Патент USA US2127108код для вставки
Aug. 16, 1938. D. |_. DRISCCSLL 2,127,108 WELL DRILLING APPARATUS Filed March 4, 1936 4 Sheets-Sheet l H16 Hilary Aug. 16, 1938. D_ .|__' DRISCOLL _ 2,127,108 WELL DRILLING APPARATUS Filed March 4, 1936 .. 47,4,; 45'” 4 Sheéts-Sheet 2 '17; .J. (\a) .Z'n yen for _ ?aw/15 L. D2166 OLL a Aug. 16, 1938. v ' D. L. DRISCOLL , 2,127,108 ~ WELL DRILLING APPARATUS Filed March 4, 1936 4 Sheets-Sheet 3 Aug- 16, 1938- ‘ D. L. DRISCOLL , 2,127,108 WELL DRILLING APPARATUS Filed March 4, 1936 4 Sheets-Sheet 4 2,127,108. Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE 2,127,108 WELL DRILLING APPARATUS Dennis L. Driscoll, Los Angeles, Calif., assignor to Lawrence F. Baash, Los Angeles, Calif. Application March 4, 1936, Serial No. 67,080’ 18 Claims. (01. 24-263) This invention relates to well drilling apparatus and relates more particularly to a rotary table 0 bushing and slips therefor. A general object of this invention is to provide an improved rotary table bushing and slip assembly that is particu larly effective and long wearing. Another object of this invention is to provide a practical rotary table bushing and slip assembly in which the slips all have extensive and equal seating engagement with the bushing and have uniform gripping contact with the pipe or object handled. The extensive engagement of the slips in the bushing allows the slips to be of light con struction and of substantial length. Another object of the invention is to provide 15 a master bushing for a rotary table that has in clined grooves or slots in its interior of uniform width throughout their lengths and slips shaped and proportioned to ?t the slots whereby they may have extensive continuous engagement with the walls of the slots while gripping the pipe and when in any vertical position they may assume while contacting the pipe. Heretofore it has been the usual practice to provide a round tapered opening or a, round opening of downwardly di minishing diameter in the bushing of a rotary table to receive the pipe gripping slips. When a bushing is provided with such a tapered opening there is only one vertical position in which the 30 slips have full cooperation with the walls of the bushing and when the slips assume different vertical positions as they often do when gripping a pipe, certain of the slips have only line contact or partial contact with the bushing. In the as .35 sembly of my invention the slips have full surface contact with the walls of the bushing slots re gardless of the vertical positions they may assume 40 when contacting the pipe. Another object of this invention is to provide a slip receiving bushing for a rotary table having an opening of uniform dimensions throughout its length to more readily pass drill pipe protectors and other drilling equipment. Another object of this invention is to provide an improved assembly of a rotary table bushing and pipe gripping slips in which the slips cannot foul one another and cannot turn or tilt laterally in the bushing. Another object of this invention is to provide 50 a rotary table bushing and slip assembly in which all of the several slips have uniform gripping en a rotary table bushing and slip assembly that em bodies practical effective rests or cradles for the slips when they are removed from the bushing which cradles support the slip in positions for immediate insertion in the slots of the bushing. Another object of this invention is to provide slips having simple and very inexpensive replace able pipe engaging parts or liners whereby they may be readily reconditioned or adapted for the handling of pipe of various diameters. The various other objects and features of my invention will be fully understood from the fol lowing detailed description of typical preferred forms and applications of my invention, through out which description reference is made to the 15 accompanying drawings, in which: Fig. 1 is a top or plan elevation of one form of assembly provided by this invention. Fig. 2 is an enlarged fragmentary horizontal detailed sec tional view taken substantially as indicated by line 2—2 on Fig. 3. Fig. 3 is an enlarged frag mentary vertical detailed sectional view taken as indicated by line 3-3 on Fig. 1. Fig. 4 is a fragmentary elevation view of the upper portion of one of the cradles being a view taken substan tially as indicated by line 4—4 on Fig. 3. Fig. 5 is an enlarged fragmentary horizontal detailed sectional View taken as indicated by line 5—5 on Fig. 3. Fig. 6 is a top- or plan elevation of another form of assembly provided by this invention. Fig. 7 is a fragmentary vertical detailed sectional view taken as indicated by line ‘I—'I on Fig. 6. Fig. 8 is a fragmentary horizontal detailed sectional view taken as indicated by line 8-8 on Fig. 7. Fig. 9 is a perspective view of the inner side of one of the bushing sections of the form of the invention illustrated in Figs. 6, 7 and 8; and Fig. 10 is a top or plan elevation of still another form of assembly provided by the invention. The form of the invention illustrated in Figs. 1 to 5, inclusive, of the drawings, includes gener ally, a bushing I0 for arrangement in a rotary table T and having slots II in its interior, slips I2 adapted to fit in the slots II to grip a pipe P or the like, and rests or cradles I3 for carrying the slips l2 when they are removed from the bushing Ill. The bushing 10 is what is usually termed a master bushing and is intended for arrangement in the opening M of the rotary table T. In'the 50 particular form of the invention being described the bushing I0 is round or cylindrical to‘?t the gagement with the object or pipe throughout their lengths to dependably grip the pipe without tend . correspondingly shaped opening M of the table T. An annular outwardly projecting ?ange I5 ing to distort it. is provided at the upper end'of the bushing H) to 55 .55 Another object of this invention to provide 2 . 2,127,108 ?t in an enlargement or annular groove IS in the upper end of the table opening I4 and to seat on a shoulder |6a in the opening I4. Lugs l7 project radially from the periphery of the flange It‘: to ?t bayonet slots I8. in the table T. Lock blocks l9 are inserted in the bayonet slots |8 to lock the lateral arms of the lugs II in the lateral portions of the slots I8. A rotary table of the general type just described having full or extensive contact of the slips l2 with the slot walls. The slots || may extend from the face or upper end of the bushing H] to the lower end of the bushing. The slips l2 are provided to grip and suspend pipe P, tubing or other well drilling equipment extending through the bushing opening 2|. The slips |2 are shaped and proportioned to properly ?t and operate in the above-described slots ||. The pipe gripping slips |2 are elongate members 10 having ?at parallel opposite sides 23 for cooper~ ating with the side walls of the slots H and hav ing cylindrically convexed rear surfaces 24 for bayonet slots for receiving lugs on a bushing is fully described and claimed in'my co-pending application entitled Rotary well drilling appa ratus, ?led November 11, 1935, Serial No. 49,175. t is to be understood that the bushing ||l being‘ ' shiftably bearing on the inner walls 22 of the 15 described may be shaped to ?t any type of rotary table opening without departing from . the in vention. It is to be noted that when the bushing I0 is designed for use in the particular rotary‘ table T illustrated that it has a cylindrical pe riphery throughout its length and, therefore, has a substantial and uniform wallthickness. The Wall of the bushing I0 may be chambered and provided with suitable internal reinforcing webs 20. ' " . ' The bushing I0 is preferably sectional to fa cilitate its insertion in the rotary table T. In the preferred construction the bushing |0 com prises two sections A and B of substantially equal extent as illustrated in Fig. 1 of the drawings. 30 A central vertical opening 2| is provided in the bushing ID to receive and’ pass the pipe P, tubing and other drilling equipment. It is afeature of the invention that the opening 2| is of uniform diameter or dimensions throughout its length, 35 that is, the opening 2| has vertical walls and is not tapered or of downwardly diminishing ca pacity. This formation of the opening 2| ‘per mits the ready passage of drill pipe protectors 25 and other devices throughthe bushing l8 which 40 often interfere with the lower ends of the usual master bushings having’ central openings of downwardly diminishing diameter. 'In the par ticular form of the invention being described the opening 2| is round in cross section or is 45 cylindrical, it being understood that the opening 2| of the bushing l0 may be polygonal, as illus trated in Figs. 6, 8, 9 and 10 of the drawings. It is a feature of the invention that- longi tudinal or vertical slots || areprovided inthe 50 wall of the opening. 2| to receive thegslips l2. The slots | I are circumferentially-spaced to pro vide for the spaced engagement of the slips |2 with the pipe P. In the drawings I have shown four equally spaced slots ||,’it being understood 55 that the bushing ||l may be provided with two slots, three slots or any desired number of slots II, as desired. In accordance with the invention the slip receiving slots H are of uniform con ?guration and width throughout their lengths 60 and are of substantial length to present'extensive walls or surfaces for engagement, by the slips l2. The opposite side walls of the slots | I are paral lel and‘are preferably vertical to‘ provide for the easy insertion of the slips |2. In the particular inwardly through the walls the slots H are polygonal or provided with flat inner 20 walls the rear surfaces 24 of the slips |2 may be flat to have proper cooperation therewith. When seated in the slots | | the slips l2 project into the bushing opening 2| to have suspending and grip ping engagement with the object or pipe P. 25 The active faces or sides of the slips |2 may be suitably roughened or toothed to properly grip the object or pipe P. The invention, how ever, provides. simple and particularly effective replaceable plates or liners 25 for the active sides of the slips I2. The liners 25 are secured to the inner or active faces of the slips l2 and are adapted to have direct engagement with the object or pipe P and thus assume the wear. The faces of the‘ slips | 2 are provided with longitu 35 dinal or vertical grooves 26 for receiving tongues or keys 2'! on the liners 25. The lowerywalls 28 of the grooves 26 are inclined downwardly and outwardly. The lower ends 29 of the keys 2‘! are correspondingly inclined to have locking cooperation with the walls 28. The invention in cludes simple positive ‘means for removably se- ' curing the liners 25 to the slips l2. Pins or rods 30 are inserted in transverse openings in the slips I2 and the keys 2'! of the liners 25. The 45 ends of the rods 30 may be riveted over whereby the rods are dependably held against displacement to form positive connections be tween the slips and the liners 25. The ac tive faces of the liners 25 are cylindrically con 50 caved to conform to the object or pipe P and are provided with wickers or teeth 3|. The teeth 3| are adapted to have gripping and sup porting contact with the pipe P and preferably face upwardly and inwardly. If desired the 55 teeth 3| may be grooved vertically to more effec tively resist relative rotation between the pipe P and the slip liners 25. The liners 25 may be replaced with liners of different thicknesses to adapt the slips It! to handle pipe of different 60 diameters. The bodies of the slips I2 are preferably hol low or provided with chambers 32 to be light in weight. Reinforcing webs 33 may extend through form 'of the invention illustrated'in Figs..1 to 5, ‘inclusive, of the'drawings the inner walls.22 of ‘the chambered interiors of the slips. Guide ?n~ 65 the slots | l are cylindrically concaved. " These slips B2. The ?ngers 34 project from the lower ends of the slips l2 at their outer and side sur faces and slope or curve downwardly and. in wardly. The mouths or upper ends of the bush 70 ing slots’ Il may have downwardly and inwardly inclined guide walls or surfaces 35 to assist in entering and guiding the slips If! in the slots ||. When entering the slips 12 in the slots | | the ?n gers 34 may cooperate with the surfaces 35 to 75 inner walls 22 of the slots II are inclined down wardly and inwardly to slidably receive the slips | 2 and to provide for the wedging of the slips against the object or pipe P. The curvature of the inner walls 22 of the slots is the same throughout their lengths having a uniform ra ‘is ' slots. The curved or conveXed surfaces 25 of the 15 slips l2 are inclined downwardly and but have the same radius of curvature out their lengths to‘uniformly engage 22. It is to be understood that when dius of curvature. The above described shape and proportions of the slots || provide for the gers 34 may be provided on the lower ends of the 3 2,127,108 guide the slips. The slips l2 usually project it is desired to engage or suspend a pipe P pass above the upper surface of the bushing II) when engaging the pipe or object P. The invention provides means for preventing the slips l2 from falling through or from the slots H. Stop lugs 36 project from the upper portions of the slip sides 23 and are adapted to ?t in recesses 36a in the upper face of the bushing ID to limit the downward and inward movement of the slips l2. The recesses 368L are suitably shaped and propor tioned to provide for the necessary play or move ment of the slips I2. The invention provides handles H on the slips I2 to facilitate their insertion in and removal from the slots ||. The handles H have forks or 15 yokes 31 on their lower ends extending into re ing through the bushing opening 2| the slips l2 are introduced into the slots H and allowed to ?t downwardly therein until their liners 25 grip the pipe P. The operator or operators may read ily disengage the handles H from the forks 45 to allow the slips l2 to slide downwardly in the saddles 46. The ?ngers 34 on the lower ends of the slips readily guide the slips into the slots ||. The slips are free to move downwardly in the 1O slots || until the toothed inner sides of the liners 25 grip or contact the pipe P. The convex outer rear sides 24 of the slips |2 have full, even bear ing engagement with the walls 22 of the slots cesses 31a in the upper ends of the slips |2. Pivot pins 38 pivotally connect the forks 31 with the bodies of the slips |2. Cams or stopv projections 9 may be provided on the forks 31 to limit the in ward swinging of the handles H. The handles I-I include stems 39 extending upwardly from the forks 31 and lateral heads 39a carried on the stems 39. If desired or found necessary the hamdles H of adjacent slips l2 may be connected 25 whereby two of the slips may be handled simul taneously. The rear walls of the recesses 31‘a may be engageable by the handles H to» limit the out 20 || regardless of the vertical positions assumed 15 by the slips l2 when they contact the pipe P. The engagement of the surfaces 24 with the slot walls 22 also maintains the active inner sides of the liners .25 vertical to properly grip the pipe P. The ?t of the slips l2 in the slots H is such that 20 the pipe is dependably gripped and supported. ward and downward pivoting of the handles. The rests or cradles l3 are provided to support or carry the slips l2 when the slips are with drawn from the slots | | and are operable to sup port the slips in positions where they are entirely clear of the bushing opening 2|. A cradle I3 is provided on the bushing ID for each slip l2. The 35 cradles l3 are adapted to be removably secured to the upper end of the bushing ID in radial align ment with the slots ||. Each cradle l3 includes a leg 40 having a substantially horizontal foot 4|. Recesses 42 are provided in the upper side of the bushing Hi to receive the feet 4|. Coun tersunk or flush plates 43 extend transversely across the upper ends of the recesses 42 and the feet 4| are adapted to be inserted under the plates 43. Clamp screws 44 are threaded through the plates 43 and are adapted to clamp against the feet 4| to securely hold the cradles l3 in place. The legs 40 project vertically from the feet 4| and have upwardly and outwardly in clined portions terminating in forks 45. Con cave supports or saddles 46 are arranged on the inclined portions of the legs 40’ to receive the slips l2. The saddles 46 are shaped and propor tioned to properly receive the convex outer sides of the slips. Means are provided for releasably supporting or holding the slips l2 in the cradles I3. The forks 45 on the upper ends of the legs 40 have flaring or V-shaped notches 41 adapted to receive handles H. When the slips l2 are raised into the cradles l3 the handles I-I may be swung down wardly so that their stems 39 are engaged in the notches 41. The heads 39a of the handles H are adapted to engage against the forks 45 to hold the slips |2 in the cradles l3 in positions where they are entirely free of the bushing opening 2|. This elevated or inoperative position of the slips I2 is illustrated in broken lines in Fig. 3. The handles H may be easily disengaged from the forks 45 to allow the slips I2 to enter or move 70 downwardly into their respective slots H. In the use or operation of the assembly illus trated in Figs. 1 to 6, inclusive, of the drawings, the bushing I0 is normally arranged in the table T as illustrated in Fig. 1 of the drawings. When 75 Due to the fact that each of the slips l2 ‘has uni form and complete engagement with the inner wall 22 of its respective slot H the several slips have even or equal engagement with the pipe P to dependably grip the pipe without distorting it. The slips |2 engaging in the slots II are adapted to form a positive drive for the pipe P in the event it is desired to rotate the pipe. The ?at parallel sides 23 of the slips H are adapted to engage the side walls of the slots II for the transmission of turning forces. When the slips l2 are no longer required they may be easily pulled upwardly and outwardly to rest in the saddles 46. The handles H may be . swung downwardly to engage the stems 39 in the notches 41 so that the slips are held in the cra dles H3. The slips |2 are very easy and conven ient to manipulate and are light in weight. The cradles |3 may be easily disengaged from the bushing Ii]. The various parts of the assembly are simple and inexpensive of manufacture. The slots || may be cored in the bushing I0‘ and the slips l2 do not require special machining. The liners 25 of the slips l2 may be sections of strips or long stock of the desired cross section and are very inexpensive to manufacture. The form of the invention illustrated in Figs. 6 to 9, inclusive, of the drawings includes, gener ally, a master bushing 5|! having internal slots 5|, slips 52 for arrangement in the slots 5| to grip a pipe P or the like and means 53 for preventing displacement of the slips and for supporting the slips 52 when they upper ends of the The bushing 53 in the opening of 53 may be shaped are moved to positions at the slots 5|‘. 55 is intended for arrangement a rotary table. The bushing for arrangement in the table T illustrated in Fig. 1 of the drawings or may be polygonal or square, asillustrated in Figs. 6 and 9 of the drawings for arrangement in a typi cal rotary table. It is to be understood that the bushing 50 is adapted to be supported in a rotary table to be driven or rotated thereby. A cen tral vertical opening 54 is provided in the bush~ 65 ing 50 to pass the pipe P and other drilling equip ment. In accordance with the form of the inven tion being described the opening 54 is polygonal or square in cross section. The opening 54 may be round or cylindrical if desired. The opening 70 54 is of uniform width or dimensions. through out its length, having vertical Walls. This is important as it permits the easy free passage of the drilling equipment through the bushing 50. The bushing 53 is preferably sectional for ready 75 4 2,127,108 assembling in a rotary table. As shown in the drawings the bushing 50 preferably includes two sections M and N. The bushing 55 is preferably divided or separated in a vertical plane which intersects two side walls of the opening 54. In the preferred construction the slots 5| for receiv ing the slips 52 occur in the corners of the open ings 54. The slots 5| are preferably alike in size and shape and there may be one slot 5| in each corner of the opening 54. It is to be understood that the invention contemplates the provision of two or more slots 5| in the bushing opening 54. In the form of the invention being described the slots 5| are polygonal or flat walled. 15 The side walls of the slots 5| are flat and ver tical and lie in planes tangent to a circle con centric with the central longitudinal axis of the opening 54. The parallel relationship and, there fore, the uniform spacing of the side walls of the 20 slots 5| continues throughout the entire lengths of the slots. The slots 5| may extend between the upper and lower ends of the bushing 55. The innermost walls or inner walls 55 of the slots 5| are ?at and are inclined downwardly and in 25 wardly. ‘Curved or inclined surfaces 56 join the upper ends of the slots. 5| to assist in entering or guiding the slips 52 into the slots. The slips 52 are adapted to be inserted in the slots 5| to grip and suspend the pipe P 30 or other object. The several slips 52 are alike and there is preferably a slip 52 provided for each slot 5|. The slips 52 are shaped to prop erly ?t the slots 5| having flat parallel sides 51 and downwardly and inwardly inclined rear sur 35 faces 58 for shiftably bearing on the inclined walls 55 of the slots. The slips 52 are prefer ably proportioned to have proper play or clear ance in the slots 5|. The active sides of the slips 52 are preferably vertical and if desired teeth or gripping parts may be formed directly on the slips to cooperate with the pipe P. It is preferred, however, to provide replaceable shoes or liners 59 on the slips 52 for gripping the pipe P. The slips 52 are shaped to receive the liners 59 having vertical channels or grooves 6|] which terminate at their lower ends in downwardly and outwardly inclined walls 6|. Tongues or keys 62 are provided on the liners 59 to fit the grooves 60 to form positive driving connections between the liners and slips. The lower ends of the keys 62 are inclined downwardly and out wardly to have locking cooperation with the groove walls 6|. ’ Means is provided for removably attaching 55 the liners 59 to the slips 52. Rivets or rods 63 are passing through transverse openings in the slips and keys 62 to secure the liners 59 to the slips. The opposite ends of the rods 63 may be headed or riveted. The active faces of the 60 liners 59 are cylindrically concaved to conform, generally, to the pipe P and are provided with suitable wickers or teeth 64. The teeth 64 pref erably face upwardly and inwardly and may be interrupted by vertical grooves to have more effi cient engagement with the pipe. The liners 59 may be replaced by liners of various thicknesses to adapt the slips 52 for the proper handling of pipe and other objects of various diameters. The bodies of the slips 52 may be chambered or hollowed to be light in weight. Reinforcing webs 65 may extend through the hollow inte riors of the slips. Handles H1 are provided on the slips 52 to facilitate the manipulation of the slips. The handles H1 may be identical with ~75 the handles H described above and reference is hereby made to the detailed description of the handles H. Corresponding reference numerals are employed to designate corresponding parts of the handles H and H1 and their mountings. The means 53 is provided to prevent loss or displacement of the slips- 52 from the slots 5| and to assist in supporting the slips in retracted or inoperative positions at the upper‘ ends of the slots. The means 53 comprises? elongate grooves or slots 10 in the side walls of the slip 10 receiving slots 5|. There may be a slot 10 in each side wall of each slot 5|. The slots 1|] are parallel with the inclined inner walls 55 of the slots 5| and terminate some distance above the lower ends of the slots 5|. Lugs or pins 7| pro 15 ject from the sides of the slips 52 to shiftably operate in the slots 10. The cooperation of the ' pins ‘II with the slots 10 is such that the slips 52 may properly work and shift in the bushing slots 5| . The pins 1| are adapted to cooperate 20 with the lower ends of the slots 10 to de?nitely limit the downward travel of the slips 52 and thus prevent the loss of the slips from the bush ing 5|]. The upper ends of the slots 15 are spaced some distance below the upper end of the bush 25 ing 59. The slots 10 and the pins 7| are related so that the pins cooperate with the upper ends of the slots 10 when the slips 52 are brought to positions where they may be pivoted onto the surface 56. The cooperation of the pins 1| with the upper ends of the slots 70 assists in retaining or supporting the slips 52 in their up or inoperative positions on the surfaces 55. Fig. 7 of the drawings illustrates in broken lines a slip 52 in its retracted position where it rests on 35 the surface 55 with the pins ‘H in cooperation with the upper ends of the slots 15. In prac tice removable plates 73 may be recessed or coun tersunk in the upper ends of the bushing 55 to close the upper ends of the slots 10. The plates 40 13 thus form the upper ends or walls of the slots 15 and may be removably secured to the bushing by screws or other suitable means. The plates. 13 are removable to permit the entrance of the pins 1| in the slots 10 when the slips 52 are as 45 sembled in the bushing 50 and are removable to permit the withdrawal of the pins 1| from the slots 15 when the slips are to be removed from the bushing. It is to be understood that the invention con 50 templates the embodiment of cradles similar to the cradles 53 described above, in the form of the invention illustrated in Figs. 6 to 9, inclusive, of the drawings, in substitution for the means 53 just described, and contemplates the embodiment 55 of the means 53 in the form of the invention illus trated in Figs. 1 to 5, inclusive, of the drawings in substitution for the cradles I3. The use or operation of the assembly illustrated in Figs. 6 to 9, inclusive, of the drawings is sub 60 stantially the same as the operation of the pre viously described form of the invention. The slips 52 maybe easily passed downwardly into the slots 5| to contact and grip the pipe P. The handles H1 facilitate the lowering of the slips and 65 the pins 1| cooperating with the slots 10 effec tively enter the lower ends of the slips in the slots. As the slips 52 move downwardly in the slots 5| their rear surfaces 58 contact the inner ' walls 55 of the slots 5| and this engagement 70 urges the slips inwardly against the pipe P. Thus the slip-s 52 obtain ?rm dependable gripping con tact with the pipe P. The rear sides 58 of the slips 52 are adapted to have full or extensive cooperation with the inner walls 55 of the slots 75 2,127,108 5| regardless of the vertical positions assumed by the slips when they contact or grip the pipe. Accordingly, the slips 52 assume equal loadsin suspending or engaging the pipe. The flat sided slips 52 ?tting in the ?at sided slots 5| cannot possibly tilt or turn and are adapted to form posi tive effective drives in the event it is desired to rotate the pipe. The liners 59 are operable to having a polygonal opening forreceiving a piece of drilling equipment, and having longitudinal slots in the corners of the opening, said slots having substantially parallel side walls and down wardly and inwardly inclined inner walls, and slips shiftably ?tting the slots to grip the piece of obtain ?rm dependable gripping engagement with equipment. 4. In combination, a bushing for a rotary table having an opening for receiving a piece of drilling the pipe P without subjecting the bodies of the slips proper to wear. When the slips 52 are no longer required to grip the pipe P they may be easily and quickly removed from the slots 5|. The slips 52 may be easily pulled upwardly from the slots to positions where they are supported 15 on the surfaces 56 with their pins 1| bearing on the plates 13 which form the upper walls of the slots 10. The cooperation of the pins ‘H with the upper ends of the slots 10 operates to retain the slips in their inactive positions on the surfaces 56. The bushings 50 and the slips 52 are simple and equipment, and having spaced slots in the wall of 10 the opening provided with parallel side walls and cylindrically concaved inner walls, and slips in the slots for engaging the piece of equipment and having parallel sides and cylindrically convex easy to manufacture. ' The slots 5| may be cored directly in the sections of the bushing 5|! and the slips 52 do not require extensive machining. The liners 59 may be easily replaced to recondition the 25 slips 52 or to adapt the slips for the engagement of pipes of diiierent diameters. Fig. 10 of the drawings illustrates a form of the invention embodying a master bushing 80 30 comprising two unequal sections X and Y. The bushings 80 may be of the same con?guration as the bushing H] or the bushing 50. In the particular case illustrated the bushing 80 is of the same general con?guration as the bushing 50. The polygonal opening 8| of the bushing 85 has 35 flat walled slots 82 in its corners for receiving slips 83. The slips 83 may be identical with the slips 52. The bushing 8|) is divided into the two sections X and Y in a vertical plane 85 spaced from the central longitudinal axis of its opening 8|. The line or plane 85 of division of the bush ing 80 preferably angularly intersects two adja cent sides of the polygonal opening 8|. When the rear sides for cooperating with the walls of the 15 slots. 5. A slip for arrangement in a rotary table bushing comprising a slip body having substan tially parallel sides, and a downwardly and in wardly inclined rear surface, and means pro 20 jecting from the lower end of the slip body for guiding it in a slot in the bushing. 6. A slip for arrangement in a rotary table bushing comprising a slip body having substan tially parallel sides, and a cylindrically curved 25 downwardly and inwardly inclined rear surface extending between said sides, and means on the active face of the slip body for engaging an ob ject extending through the bushing. 7. A master bushing comprising a body having 30 a polygonal opening with substantially vertical walls, and having substantially vertical slots in the corners of the opening, said slots having sub stantially parallel side walls and inclined inner co Walls. 8. A master bushing comprising a body having an opening with a cylindrically curved wall, and having spaced vertical slots in the wall of the opening, said slots having substantially parallel 1'a 40 side walls and inclined inner walls. 9. Apparatus of the characterv described com prising a master bushing having a polygonal opening with substantially vertical walls and hav ing substantially vertical slots in the corners of bushing 85 is divided in this manner one section X has three slots 82 while the other section Y has one slot 82. Where the one section X carries three slips 83 the bushing 8|] cannot spread or work and a very positive suspension or gripping the opening, said slots having substantially paral 45 lel side walls and inclined inner walls, and slips engagement with the pipe P is obtained. The operation and the mode of handling the slips 83 50 are the same as described above in connection with the slips 52. When I use the term “liner” I refer to the shoe or shoe-like part that actually engages the pipe or the object handled. Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the speci?c details herein set forth, but wish to reserve to myself any variations or modifications that may appear 60 to those skilled in the art or fall within the scope of the following claims: Having described my invention, I claim: 1. A bushing for a rotary table comprising a body having a polygonal opening of unvarying width, and having slots in the walls of the open ing for receiving slips. 2. In combination, a bushing for a rotary table having a polygonal opening for receiving a piece of drilling equipment, and having longitudinal slots in the corners of the opening, said slots having inclined walls, and slips arranged in the slots to grip the piece of equipment and having inclined surfaces cooperating with said walls. 75 3. In combination, a bushing for a rotary table arranged in the slots to grip an object extending through the opening, the slips having substan tially parallel sides and inclined surfaces for co operating with the inclined walls of the slots. 10. Apparatus of the character described in cluding a master bushing for a rotary table, the bushing having an opening for passing drilling equipment and slots in the wall of the opening, gripping slips adapted for insertion in the slots, 55 and stationary cradles carrying the slips for ready entrance to the slots. 11. Apparatus of the character described in cluding a master bushing for a rotary table, the bushing having an opening for passing drilling 60 equipment and slots in the wall of the opening, gripping slips adapted for insertion in the slots, stationary cradles on the upper side of the bush ing for supporting the slips in radial alignment 65 with the slot for insertion therein. 12. Apparatus of the character described in cluding a master bushing for a rotary table, the bushing having an opening for passing drilling equipment and slots in the wall of the opening, gripping slips adapted for insertion in the slots, 70 handles on the slips, cradles for supporting the slips above the openings, and parts on the cradles cooperable with the handles to releasably retain the slips on the cradles. 13. In combination with a rotary table bushing 75 2,127,108 and a slip for use therein, a cradle for supporting the slip comprising a support to be mounted on the bushing, and a saddle on the support for car rying the slip. 14. In combination with a rotary table bush ing and a slip for use therein, a cradle for, sup porting the slip comprising a support to be mounted on the bushing, and a saddle on the support having a concave surface inclined down wardly and inwardly toward the opening of the bushing to receive the slip. 15. In combination with a rotary table bushing, a slip for use in the bushing, a handle on the slip, a support on the bushing, a saddle on the 15 support for carrying the slip, and a fork on the 17. In combination, a rotary table bushing hav ing an opening for passing drilling equipment, there being a slot in the wall of the opening hav ing an inclined inner Wall, and a groove in a side wall of the slot substantially parallel with said inclined wall, a seat at the upper end of the slot, a slip shiftable in the slot operable to engage an object in the opening and shiftable to a retracted position on the seat,-and a projection on the slip operable in the groove and cooper 10 able with the upper end of the groove to retain the slip on the seat. 18. In combination, a rotary table bushing having an opening for passing drilling equip support engageable by the handle to retain the ment, there being a slot in the wall of the open ing having an inclined inner wall, and a groove slip in the saddle. 16. A rotary table bushing comprising a body in a side wall of the slot substantially parallel with said inclined wall, a slip shiftable in the having a vertical opening and circumferentially slot operable to engage an object extending spaced slots in the wall of the bushing, the body through the opening, and a projection on the slip being divided in a vertical plane spaced from the operating in said groove to prevent displacement central axis of the opening to comprise two sec of the slip from the slot. tions, one of said sections having more slots than the other. DENNIS L. DRISCOLL.