CA1232601A

CA1232601A - Drill pipe pull-up mechanism

Info

Publication number: CA1232601A
Application number: CA000508327A
Authority: CA
Inventors: Floyd Walter Becker
Original assignee: ALBERTA OPPORTUNITY Co
Current assignee: ALBERTA OPPORTUNITY Co
Priority date: 1986-05-02
Filing date: 1986-05-02
Publication date: 1988-02-09

Abstract

ABSTRACT OF THE DISCLOSURE The present invention provides a drill pipe coupling tool adapted to be removably mounted in a rotary drive mechanism of an earth drilling apparatus for coupling a drill pipe to the drive mechanism, the tool comprising a body portion defining a rotary axis, first coupling arrangement on the body portion for coupling the tool to a length of drill pipe for rotation of the tool and the drill pipe about the rotary axis, and a second coupling means on the body portion for coupling the tool to the drive mechanism for rotation of the tool about the rotary axis.

Description

~3~

This application is a division of Canadian Patent Application Serial No. 39~,947 Filed February 24, 1982.
This invention relates to an apparatus for drilling in earth forma-tions and, more particularly, to a drill pipe coupling tool for use with a rotary drive mechanism of a drill rig employed in mineral e~ploration and the like.

_ACK~ROUND OF T ~ I_ ENTION
As is well known, there are various types of earth drilling techniques, including those known as dual tube drilling, and drilling, diamond drilling, conventional drilling, and drilling with au~ers. Heretofore, clrill rigs or apparatus have been especially designed for each 15 different type of drilliny and substanti~l changes of the drill rig were necessary in order to change from one type of drilling to another type of drilling. Further, many conventional drill rigs were specifically adapted for driving one size of drill string. Again, 20 substantial modifications of the apparatus are necessary to adapt the apparatus for a different size of drill string. A still further drawback of conventional drill rigs is that they are not adapted for carrying out all of the Eunctions which are necessary to drive and 25 e~tract a drill string.
With petroleum reserves diminishing at an ever increasing rate, petroleum exploration is being extended to more remote areas, including mountainous regions, rendering it more difficult to transport drilling 30 equipment and personnel to the drill site. For reasons which are apparent, the helicopter has received much favour as a mode of transportation. However, because of their limited carrying capacity, helicopters are unable to transport heavier conventional drilling rigs to 35 remote locations, particularly those in elevated reyions.
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SUMMARY OF T~E ~NVENTION
The present invention provides an arrangement which is easily and quickly modiEied for assembling drill string and drilling a bore hole, dismantling a drill string and use with differen-t sizes of drill pipe. The foregoing are achieved, in part, by the provision of a drill pipe drive mechanis-m, which orms part oE the aforementioned application, adapted to rotatably drive any one of a plurality of removable generally tubular drill pipe coupling tools, to which the present inven-tion relates.
In general, the drive mechanism includes a housing and a coupling tool drive member or spindle rotatably and drivingly mounted in the housing. The spindle extends through the housing and is formed with an axial opening having means, such as splines or the like, for ~elescopically receiving and non-rotatably coupling the drive spindles to any one of the coupling tools.
In accordance with the present invention, there is provided a drill pipe coupling tool adapted to be removably mounted in a rotary drive mechanism of an earth drilling apparatus for coupling a drill pipe to the drive mechanism. The coupling tool comprises a body portion having an axis, first coupling means on the body portion for non-rotatably coupling the tool to a length of drill pipe for rotation of the tool and the drill pipe about the axis, second coupling means on the body portion for non-rotatably coupling the tool to the drive mechanism for rotation of the tool about the axis; and means for removably maintaining the tool operatively positioned on the drive mechanism. The maintaining means includes a flange extending radially outwardly of one end of the body portion for abutting engagement with a first portion of the drive mechanism and removable retaining means mounted at the other end of the body portion for engagernent with a second portion of -the ~;b drive mechanism remote from the first portion.

26~

BRI F DESCRIPTION OF THlE: DRAWINGS
These and other features of ~he invention will become more apparent from the following description in which reference is made to the appencled drawings wherein:
FIGURE 1 is a view illustrating a form of drill pipe with which thP present drill rig is adapted to be used;
FIGUR~ 2 is a diagrammatical, perspective view 10 illustrating the various components of the drill rig of the present invention;
FIGURE 3 is a side elevational view of the carriage and pipe drive meohanis~;
FI~UR~ 4 is a rear elevational view of the assembly 15 of FIGUR~ 3;
FIG~RE ~ is a partial cross-sectional view of a portion of the pipe drive mechanism;
FIG~R~ 5a is a partial.ly broken elevational view of an air swivel discharge device connected to a coupling 20 tool and the inner pipe member of a dual-wall drill pipe;
FIGURE 6 is a partiallv broken top view of the pipe drive meohanism illustrated in FIGURE 5;
FIGURE 7 is a top view of a pipe engaging tool used 25 for dismantling or "breaking" a pipe joint;
FIGUR~ 8 is a cross-sectional view taken along line 8-8 of FIGURE ~;
FIG~R~S 9 and 10 are views similar to FIGUR~S 7 and 8 respectively but illustrating a tool for use with a 30 smaller size of pipe;
FIGURE 11 is a cross-sectional view of a pipe drive tool similar to that illustrated in FIGUR~ 5 but for use with smaller drill pipe;
FIGU~S 12 and 13 are a top and edge view, 35 respectively, of a split ring for use in retaining a pipe engaging tool on the top drive;
., - ~S

~ 3~

~ IGURES 14 and 15 are a top and cross-sectional view taken along line 15-15, respectively, of a thrust retainer r.ing associated with the split ring;
FIGURE 16 is a side, partially cross-sectional view of the carriage;
FIGURE 17 is a front view of the carriage and top drive assembly;
FIGUR~S 18 and 19 are side and front views, respectively, of a carriage actuatin~ mechanism pull-up 10 assembly showing the mast in dotted and dashed lines;
FIGURES 20 and 21 are views similar to FIGURRS 18 ~nd 19 but illustrating a carriage actuating mechanism pull-down assembly;
FIGUR~S 22 and 23 are views si~ilar to FIGUR~S 18 15 and 19, respectively, but illustrating the hoist mechanism;
FIGURE 24 is an elevational view of a hoist plug;
; and FIGUR~ 25 is a top view of the break--out wrench 20 mechanism illustrating the wrench operatively engaged with a section of pipe.

DETAIL DESCRIPTION OF A PREFERR D EMBODIM~NT
The primary function of the drill rig of the 25 present invention is to assemble and rotatably drive a drill string into an earth for~ation at a desired drilling site and extract and dismantle the drill string. A drill string is comprised of serially connected lengths of drill pipe. Ea~h length of pipe is : 30 normally about 10 feet in length and threaded at each end for threaded engagement with one end of an adjacent pipe.
As shown in FIGUR~ 1, one end of the pipe 10 is formed with an internal thread and is referred to as a 35 I'box'l 12. The other end of the pipe is formed with an external thread, referred to as ~ "pin" 14, and is normally the lower end o~ the pipe. A cuttin~ bit (not ~.~3~

shown) i5 threadedly mounted onto the pin of the lowermost pipe section.
Adjacent the box and pin of each pipe section are a pair of flattened diametrically opposed recesses or slots. The slots are provided for threadedly engaging and disengaging ("breaking") a pair of pipe sections.
The 510ts adjacent the box, are engageable with a hydraulic break-out wrench and callecl "box end break-out slo-ts" 16, while the 510ts adjacent 1:he pin, called "pin 10 end brea~-out 510ts" 18, are engageable with pivoted dogs of a break-out tool removably mounted in the pipe drive mechanism.
While not limited thereto, the present invention is particularly intended for use wi~h double or dual-wall 15 pipe sections wherein an inner pipe 20 is concentrically mounted within the above described pipe in a well known manner. The inner and outer pipe members together define an annular passageway 22 for communicating a fluid, such as air, from the surface to the cutting bit 20 and the inner pipe defines a bore 24 for communicating the fluid and cuttings to the surface.
The major components of the drill rig are provided by two separate modules 25 and 26, each having a weight which is readily transportable by helicopter. Module 25 25 includes a sled or base 27 on which are mounted a mast assembly 30, a prime mover 28, such as a diesel engi~e, a hydraulic system 29 including a hydraulic pump and reservoir for supplying pressured fluid to various hydraulic cylinders and motors of a mast assembly 30.
30 Module 26 includes a sled 31 carrying a compressed air system 33, including an engine 35, a compressor and reservoir 37, for supplying pressurized air via conduit 39 to an air swivel discharge device 41 mounted on a drill pipe drive mechanism of assembly 30. The 35 discharge device, in ~urn, supplies air to passageway 22 -! as explained earlier. The air ~wivel discharge device also connects the outlet of bore 24 of inner pipe 20 to a cyclone 43 via conduit 45 in a manner well known to those skilled in this art. Lengths of pipe sections 10 are stored in a pipe rack 47 as shown in FI~URE 2.
The drill rig includes a mast assembly 30 (FIGURE

2) includes a mast 32 having a track 34, a carriage 36 moveable along the track, a drill pipe rotary drive m~chanism 38 mounted on the carriage, a carriage actuating mechanism 40 mounted on the mas~, a hoist mechanism 42 for hoisting the drill string or the drive mechanism mounted on the mast and a "break-out wrench"
10 mechanis~ 44 (~I~URE 25) mounted on the base of the mast. Each of these components is described in greater detail hereinafter. The following description outlines the gener~l features and purpose of these components.
The mast 32 serves to operatively support the other 15 above mentioned components of the assembly 30. It is operatively supported in a vertical position. The track

3~ extends longitudinally of the mast and is comprised of a pair o~ facing channels disposed at two adjacent corners at the front side o~ the mast. The mast is 20 illustrated in detail in FIGURES 2 and 18-23 (in phantom lines).
The carriage 36 is connected to actuating ~echanism 40 for vertical movement along track 34. Its primary function is to support the pipe drive mechanism 38.
25 Carriage 36 is best illustrated in FIGVRES 3, 4, 16 and 17.
The rotary pipe drive mechanism 38, hereina~ter called "top drive", deflnes a rotary axis and is mounted on the carriage for movement therewith longitudinally of 30 the mast and pivotal movement about a horizontal axis between a first position and a second position. The first position is the normal operating position of the top drive wherein the rotary axis is substantially vertical and the top drive rotatably drives a pipe 35 coupling tool for driving a drill string, threadedly enga~es or disengages a pair of pipe sections or hoists the drill string as will be explained in greater detail later. The second position is the position in which the ~.~23~

top drive is disposed when pipe is added and re~oved.
In this position, the top drive is disposed about 90 from the first position with the underside of the top d~ive facing outwardly away from the mast and the rotary axis is substantially horizontal. A detent mechanism is provided for resiliently re-taining the top drive in either position. The top drive is illustrated in FIGURES 3-6.
The carriage actuating mechanism 40 is generally comprised of a pair of hydraulic cylinders disposed on opposite sides of the mast, adjacent the side on whi.ch the carriage is moveable, and mounted on the base of the mast. The hydraulic cylinders are operatively connected to the carriage by cables arranged for selectively, reversibly actuating the carriage. The actuating mechanism is best illustrated in FIGU~ES 18-21.
The hoist mechanism 42 is generally comprised of a single hydraulic cylinder disposed adjacent the side of the mast opposite the side on which the carriage is mounted and is mounted on the crown of the mast. The hoist mechanism is selectively connected to either the upper length of pipe of drill string or the top rive for raising the drill string, as ~ill be explained in greater detail hereinafter. The hoist mechanism is best illustrated in ~IGURES 22 and 23.
The break-out wrench mechanism 44 is a hydraulical-ly actuated, extendable and retractable wrench for selectively engaging a pipe section and preventing rotation thereof during assembly and disassembly of a drill string. The break-out mechanism is best il-lustrated in FIGURE 25.

ROTARY PIPE DRIVE MECHANISM - TOP_DRIVE
The top drive 38, illustrated in FIGURES 3-6, is generally comprised of a transmission or gear box 50, a speed reducer 52, and a hydraulic motor 54. The speed reducer 52 is drivingly connected to the input shaft 56 of the gear box and bolted to the gear box casing 58 ~2~

while the hydraulic motor 54, which i5 preferably of the reve~sible, variable dis~lacement type, is drivingly connected and bolted to the speed reducer 52, as shown in FIGURES 3 and 4. The motor is connected -to hydraulic system 29 via approprlate conduits 53 (FIGURE 4). The speed reducer and motor are of conventional construction and accordingly are neither illustrated nor described in detail herein.
Casing 58 is generally of box~shaped conEiguration and houses a drive pinion 60~ which in the illustrated embodiment is integral with input shaft 56, a crown gear 62 which meshingly engages with pinion 60 and a tubular drive spindle 64 bolted to crown gear 62. As will be described more fully later, the drive spindle is adapted to removably receive and drive any one of several pipe engaging or coupling devices so that the top drive can be quickly and readily modified to drive pipe of different sizes and carry out functions other than driving the drill string including threadedly engaging and disengaging adjacent pipe sections and hoisting the drill string.
Drive spindle 64 is formed with a radially outward-ly ending flange 66 ad]acent its midpor-tion, which flange is abuttingly engaged with and secured by bolts 68 to a radially, inwardly extending flange 70 o~ crown gear 62, as best shown in FIGURE 5. The drive spindle 64 and crown gear 62 are rotatably mounted in the casing 58 by upper and lower ball bearing assemblies 72 and 74.
Upper and lower oil seals 76 and 78 are disposed between each end of the drive spindle 64 and bore 80 o~ the casing as shown in FIGURE 5. The oil seals are protec-ted and retained in position by upper and lower oil seal guard rings 82 and 84 bolted to casing 58.
Drive spindle 64 is also formed with a bore 86 which telescopically and removably receives the pipe coupling devices. Bore 86 is formed with at least one, but pre~erably a plurality o~, longitudinal.ly extending keyways 88. ~s will be explained later, upper annular edge 90 of spindle 64 ser~es to suppo~t the remova~l~
pipe coupling tools.
It will be seen that actuation of motor 54 effects rota~ion of shaft 56 and pinion 60 in one direction and rotation of crown ear 62 and spindle 64 in the opposite direction. Reverse rotation of the motor results in reverse rotation of the spindle and, inasmuch as the motor is of the variable di~placement type, the spindle 10 can be driven at various speeds and used for various purposes such as rotatably driving a drill string and making and breaking tool joints between adjacent pipe sections.

i5 PIP~ C OE LING TOOLS
FIGURES 5 and 7-11 illustrate pipe coupling clevices or tools to which the present invention i5 particularly concerned. The tool generally desi~nated by reference numeral 100 in FIGURES 5 and 11 is ~ ed primarily for 20 rotatably driving a drill string and threadedly engaging adjacent, axially aligned pipe sections. The tool generally designated by reference numeral 1~0 in FIGURES
7-10 is intended for u~e primarily as a break-out tool, i.e., for threadedly disen~aging adjacent pipe sections.
25 However, both tools can also be used for hoistin~ the drill str.ing.
Drive tool 100 is generally comprised of a cylindrical body portion 102 having an internal thread 104 at its lower end 106, at least one, but preferably a 30 plurality of longitudinal, equally spaced keys 108, and a radially outwardly extending flange 110 at its upper end 112. An externally threaded neck portion 114 extends axially from the upper end of tool 100. An external radially outwardly facing circumferential slot 35 116 is formed adjacent the lower end 106 of the tool.
Thread 104 is formed to threadedly receive one end ~' of a cylindrical tool known as a "saver sub". A saver sub i~ generally a short length of pipe, ext~rnally ~3~6~

threaded at both ends, and is normally u~ed at locations where exten~i~e threading and unthreading occurs. Thus, the relatively inexpensive saver sub takes most of the wear. The other end of the saver sub is threacledly received in the box end of a length of drill pipe. It will be understood that the lower end of the tool 100 could be formed with an external thread adapted to be eonnected directly to the box end of a drill pipe thereby obviating the need of a saver sub if 50 desired.
In the embodiment shown, the keys 108 are formed by welding elon~ated steel bars 118 in four elongated, longitudinal slots 120 formed on the outer cylindrical periphery of the tool 100. The keys are received in keyways ~8 of drive spindle 64 and serve to transmit 15 torque ~rom the drive spindle 64 to the body portion of the tool. The term axial splines used hereinafter is intended to-refer to any arrangement which non-rotatably couples ~wo components while permitting relative axial movement therebetween.
Flange 110 defines a radial annular shoulder 122 which abuttingly engages upper annular edge 90 of spindle 64. Thus, the -tool is thereby vertically supported in the top drive by the spindle 64. In addition to serving as the mean~ of supporting the tool 25 in the top drive, the flange serves as a "flinger" - a means whereby contaminants, such as dirt, are centrifugally propelled away from the upper oil seals 76.
Threaded neck portion 114 is adapted to be 30 threadedly connected to an air discharge swivel 41, as illustrated in phantom in FIGURE 5a. The neck 114 defines an opening 124 to receive an inner pipe section, as also shown in FIGURE 5a, which i5 sealingly connected to the air discharge swivel and provides an annular 35 passageway between the inner pipe and opening 124 ~or communicating air to passageway 2~. As explained earlier, an air discharge swivel i5 a device Eor ; connecting a supply of air to annular passageway 22 and ~3~6~

bore 24 of the inner pipe to an exhaus~ conduit which, in turn, is connected to a cyclone 43 for separating air from cuttings while the drill string rotates. Air swivel discharge devices are well known and therefore are not described in detail herein. In practice, pipe coupling tool 100 remains connected to the air discharge swi~el unless a ~ool for use with a clifferent sized pipe is required. In such case, the tool is simply threadedly removed and the desired tool is thre~ded onto 10 the air discharge swivel.
A split thrus~ ring 130 and a retaining ring 132 are provided for preventing inadvertent xemoval of the drive tool 100 and for limiting longitudinal or axial travel of the tool 100 relative to the top drive. As 15 will be described in greater detail later, such movement i5 desirable when threadedly engaging adjacent lengths of pipe.
As shown in FIGUR~S 12 and 13, split ring 130 is comprised of a pair of arcuate arms 134, 134 connected 20 at one end for pivotal ~novement about a pin 136. In the position shown in FIGURE 13, arms 134, 134 define a cylindrical surface 138 whose diameter is slightly larger than the inner diameter of peripheral slot or groove 116 of tool 100. Thus, ring 130 is adapted to be 25 fitted into the slot 116 and i5 readily removable therefrom by pivotally manipulating arms 134, 134.
Retaining ring 132, shown in FI~URES 14 and 15, is provided to prevent separation of arms 134, 134 of the split ring yet permit quick removal of the split ring 30 from the tool and the tool from the top drive. Ring 132 is formed with a skirt portion 140 and an annular shoulder portion 142. Shoulder portion 142 defines axial opening 144 which telescopically receives body portion 102 of tool 100. Opening 144 is formed with 35 four keyways 146 for slidingly receiving keys 103 of the tool. The skirt p~ortion 140 is formed with an openin~
147 sized to loosely receive the outer periphery of split ring 130 as shown in FIGURE 5. The retainer ring 3~

132 is m~intained in the position shown in FIGURE 5 by gravity.
Thus, in order to remove the drive tool from the top drîve, retaining ring 132 is telescopically moved upwardly, as viewed in FIGURE 5, the split ring 130 is re~oved from 510t 116 by opening or separating arms 134, 134, and ring 132 i5 slid downwardly and away ~rom the tool. The tool (and its associated air discharge swivel) is then free to be removed from the top drive by 10 moving it axially upwardly and outwardly of the drive spindle. The reverse procedure i5 adopted to operatively locate a tool in the top drive.
The distance between the shoulder 122 of the drive tool 100 and the upper surface 148 of ring 132 is 15 arranged to be longer than the axial length of the drive spindle 64 by an amount at least equal to the length of the thread of the box (or pin) of a drill pipe. This avoids the need of incrementally lowering the -top drive when the top drive is used to thread an additional pipe 20 section to the drill string in a manner to be described later. However, it is pointed out that during such procedure, assuming a length of pipe has been mounted on the saver sub attached to the drive tool and the pin end of the drill pipe has been aligned with and brought into 25 abutting engagement with the box end of the upper pipe of the drill string, the top drive is lowered until the lower end of the drive spindle 64 abuts surface 148 of ring 132. Then, the drive spindle 64 is rotated in a clockwise direction (viewed downwardly in FIGUR~ 5).
30 Such rotation threadedly engages the pin of the pipe being added to the upper box of the drill string. As this occurs, the pipe being added and the drive tool move downwardly relative to the top drive so that no vertical adjustment of the position o~ the top drive is 35 required during this operation.
-~Coupling tool 150 illustrated in FI~URE 11 i5 in `~:`all material respects the same as that illustrated in FIGURE 5 except that it is constructed ~or use with 3~261~

drill pipe of smaller outside diameter. Specifically, the body portion 152, keys 154, annular flange 156, neck portlon 15~ and peripheral slot 160 are identical to those of tool 100 so that tool 150 cooperates with drive spindle 64 and split and retaining rings 130 and 132 in preci~ely the same manner as tool 100. However, an insert 162 replaces internal thread 104 of tool 100 and provides an internal thread 16~ of smaller diameter than thread 10~ for use with smaller drill pipe~ As shown, 10 insert 162 i~ welded to the 'oody portion.
It wil1 be understood that in addition to transferring torque to the drill ~tring, the above described coupling tools can be used to transmit axial forces to the drill string in situations where hoisting 15 effort is required. Thus, should the drill string become jammed, as sometimes occurs, the carriage actuating mechanism is actuated so as to apply a vertical force to the carriage which force is transmitted to the top drive casing. The force is in 20 turn transmitted to the drive spindle, via the ball bearing assemblies and then to the drive tool flange, body portion and drill pipe.
FIGURES ~ and 8 illustrate a "break-out" tool 170 intended for use in threadedly disengaging two pipe 25 sections and, hoisting the drill string in the event that additional hoisting effort is required to release a jammed drill strin~.
Break-out tool 1~0 is constructed 60 as to be received in and rotatably driven by drive spindle 64 in 30 the same manner as drive tool 100. Thus, tool 170 is formed with a tubular body portion 172 having four equally spaced keys 174 and a peripheral slot 1~6 adjacent lower end 178 thereof for reception of split ring 130 and retaining ring 132. The upper end 180 is 35 formed with a flange 182 having an annular shoulder 184 for abutting engagement with upper edge 90 o~ drive , spindle G4 and application of an upward thrust to the tool when required. As with tools 100 and 150, the ~3~6~

length of tool 170 is such so as to permit a~ial 'cravel of the tool relative to drive spindle 64 and thereby avoid the need of incre~nentally raising the top drive as a pipe section is unthreaded. Further, tool 170 is mounted on and removed from the drive spindle 64 in precisely the same manner as tools 100 and 150.
The body portion is formed with an axial bore or opening 1~6 adapted to telescopically receive a length of pipe section as shown in dotted lines in FIGURE 8.
Secured to flange 182 by bolts 185 are a pair of concentric annular discs 187 and 188 between which are confined a pair of diametrically opposed dogs 190. Each dog 190 is formed with a cylindrical portion 192 from the opposite ends of which extend stub shafts or pins 15 194 received for pivotal movement in blind bores 196 formed in abutting surfaces 19~ and 200 of discs 187 and 188 respectively. Also formed in discs 187 and 188 adjacent each bore 196 are chambers 202 which receive torsion or spiral sprinys 204 which ~erve to bias dogs 20 190 toward the solid line position shown in FIGUR~ 8.
Extending radially outwardly and longitudinally of each dog 190 is a jaw portion 206 adapted to be received in previously mentioned pin end break-out slots 18 of a pipe section as shown in ~I~UR~ 8.
The break-out tool 208 illustrated in FIGURES 9 and 10 i5 in all material respects the same as the tool illustrated in FIGURES ~ and 8 except that it is used with a pipe section of smaller outside diameter. This tool utilizes the same tubular body portion 172 but 30 discs 210 and 212 having a smaller inside diameter and locating the do~s 214 closer together are utili~ed. In addition, an inner cylindrica~l tube 216 is concentrically disposed within the tubular body portion.
As shown, the upper end of the inner tube is welded to 35 the lower disc 212 while a spacer block 213 is disposed between the lower end o~ the inner tube 216 and the body portion 172.

~3~

When it is desired to remove the drill string from the bore hole, the drive tool 100 ancl air discharge swi~el 43 are removed from the top drive in the manner previously explained and the break-out tool 170 is operati~ely positioned on the top drive as also previously explained Wi th re~pect to clrive tool lO0.
The carriage actuating mechanism i5 then actuatecl to lower the carria~e, ancl hence the top drive, to a position adjacent the bottom of the mast. I~ will be 10 unclerstood that the top drive will remain in this position durincJ the break-out operation unles~ the hoist mechanism is incapable of raising the drill string in which case the carria~e actuating mechanism is used to provide additional vertical thrust.
It will also be understood that the break-out wrench has been engaged with the box end break-out slots 16 of the uppermost pipe section of the drill string and supports the drill string, at least in part. So arranged, the rig is ready for the break-out operation.
A hoist plug, secured to the free end of a cable connected to the hoist mechanism to be described in greater detail later, is passed through the break-out tool bore 186 and threaded into the box end of the uppermost pipe section of the drill string. The hoist 25 mechanis~ is then actuated slightly so as to remove the weight of drill string from the break-out wrench and the wrench is retracted. The hoist mechanism is thereafter actuated to raise the drill string the length of a pipe section. As the drill string is raised, the periphery 30 of the drill pipe surface pivots the dogs 190 to the dotted line position shown in FIGURE 8 against the bias of torsion springs 204. Once the pin end break-out slots 18 reach dogs 190, the dogs snap into the slots to the solid line position shown ln FI~UR~ 8 assuming the 35 910ts are properly angularly aligned with the dogs. If not, the break-out tool ancl drill pipe are rotated , ~t slicJhtly by actuating the top dri~e. The hoist mechanism is then lowerecl sllghtly until the upper ~3~

flattened surface 206 of the do~s engage the upper transverse edges 210 of slots 18. This vertically aligns the box end break-out slots of the next pipe sectiorl with the break-out wrench which is then extended to en~age such slots. It may be necessary to rotate the drill string by actuating the top drive in order to angularly align the box end break-out slots with the wrench. Once 50 engaged, the wrench prevents rotation of the drill string.
The top drive i9 then reversely rotated thereby re~ersely rotating the uppermQst pipe section, via dri~e spindle 64 and break--out tool 190. A5 the upper pipe section is rotated, its pin unthreads from the box of the ne~-t lower pipe section and the pipe moves upwardly 15 under the influence of the threads as well as that of a spring mechanism associated with the hoist mechanism.
Further, dogs 190 move relatively downwardly in the pin end break-out slots 18 and thus slots 18 must be of sufficient len~th to accommodate such movement.
Once the upper pipe section has been 6eparated from the ne~t pipe section, the hoist mechanism is actuated to raise the separated pipe section free of -the top drive. The hoist is then actuated to lower the pipe section which is placed in a pipe rack 47 (FIGUR~ 2) 25 disposed ad~acent the drill rig. The hoist plug is removed from the pipe section and the operation is repeated until the drill string is completely dismantled.

30 T~E MAST
As shown in FIGURE 2, the mast 32 is an elongated parallelepiped structure defined by two rear tubular steel corner posts 230, two front posts 232 ~onstructed of channel members, whose open sides face one another 35 and define track 34, and intermediate tubular steel braces 234. The mast is also formed with a base 236 and ~- a crown 238.

~3~

As also shown in FI~UR~ 2, the mast is disposed in an upright position during use. However, the mast i5 adapted to be pivoted to a horizonta:L position during transport on sled or skid 27. This :Is achieved by a pair of outwardly projecting pins 242 welded or otherwîse secured to a brace member 234, as shown. The pins 247 are received in cradle~ 244 of support posts 246 associated with sled 27. A support bracket 248 supports the upper end of the mast during transport and 10 a wedge lock at the base of the mast will maintain the mast in its upright position during use.

TH~ CARRIAGE
The carriage 36 is comprised of two sections 250 15 and 252 which are mirror images of one another. Section 2S0 is associated with and supports the left side of the top drive and section 252 i8 associated with and supports the right side of the top drive. While the following description is referable to section 250, it is 20 to be understood that the description i5 equally applicable to section 252.
With re~erence to FIG~R~S 3, 4, 16 and 17, carriage section 250 includes an elongated outer plate 254 having rollers 256 and 258 rotatably mounted at its opposite 25 ends. Rollers 256 and 258 are disposed for movement within the channel shaped members defining track 34.
Spaced laterally inwardly of plate 264 i~ an inner plate 260 connected to plate 254 by laterally extending, spaced connector plates 262, 262. Inner plate 260 is 30 formecl with an arcuate, rearwardly extending detent plate 264 having an arcuate guide surface 266 and recesses 268 and 270 spaced approximately 90 apart.
Extendiny between plates 254 and 260 is a pivot pin 272 having an inwardly disposed head 274. The opposite 35 end of pin 272 is welded or otherwise secured to plates ",~ 254 and 260. Pin 272 extends inwardly beyond inner ~r~ plate 260 and defines between plate 260 and head 274 a journal portion received in a two part support and pivot ~L~3~

block 276 bolted to the casing Qf t~e top drive. Thus, the top drive is supported for pivotal mo~ement about the axi~ of pins 2~2 between a first and a second position. In the first position, illustrated in FIGUR~S
3 and 4, the rotary axis of drive spindle is vertically dispo6ed ~nd the top drive may be used for the previously described operations. The second position of the top drive facili-tates the addition o~ lengths of pipe to the top drive. Xn this position, the top drive 10 is disposed about 90 about the axis or pin~ 272 from the first position with the underside of top drive facing away from the mast. When so disposed a length of pipe section may be threaded onto the saver sub attached to the drive tool by either manually rotating the pipe 15 or slowly rotating the top drive.
Secured to the underslde of the top drive casing is a detent roller assembly 280 which houses a spring biased roller 282 (FIGURE 16). Roller 282 engacges guide surface 266 of det&nt portion 264 of plate 200.
20 Recesses 268 and 270 define the first and second positions respec~ively of the top drive. The load of the sprincJ within detent roller assembly 280 may be adjusted by nut 284.
A tor~ue and guide member 286 engageable with 25 detent roller assembly 280 positively locates the top drive in the first position.
Secured to one of the pivot blocks 276 is an air sw:ivel torque slide 288 for preventing rotation of the outer housing of the air discharge swivel.
CARRIAG~ ACTUATING MÆCHANISM
The carriage actuating mechanism 40 is comprised of a "pull-up" assembly 300 (FIG~RES 18 and 19) and a "pull-down" assembly 302 (FIGVRÆS 20 and 21). Both 35 assemblies are actuated by the same two hydraulic cylinders 304, 304 vertically disposed on laterally ~! opposed sides of the mast 32. The two cylinclers are ecured to the base of the mast by a support bracket 306 g~Z3~6~L

(see FIGURES 18 ~nd 20). Attach~d to the free end of the piston rod o~ each cylinde~ is a pulley assembly 307 having pulleys 308 and 310.
With re~erence to FIGURES 18 ancl 19, the pull-up S asscmbly includes a cable 312 having one end 314 secured to one section of the carriage in the manner shown in FI~UR~S 16 and 17. Cable 312 is trained about pulley 30~ of one pulley assembly 307, pulleys 316 and 318 (FI~URE 19) rotatably mounted in the mast base, and 10 pulley 303 of the other pulley assembly 307. The other end 319 of cable 312 is then releasably connected to the other section of the carriage as also shown in FI~URES
16 and 1~. A turnbuckle 322 is provided for adjustably tensioniny the cable. Thus, it will be seen that when 15 cylinders 304 are actuated in unison to extend the piston rods, the ends 314 and 319 of cable 312 will move upwardly and thereby apply a vertical thrust to the top drive. It will be noted that the top drive will move upw~rdly at twice the rate of the piston rods.
With reference to FIBURES 20 and 21, the pull-down assembly 302 is compri ed of two cables 330 and 332 each associated in an identical manner with one o~ the hydraulic cylinders 304. One end 334 of each cable is adjustably and removably connected to the crown of the 25 mast, as best shown in ~IGURE 20, while the other end 336 o~ each cable is removably secured to a respective section of the carriage, as shown in FIGURES 16 and 17.
From end 334, each cable extends downwardly and trained about upper pulley 310 of pulley assembly 307, 30 upwardly and trained about pulley 338 rotatably mounted on the crownl and downwardly and -trained about pulley 340 rotatably mounted in the mast base.
Thus, when cylinders 304 are actuated in unison to retract their respec~ive piston rods, ends 336 of the 35 cables 330 and 332 move downwardly and apply a downward thrust or force to the carriage and, hence, the top drive.
-~i, ~:3;~

Two impor-tant features are to be noted. Firstly, it is known that the capacity of hydraulic cylinders i9 larger when its piston rod i5 extended than when it is retracted. In the present instance, the larger capacity of the cyli~ders i5 utilized for pulling up where higher capacity i5 required. Secondly, the hydraulic cylinders are mounted on the base rather than on the crown as is known. Thus, the mast need not absorb as much of a load and may therefore be made llghter, it being understood 10 that weight i5 an important consideration in helicopter transportable drill rigs.
It will be understood that means is provided for vertically guiding the piston rods.

15 TH~ HOIST MECHANISM
_ _ _ _._ The hoist or haul-out mechanism 42 is illustrated in FIGURES 2~ and 23 and i~ comprised of a single inverted, vertically extending hydraulic cylinder 350 mounted on the mast crown adjacent the rear side 352 20 (remote ~rom the top dri~e) of the mast. A pulley 354 is secured to the end of the piston rod 356 of the cylinder. A pivot head assembly 358 pivotally mounted atop the mast crown, as shown in FI~URE 23, is comprised of a pair of spaced arms 360 connected at one end 362 to 25 the crown and centrally supported by a compression spring assembly 364. A $top 363 is provided to limit downward travel of the assembly. A pair of pulleys 366 and 368 are rotatably mounted on arms 360 as shown.
A cable 370 has one end 372 connected to the crown 30 and its intermediate portion trained about pulley~ 354, 366 and 368. The other end 374 of the cable 370 i5 fitted with a hook (not shown) or the like for connection to a hoist plug 376 or a bail (not shown) secured to the upper end of the air discharge swivel.
The pivot head assembly 358 is provided to maintain cable 370 in tension during the break-out operation as well as maintain an upward force on the pipe section bein~ removed without incrementally raisiny the hoist mechanism.
Hoist plug 376 is illustrated in ~IGUR~ 24 and is comprised of a t~bular body portion 380 having a head 382 at one end and an external thread 38~ at the other end. A clevis 386 ex-tends from head 382 and i~ provided for reception of a hook attached to end 3~4 of cable 370. Thread 3B4 is provided for engagement with the box of a length of drill pipe.
Thus, when it is desired to use the hoist mechanism, end 374 of cable 370 is secured to clevis 386 and the lower end 3~8 of the plug i5 passed through bore 186 of tool 170 and threadedly engaged with the box of the uppermost drill pipe section of the drill string.
15 Cylinder 350 i5 then actuated to extend piston rod 356 and raise end 374 of cable 370, the hoist plug 376 and the drill string. Once the upper drill pipe ~ection of the drill string has been removed from the drill string and the top drive, piston rod 356 is retracted to lower 20 the drill pipe section, the drill pipe section is unthreaded from the hoist plug section and placed in the pipe rack.

~ _ R~ -OUT WRENCH ASSEMBLY
The break-out wrench assembly is illustrated in FIGURE 25 which i5 a top view of the mast base. The assembly includes a wrench member 400 having a wrench head 402 and an elongated body portion 404. Wrench member is slidably mounted on the upper surface 406 of 30 the mast base for reciprocation from a first extended position illustrated in ~IG~RE 25 whereat the wrench is in engagement with a sec-tion of pipe and a second, retracted position whereat the wrench i5 clear of the drill string permitting ro~a~ion and/or axial movemen-t 35 of the latter.
Wrench head 402 is formed with a pair of opposed flattened surfaces 408 slidingly engageable with the box end break-out slots 16 of a pipe section. The wrench ~L~3~
- ~2 -member i5 guided for reciprocal movement by a bracket 410 bolted to surface A06 and associated with body portion 404 and a pair of guides 412 secured to surface 406 and associated wing projection~ 414 extending from head 402. As shown in dotted line~ in FIGURE 25, a bar 416 secured to body por~ion A04, extends through a slot 418 in surface 406 into the mast base ancL i connected to a hydraulic cylinder 420 disposed within the base.
The wrench head i5 supported by a sur~ace 422 of a pipe 10 guide member 424 formed in the mast base.

AS_ MBLIN~ _IL STRI~G AMD DRILLING
Initially, the carriage actuating mechanism 40 is actuated to move the top drive mechanism 3~ to a 15 convenient lower position on the mast. An air discharge swivel mechanism having an appropriate pipe coupling tool 100 or 150 attached thereto is inserted into the bore 86 in spindle 64. The split thrust ring 130 and retaining ring 132 are then assembled on the pipe 20 coupling tool.
The top drive 38 is manually pivoted about pins 272 from its first position to its second position. The top drive is maintain~d in the second position by the detent assembly. It should be noted at this point that the 25 pins 272 extend through or near the centroid of the top drive, speed reducer, motor and air discharge swiv21 SO
that relatively little effort is required to move the top drive between its two positions.
An appropriate cutting bit i5 attached to the pin 30 end of the first drill pipe and the bo~ end of such pipe is threaded onto the saver sub extending ~rom the drive tool either by manually rotating the drill pipe or rotati~g the top drive while the pipe section is held st~tionary.
The carriage actuating mechanism is actuated to ~AC raise the top drive to the upper end of the mast 32. As the top drive rises, the weight of the pipe overcomes the effort of the spring detent assembly and the pipe ~3~6(~

moves towards a vertical position. The stop 286 en~ayes the detent housing and thereby positively locate~ the top clrive in its first, driving position.
The lower end of the pipe is placed above the pipe guide in the mast base and the carriage actuating mechanism i5 actuated to lower the top drive until the cutting bit engages the ground. The carriage actuating mechanism is deac-tivated and ~he rig is ready for drilling.
Motor 5~ is actuated to begin the drilling operation. The drilling continues un~il the box end break-out slots 16 are vPrtically aligned with the break-out wrench. ~ydraulic cylinder 406 is actuated to extend break-out wrench 400. The top drive is rotated 15 if necessary in order to angularly align the box and break-out slots with the flattenecl surfaces 40~ of wrench 400. Thus, the portion of the drill string in the bore hole i5 held against rotation. Motor 54 of the top drive is reversed so as to threadedly disengage the 20 saver sub ~rom the box of the drill pipe. Thereafter, the carria~e actuating mechanism i9 activated to raise the top d~ive slightly. The top drive is then pivoted to its second position and is ready to repeat the foregoing procedure.
The mode of adding the second and subsequent pipe sections to the drill string is substantially the same as the mode of adding the first pipe.
A new length of pipe is threaded onto the saver sub as explained previously. The top drive is raised until 30 the pin of the new pipe clears the box of the pipe already in place. The top drive is then lowered while the pin of the new pipe entPrs the box of the pipe already in place and the lower edge of the drive spindle abuttingly engages the upper surface 148 of retainîng 35 ring 132. The top drive is then rotated until the new pipe is fully threadedly engaged with the pipe already in place. It will be noted that as -the new p~pe is being threaded, it moves downwardly with respect to the ~3~

top drive by virtue of the lon~itudinal clearance originally provided between the drive tool and the drive spindle so that it is not necessary to incrementally lower the top drive as the new pipe Clection is being threaded.
In the event that the drill string becomes jammed in the bore hole, the carriage actuatiny mechanism is actuated to apply an upward thrust to the clrill strip via the top drive and coupling tool. Should the 10 carriage actuating mechanism be incapable of raising the drill string, the hoist mechanism is attached to a bail (not shown) on the air discharge swivel or the top drive and it is actuated to apply an additional upward thrust to the drill string. Once the drill string i8 cleared, 15 the hoist mechanism is discormected and the top drive motor i5 activated to ream the bore hole and continue drilling.

DISASSEMBLING A DRILL STRING
When it is desired to remove the drill string from the bore hole, the break-out wrench is engaged with the box end breakout slots 16 of the uppermost pipe section of the drill string and the top drive i5 reversely rotated so as to disengage the sa~er sub from the box 25 end of the uppermost pipe of the drill string. The top drive is then raised to a convenient position whereat the air discharge swivel and its accompanying pipe coupling tool 100 (or 150) are removed by removing split thrust ring 130 and retaining ring 132 as previously 30 explained. Following this, a break-out tool 170 is inserted into the drive spindle 64 and the split thrust ring and retainer ring are assembled thereon so as to retain the break-out tool operatively disposed on the top drive.
The top drive i5 then lowered to a position ,J adjacent the lower end of the mast. A hoist plug 380 i5 .^r~, then se~ured to the end 3~4 of cable 370 of the hoist mechanism, extended through the opening in the break-out tool 1~0 and threadedly engaged with the threads in the box end of the uppermost pipe of the drill string.
Thereafter, the hoist mechanism is actuated to raise the drill string sliyhtly so as to move the weight o~ the drill string from -the break-out wrench. The break-out wrench is retracted and the hoist mechanism i9 actuated to raise the drill string the length of a drill pipe.
As this occurs, the drill string pas~es through a~ial bore 186 of the break-out tool and the dogs 190 are pivoted outwardly of bore la6 ayainst the bias of spring 204. The drill string is raised until the box end break-out slots of the next pipe are vertically alig~ed with the break-out wrench and the dogs 190 are vertically aligned with the pin end break-out slots. As previously explained, it may be necessary to rotate the top drive so as to angularly align the dogs 190 and break-out wrench 400 with the pin end break-out slots 18 and box end br-eak-out slots 16, respectively. At this point, it is to be notecl that shoulder 184 of f lange 182 of break-out tool 170 abuttingly engages annular surface 90 of drive spindle 64 and the dogs 190 are disposed at the upper end of the longitudinally elongated pin and break-out slots. Additionally, the compression spring assembly 364 of pivot head assembly 358 o~ the hoist mechanism are compressed and upwardly bias the drill string. Thus, as the top drive is reversely rotated, the upper drill pipe is unthreaded from the drill striny and moves upwardly both under -the influence of the action of unthreading and the bias of the compression spring assembly.
Further, it will be noted that do~s 190 move relatively downwardly axially of the pin end break-out slots and the break~out tool moves upwardly relative to the top drive. As previously explained, incremen-tal vertical adjustment of the top drive is not necessary.
Once the upper drill pipe has been completely unthreaded, the hoist mechanism i5 retracted and the decoupled pipe i8 plaoed in the pipe rack. The above ~ ~3~
- 2~ -described pr~cedure is then repeated until the drill string is fully dismantled.

Claims

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

1. A drill pipe coupling tool adapted to be removably mounted in a rotary drive mechanism of an earth drilling apparatus for coupling a drill pipe to said drive mechanism; said tool comprising:
a body portion having an axis;
first coupling means on said body portion for non-rotatably coupling said tool to a length of drill pipe for rotation of said tool and said drill pipe about said axis;
second coupling means on said body portion for non-rotatably coupling said tool to said drive mechanism for rotation of said tool about said axis; and means for removably maintaining said tool opera-tively positioned on said drive mechanism, said main-taining means including a flange extending radially outwardly of one end of said body portion for abutting engagement with a first portion of said drive mechanism and removable retaining means mounted at the other end of said body portion for engagement with a second portion of said drive mechanism remote from said first portion.

2. A coupling tool as defined in claim 1, said second coupling means permitting axial travel of said tool relative to said drive mechanism during operation of said drive mechanism.

3. A coupling tool as defined in claim 2, said body portion being cylindrical and tubular and said second coupling means including axial spline means on the outer periphery of said body portion for engagement with mating spline means in said drive mechanism.

4. A coupling tool as defined in claim 3, said means for maintaining including means on said body portion cooperable with said drive means for limiting axial travel of said tool between predetermined limits.

5. A coupling tool as defined in claim 4, said travel limiting means including shoulder means extending outwardly on one end of said body means for abutting engagement with a portion of said drive means.

6. A coupling tool as defined in claim 5, further including a radially outwardly extending flange defining said shoulder means.

7. A coupling tool as defined in claim 4, said travel limiting means including retaining means removably mounted at one end of said tool, said retaining means being abuttingly engageable with said drive means for limiting axial travel of said tool relative to said drive means in one direction.

8. A coupling tool as defined in claim 7, further including a radially outwardly facing groove in the outer periphery of one end of said body portion, said retaining means including a split ring having a pair of arcuate arms pivotally connected at adjacent ends and removably receivable in said groove and a retaining ring telescopically movable along the outer periphery of said body portion between a first position engaging said split ring and preventing separation of said arms and a second position permitting separation of said arms and removal of said split ring from said groove.

9. A coupling tool as defined in claim 8, said retain-ing means defining a shoulder engageable with said drive mechanism for limiting axial travel in one direction of said tool relative to said drive mechanism.

10. A coupling tool as defined in claim 1, said maintaining means including a flange extending radially outwardly of one end of said body portion for abutting engagement with a portion of said drive mechanism and removable retaining means mounted at the other end of said body portion and engageable with said drive mechanism.

11. A coupling means as defined in claim 10, said maintaining means permitting axial travel of said tool relative to said drive mechanism during operation of said drive mechanism.

12. A coupling tool as defined in claim 1, said first coupling means including thread means.

13. A coupling tool as defined in claim 12, further including an axial opening extending through said body means, said thread means being formed at one end of said opening.

14. A coupling tool as defined in claim 1, further including an axial opening extending through said body portion, said first coupling means including at least one pair of dogs mounted at one end of said body portion on diametrically opposed sides of said opening, each said dog being pivotable between a first position whereat a portion of said dog extends into said opening for engagement with a flattened recess of a drill pipe telescopically disposed in said opening for non-rotatab-ly coupling said pipe to said tool and a second position whereat said dog is disposed exteriorly of said opening permitting axial and rotary movement of said drill pipe relative to said tool.

15. A coupling tool as defined in claim 14, each said dog being resiliently biased towards said first posi-tion.

16. A drill pipe coupling tool adapted to be removably mounted in a drill pipe rotary drive mechanism of an earth drilling apparatus, said mechanism having a drive member having a coupling tool receiving opening defining a rotary axis and shoulder means at each end of said opening, said tool comprising:
a tubular cylindrical body portion defining an axial drill pipe receiving opening and being telescopi-cally receivable in said tool receiving opening;
first coupling means on said body portion for coupling said tool to a drill pipe for rotation of said tool and said drill about said rotary axis;
second coupling means on said body portion for coupling said tool to said drive member and permitting axial travel of said tool relative to said drive member during operation of said drive member;
flange means extending radially outwardly of one end of said body portion, said flange means being abuttingly engageable with said shoulder means at one end of said drive member for limiting axial travel of said tool in one direction; and retaining means at the other end of said body portion and being operable to permit telescopic inser-tion and removal of said tool in said tool receiving opening and being engageable with said shoulder means at the other end of said drive member for limiting axial travel of said tool in the direction opposite said one direction during operation of said drive mechanism.

17. A coupling tool as defined in claim 16, said second coupling means comprising axial spline means formed on the outer periphery of said body portion.

18. A coupling means as defined in claim 16, said retaining means including a radially outwardly facing groove in the outer periphery of said other end of said body portion, a split ring having a pair of arcuate arms pivotally connected together at adjacent ends and removably receivable in said groove and a retaining means telescopically removable along the outer periphery of said body portion between a first position engaging said split ring and preventing separation of said arms and a second position axially removed from said first position permitting separation of said arms and removal of said split ring from said groove.

19. A coupling tool as defined in claim 16, 17 or 18, said first coupling means including internal thread means formed at said other end of said opening of said body portion.

20. A coupling tool as defined in claim 16 or 17, said first coupling means including at least one pair of dogs mounted on said body portion at said one end thereof on diametrically opposed sides of said opening, each said dog being pivotable between a first position whereat a portion of said dog extends into said opening for engagement with a flattened recess on a drill pipe telescopically disposed in said opening for non-rotatab-ly coupling said pipe to said tool and a second position whereat said dog is disposed exteriorly of said opening permitting axial and rotary movement of said pipe relative to said tool, each said dog being resiliently biased towards said first position.

21. A drill pipe coupling tool adapted to be removably mounted in a rotary drive mechanism of an earth drilling apparatus for coupling a drill pipe to said drive mechanism, said tool comprising:
a cylindrical, tubular body portion defining a rotary axis;
coupling means on said body portion for non-rotatably coupling said tool to a length of drill pipe for rotation of said tool and said drill pipe about said rotary axis;
axial spline means on the outer periphery of said body portion for engagement with mating spline means in said drive messianism, said spline means non-rotatably coupling said tool to said drive mechanism for rotation of said tool about said rotary axis and permitting axial travel of said tool relative to said drive mechanism during operation of said drive mechanism;
means on said body portion for limiting axial travel of said tool between predetermined limits, said travel limiting means including retaining means removab-ly mounted at one end of said tool, said retaining means being abuttingly engageable with said drive mechanism for limiting in one direction axial travel of said tool relative to said drive mechanism;
said travel limiting means including a radially outwardly facing groove in the outer periphery of one end of said body portion, said retaining means including a split ring having a pair of arcuate arms pivotally connected at adjacent ends and removably receivable in said groove and a retaining ring telescopically movable along the outer periphery of said body portion between a first position engaging said split ring and preventing separation of said arms and a second position permitting separation of said arms and removal of said split ring from said groove.

22. A coupling tool as defined in claim 21, said travel limiting means including first shoulder means extending outwardly of the other end of said body portion for abutting engagement with a portion of said drive mechanism.

23. A coupling tool as defined in claim 22, said shoulder means being a radially outwardly extending flange.