Rotary drive and joint breakout mechanism
[ Apr. 1,1975  
 ABSTRACT bushing A rotary table drive for a blasthole drill has a pair of roller elements pivotally mounted in a table and engageable with cooperative longitudinal flat sided recesses formed on the exterior of a heavy walled cylindrical drill pipe to form the rotary dri connection with the drill stem. Multiple sections of the drill pipe may be used to make up a drill stem. A pulldown traverse frame mounted for longitudinal movement along the rig mast includes a rotary coupling member connected to the top end of a drill pipe section. The traverse frame also includes a drive transfer mechanism which is engageable with the rotary table for transferring the rotary drive effort from the table through the coupling member to the drill stem when the top end of a drill pipe section is passed downward through the table bushing. The: drive transfer mechanism can be nonrotatably locked to provide for breakout of the threaded joint between a drill pipe section MECHANISM [75] Inventors: Robert W. Hisey, Richardson; Larry E. Halwas, Garland, both of Tex.  
 Assignee: Gardner-Denver Company, Quincy,  
 July 16, 1973 Appl. No.: 379,664  
  64/235, 173/163, 175/195 Int. Fl6d 3/06 64/235, 23.6, 23.7, 23 R; 175/195; 173/163 References Cited UNITED STATES PATENTS United States Patent Hisey et al.  
 [ 1 ROTARY DRIVE AND JOINT BREAKOUT [22] Filed:  
 [58] Field of Search.........  
 FMENTED APR 7 1915 sum 7 or a PATENTEDAPR Mars 2314.196  
 SHEET 8 BF 8 ROTARY DRIVE AND JOINT BREAKOUT MECHANISM BACKGROUND OF THE INVENTION Rotary table drives for earth drilling rigs hold certain advantages over so-called top drive arrangements in that the weight of the rotary drive mechanism is not required to be supported by the drill rig mast or derrick and the reaction torque from the drill stem rotative effort can be transferred directly to the main frame of the drill rig instead of being imposed on the mast structure. These advantages simplify the structural requirements of the mast itself. Additionally, the power transmission system is more compact and easily arranged for a rotary table drive and often a portable drill rig may require a total of only one or two drive motors for propelling the rig, pulldown and hoisting of the drill stem, and rotation of the drill stem.  
  A longstanding problem in the use of rotary table drives for large earth drilling rigs for drilling blastholes and other relatively shallow holes in hard rock is that the use of a conventional noncylindrical cross section drill pipe or kelly for transmitting rotary motion from the table to the drill stem does not provide a suitable annular area in the drill hole for effective removal of the drill cuttings by the hole cleaning fluid. ln order to provide suitable annular areas for drill cutting removal a flat sided drive member is required to be so large that the corners formed by the intersections of the sides of the member are disposed closely adjacent the side wall of the drill hole and are subject to severe wear from unavoidable rubbing against the side wall. Additional severe wear which tends also to round of the corners and the flat sides of a conventional drive member is caused by abrasion from the constant stream of drill cuttings passing upward during drilling around the exterior of the drill stem portion which is in the hole. In a short time an unsuitable driving connection is formed between the socket or complementary opening in the rotary table and the drive member due to wear which changes the cross sectional shape of the drive member itself.  
  Furthermore, if a square cross section or otherwise special rotary drive member or kelly is used together with cylindrical cross section drill pipe, then the process of adding and removing drill stem sections is somewhat more complex and time consuming. Since the drive member or kelly is the only drill stem member which can be driven by therotary table the kelly itself must be disconnected from the drill stem and set aside in the mast or placed down an auxiliary hole while additional drill pipe sections are added to or removed from the drill stem and then the kelly must be reconnected to the drill stem and reinserted in the rotary drive bushing when rotation of the stem is desired. Conversely, if the drive member or kelly is retained in connection with the hoisting mechanism and over the drill hole centerline, then the mast height must be sufficiently great to hoist the length of the kelly and at least one section of drill pipe up out of the table.  
  Accordingly, it is desirable to provide a rotary table drive for earth drill rigs in combination with a drill stern which will provide for use of the drill pipe members making up the drill stem to be used as drive members engaged with the table drive itself. Such drill stem members are also desirably of a configuration which will provide an annular area in the drill hole between the drill pipe exterior and the side wall of the hole which will be of the proper size: to permit effective drill cutting removal from the bottom of the hole without using unnecessarily large quantities of hole cleaning fluid. It is further desirable in large rotary blasthole drills to be able to use relatively thick walled cylindrical drill pipe which can be driven directly by a rotary drive mechanism because such pipe configurations are capable of withstanding large axial pulldown forces without being susceptible to bending or kinking.  
 . SUMMARY OF THE INVENTION The present invention provides an improved rotary drive arrangement for an earth drilling rig wherein a novel rotary table drive mechanism is used in combination with novel drill pipe or stem components which are adapted to be driven directly by the rotary table without the use ofa special drill stern drive section. The rotary table drive mechanism of the present invention provides for driving a drill stem made up of one or more substantially cylindrical drill pipe sections adapted to engage driving members mounted in the rotary table. The rotary table drive mechanism of the present invention also includes drill stem driving members which provide positive and low friction driving engagement with the drill stem and are mounted in such a way that they are drivingly engageable with each drill pipe section which is added to the drill stem as the drill pipe sections pass through the rotary table. With the rotary table drive arrangement of the present invention cylindrical cross section or tubular drill pipe in a modified form is advantageously used as sectional drill stem members which are directly driven by an improved rotary table drive mechanism wherein wear on the pipe itself does not have harmful effects on the drive connection with the rotary table.  
  The present invention also provides a rotary drive transfer mechanism for use with a rotary table drive in an earth drilling rig wherein sectional drill stem members may be rotatably driven while the end portions thereof are passed through the rotary table. The rotary drive transfer mechanism of the present invention is particularly advantageous for use with a rotary table drive which includes members engageable with cooperating drive surfaces on a drill stem member and wherein positive driving engagement between the table and the drill stem member cannot be provided when an end portion of a drill stem member is passed through the table during drilling operations.  
  The rotary drive transfer mechanism of the present invention also includes means for nonrotatably locking a rotary coupling between a drill stem and a pulldown traverse frame whereby the drill stem members may be easily disconnected from the traverse frame.  
  The present invention further includes improved means for breaking out threadled joints between sectional drill stem members and between a drill stem member and a drill bit portion. The joint breakout means of the present invention includes a power operated wrench for holding a drill stem member during breakout operations and which also provides for handling the detachable drill bit portion in a fast and work saving manner.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal side elevation of an earth drilling rig including the rotary drive and joint breakout mechanisms of the present invention;  
 FIG. 2 is a front elevation of the drill rig of FIG. 1;  
  FIG. 3 is a plan view of the rotary table of the present invention taken from line 33 of FIG. 2;  
  FIG. 4 is a view from line 4-4 of FIG. 3; FIG. 5 is a section view taken along line 5-5 of FIG.  
  FIG. 6 is a sectional elevation of the rotary table and drive bushing;  
  FIG. 7 is a longitudinal view of a section of drill pipe in accordance with the present invention;  
  FIG. 8 is a section view taken along line 8-8 of FIG.  
  FIG. 9 is a section view taken along line 99 of FIG.  
  FIG. 10 is a plan view of the rotary drive bushing of the present invention;  
  FIG. 11 is an elevation view of the rotary drive bushing shown in FIG. 10.  
  FIG. 12 is a plan view of a power operated holding wrench and bit handling tool;  
  FIG. 13 is a side elevation of the power operated holding wrench and bit handling tool of FIG. 12;  
  FIG. 14 is a view of a pair of removable shoes for use with the power operated holding wrench of FIGS. 12 and 13;  
  FIGS. 15 through 18 are views of the rotary drive transfer and breakout mechanism showing the operation thereof;  
  FIG. 19 is a section view taken along line 1919 of FIG. 15; and,  
  FIG. 20 is a section view taken along line 20-20 of FIG. 18.  
 DESCRIPTION OF THE PREFERRED EMBODIMENTS The rotary table drive and joint breakout mechanism of the present invention is particularly suitable for use with relatively large rotary blasthole drills which are designed for drilling holes to a maximum depth usually in the range of 100 to 150 feet. Such types of drills are characterized by mechanism for exerting a heavy axial down thrust or pulldown force on the drill stem and bit portion while the drill stem including the bit is rotated to provide for localized crushing and grinding of the rock and earth to form the drill hole. However, since the mode of drilling is generally similar to that practiced with other types of drilling rigs such as oil and water well drilling equipment it is contemplated that the present invention could be utilized with these as well as other rotary drilling devices.  
  Referring to FIGS. 1 and 2 a portable rotary blasthole drilling rig is illustrated and generally designated by the numeral 22. The drill rig 22 is characterized by a frame 24 which is mounted on spaced apart crawlers 26. The frame 24 supports an elongated mast 28 which is mounted on support means 30 for pivotal movement between the erect or working position shown and a substantially horizontal position when the rig is being propelled from one drilling site to another. The mast 28 includes two spaced apart longitudinal posts 32 on which are formed gear racks 34. The mast 28 is adapted to support a longitudinal traverse frame 36 which includes a pair of spaced apart rotatable shafts 38 and 40 each having pinions 42 mounted thereon and engaged with the racks 34. Suitable flexible drive means such as endless chains designated by numeral 44 are supported by the mast 28. The drive chains are suitably engaged with the shafts 38 and 40 for rotating the shafts to advance the traverse frame reversibly along the mast.  
  The traverse frame 36 includes a transverse yoke member 46 including means for rotatably supporting a coupling member 48 for connecting the traverse frame to a drill stem generally designated by numeral 50 and made up of one or more elongated drill pipe sections 52. The drill stem 50 also includes a stabilizing sub 54 and a rotary bit 56 connected to the lower end thereof for forming a drill hole 58. The traverse frame 36 is reversibly driven along the mast 28 by the chains 44 to exert an axial feed or pulldown force on the drill stem 50 and to hoist the drill stem components out of the drill hole. A drive motor and transmission unit 60 mounted on the rig 22 is connected by drive means 62 to the endless flexible chains 44 for driving the traverse frame 36 along the mast. A more detailed description of the pulldown traverse frame 36 and its associated drive means is disclosed in US. Pat. application Ser. No. 362,576 filed May 21, 1973.  
  In many applications of the rig 22 a single traversal of the frame 36 down the mast will be sufficient to cause the formation of a drill hole of desired depth. However, when it is desired to form a hole depth greater than that provided for by one pass of the frame 36, additional drill pipe sections must be added to the drill stem. Accordingly, the drill rig 22 is provided with a storage rack 64 for holding a second drill pipe section 52. The storage rack may take various forms and may be adapted to hold a plurality of drill pipe sections. The  
 rack 64 is exemplary and is of the type which is mounted in the mast 28 on pivotal linkage members 66 and 68 adjacent the top and bottom of the rack, respectively. A pressure fluid operated cylinder and piston device 70 is connected to the member 68 for moving the rack 64 from the retracted position shown in FIG. 1 into a position whereby the pipe section 52 held by the rack is in line with the longitudinal axis of the drill stem 50.  
  Referring to FIGS. 1 through 3 and FIG. 6 the drill rig 22 is characterized by a rotary table drive mechanism for imparting rotary motion to the drill stem 50. The rotary table drive mechanism of the present invention is generally designated by numeral 72 and includes a boxlike housing 74 mounted on the frame 24. The housing 74 includes bearings 76 and 78 mounted therein for supporting a rotating table member 80. The table member 80 is characterized by a circular flange 82 having radially projecting teeth 84 formed on the periphery thereof. An axial opening 86 through the table member 80 includes a square or flat sided portion 88 which forms a socket for receiving a removable rotary drive bushing 90. The table member 80 also includes a bevel gear 92 fixed on the underside of the flange 82 and engaged with a bevel pinion 94 rotatably mounted in the housing 74. The pinion 94 is connected to a shaft 96 which in turn is drivenly connected to the drive motor and transmission 60. The table housing 74 is mounted on the frame 24 so that the table member 80 extends slightly above the deck or platform 98, FIG. 1. A hinged cover 100 is shown in FIG. 3 for partially covering the table member 80 in the vicinity where drill operating personnel normally work when making up and breaking out threaded connections between the bit. stabilizing sub, and drill pipe sections.  
  The rotary table drive of the present invention includes the improved drive bushing 90 which in combination with the drill pipe sections 52 shown in FIGS. 7 through 9 provides for use of sectional drill stem members as the rotary driven member or what is sometimes referred to as the kelly. Referring to FIGS. 6 through 11, the rotary drive bushing 90 is characterized by a flat sided and square depending portion 101 which is removably fittable in the complementary socket portion 88 in the table 80. A circular flange 102 formed on the bushing includes a plurality of circumferentially spaced teeth 104 which project axially upwardly when the bushing is fitted in the table. The bushing 90 also includes a central opening 106 through which the drill pipe sections 52 pass during drilling and hoisting opera tions. Recesses 108 are formed in two opposed sides of the portion 101 and intersect the opening 106. The recesses 108 are formed to accommodate a pair of drive rollers 110 which are mounted to be substantially par allel to each other and to project partially into the opening 106. The rollers 110 are each rotatably mounted on a support plate 112 having a hub portion 114 for mounting the rollers to swing about a substantially vertical pivot formed by pins 116 projecting through the hub portion of each support plate. The pins 116 are suitably retained on the bushing 90. The hub portions of the support plates 112 each include a recess 118 in which is positioned a torsion coil spring 120 surrounding the pin 116 and engaged with the support plate for biasing the roller 110 inwardly toward the center of the opening 106. The support plates 112 also include projecting tabs 122, as shown in FIGS. and 11, which engage projections 124 formed on the bushing 90 so as to limit the inward swinging movement of the rollers toward the center of the opening 106. The bushing 90 also includes a pair of recesses 126 located adjacent to the opening 106 and opposed to each other along a line through the center of the opening as shown in FIGS. 6 and 10. The recesses 126 have disposed therein pivotally mounted dogs 128 which may be pivoted to project into the opening 106 for engaging holding slots formed in a drill stem member such as the pair of slots 130 in the stabilizer 54 as shown in FIG. 6. When not required for holding a drill stem member the dogs 128 may be swung away from the opening 106 to lie along the sloped surfaces of the recesses 126.  
  Referring to FIGS. 7 through 9 a drill pipe section 52 is illustrated which is adapted to be used as the member rotatably driven by the rotary table bushing 90 and which may be used as part of the drill stem disposed in the drill hole without suffering wear which would be harmful to the driven surface portions engaged with the rollers 110. The drill pipe section 52 is basically a cylindrical thick walled steel tube having a central longitudi nal passage 131 for conducting hole cleaning fluid through the drill stem to the bottom of the drill hole. The drill pipe section 52 includes an externally threaded portion or pin 132 at one end and an internally threaded portion 134 or box at the opposite end. The threaded portions 132 and 134 will be assumed to be of the &#34;right hand&#34; for purposes of this disclosure. A slightly reduced diameter portion 136 is formed at the pin end of the section 52. The drill pipe section 52 also includes a pair of longitudinal recesses 138 formed in the outer cylindrical wall surface 139. The recesses 138 extend over a major portion of the drill pipe section 52 and include parallel and opposed surface portions 140. The surfaces 140 are each intersected by a surface 142, which intersection is such that the surfaces 140 and 142 of each groove 138 are substantially perpendicular to each other. The surfaces 142 are formed to be coplanar and lie in a longitudinal plane which passes through the longitudinal rotational axis 143 of the drill pipe section 52.  
  As shown in FIG. 10 the surfaces 142 of the grooves 138 are disposed to be engaged by the rollers 110 whereby rotation of the bushing will impart rotation to the drill pipe section 52. As may be seen in FIG. 10 the drive faces 144 of the rollers are provided with a taper or slope with respect to the axis of rotation of the rollers which provides for clearance along the surface 140 of the grooves 138 with respect to the sides of the rollers when the rollers are drivingly engaged with the surfaces 142. As may be noted also from FIG. 10 the location of the pivot pins 116 for the roller support plates are radially further from the rotational axis of the drill pipe section&#39;52 than the drive surfaces 142 which engage the rollers and are positioned such that when the rollers are driving the drill stem rotatably a force couple is formed about the pivot pins 116 which tends to swing the rollers inwardly toward the center of the opening 106 to assure maximum engagement of the surfaces 142 with the roller drive faces 144. With the arrangement of the rollers 110 and drive surfaces 142 as provided on the drill pipe section 52 the drill pipe can be easily proportioned to be of the proper size to provide the desired annular area in the drill hole for effective drill cuttings removal and furthermore the drive surfaces 142 are not affected by rubbing of the drill pipe against the side wall of the hole or by abrasion from the drill cuttings passing upward out of the hole around the drill stem. Moreover. by providing the drill pipe section 52 with surfaces 142 which are substantially flat and radially extended with respect to the longitudinal axis of the pipe section the direction of the driving force transmitted from the rollers 110 to the drill pipe section 52 is more effective for turning the drill stem 50. Accordingly, a more positive and long lasting drive connection may be maintained with the rotary device disclosed herein.  
  The drill pipe section 52 also includes a pair of slots or recesses 148 in the outer wall surface near the pin end which recesses are for engagement with the dogs 128 in the rotary bushing for holding the drill pipe section in the bushing during joint makeup and breakout operations. The drill pipe section 52 also is characterized by a pair of opposed grooves 150 disposed near the lower end which are .cooperable with a pair of jaws of a holding wrench to be described herein. If multiple pass drilling is performed by the drill rig 22 all of the drill pipe sections may be of the same configuration as the section 52 shown in FIGS. 7 through 9. As shown in FIG. 7 and FIGS. 15 through 18 the grooves 138 are formed such that the surfaces are sloped radially outwardly with respect to the longitudinal axis of the drill pipe section toward the outside wall surface at the reduced diameter portion 136. This flaring out of the grooves 138 provides for the rollers 110 to be urged to swing outwardly away from the center of the opening 106 as the end portion of the drill pipe section 52 passes down through the opening whereby the lower end of the next drill pipe section added to the drill string may be initially passed into the opening 106 regardless of any longitudinal misalignment of the drive surfaces 142 on one drill pipe section with the corresponding surfaces on the adjacent drill pipe section. When the pipe sections are being removed from the drill hole the table 80 may be rotated in the reverse or nondriving direction slightly to cause the rollers 110 to swing outwardly with respect to the opening l06so as not to engage or catch on the transverse end faces of the pipe sections as they are withdrawn from the hole. If single pass drilling only is to be performed the grooves 138 may be formed to extend entirely the length of the pipe section 52 to thereby provide driving engagement of the rollers 110 throughout the entire length of the section. With the drive transfer mechanism disclosed herein it is advantageous to form the grooves 138 as shown in FIG. 7 since the rollers are not drivingly engaged with the drill pipe at the end portion 136 anyway.  
  For drilling operations wherein more than one section of drill pipe is to be used to increase the length of the drill stem for drilling deeper holes a drive transfer mechanism may be advantageously used with the rotary table drive mechanism of the present invention so that the grooves 138 of one drill pipe section 52 are not required to be longitudinally aligned with the corresponding grooves on an adjacent drill pipe section in the drill stem. Referring to FIGS. 1, 2 and through the rotary drive transfer mechanism of the present invention includes the rotary coupling member 48 which is rotatably supported in bearings 152 and 154 mounted in a housing 156 on the yoke 46. The member 48 includes an internal passage 158 in communication with a drill hole cleansing fluid conduit 160. The lower end of the member 48 is characterized by an internally threaded portion 162 for receiving the pin end 132 of a drill pipe section 52. The member 48 also includes a plurality of longitudinal keyways 164 in which are slidably fitted keys 166. The drive transfer mechanism further comprises a coupling sleeve 168 having complementary grooves 170, FIG. 18, in which the keys 166 are disposed to form a rotary driving connection between the sleeve and the member 48. The sleeve 168 includes a flange 172 at one end having a ring of circumferentially spaced and axially projecting teeth 174 which are engageable with complementary teeth 176 formed on a collar 178 fixed to the yoke 46. The lower end of the sleeve 168 also includes circumferentially spaced teeth 180 which project axially downwardly and are voperable to be interfitted with the teeth 104 on the bushing 90 to form a driving connection between the bushing and the sleeve. The sleeve 168 also includes a flange 182 which has disposed on its circumference a plurality of rollers 184. The rollers 184 are disposed in a radially inward facing channel 186 formed on a circular plate 188. The plate 188 is attached to the ends of a pair of pressure fluid cylinder and piston type actua tors 190. The cylinders 190 are slidably guided in tubular sleeves 192 disposed on the yoke 46. The distal ends of the cylinder piston rods 194 are suitably fixed to the yoke 46 shown in FIG. 15.  
  The drive transfer mechanism also includes a second sleeve member 196 disposed in a bore 197 in the sleeve 168 and adapted to surround and frictionally grip the reduced diameter portion 136 ofa drill pipe section 52 as shown in FIGS. 15 and 16. The sleeve 196 includes keyways 198, FIG. 19, in which are disposed the keys 166 to form a driving connection with the member 48.  
  As shown in FIG. 20 the sleeve 196 includes a plurality of slots 200 which extend longitudinally a portion of the length of the sleeve along which portion the exterior surface 202 of the sleeve is also sloped and is engageable with a correspondingly sloped collar 204 as shown in FIGS. 15 through 18. The collar 204 is suitably retained in the interior of the sleeve 168 and is engageable with an inwardly projecting shoulder portion 206. The sleeve 196 also includes a shoulder portion 208 engageable with the shoulder portion 206 on sleeve 168, as shown in FIGS. 17 and 18. The drive transfer mechanism provides for rotatably driving the drill stem when an end portion ofa drill pipe section 52 is passed through the rotary bushing so that sufficient hole depth is achieved to permit the addition of a drill pipe section to the drill stem and engagement of the rollers with the groves 138 of the section added to the drill stem at the onset of drilling after the section has been added. The drive transfer mechanism also is adapted to be used to break out the threaded connection between the member 48 and a drill pipe section.  
  An operating sequence of the drill transfer mechanism will now be described in connection with viewing FIGS. 15 through 18. During drilling operation, with the rotary drive being imposed on the drill stem 50 by the driving connection between the rollers 110 and a drill pipe section 52, the cylinders 190 are extended as shown in FIG. 15 to cause the collar 204 to compress the sleeve 196 to grip the reduced diameter portion 136 ofa drill pipe section. This prevents the right-hand thread connection between the member 48 and the drill pipe section 52 from breaking loose due to the rotary driving effort imposed on the drill string which is in the direction of the arrow 210 in FIG. 10.  
  As the pulldown traverse frame 36 feeds the drill stem downwardly to the position shown in FIG. 16, the complementary teeth and 104 on the sleeve 168 and bushing 90 become engaged and rotary driving effort is transferred from the bushing 90 to the coupling member 48 by way of the sleeve 168. Accordingly, rotation of the drill stem 50 is now no longer dependent on the rollers 110 driving against the surfaces 142 on the drill pipe section. Continued axial down thrust by the traverse frame will result in axial sliding movement of the member 48 downward, viewing FIGS. 16 and 17, with respect to the sleeve 168 which will also cause the sleeve 196 to move downward with respect to the collar 204. The sleeve 196 will, upon moving free of the radial inward wedging action of the collar 204, release its grip on the portion 136 of the drill pipe section 52, as shown in FIG. 17. The rotary drive now being from the member 48 to the drill pipe section 52 will, of course, tend to tighten a right-hand threaded connection therebetween. The cylinders will be allowed to telescope into the sleeves 192 as the traverse frame 36 moves downward from the FIG. 16 position to the FIG. 17 po&#39; sition. As shown in FIG. 17 the top end of a drill pipe section 52 is now below the rollers 110 and a drill pipe section to be added to the drill stem could be lowered into the opening 106 so that the rollers could engage the drive surfaces 142. Prior to adding a drill pipe sec tion the threaded connection between the member 48 and the upper end of a drill pipe section 52 must be broken out. To accomplish this the traverse frame 36 is reversed to hoist the drill pipe section 52 up through the bushing 90 until the dogs 128 can be pivoted into position in the recesses 148 to hold the drill pipe section in the position shown in FIG. 18 and in the same manner as shown for the stabilizer 54 in FIG. 6. The cylinders 190 are then actuated to move the sleeve 168 upward until the teeth 174 are interfittingly engaged with the teeth 176 as shown in FIG. 18 whereby the sleeve 168 and member 48 are nonrotatably locked. The rotary table 80 is then driven in the direction of the arrow 210 of FIG. to rotate the pipe section 52 with the rollers 110 as well as the dogs 128 drivingly engaged in their respective recesses until the pipe section 52 is disconnected from the member 48. After moving the traverse frame 36 up the mast 28 an additional drill pipe section 52 can be added by positioning a suitable storage rack such as the rack 64 over the axis of the drill stem and rotating the table 80 in reverse to make up a threaded connection between the drill pipe section supported in the table and the section being added. The traverse frame 36 is then lowered to engage the coupling member 48 with the section added to the drill stem whereby further reverse rotation of the table would thread the pin end 132 ofa drill pipe section into the threaded portion 162 on the coupling member. The cylinders 190 are extended after the coupling member is reconnected to the drill string to unlock the sleeve 168 and to cause the sleeve 196 to be lowered into frictional gripping engagement with the top portion of the drill pipe section now connected to the coupling member 48.  
  If a drill pipe section is to be removed from the drill stem 50 the threaded connection between a drill pipe section 52 and the coupling member 48 would be broken loose generally in accordance with the above described procedure. Then, prior to complete separation of the coupling member 48 from the drill pipe section, the traverse frame 36 is raised up the mast to pull the pipe section to be removed from the drill stem up through the table bushing 90 until the upper portion of the drill pipe section which is below the one to be removed is in position to have the recesses 148 engaged by the dogs 128 and the recesses 138 engaged by the rollers 110. With the drill pipe storage rack in position to receive the pipe section being removed from the drill stem or an auxiliary hoisting line connected thereto, the table 80 is rotated forward, the direction of arrow 210 in FIG. 10, until the coupling member 48 is separated from the pipe section being removed. Then a suitable holding wrench such as the wrench described hereinbelow is engaged with the grooves 150 of the pipe section being removed from the drill string while the table 80 again is rotated forwardly to break out the joint between the section being removed and the section supported in the table bushing 90.  
  The rotary drive and joint breakout mechanism of the present invention includes improved auxiliary breakout and drill stem component handling devices.  
 Referring to FIGS. 3 through 5 a rotary table turning arm 230 is supported for sliding movement in the frame 224 and includes a hook 234 formed on the end which is opposite the end connected to the piston rod 228. The frame 224 is suitably connected to a pressure fluid actuator 236 by way of a member 238 whereby in response to operation of the actuator the device 220 may be pivoted into the position shown in FIG. 3 and held for engagement of the hook 234 with one of the radially projecting teeth 84 on the table 80. The actuator 236 is mounted on bracket 240 which is disposed on the deck 98 and which also partially supports the frame 224. With the hook 234 positioned to engage a tooth on the table the cylinder 226 may be actuated to retract the piston rod 228 so as to rotate the table 80 with great force a small portion of a. revolution for breaking out drill string connections which cannot be loosened with the turning effort available from the motor and transmission 60 through the table drive gears 92 and 94. When the breakout device 220 is not in use the actuator 236 is energized to pivot the frame 224 so that the hook 234 is moved radially away from the table 80.  
  Referring to FIG. 3 and FIGS. 12 through 14 the drill rig 22 includes a drill stem holding wrench 250 which is also adapted to handle a drill bit for adding and removing the same with respect to the drill stem 50. The wrench 250 includes a power rotated base 252 having a shaft portion 254 rotatably mounted in a bearing sleeve 256 supported on the rig substantially below the deck 98. The base 252 includes a sprocket 258 fixed thereon and engaged with a chain 260 which is drivenly connected to a sprocket 262 mounted on the shaft of a suitable drive motor, not shown. The base 252 includes an upstanding part 264 upon which a boom 266 is mounted for movement about a horizontal pivot 268. A hydraulic cylinder 270 is connected between the boom 266 and the part 264 for raising and lowering the boom about the pivot 268. The boom 266 is adapted to receive a partially tubular member 272 which is secured against rotation with respect to the boom by a pair of removable pins 274. The member 272 includes a portion formed in part by two spaced apart plates 276. A pair of holding jaws 278 and 280 are mounted between and supported for pivotal movement with respect to the plates 276. Each jaw includes a short arm portion 282 which is connected by means of a link 284 to a clevis 286. The clevis 286 is connected to a piston rod portion of a linear pressure fluid actuator 288 mounted on the member 272 for moving the jaws between the closed position shown by the solid lines in FIG. 12 and the open position shown by the dashed lines. The holding jaws 278 and 280 have removable shoes 290 secured on the jaws by pins 294. The jaws 278 and 280 each also includes a depending member 296 having a projection 298 formed on the lower end thereof, viewing FIG. 13, which is engageable with a bail 300 mounted on a bit holding fixture 302.  
  The bit holding fixture 302 is characterized by a cylindrical portion 304 which is adapted to be retained in suitable receptacles 306, one shown in FIG. 3, in the deck of the rig 22. A flat sided flange 308 is attached to the portion 304 and is adapted to fit in the socket or opening 88 of the table 80 in place of the bushing 90. The flange 308 also has a socket opening 310 formed to closely fit around the integral legs of a roller type rotary bit such as the bit 56 in FIGS. 1 and 2, whereby with the fixture disposed in the table 80 and surrounding the bit the table may be rotated to make up or break out a connection between the bit and the stabilizer 54.  
  The process of changing bits on the drill rig 22 may be performed by raising the traverse frame 36 and drill stem up the mast 28 until the lower end of the bit 56 is pulled up through the table 80 and above deck level sufficiently to permit swinging the holding wrench 250 from a retracted position, as shown in FIG. 3, with a fixture 302 attached thereto into position over the table. The fixture 302 is then lowered into the opening by operation of the cylinder 270 and the jaws 278 and 280 are at least partially closed to disconnect the members 296 from the bails 300. When the drill string is removed from the hole the flutes 55, see FIG. 6, on the stabilizer 54 engage the bushing 90 and carry it upwardly out of the table 80 to provide for accommodation of the fixture 302 in the table opening 88. After placement of the fixture 302 in the table 80 the bit 56 is lowered into the socket 310 and the jaws 278 and 280 with modified shoes 314, as shown in FIG. 14, disposed thereon are closed so that projections 316 on the shoes 314 are engaged with the sides of grooves 57 in the stabilizer. The table 80 is then rotated, while the stabilizer 54 is prevented from rotation, to break a threaded connection between the bit and stabilizer. The bit fixture 302 with a bit disposed therein may then be removed from the table by the wrench 250 and deposited in a receptacle 306, and a similar fixture and bit can then be picked up and swung into place in the table opening. With the new bit disposed in the table the drill stem and stabilizer are lowered and the table rotated in reverse to make up a joint between the bit and stabilizer. The wrench 250 may be used to hold the stabilizer nonrotatably while the joint is being made up. The drill stem including the new bit is then raised to remove the bit from the fixture 302 and after retraction of the wrench 250 and fixture to the stored position the drill stem is lowered into the table and the bushing 90 returned into the opening 88 preparatory to a drilling operation.  
 The wrench 250 is also used to hold a drill pipe section 52 while threaded joints between sections are made up or broken loose. By rotation of the base 252 and operation of the boom cylinder 270 the wrench may be moved when desired into a position with the jaws 278 and 280 surrounding the drill stem 50. The  
 shoes 290 shown in FIG. 12 include surfaces 292 engageable with the sides of the grooves 150 for holding a drill pipe section 52 while the table is rotated to break one section loose from another.  
  The wrench jaws 278 and 280 may also be inverted by removing the pins 274, rotating the member 272 in the boom 266, and then reinserting the pins. This inversion of the jaws 278 and 280 may be performed so that the shoes 290 can be engaged with the surfaces 142 to hold one drill pipe section from rotating while the table 80 is rotated in reverse, with another drill pipe section or stabilizer 54 supported therein by the dogs 128, to tighten a joint.  
  As may be appreciated from the foregoing description the present invention provides improved rotary drive means for rotating a drill string in a rotary earth drilling rig. The rotary drive means of the present invention together with a novel drive transfer mechanism and the holding wrench and bit handling device 250 provides for more rapid and efficient drilling operations on rotary drill rigs than was heretofore known.  
 What is claimed is:  
 l. A rotary drive arrangement for rotating a drill stem on an earth drilling rig comprising:  
 a member disposed for rotation on said drilling rig and including an opening in which said drill stem is disposed for longitudinal movement with respect to said member;  
 said drill stem comprising at least one elongated drill pipe section having a pair of opposed recesses in the outer wall surface of said drill pipe section, each recess forming a drive surface extending inward from the intersection of said recess with said outer wall surface generally toward the longitudinal axis of said drill pipe section, said drive surfaces extending longitudinally over a major portion of the length of said drill pipe section; and,  
 a pair of drive rollers engageable with said drive surfaces for rotating said drill pipe section in response to the rotation of said member, said rollers being disposed on support members which are mounted on pivot means on said member so that said rollers may be pivotally moved into and out of engagement with said drive surfaces.  
 2. A rotary drive arrangement for rotating a drill stem on an earth drilling rig comprising:  
 a member disposed for rotation on said drilling rig and including an opening in which said drill stem is disposed for longitudinal movement with respect to said member;  
 said drill stem comprising at least one elongated drill pipe section having a pair of opposed recesses in the outer wall surface of said drill pipe section, each recess forming a drive surface extending inward from the intersection of said recess with said outer wall surface generally toward the longitudinal axis of said drill pipe section, said drive surfaces being parallel and coplanar and extending longitudinally over a major portion of the length of said drill pipe section; and,  
 a pair of drive rollers engageable with said drive surfaces for rotating said drill pipe section in response to the rotation of said member, said rollers including drive surfaces which are tapered with respect to the axis of rotation of said rollers and are engageable with the drive surfaces of said drill pipe section in such a way that surface portions of said recesses other than said drive surfaces are substantially prevented from engagement with said rollers when said rollers are rotatably driving said drill pipe section.  
 3. A rotary drive arrangement for rotating a drill stem on an earth drilling rig comprising:  
 a member disposed for rotation on said drilling rig and including an opening in which said drill stem is disposed for longitudinal movement with respect to said member;  
 said drill stern comprising at least one elongated drill pipe section having recesses in the outer wall surface thereof, each recess forming a drive surface extending inward from the intersection of said recess with said outer wall surface generally toward the longitudinal axis of said drill pipe section, said drive surfaces extending longitudinally over a major portion of the length of said drill pipe section; and,  
 drive means engageable with said drive surfaces for rotating said drill pipe section in response to the rotation of said member, said drive means being disposed on support members which are mounted on pivot means on said member so that said drive means may be pivotally moved into and out of engagement with said drive surfaces.  
 4. The invention set forth in claim 3 wherein:  
 said pivot means for mounting said support members on said member are disposed on said member further from the longitudinal axis of said drill pipe section than the point of engagement of said drive means with said drive surfaces on said drill pipe section so that in response to said drive means forcibly engaging asid drill pipe section a force couple is formed which tends to pivot said drive means to ward said longitudinal axis of said drill pipe section.  
 5. The invention set forth in claim 3 together with:  
 biasing means on said member engaged with said support members for biasing said drive means into said opening in said member.  
 6. The invention set forth in claim 5 together with:  
 stop means on said support members for engaging cooperating stop means on said member for limiting the pivotal movement of said drive means into said opening.  
 7. The invention set forth in claim 1 wherein:  
 said pivot means for mounting said support members on said member are disposed on said member further from the longitudinal axis of said drill pipe section than the point of engagement of said rollers with said drive surfaces on said drill pipe section so that in response to said rollers forcibly engaging said drill pipe section a force couple is formed which tends to pivot said rollers toward said longitudinal axis of said drill pipe section.  
 8. The invention set forth in claim 1 together with:  
 biasing means on said member engaged with said support members for biasing said rollers into said opening in said member.  
 9. The invention set forth in claim 8 together with:  
 stop means on said support members for engaging cooperating stop means on said member for limiting the pivotal movement of said rollers into said opening.  
 10. The invention set forth in claim 3 wherein:  
 said rotary drive arrangement comprises a rotary table having a housing supporting a rotatable table member, and said member comprises a bushing removably fitted on said table member to be rotatably driven by said table member.