latch disk 123 out of the pivot rod recess 124 and into cam tube slot 182a.
After the bit has been moved axially so that it no long-er extends transversely between the drive lugs, and pin 139abuts against the inner end of slot portion 180a, further axial movement of the drive slug 148 does not move pivot mem-ber 134 axially, however, it does continue the axial inward movement of pivot member 118. This results in pivot member 136 being pivoted in the direction of the arrow 423 about the pivot axis of pivot member 115 whereby the annular float-er and the bit that is locked thereto is pivoted about the axis of pivot member 115 which extends transversely. It is to be noted that bit axis Y-Y is parallel to the pivot axis of pivot 115. As the bit is pivoted about the axis of pivot llS, it c~ntinues to be moved axially inwardly.
After the blt has been rotated about the axis of pivot 115 and moved axially inwardly sufficiently that the arcuate edge of the bit transversely opposite pivot member 115 will clear the drill hole cylindrical walls, the reaming shell and its drive lugs, the rotation pin is at the inner end of the cam tube slot portion 181a and in position to move into the circumferentially and axially inwardly inclined slot por-tion 181b. Now, as the drive slug 148 continues to move ax-ially inwardly, the floater is continued to be pivot aboutthe axis llS, and at the same time due to the rotation pin moving in slot portion 181b, the pivot rod 118 is forced to rotate about the central axis of the cam tube and drill stem, and accordingly the bit is also rotated about said central axis. As the pivot rod is rotated about the drill stem cen-tral axis, the transfer pin 139 moves in the slot portion 180b in the direction circumferentially away from slot por-tion 180a while the latch disk is moved relative the cam tube and slot portion 182a towards slot portion 182b. When the rotation pin has moved in slot portion 181b of the camming tube to be axially aligned with slot portion 181c, the later-al rotation of the bit (about pivot axis 115) and the axial rotation of the bit (about the central axis of the drill stem) has been completed. The rotation pin moves into the inner end of slot 181c, the transfer pin 139 being adjacent the end of slot portion 180b that is remote from the slot portion 180a and the latch disk 123 being adjacent but spaced from slot portion 182b. This prevents any further rotation of the pivot member 118 in the direction opposite arrow 178 relative the cam tube and axial inward movement of the pivot ~ 3 member reLative ~he cam tube. It ls noted that slot portion 182b is provided to flcilitate assembly of parts and that during operation of the tool, disk 123 is not moved over to slot portion 182b.
Not previously mentioned is that during the time the pivot rod was rotating relative the cam tube, the arcuate slot 122 was adjacent the finger 99. Thus, even though the pivot rod surface 118b extends transversely inwardly of the finger, the finger does not prevent rotation of the pivot member 118 in the above discussed manner. The drive slug 148 is moved slightly further axially inwardly, this result-ing in spring 130 being compressed in a manner previously indicated. Prior to the time shaft 129 can abut against drill slug 148, the latching of tool 77 to the drill stem is released as will be set forth.
After the lateral and axial rotation of the bit has been completed, the axial inner and outer, general planar surfaces 13 and 14 of the bit extend generally parallel to the central - axis of the drill stem with surface 13 transversely more re-mote from the central axis than surface 14; and the bit axis Y-Y is generally parallel to the drive lug planar surfaces 36a, 37a. Thus other than being axially inwardly of the drive lugs, bit surfaces 13, 14 are generally parallel to lug surfaces 36a, 37a and bit surfaces 11, 12 are generally perpendicular to lug surfaces 36a, 37a. Now the bit is in a position that it can be retracted through the drill stem.
Prior to the time the last mentioned inward movement of the pivot rod 118 relative the cam tube 98 has been com-pleted, the piston tube 218 has been moved axially outwardly relative the cam sleeve 224 and head tube 217 so that pins ~ t~3 226 are located closely adjacent and just axially outwardly of the cam groove portions 223b (Figure 32). A continuing application of axial outward force on the safety release tube moves the piston tube relative pins 226 so that the pins pass through slot portions 223b, this rotating the cam sleeve in the direction of the arrow 231 relative the piston tube.
This last rotation of the cam sleeve results in it moving relative to the latch balls to a position the latch balls 230 are radially aligned with recesses 228 to move there into and out of latching engagement with the landing ring. When the cam sleeve has moved to a position that the latch balls are radially aligned with recesses 228, the position of the ball that was in recess 227a relative the piston tube is in-dicated by P40, this ball now being radially aligned with recess 228a. Slightly further outward movement of the safety release tool results in the piston tube being moved adjacent the inner ends of cam groove positions 223c but slightly spaced therefrom, and the piston 218 moved into abutting re-lationship to the inner end of cam sleeve 224. This last mentioned movement of the piston tube occurs while spring 130 is being compressed, pin 139 now preventing further in-ward movement of pivot member 118. Since the cam sleeve 224 is retained in a fixed axial position in the head tube and the piston now abuts against the sleeve, further axial out-ward movement of the safety release tool retracts the re-traction tool 77 and the bit attached thereto through the drill stem.
The bit installation tool, generally designated 450, is of a construction that is the same as tool 77 other than the threading on the lower ball screw shaft is just opposite 1~ 3~ 3 that of the lower ball screw shaft for the tool 77. In in-stalling a bit, the installation tool has the cam tube, pivot rod, actuating rod, latch disk, floater, and floater plunger in the same relative positions described with reference to the corresponding members of the bit removal tool at the time the rotation of the bit about the axis of pivot 115 and cen-tral axis of the drill stem have been completed. Thus the latch disk is in slot portion 182a adjacent to 182b (but does not extend thereinto), the rotation pin in slot portion 181c~
the transfer pin in the end of slot portion 180b remote from slot portion 180a, the locking pins 75 and 76 in the axial inner end portion 176b of slots 176, plunger 104 extends into recess 96, and the plunger recesses 102 are axially inwardly of the floater apertures 92 whereby balls 103 are retained extended into bit recesses 21 to lock the bit to the floater.
Further the lower ball nut is at the inner axial end of the lower ball shaft. However, the relative positions of the portions of the bit installation tool above the inner (lower) ball screw is the same as that described for the bit removal tool, including the outer ball nut 193 being at the axial - inner end of the ball screw 192 as shown in Figure 7. As the bit installation tool is lower in the drill stem, the orient-ing pins 84 move into slots 175 and the cam tube rotates to be in proper angular relationship to the outer barrel assem-bly 30 as described with reference to the bit removal tool.
After the bit installation tool has been lowered in the drill stem so that its head tube shoulder 319 seats on the landing ring, first fluid under pressure is applied in the drill stem to move the piston tube inwardly and rotate the cam sleeve 224 so that the latch balls 230 are moved to a ~ 3 landing ring latching position in the manner indicated fortool 77. At this time the bit on the installation tool is located axially inwardly of the drive lugs with bit faces 13 and 14 parallel to the central axis of the drill stem and axially inwardly of and generally parallel to the planar faces 36a and 37a, respectively of the drive lugs and bit surfaces 11, 12 are generally perpendicular to faces 36a, 37a; and bit axis Y-Y is generally parallel to drive lug sur-faces 36a, 37a. Additionally, at this time the lock keys are in their unlocking position.
After the bit installation tool is latched into position and the safety release tool is pulled axially outwardly to move the lift rod 212 in same direction, the upper ball nut is moved axially outwardly to rotate the outer (upper) ball screw and therethrough the inner (lower) ball screw in the direction to move the inner (lower) ball nut axially out-wardly. As the rotational pin moves from slot portion 181c into slot portion 181b, the pivot rod rotates relative the cam tube and moves axially inwardly whereby the drill bit is pivoted about both the central axis of the drill stem and about pivot 115 in the direction opposite arrow 423. After the rotational pin moves out of slot portion 181b into slot portion 181a, the drill bit has been rotated about the drill stem control axis sufficiently that the planar faces of the bit are located between inwardly extensions of the planar faces of the drive lugs (axis Y-Y generally perpendicular to the drive lug planar faces). Further axial outward movement of the drive slug 148 results in the rotation pin being moved into slotted portion 181a and to the outer end of slot 138 whereupon the actuating rod 131 commences moving axially with ~ 3 the pivot rod 118. This m~,vement of rod 131 moves the latch disk out of slot 1~2 and into recess 124 of the pivot rod so that the actuating rod moves axially with the pivot rod. At the time the rotation pin moves into slot portion 181a, trans-fer pin 139 has been moved into slot portion 180a.
At the time the latch disk moves into recess 124, the floater has been pivoted about pivot axis 115 to a position that the plane of the central axis of pivot members 136, 115 is perpendicular to the central axis of the drill stem. Fur-ther axial movement of the drive slug 148 results in the floater being translated axially outwardly with the orienting recesses 23 of the bit axially aligned with the adapter flang-es. Due to the bevel inner surfaces of the recesses 23 and the orienting flanges 34a, as the bit is moved axially out-wardly, it is centered relative the central axis of axis of the drill stem. At this time the floater has been moved to a position that the plunger 104 is closely adjacent the finger 99, further inward axial movement of the floater resulting in the finger camming the plunger 104 out of the recess 96.
After the bit has been moved to a position that the lock recesses 24, 25 are radially opposite the lock keys, the lock-ing pins 75, 76 have been moved outwardly in slots 176 to pos-- itions to engage cam portions 177. As the transverse outward flanges (75b for pin 75) of the locking pins move along cam surfaces 177c, to position P71, the pins moved radially away from one another to a position that pin 75 extends between edges 73 and 62 of sleeves 70, 44; and pin 76 extending be-tween edges 74, 66. The axial outward movement of the pins with the drive slug moves pin 75 outwardly of edge 61 and then pin 76 is moved into abutting engagement with edge 65.

Further a~ial outward movement of pin 76 results in the lock-ing sleeve being rotated in the direction of the arrow 54 an~
thereby the locking keys into the bit locking recesses 23, 24. Now the pins ride over the cam surfaces 177d and resil-iently moved radially inwardly of sleeves 44, 70. As the locking sleeve was rotated, the dimple 52 of detent spring 51 was moved out of groove 32 and into groove 33 of the shell tube 31.
After the locking keys have been moved into the bit re-cesses, the bit is in abutting relationship with the adapterring and can no longer move axially inwardly with the floater since the lock balls 103 are still extending into the bit re-cesses 21 the floater remains stationary. However the con-tinued axial outward movement of the drive slug 148 results in the plunger 101 moving outwardly relative to the floater to a position that plunger recesses 102 are radially aligned with floater aperture 92. Now the balls 103 are cammed into recesses 102 and thence the floater moves axially with the plunger 101. The recesses 102 are axially elongated to per-mit limited movement of the plunger 101 relative the floaterafter the lock keys move into bit recesses and prior to latch balls 230 being to their release position.
While recesses 102 are moving into radial alignment with recesses 21, cam slots 232-234 of the piston tube move rela-tive pins 226 so that the pins move through slot portions 223b to rotate the cam sleeve relative the head tube to a position the cam sleeve recesses 228 are radially aligned with the latch balls 230. This results in the installation tool being released from latching engagement with the drill stem; and accordingly, further axial outward movement of the ~ 3 safety release tool withdraws the installation too~ through the drill stem. After the tools and tube 326 tlave been re-moved from the drill stem, the core drilling operation may be continued until it is time to replace another bit.
Even though an overshot can be coupled directly to the respective one of the bit installation and removal tools, it is preferred that the overshot is coupled to the safety re-lease tool described which in turn is coupled to the respec-tive installation and removal tool.
If it were not for the provision of the safety release tool and the respective one of the bit installation tool and bit removal tool should become lodged in the drill stem and an overly great pulling force were exerted thereon, the re-spective removal or installation tool could be damaged. How-ever, due to the provision of the safety release tool, exert-ing a greater than a predetermined pulling force on the tool, will result in the latching engagement between the safety release tool and the respective installation or removal tool being released. That is, the adjustment member 293 is thread-ed into the compression spring cylinder 292 a distance that more than a predetermined amount of force is required to com-press the spring 294 sufficiently to allow rollers 315 to roll axial outwardly into alignment with shoulders 311. When rollers 315 are axially aligned with shoulders 311 the latches can pivot in the direction of arrow 310 to release the latching engagement with the retaining ring 285, 286.
Now the safety release tool may be withdrawn while the re-spective one of the bit installation tool and bit removal tool remains in the drill stem.
After the safety release tool has been removed, the -6~-~ 3 drill ste~ may be ~oved ~o see i~ such dislodges the respec-tive one of tools 77, 450; and/o fluid under pressure may be pumped into the drill stem In the event the lift rod has been moved axially relative the head tube prior to the safety release releasing from the respective bit replacement tool, fluid under pressure can exert a force on the piston surfaces of the tool to move the piston tube axially inwardly relative the head tube and upon thrust collar abutting against pin 267 move the lift rod axially inwardly to recock the replacement tool, and thereafter the safety release tool lowered to again latchingly engage the tool retaining rings 285, 286. Now another attempt may be made to withdraw the replacement tool, it being understood the replacement tool may be lodged such that it cannot be recocked or cannot be withdrawn through the drill stem through use of the safety release tool.
To recock the bit removal tool after it has been removed from the drill stem; the outer lift tube 269 is moved axially relative the axial outer sleeve 261 to a position that pin 272 is circumferentially aligned relative slots positions 2820 Now the lift tube~269 is rotated relative sleeve 261 to a position pin 271 is located in slot portions 282 and then the lift tube moved axially inwardly relative the head tube. Further inward movement of the lift tube moves the sleeve relative to the lift rod so that spring 264 is com-pressed sufficiently (or the thrust collar 262 abuts against pin 267) to move the lift rod inwardly, the lift rod moving inwardly results in the ball nuts moving on the ball screws and the floater and other structure mounted for movement rela-tive the cam tube moving to relative the positions shown in ~ f~3 Figures 5-8 f~r the remov~l tool whereby the bit may be slip-ped off the floa:er. The above movement also results in the piston tube moving axially relative the pins 252 whereby the piston tube is rotated to radially align the cam sleeve re-cesses 227 with the latch ball apertures 229. Thus the re-moval tube is recocked for use.
An analogous procedure is used for recocking the bit installation tool after it has been removed from the drill stem. Advantageously another bit is slipped on the floater of the bit installation tool after it has been removed from the drill stem and prior to recocking.
One way of adjusting retraction tool to properly se-quence to relative movement of parts is to first adjust the threading of the head tube in tube 211 so that the tool is of a proper length relative the outer barrel assembly 30 with which it is to be used. Thereafter, with the locking sleeve 258 loosen and pins 252 abutting against either of cam track shoulders 250, 253 9 the adjustment sleeve 257 is threaded in the piston tube until pin 267 abuts against collar 262 and then is backed off about a quarter of a turn, and then the locking sleeve is tighten. Upon being properly adjusted the piston tube can be moved axially between a position that pins 252 abut against the shoulders defined by edges 242, 243 of the cam track and shoulders 253 without moving the lift rod.
When the lift rod is in its axial inner position, drive slug 148 abuts against snap ring 150 whereby the lift rod inward movement is limited while the lift rod outward movement is limited by piston 218 abutting against cam sleeve 224.
As to the installation tool the above mentioned length adjustment is made. With the lift rod in its axial outer position, sleeve 257 and the piston tube are relatively threa-dedly adjusted so that pin 26~ is abutting against collar 268 and the piston 218 abuts against the cam sleeve. When the installation tool is properly ad~usted and the lift rod is in its axial inner position, drive slug 148 abuts against washer 132.
In both of the removal and installation tools spring 264 cushions movement of the piston tube relative the lift rod during a lowering operation so that the lift rod does not move the structure in the cam tube through a cycle of operation; for example relative movement resulting from the tool temporarily hanging up in the drill stem.
The threaded adjustment of the sleeve 257 relative the piston tube can be made by first removing the pin 271 and the lift tu~e 269 to expose the sleeve,257 and the piston tube, or with pin 271 left in place and tube 269 axially spaced from the head tube, tube 261 can be unthreaded from sleeve 257 and thence removed to expose sleeve 257.
Referring now to Figures 41-45, the manner of using the surface tool 325 will now be set forth. After the bit in-stallation tool has been lowered in the drill stem to a posi-tion the latch balls are radially opposite the latch ring and pressure exerted so that the latch balls are cammed into latching engagement with the landing ring, the surface tool is mounted on the mounting tube subassembly M in a manner previously described. At the time or after the surface tool is mounted on the mounting tube subassembly, the spring act-uated plunger devices 409 and 436 are moved to positions that their plungers extend into the respective one of cover plate apertures 410, 435 whereby the left hand and right hand lift l~gs of the respective subassembly are retained transversely spaced in their wire line release (nonclamping) position.
Further, at this time it will be assumed that the nut 440 is in a position closely adjacent the transverse plate 366.
With the surface tool thus mounted on the mounting tube sub-assembly, the wire line extends through the lug recesses 401, 415. Now the plungers of the spring actuated plunger devices 436 are moved out of the cover apertures 435 and the lugs are moved axially toward the drill stem so that the walls defining the wire line recess portions 401, 415 of lugs 429, 430 abut against the wire line. Upon rotating the handle 382 in the appropriate direction, the screw shaft 376 is ro-tated to move the nut 440 axially away from the drill stem, stops 441 abutting against side walls 368 preventing the nut rotating with the shaft. Once the nut has moved to the oppo-site end of the screw shaft and it is desired to use a sur-face tool to continue to move the line in the same direction, the spring actuated plunger devices 409 may be operated to remove the plungers from apertures 410 and the lugs of the stationary clamp assembly move to their wire line clamping position. Now the handle 382 may be rotated in the opposite direction to allow slack in the wire line intermediate the movable and stationary clamps K and J and thence the spring actuated plunger devices 436 moved to retain the right and left hand lugs of the movable clamp in their wire line re-leased position. Then the handle 382 is rotated to move the movable clamp assembly closely adjacent the stationary clamp assembly, and thereafter the right and left hand lugs of mov-able clamp assembly again move to a wire line clamping posi-tion. Upon rotating the handle to move the nut 440 a slight ~ 3 distance above plate 366, the downward pull of the wire line on the stationary right and left hand lugs is removed and the lugs may be moved to their wire line released position. This operation may be repeated a number of times if desired for removing the wire line a limited distance. Further, with the nut 440 remote from the plate 366 and the lugs of the movable clamp assembly in clamping engagement with the wire line, and lugs of the stationary clamp assembly out of clamping relationship with the wire line, the handle 382 may be ro-tated in the direction to move the nut toward plate 366 andthereby allow the weight on the inner end of the wire line to move the wire line downwardly in the drill stem. Thus the surface tool may be used to move the wire line in an axial outward direction, or control the rate of movement of the wire line in an axial inward direction. By using the surface tool the operator has a greater feel of what is happening at the àxial inner end of the drill hole.
When the wire line is being retracted and after it is extended between the jaw members, the jaw members of the sta-tionary clamp assembly do not have to be manually moved totheir release position after the first time since the wire line in being retracted by the movable clamp assembly will move the jaws member of the stationary clamp assembly suf-ficiently relative the clamp block to permit the wire line moving-therethrough. Likewise when the wire line is clamp-ingly held by the stationary clamp assembly and the movable clamp assembly is remote from the stationary clamp assembly, the wire line may be held on the opposite side of the movable clamp assembly from the stationary clamp assembly and upon moving the movable clamp assembly toward the stationary clamp assembly, the jaw ~embers of the movable clamp assembly will be moved relative their clamp block sufficiently by moving along the wire line that the jaw members do not have to be manually moved to their release position, i.e. the plunger devices do not have to be operated after the first time they are moved out of the cover plate apertures 435.
To be mentioned is that the surface tool can be used with wire line equipment other than with the bit removal and installation tools herein described. Also even though it is advantageous to use the surface removal tool, other con-ventional equipment can be used for moving the wire line to operate the installation and removal tools described here-in.
In the event the safety release tool is not to be used in combination with the bit replacement tool, in place of slot 287, snap ring 284 and retainer ringes 285, 286, the axial outer end portion of the lift tube 269 can be provided with an overshot coupling head portion, for example a spear point (not shown), that extends into the lift tube axial-out-20 er end and is secured thereto by a pin (not shown) whereby the head portion axial inner transverse surface is located at least as far axially outwardly of slots 281 as wall portion 302e.
In using a conventional wire line core barrel inner tube assembly (not shown), for example the first embodiment~of U.S. Patent 3,333,647 or U.S. Patent 3,103,981, the drill string is provided with a latch recess shoulder (not shown) axially outwardly of the landing ring 317 to be latchingly engaged by the inner tube assembly latches while the annular shoulder of the latch body seats on the axial outer transverse surface of landing ring 317 and the core lifteris retained slightly spaced from the bit 10 to have core cut by the bit move into the core lifter. Since the orienting pins 84 are resiliently mounted, they are moved radially out-wardly by the core barrel inner tube (core lifter case) mov-ing a~ially inwardly to a core receiving position adjacent the bit.
Even though the bit has been described as having frusto-conical surface portions, it is to be understood that sur-faces 16 may be of a cylindrical shape between surfaces 11 and 12 and of diameters the same as or substantially the same as the diameters of surface 15.
Alternately, surface portions 16 may be of a stepped con-figuration, for example cylindrical arcuate surface portior.s that are of progressively smaller outer radii of curvature in an axially inner direction.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An annular drill bit replacement tool comprising a head tube having a central axis, detent first means mounted by the head tube for movement between a drill stem latch seat engag-ing position and a release position, operative second means on the head tube for moving the detent means between the detent means release and latch seat engaging positions, operative third means having a central axis for releasably mounting an annular drill bit and being operative between an annular drill bit locking position and a drill bit release position, opera-tive fourth means connected to the drill bit mounting means for rotating it about its central axis and an axis generally perpendicular thereto, moving the drill bit mounting means in the general direction of the extension of the head tube central axis, and when the drill bit is locked against axial movement along the head tube central axis, operate the third means be-tween its locking and release positions, and fifth means mounted by the head tube for movement relative thereto for operating the detent operative means between its position and the fourth means to move the third means between its posi-tions.

2. The tool of Claim 1 further characterized in that drill bit mounting means comprises a drill bit mounting member, drill bit detents mounted by the drill bit mounting member for movement between a drill bit locking position and a drill bit release position, sixth means mounted by the drill bit mount-ing member for movement relative thereto for moving the drill bit detents between their positions and seventh means for mov-ably connecting the drill bit detent moving means to the fourth means.

3. The tool of Claim 2 further characterized in that the fourth means comprises a cam tube having an axial inner end portion and an axial outer end portion, eighth means for mount-ing the cam tube axial outer end portion to the head tube to extend axially relative thereto, and drive slug ninth means mounted in the cam tube for rotatable and axial movement rela-tive thereto for moving the drill bit mounting means axially and rotating it about its central axis and said axis that ex-tends perpendicular thereto, said cam tube and drive slug means having cooperating means for rotating the drive slug means during at least part of its axial movement in the cam tube, said drive slug means being connected to the fifth means for being moved thereby.

4. The tool of Claim 3 further characterized in that the seventh means comprises first and second pivots that have spaced generally parallel pivot axes that extend generally perpendicular to drill bit mounting means central axis, that the drive slug means comprises a pivot member mounted in the cam tube for axial and pivotal movement relative thereto, said pivot member being connected to the first pivot, an actuating member mounted by the pivot member for axial movement relative thereto, linkage means connected to the second pivot and pivot-ally connected to the actuating member for pivoting the second pivot about the first pivot axis as the actuating member moves axially relative the pivot member and means for connecting the pivot member to the fifth means for being moved thereby and rotational movement relative thereto, said cooperating means including means to permit limited axial movement of the actu-ating member relative the pivot member whereby the drill bit mounting member is pivoted about the pivot axis of the first pivot.

5. The tool of Claim 3 further characterized in that the cooperating means comprises a cam surface on the cam tube that in an axial direction toward the cam tube inner end ini-tally extends predominately axially and thence extends both axially and angularly through a substantial angle, and a cam follower on the drive slug means for following the cam surface as the drive slug means moves axially relative the cam tube and rotate the drive slug means as the follower abuts against the surface that extends both axially and angularly.

6. The tool of Claim 3 further characterized in that the cam tube has an axially elongated slot extending radially there-through, and that the drive slug means includes a drive slug axially movable in the cam tube radially adjacent said slot, an outer barrel assembly locking sleeve operating stud mounted by the drive slug for radially movement between a retracted first position within the cam tube and a second position ex-tending radially outwardly through the slot beyond the cam tube, and means on the cam tube for moving the stud from its first position to its second position as the drive slug moves axially in the cam tube and thence permitting the stud to move to its first position.

7. The tool of Claim 6 further characterized in that the drive slug means includes resilient means for resiliently urg-ing the stud to its first position and that the means for mov-ing the stud comprises a cam portion on the cam tube for mov-ing the stud from its first position to its second position when the drill bit mounting means central axis extends in sub-stantially the same direction as the head tube central axis.

8. The tool of Claim 3 further characterized in that the drive slug means includes a pivot member mounted in the cam tube for axial and rotational movement relative thereto and having an axial inner end portion and an axial outer end por-tion, means for connecting the inner end portion of the pivot member to the seventh means for moving the seventh means axi-ally with the pivot member and pivot the seventh means about the generally perpendicular axis, a drive slug mounted in the cam tube for axial movement relative thereto, and means connect-ing the pivot member outer end portion to the drive slug for rotation about an axis that extends generally in the same di-rection as the head tube axis and resiliently urge the pivot member away from the drive slug to permit limited axial move-ment of the drive slug in the cam tube while the pivot member remains in a given axial position in the cam tube.

9. The tool of Claim 8 further characterized in that the eighth means and the drive slug have cooperating means for re-taining the drive slug in a fixed angular rotative position relative the cam tube as the drive slug moves axially in the cam tube.

10. The tool of Claim 9 further characterized in that the fifth means includes a rotatable member having an axis of rota-tion that extends in generally the same direction as the head tube central axis, means connected between the rotatable member and the drive slug for moving the drive slug axially as the ro-tatable member is rotated, and operable means mounted by the head tube for movement relative thereto to rotate the rotat-able member as it moves relative the head tube.

11. The tool of Claim 1 further characterized in that the second means includes a cam member mounted by the head tube for rotation about the head tube central axis for moving the detent means from its release position to its latch seat engaging po-sition, and that the fifth means includes coupling means mounted by the head tube for axial movement for rotating the cam member.

12. The tool of Claim 11 further characterized in that the de-tent means comprises a latch ball, the head tube having a latch ball mounting aperture extending radially therethrough, and that the cam member has a recess for the ball to extend into in the release position and a radially outer surface portion for forcing the ball to the detent means latch seat engaging position.

13. The tool of Claim 12 further characterized in that the cam member is a cam sleeve, and that the coupling means includes an axially elongated member axially movably extended through the cam sleeve in fixed angular relationship thereto, the elon-gated member having a cam track and a cam follower mounted by the head tube and extended into the cam track for rotating the elongated member relative the head tube during axial movement of the elongated member relative the head tube.

14. The tool of Claim 13 further characterized in that the coupling means includes a latch engageable member connected to the elongated member for moving the elongated member axially.

15. The tool of Claim 13 further characterized in that the coupling means includes an overshot coupling member and means for connecting the coupling member to the elongated member.

16. The tool of Claim 13 further characterized in that the coupling means includes a safety release tool having a main body portion, latch means mounted by the main body portion for movement between a latching position and a release position, an overshot head coupling portion, means joined to the head por-tion and mounted by the main body portion for axial movement between a position for retaining the latch means in a latching position and a release position and means for resiliently re-taining the means joined to the head portion in its latching position, and means connected to the elongated member for being latchingly engaged by the latch means in its latched position.

17. The replacement tool of Claim 16 further characterized in that the means joined to the head portion has a transverse terminal surface remote from the head portion, a slot opening to the latch means and through the terminal surface to permit the latch means moving to its release position and means mov-ably mounted in the slot to retain the latch means in its latching position until the means joined to the head portion has been moved axially outwardly against the action of the re-silient means a preselected amount.

18. The tool of Claim 13 further characterized in that the elongated member extends axially outwardly of the head tube and that the coupling means includes a tubular member having the elongated member extended thereinto, means mounted by the tubular member for mounting the elongated member for limited axial movement relative the tubular member between an axial inner position and an axial outer position and means for coop-erating with the elongated member and the head tube for form-ing a piston to move the elongated member axially inwardly in the head tube when the tubular member is in its axial inner position and an axially inward fluid force is applied thereto and to provide an open fluid passageway when the tubular member is in its axial outer position.

19. The tool of Claim 18 further characterized in that the elongated member is tubular and has an axial outer end portion extending within the first mentioned tubular member and has an axial outer end portion extending within the first mentioned tubular member and has axial slots in its outer end portion, that the first mentioned tubular member has axial slots of a greater length than the first mentioned slots, that the means to connect the elongated member to the tubular member comprises a transverse pin extended through said slots, and that the means to form a piston includes a plate mounted within the elongated member axially inwardly of its slots, the plate hav-ing an aperture extending therethrough, a stopper mounted on the pin to move therewith, resilient means acting between the stopper and the elongated member to urge the stopper to a posi-tion to block said aperture when the first mentioned tubular member is in its axial inner position, and means to form a fluid seal between the head tube and the elongated member.

20. The tool of Claim 13 further characterized in that the coupling means includes means mounted on the elongated member and forming a fluid seal with the head tube for moving the elongated member axially inwardly a limited amount relative the head tube when an axial inward fluid force is applied within the head tube.

21. The tool of Claim 20 further characterized in that the elongated member comprises a piston tube, that the means for forming a fluid seal includes a piston mounted in a fixed posi-tion on the piston tube, a lift rod axially slidably extended through the piston and means for mounting the lift rod on the piston tube for limited axial movement relative thereto, the fourth means being connected to the lift rod for being operated thereby when the lift rod is moved axially relative the head tube.

22. The tool of Claim 21 further characterized in that the fourth means includes means connected between the lift rod and the third means that, when the lift rod is moved axially out-wardly, initially moves the third means axially inwardly and thence rotates the third means while it is being moved axially inwardly.

23. The tool of Claim 21 further characterized in that the fourth means includes means connected to lift rod and the third means to both rotate and move the third means axially outwardly and thence just move the third means axially outwardly when the lift rod is being moved axially outwardly.

24. The tool of Claim 1 further characterized in that the fourth means includes a cam tube having an axial outer end con-nected to the head tube in a fixed axial position relative thereto, and a drive slug assembly axially movable in the cam tube and cooperating therewith for moving the third means, and that the fifth means includes a rotatable member, means con-nected to the rotatable member for moving the drive slug as-sembly axially when the rotatable member is rotated and means mounted by the head tube and connected to the rotatable member to selectively rotate the rotatable member.

25. The tool of Claim 24 further characterized in that the means for rotating the rotatable member includes operable means mounted in a fixed axial position relative the cam tube for rotating the rotatable member.

26. The tool of Claim 25 further characterized in that the first mentioned means for rotating the rotatable member in-cludes an overshot coupling portion and means mounted by the head tube for axial movement relative thereto and connected between the operative rotatable means and the overshot coupling portion for rotating the operative rotatable means when the overshot coupling portion is moved axially.

27. The apparatus of Claim 26 further characterized in that the means connected between the overshot coupling portion and the operative rotatable means includes a lift rod having an axially outer first end portion that has a first end and an axially inner second end portion, said lift rod being axially movable relative the head tube, means for connecting the lift rod first end to the overshot coupling portion and means con-nected to lift rod second end portion for rotating the opera-tive rotatable means when the lift rod is moved axially rela-tive the head tube.

28. The tool of Claim 27 further characterized in that each of the operative rotatable means and the rotatable member in-cludes a ball screw, that the means connected to the lift rod second end portion includes a ball nut mounted on the opera-tive rotatable means ball screw to rotate it as the above ball nut is moved axially and that the means connected to the ro-tatable member for moving the drive slug assembly axially in-cludes a ball nut mounted on the rotatable member ball screw to move axially as the last mentioned ball screw is rotated.

29. The tool of Claim 27 further characterized in that the means for connecting the lift rod to the overshot coupling por-tion includes a tubular member having the lift rod extended thereinto, means for mounting the lift rod on the tubular mem-ber for limited axial movement relative the tubular member, means acting between the tubular member and the lift rod for resiliently urging the lift rod axially inwardly and means for connecting the tubular member and the overshot portion for limited axial movement relative one another.

30. The tool of Claim 29 further characterized in that the tubular member has a cam track and that the second means in-cludes a cam sleeve rotatably mounted by the head tube and in fixed angular relation to the tubular member and a cam member mounted by the head tube and extended into the cam track to rotate the tubular member during at least part of the axial movement of the tubular member relative the head tube.