US3513665A

US3513665A - Kelly bushing floating drive means and method

Info

Publication number: US3513665A
Application number: US591215A
Authority: US
Inventors: Charles D Crickmer
Original assignee: Charles D Crickmer
Current assignee: Cooper Industries LLC
Priority date: 1966-11-01
Filing date: 1966-11-01
Publication date: 1970-05-26
Anticipated expiration: 1987-05-26
Also published as: DE1558980A1; GB1210375A

Description

y 26, 1970 u D. CRICKMER 3,51

KELLY BUSHING FLOATING DRIVE MEANS AND METHOD Filed Nov. 1, 1966 v 3 Sheets-Sheet 1 Fig.1. n

3o 34 12 \L .1 34 I4 l3 93 32 I5 JV INVENTOR. CHARLES D. CRICKMER May 26, 1970 c. D. CRICKMER 3,513,665

KELLY BUSHING FLOATING DRIVE MEANS AND METHOD Filed Nov. 1, 1966 3 Sheets-Sheet 2 INVENTOR. CHARLES D.CRICKMER y 6, 1970 c. D. CRICKMER 3,513,665

KELLY BUSHING FLOATING DRIVE MEANS AND METHOD Filed Nov. 1, 1966 3 Sheets-Sheet S INVENTOR.

CHARLES D. CRICKMER United States Patent 3,513,665 KELLY BUSHING FLOATING DRIVE MEANS AND METHOD Charles D. Crickmer, 12923 Memorial Drive, Houston, Tex. 77024 Filed Nov. 1, 1966, Ser. No. 591,215 Int. Cl. Flld 3/1 6; Fllc 1/28 US. Cl. 6423.5 19 Claims ABSTRACT OF THE DISCLOSURE A kelly bushing of either pin drive or square drive type is provided with a drive means upwardly displacable while the kelly bushing is being brought into axial alignment and face to face engagement with a corresponding master bushing, said drive means to be later moved into engagement with the master bushing upon rotation of the master bushing relative to the kelly bushing after the initial aligning contact has been made.

As is well known in oil well drilling a swivel supported kelly is rotatably driven by a kelly bushing which also permits translational movement of the kelly into a well hole. The driving torque for the kelly is transmitted from a rotary table dn'ven master bushing to the kelly bushing through either a pin type or square type drive forming part of the kelly bushing. Such pin type or square type drives are suitably received in appropriate openings in a master bushing. The improvements in the kelly bushings of the present invention reside in such drives and include essentially, longitudinally retractable and extensible drive pins or square drives carried by and projecting downwardly from the body of a kelly bushing. More specifically, the pins or square drives are comprised of suitably guided rigid bodies movable into and out of suitable housings. The pins or square drives can be urged out of the housings by resilient means, such as springs, or can be arranged to drop out of the housings by virtue of their own weight. As will be shown, such pin or square drive arrangements facilitate alignment of kelly bushings with master bushings.

Various other advantages will be apparent upon considering the following description and drawings, in which:

FIG. 1 is a front elevational view partly in section of one embodiment of a kelly bushing having a pin type drive embodying the present invention and showing the kelly bushing in operative engagement with an associated master bushing assembly together with a rotary table and rotary table frame;

FIG. 2 is a view similar to that of FIG. 1 showing the kelly bushing inserted in a master bushing assembly with the drive pins of the kelly bushing being misaligned with respect to the drive openings of the master bushing and the drive pins being retracted;

FIG. 3 is a sectional view taken along the line 33 of FIG. 1 showing further. details of construction;

FIG. 4 is an enlarged view of one pin embodiment of the present invention as illustrated in FIG. 1;

FIG. 5 is an enlarged view of a pin of the present invention as illustrated in FIG. 1 showing another embodiment thereof;

FIG. 6 is a front elevational view partly in section of another embodiment of a kelly bushing having a square drive embodying the present invention and showing the kelly bushing in operative engagement with an associated master bushing assembly together with a rotary table and rotary table frame;

FIG. 7 is a view similar to that of FIG. 6 showing the kelly bushing inserted in a master bushing with the square drive of the kelly bushing being misaligned with 3,513,665 Patented May 26, 1970 ice respect to the drive opening of the master bushing and the square drive being retracted;

FIG. 8 is a sectional View taken along the lines 8-8 of FIG. 6 showing further details of construction;

FIG. 9 is a sectional view taken along the lines 9--9 of FIG. 7 showing further details of construction and the misalignment illustrated in FIG. 7;

FIG. 10 is a front elevational view of part of a kelly drive of the present invention showing another embodiment thereof;

FIG. 11 is a view taken along the line 1111 of FIG. 10.

Referring now to FIGS. l-5 of the drawings, 10 represents a kelly bushing engaging a swivel (not shown) supported kelly 11 for rotatably driving the kelly 11 about a vertical axis while at the same time permitting relative vertical movement of the kelly 11 to advance a connected drill string downwardly within a well. As is shown, the kelly 11 has a non-circular outer surface, and to transmit rotary motion to the kelly 11 the kelly bushing 10 carries suitable means (not shown) for engaging the surface of kelly 11. Such engaging means, rollers for example, also enable the vertical longitudinal movement of the kelly 11. A master bushing 12 supports the kelly bushing 10 with the master bushing 12 coacting with the kelly bushing 10* for rotatably driving the kelly bushing 10. The master bushing 12, in turn, is suitably supported in a suitably rotatably driven rotary table 13 which rotary table is suitably supported by a rotary table frame 14.

The rotary table 13 includes a rigid open-ended body section 15 supported by rotary table frame 14 on bearings 16 for rotation about its vertically extending longitudinal axis. The body section 15 has a lower cylindrical opening 17 and a larger upper generally square shaped opening 18 which together with the lower opening 17 defines a generally square horizontal annular shoulder 19. The upper opening 18 extends up to the horizontal surface 20 of the rotary table 13.

The master bushing assembly 12 includes a rigid tubular cylindrically shaped main body portion 21 complementary in external shape with and snugly received in lower opening 17 of rotary table 13. The inner opening 22 of body portion 21 is generally cylindrically shaped. Main body portion 21 extends upwardly to an outwardly extending generally square shaped flange 24 which together with main body 21 defines a horizontal outwardly extending annular shoulder 25. The flange 24 is complementary in shape and snugly received by the upper opening 18 of rotary table 13 such that

shoulders

19 and 25 abut. The flange 24 has a horizontal upper surface 27 which, when master bushing assembly 12 is interfitted with rotary table 13, is coplanar with upper surface 20 of rotary table 13. The flange 24 also has a centrally disposed generally square shaped recess 88 extending therethrough which recess 88 communicates with inner opening 22 and has its center point coincident with the longitudinal axis of inner opening 22. Recess 88 is greater in its side dimension than the diameter of inner opening 22 of main body portion 21, so that an annular inwardly extending shoulder 89 is defined between recess 88 and inner opening 22. The flange 24 has four longitudinally extending identical open-ended cylindrical openings 26 (two of which are shown in FIG. 1) uniformly spaced at the four corner portions of the flange 24.

An insert bowl 92 is operatively received in the inner opening 22 and recess 88 of main body portion 21 and flange 24, respectively, of master bushing 12. Such an insert bowl 92, as is well known, is used to accommodate slips. Insert bowl 92 includes a rigid cylindrically shaped tubular lower body portion 93 comprising two semicylindrical identical bodies (not clearly shown) which lower body portion 93 is externally shaped complementary with and snugly removably received within inner opening 22 of main body portion 21 of master bushing 12. An outwardly extending generally square shaped tubular flange 94 comprised of two identical halves (not clearly shown) is integral with the upper end of lower portion 93. The flange 94 has an external side shape complementary with the side shape of recess 88 of flange 24 of master bushing 12, such that flange 94 is snugly received in recess 88 with the upper surface of flange 94 being coplanar with the upper surface 27 of flange 24. An inner uninterrupted opening 95 is defined by the openings in flange 94 and lower body portion 93, which inner opening 95 is shaped in a frusto-conical downwardly tapering manner.

The kelly bushing includes a rigid tubular body 28 having a longitudinally extending central opening 29 suitably shaped for receiving kelly 11. Body 28 has at its lower portion a generally centrally disposed outwardly extending generally square flange 30 shown in the figures as having substantially the same external dimensions as flange 24 of master bushing 12. The flange 30 has four longitudinally extending open-ended cylindrical openings 31 uniformly spaced at the four corners thereof (see FIG. 4) in the same relative position and substantially the same size as the openings 26 of the master bushing flange 24. A generally cylindrical tubular downwardly longitudinally extending centering skirt 32 is rigidly fixed to the undersurface of flange 30 and is coaxial with open ing 29. The centering skirt 32 is suitably externally sized to engage the small diameter wall portion of the frustoconical inner opening 95 of insert bowl 92.

The pin drive means of kelly bushing 10 includes four identical upwardly longitudinally extending generally cylindrical tubular housing 34 rigidly fixed to the body 28 and flange 30 coaxially with openings 31. As clearly shown in FIG. 4 each housing 34 has a cylindrical lower portion 35 and two diametrically opposed

cylindrical sections

36 and 37 extending upwardly from the lower portion 35. Each housing 34 has a cylindrical opening 38 through lower portion 35 which opening 38 has substantially the same diameter as opening 31 in flange 30, with

openings

38 and 31 communicating coaxially with each other.

Sections

36 and 37 define a longitudinally extending opening 39 therebetween which opening 39 has a larger diametrical dimension than the diameter of opening 38, and accordingly defines a horizontal shoulder 40 therebetween. Each

section

36 and 37 has two like peripherally spaced holes 41 near the upper ends thereof (see FIG. 3). The holes 41 of section 36 are coaxial with the holes 41 of section 37 with all of the holes 41 having their centerpoints in a common horizontal plane.

Slidably received within each housing 34 is a pin member 43 having a rigid generally cylindrical body 44 with a longitudinally extending generally cylindrical central passageway 45 therethrough. Body 44 has an upper portion 46 of longitudinal length slightly longer than the longitudinal length of opening 38 of housing 34 and with an outer diameter substantially the same as the inner diameter of opening 38 of housing 34. Upper portion 46 has an outwardly extending circular flange 47 at the upper end thereof which flange 47 has a diameter substantially the same as the diametrical dimension of opening 39 of housing 34. Body 44 also has a lower portion 48 of longitudinal length slightly less than the longitudinal length of opening 26 of the flange 24 of master bushing 12 and with a diameter substantially the same as the diameter of opening 26. Lower portion 48 has a bevelled lower end 49 to facilitate insertion of lower portion 48 into opening 26. Passageway 45 of body 44 includes an upper portion 50 which extends longitudinally substantially the length of upper portion 46 of body 44 and a lower portion 51 of smaller diameter than upper portion 50 which lower portion 51 extends longitudinally through the remainder of body 44. Upper and

lower portions

50 and 51 of passageway 45 defines a bevelled annular shoulder 52 therebetween. A helical coil spring 53 slightly in compression is longitudinally received in the upper portion 50 of passageway 45 with the lower end of such spring 53 abutting shoulder 52. Spring 53 is suitably fixed at its upper end to a circular disc washer 54 which washer has an upper surface with a diametrically extending ridge 55 defining two opposed shoulders 56 and 57. Two roll pins 58 extend transversely of opening 39 of housing 34 and are suitably retained in openings 41 of

upper sections

36 and 37 of housing 34. The roll pins 58 engage the disc washer 54 at the shoulders 56 and 57 thereof to retain spring 53 within the body 44 of pin member 43. Spring 53 is suitably compressed to urge a downwardly directed force on pin member 43 such that flange 47 abuts shoulder 40 of housing 34.

When kelly bushing 10 carrying a kelly 11 is lowered into master bushing 12, pin members 43 are received in openings 26 of flange 24 of master bushing 12, provided the pin members 43 are properly aligned with openings 26. However, as shown in FIG. 2 pin members 43 may not be received in openings 26 due to a misalignment therewith of the pin members 43 of kelly bushing. In the present invention such misalignment will result in the pin members 43 retracting into their respective housings 34 under the upward urging of the force acting between the upper surface 27 of master bushing 12 and the pin members 43 resulting essentially from the weight of kelly bushing 10. The master bushing 12 can be rotated by rotary table 13 until the pin members 43 of the kelly bushing 10 are properly aligned with openings 26 of master bushing 12 at which time the pin members 43 will be urged into the openings 26 by the force of the spring 53.

It is not necessary that the pin member 43 be subjected to the downward urging of a resilient means such as spring 53. As shown in FIG. 5 a pin member can be arranged to drop into an opening 26 in flange 24 of master bushing 12 under its own weight. The pin member 80 comprises a generally cylindrical body 81 slidably received in a tubular cylindrical housing 82 arranged with respect to the elements of kelly bushing 10 in the same general manner as are the housings 34, previously described. The roll pins 58 will function to retain the body 81 of pin member 80 within housing 82. The longitudinal movement of body 81 is limited by means of a set screw type pin 83 suitably adjustably received in an opening 84 in the wall of housing 82 with the inner end of such pin projecting into the hollow of housing 82. Body 81 of pin member 80 has a longitudinally extending slot 85 in its outer surface suitably sized to receive the inner projecting end of pin 83, which slot 85 is of a length to establish the limits of longitudinal upward and downward movements of body 81.

Although the pin drive means of kelly bushing 10 has been described as having four

members

43 or 80 it can be appreciated that more or less than four

pin members

43 or 80 can be used without departing from scope of the present invention.

FIGS. 6-9 illustrate another embodiment of the present invention, and is essentially the same as the embodiment of FIGS. 1-5 except as indicated hereinafter. Briefly, the difference in these embodiments lies in the type drive used, with the kelly bushing 10 of FIGS. l-S using the pin type drive while the embodiment to be described and as illustrated in FIGS. 6-9 uses a square type drive. Where the elements are essentially the same the same numeral will be used as used in FIGS. l-S but followed by the subscript a.

FIGS. 6 and 7 show a rotary table frame 14a supporting a rotary table 13a for driving a master bushing 12a which in turn transmits driving torque to a kelly bushing 10a suitably engaging a swivel (not shown) supported kelly 11a. The master bushing 12a has a main body portion 21a having a cylindrically shaped inner opening 22a which main body portion 21a has the same external configuration as in the first form and fits snugly in a lower opening 17a of the rotary table 13a. Main body portion 21:: has a generally square shaped flange 24a extending outwardly from the upper end thereof, which flange 24a is snugly received in the upper opening 18a of rotary table 13a. The flange 24a has a generally square shaped upper, downwardly extending recess 60 communicating with inner opening 22a and which recess 60 has its center point coincident with the longitudinal axis of inner opening 22a.

An insert bowl 98, slightly diflerent from insert bowl 92 of the embodiment of FIGS. 1-5, is operatively received in opening 22a and recess 60 of main body portion 21a and flange 24a, respectively of master bushing 12a. Insert bowl 98, as is well known, has a dual function of accommodating slips or the square drive of a square drive kelly bushing. Insert bowl 98 includes a rigid cylindrically shaped tubular lower body portion 99 comprising two semi-cylindrical identical bodies (not clearly shown) which lower body portion 99 is externally complementary in shape with and snugly removably received within inner opening 22a of main body portion 21a of master bushing assembly 12a. Lower body portion 99 has a frusto conical downwardly tapering inner opening 100 suitably shaped for receiving slips. A generally square shaped flange 101 comprised of two identical halves (not clearly shown) is fixed to and extends outwardly from the upper end of lower body portion 99. The outer side shape of flange 101 is generally complementary in shape with recess 60 of flange 24a of master bushing 12a, such that flange 101 is snugly removably received in recess 60 with the upper surface of flange 101 being coplanar with upper surface 27a or flange 24a. Flange 101 has a centrally disposed longitudinally extending generally square shaped opening 102 therethrough coaxially communicating with inner opening 100 of lower portion 99, which opening 102 has a side dimension greater than the major diameter of inner opening 100, so that an annular shoulder 103 is defined between square opening 102 and inner opening 100.

The kelly bushing a includes a rigid open-ended body 28a having a longitudinally extending central opening 29a suitably shaped for receiving kelly 11a. A generally circular flange 61 extends radially outwardly from the lower end portion of body 28a. Flange 61 is hollow, defining an upwardly extending recess 62 therein, and has a centrally disposed generally circular upper opening 63 coaxial with opening 290. An upper wall 64 extends transversely from the sides of the flange 61 to the opening 29a. The lower end of flange 61 has a generally circular shaped opening 65 (see FIG. 9) larger in diameter than the diameter of opening 63. A generally cylindrical tubular centering skirt 32a is rigidly fixed to the undersurface of upper wall 64 of flange 61, and is coaxial with opening 29a. The centering skirt 32a is suitably externally sized to engage the small diameter wall portion of the inner opening 100 of the insert bowl 98. The centering skirt 32a has a cylindrical upper portion 67 having a smaller diameter than the remainder of, or lower portion of, centering skirt 32a. The upper portion 67 of centering skirt 32a also has two identical radially outwardly extending diametrically opposed generally square cross-sectioned projections 68 extending substantially longitudinally the entire length of upper portion 67.

There is an external retaining ring 110 fixed to an intermediate section of the centering skirt 32a adjacent to and below the projections 68. The retaining ring 110 has a substantially flat upper surface 112 and an outside surface 114 tapered substantially the same amount as the upper region of the inner opening 100 of lower body portion 99 of insert bowl 98. The outer shape of the retaining ring 110 just described together with its orientation with respect to centering skirt 32a is such that when centering skirt 32a is fully received in opening 100 of insert bowl 98 the upper surface 112 is substantially coplanar with annular shoulder 103 and the outer surface 114 abuts a portion of the upper tapered surface of opening 100.

A square drive means generally designated 70 is retractably and extensibly received in the recess 62 of flange 61. The square drive means 70 comprises a tubular rigid body 71 slidably surrounding upper portion 67 of centering skirt 3211 which body 71 has a generally square sha ed lower portion 72 and a generally square flange 73 extending radially outwardly from the upper portion of the square portion 72. The square shaped portion 72 has a longitudinal length substantially the same as the depth of square opening 102 of the insert bowl 98. The external side dimensions of square portion 72 are substantially the same as the inner dimensions of square opening such that square portion 72 will be slidably received in square opening 102 in such a manner that the lower surface of square flange 73 will be flush with the upper surface 27a of master bushing 13a. Body 71 has a generally circular opening 74 extending longitudinally therethrough with the opening 74 having a diameter slightly larger than the diameter of the cylindrical portions 67 of skirt 32a. Opening 74 of body 68 also has two radially extending diametrically opposed square shaped slots 75 extending longitudinally the length of opening 74, which slots 75 are complementary in shape to and slidably receive the projections 68 of the cylindrical upper portions 67 of the centering skirt 32a. A helical coil spring '77 partly in compression is disposed in recess 62 of flange 61 between the undersurface of upper wall 64 of flange 61 and the upper surface of flange 73 of body 71. The spring 77 surrounds the upper region of the cylindrical upper portion 67 of centering skirt 32a, and is suitably retained in fixed relationship with the underside of upper wall 64 of flange 61 and the upper surface of flange 73.

As shown in FIG. 6 the square drive means 70 is completely extended out of recess 62 of flange 61 and is received in square opening 102 of insert bowl 98. Under these circumstances the master bushing 13a will transmit torque to the kelly bushing 10a through the body 71 of square drive 70 which body 71 will be prevented from rotating about the cylindrical portion 67 of centering skirt 32a through the cooperation of projections 68 on cylindrical portion 67 with slots 75 of opening 74 of body 71. However, as illustrated in FIGS. 7 and 9, the situation may arise where kelly bushing 10a is turned with respect to master bushing 1311 such that the body 71 of square drive 70 is not aligned with the square opening 102 of insert bowl 98. In the present invention such a condition will result in the body 71 of the square drive 70 being urged upwardly into recess 62 of flange 61. The master bushing 12a can then be rotated by rotary table 13a until the body 71 of square drive 70 is aligned with square opening 102 of insert bowl 98 at which time body 71 of square drive 70 will be urged into square opening 102 by the helical coil spring 77.

The square drive means may also be arranged to extend into square opening 102 of insert bowl 98 without being urged by any means such as a helical coil spring 77 as shown in FIGS. 10 and 11 wherein the square drive is represented by 120. That is, upon proper alignment of the kelly bushing 10a. and master bushing 12a the square drive will drop unassisted into the square opening 102 in insert bowl 28 by virtue of its own weight.

It will also be appreciated that the helical coil spring 77 can be replaced by one or more smaller diameter springs or the like suitably positioned between the under surface of upper wall 64 of flange 61 and the upper surface of flange 73 of body 71. That is, if such smaller diameter springs are used they can be arranged with their axes spaced from the longitudinal axis of kelly bushing 10a and substantially parallel therewith. Other arrangements of urging means for this square drive means 70 can be readily visualized by those skilled in this particular art.

It should also be noted that means other than the retaining ring 110 can be used to limit the downward movement of square drive 70. For example, as shown in FIGS. and 11 an upper portion 130 of centering skirt 32a could be made generally square in cross-section and of a side dimension smaller than that of the large diameter of the taper of centering skirt 32a. Further, the inner opening 12a of the square drive 70a can be square in cross-section to slide over the square upper portion 130 of centering skirt 32a. Thus, the downward movement of square drive 70 will be limited by the tapered portion of centering skirt 32a. It should also be apparent that the modifications set forth in the above example will serve to prevent square drive 70 from turning with respect to centering skirt 32a when the master bushing 12a is transmitting drive torque to kelly bushing 10a. That is, the above modification will serve the same function as the cooperation of projections 68 of centering skirt 32a with slots 75 of square drive 70.

What I claim is:

1. In an assembly of a square drive kelly bushing and a master bushing alignable along a common central axis in which the master bushing has an upper surface normal to said axis with a central opening extending axially inwardly thereof and said opening has a generally square portion and the kelly bushing has a downwardly facing surface normal to said axis with a projection extending axially downwardly therefrom, the improvement comprising; a rigid tubular member of generally square external surface matable with said portion of said opening captively slidably mounted on the external surface of said projection, said tubular member and said projection having cooperable means for establishing a driving relationship between said tubular member and said projection and said member being located on said projection to be in register with said square portion of said opening when rotated and said member being freely movable into said opening when said square portion and said square surface are in register.

'2. An assembly as specified in claim 1 further requiring that said central opening extends downwardly from said square portion to a smaller circular portion and said projection has a generally cylindrical upper portion and extends downwardly to a smaller circular centering skirt portion engageable with said circular portion of said opening to effect alignment of the two bushings.

3. An assembly as specified in claim 2 wherein a resilient biasing means captively mounted on said projection between said downwardly facing surface of said kelly bushing and said tubular body applies a downward force on said body relative to said kelly bushing.

4. The improvement as set forth in claim 2 including at least one spring fixed between said kelly bushing and said tubular member to urge a downwardly directed force on said tubular member, said spring being compressible by an upwardly directed force transmitted through said tubular member with such compression being at least equal in magnitude to the distance of upward movement of said tubular member caused by such upwardly directed force.

5. The improvement as set forth in claim 4 wherein said spring member is a single helical coil spring surrounding an upper portion of said centering skirt and fixed to the lower portion of said kelly bushing and the upper surface of said tubular member, said helical coil spring having such a length and characteristics as to limit the extent of the upward and downward movement of said square drive tubular member.

6. The improvement as set forth in claim 1 wherein said member is movable in a longitudinal direction upwardly on said projection a distance equal to the length of said portion of said member extending outwardly of said kelly bushing.

7. The improvement as set forth in claim 1 including biasing means between the upper portion of said member and said kelly bushing for urging a downwardly directed force on said member, and said biasing means being compressible by an upwardly directed force transmitted through said member with such compression being at least equal in magnitude to the distance of upward movement of said member caused by said upwardly directed force.

8. The improvement as set forth in claim 7 wherein said biasing means is a spring fixed to said main body and said member.

9. The improvement as set forth in claim 8 wherein said spring is of such length and characteristics to limit the extent of the upward and downward movement of said member.

410. In an assembly of a pin drive kelly bushing and a master bushing alignable along a common central axis in which the master bushing has an upper surface normal to said axis with a central opening extending axially inwardly thereof and a plurality of circumferentially spaced pin receiving bores extending axially inwardly thereof and which pin receiving bores are radially spaced outwardly of said central opening and in which assembly the kelly bushing has a downwardly facing surface normal to said axis with a projection extending axially downwardly therefrom which projection is receivable within such central opening to effect an axial alignment of the kelly b ushing with the master bushing while permitting rotation of the master bushing with respect to the kelly bushing the improvement comprising; a plurality of downwardly open pin retaining bores extending axially inwardly of said kelly bushing from said downwardly facing surface, drive pins captively slidably retained in said pin retaining bores, respectively, said pin retaining bores being located to be in register with said pin receiving bores when rotated, and said drive pins being freely axially movable into said pin receiving bores when said pin retaining and said pin receiving bores are in register.

11. The improvement as set forth in claim 10 wherein said projection is a stabbing skirt for centering said kelly bushing on said master bushing.

12. In an assembly as set forth in claim 10 the further improvement comprising resilient biasing means for applying a downward force on said pins.

13. In an assembly as set forth in claim 12 wherein said biasing means is a spring element freely received in each of said pin retaining bores and captively secured between the respective one of said pins and a retaining ineans at the upper end of the respective one of said ores.

14. The improvement as set forth in claim 10 including a spring fixed between the upper portion of each of said pins and a portion of said kelly bushing to impart a downwardly directed force to each of said pin members.

15. The improvement as set forth in claim 14 wherein each of said springs are of such lengths and characteristics as to limit the extent of the upward and downward movement of each of said pins.

16. The improvement as set forth in claim 10 including upwardly extending tubular housing fixed to said main body coaxially with each of said apertures, and wherein each of said pins has an upper portion thereof slidably disposed in each of said tubular housings, and further including a spring member fixed between the upper portion of each of said pins and an upper portion of each of said tubular housings.

17. The improvement as set forth in claim 16 wherein each of said pins has a radially outwardly extending portion at the upper portion thereof, said limiting means includes a radially inwardly directed shoulder on the inner wall of each of said tubular housings, each of said shoulders extending inwardly to adjacent to the main portion of each of said pins.

18. A method of establishing a driving connection between a master bushing and a kelly bushing, comprising,

lowering a kelly bushing with respect to the master bushing so that the bushings are axially aligned by interengaging means on said bushings which when interengaged permit relative rotation between said bushings, displacing drive means on the kelly bushing upwardly Within the body of said kelly bushing during the portion of said lowering at least immediately preceding f=ull engagement of said interengaging means, rotating said master bushing so that integral means therein are placed in register with said displaced drive means, and dropping said drive means into said integral means 'while said drive means and said integral means are in register.

19. The method as set forth in claim 18 wherein during said displacement of the drive means a downward force is applied to said drive means and said dropping of said drive means is aided by said downward force.

References Cited UNITED STATES PATENTS 1,259,852 3/1918 Greve 6423.5 1,297,625 3/ 1919 Willard 64-23.5 1,312,565 8/1919 Noftz 6423.5

Foster 175195 Davidson 64-23.5 Teis 64-235 Spalding 64- 23.5 Anderson 175l98 X Long 64--23.5 Wright 64-23.5 Patterson 19267 Ball 64--23.5 X Wilson 64-23.5 X Blazek 308613 Charlat 19267 Italy.

MARTIN P. SCHWADRON, Primary Examiner L. L. JOHNSON, Assistant Examiner US. Cl. X.R.