US2141841A - Rotary rock bit - Google Patents

Description

' Dec. 27, 1938. J. H. HOWARD ET AL ROTARY ROCK BI T 2 Sheets-Sheet 1 Filed May 24, 1937 Beef 27, 1938.

J. H. HOWARD ET AL 2,141,841

ROTARY ROCK BIT Filed May 24, 1937 2 Sheets-Sheet 2 I l l 5a 00 72 @740; 6'4 a? 6;: 70077774724 Patented Dec. 27, 1938 UNITED STATES PATENT OFFICE 2.141.841 V ROTARY noon m'r Application May 24, 1937, Serial No. 144,380

7 Claims.

This invention relates to well drilling tools and relates more particularly to a rotary rock bit. A general object of this invention is to provide a practical dependable bit for use in the rotary method of well drilling, that embodies novel and very effective cutter mounting means.

Another object of this invention is to provide a well bit of the character mentioned in which the two sets of transverse cutters or inner cut- 10 ters are rotatably supported by a single pin directly supported at its ends and at its intermediate portion by integral parts of the bit body.

Another object of this invention is to provide an improved anti-friction bearing means for rotatably mounting the cutters of a well bit in which the balls or anti-friction member have extensive cooperation with the inner races whereby the wear and the forces are evenly distributed over large areas of the races effecting a marked reduction in the intensity of the pressures between the balls and the race surfaces.

Another object of this invention is to provide a rock bit in which each roller cutter is supported by axially spaced rows of balls each row 5 of balls assuming end thrusts in both directions,

as well as radial thrusts.

Another object of this invention is to provide a rock bit in which the cutter supporting elements or pins have direct force-transmitting cooperation withthe bit body thus eliminating relative play and wear between the parts and removing practically all of the stresses from the welds which tie the thrust washers to the body. Another object of this invention is to provide a rock bit of the character mentioned embodying novel means for preventing relative rotationbetween the inner races of the cutter supporting bearings.

A further object of this invention is to provide 40 novel nozzle elements or flow-beans that may be easily and quickly replaced to adapt the bit for use under various operating conditions.

The various objects and features of our invention will be fully understood from the following detailed description of a typical preferred form and application of the invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. l is a vertical detailed sectional view of the bit provided by this invention illustrating the outer cutters and their mounting means. Fig. 2 is an enlarged, fragmentary vertical detailed sectional view illustrating the anti-friction mounting means of one of the outer cutters. Fig. 3 is an. end elevation of the race member embodied in one of the outer cutter mounting means. Fig. 4 is a vertical detailed sectional view of the bit with the upper portion in elevation and illustrating the mounting means of the inner cutters. Fig. 5 is .an enlarged fragmentary vertical de- 5 tailed sectional view illustrating the mounting means of one set of the inner cutters and Fig. 6

is an end elevation of a race member of one of the inner cutter bearings.

The improved rotary rock bit of the present 10 invention includes, generally, a body l0, outer roller cutters ll, anti-friction bearing means l2 rotatably mounting the outer cutter H on the lower end of the body l0, sets of inner roller cutters l3 and I4, anti-friction bearing means I5 5 for rotatably mounting the sets of inner cutters l3 and M on the lower end of the body l0- and means l6 for directing the circulation fluid against the cutters ll, l3 and H.

The body I0 is adapted to be connected with go the lower end of a well drilling string and is shaped to carry the cutters ll, l3 and I4 and their hearing means. Means is provided at the upper end of the body ill to facilitate its connection with the well drilling string. In the case 25 illustrated a tapered screw threaded pin I1 is provided on the upper end of the body III to connect with a threaded member of the drilling string. A circulation passage 18 enters the body In from the upper end of its pin [1 to deliver 30 the circulation fluid to the nozzle means Hi. In accordance with the invention sets or pairs of legs l9 and 20 project from the lower end of the body 10. The legs I9 and 20 are integral parts of the body. The legs iii are diametrically oppo- 35 site and project outwardly as well as downwardly from the lower end of the body. There are two diametrically opposite legs I9 and the inner sides of the legs I9 are inclined downwardly and outwardly with respect to the vertical axis of the bit. 40 Raised bearing faces 2| are provided on the inner sides of the legs l9 adjacent their lower ends. The legs 20 are diametrically opposite and are spaced substantially from the legs IS. The inner and outer sides of the principal or lower 5 portions of the legs 20 are substantially vertical. Raised bearing faces 22 are provided on the inner sides of the legs 20 adjacent the lower ends of the legs.

The body I 0 further includes a substantially 50 central web 23 projecting downwardly within the series of legs l9 and 20. The web 23 is an integral part of the body l0. Cylindrical bosses 24 project transversely or horizontally from the web 23 adjacent the lower end of the web. The bosses 24 project outwardly or radially in the direction of the legs 26 and raised faces 25 are provided at the bases or inner ends of the bosses 24. The web 23 is of substantial width in the direction of the legs l9 to have ample strength. Downwardly and outwardly projecting wings 26 are provided on the widened portion of the web 23 and oppose and are in substantial parallelism with the legs l6. Raised bearing faces 21 are provided on the outer sides of the wings 26, to oppose the bearing faces 2| of the legs.

The outer cutters H are provided to cut the well bore to gauge and toact on the outer portion of the bore at its lower wall. The cutters II are in the nature of slightly tapered or frustoconical roller cutters. There are two roller cutters one being arranged between each pair of opposing legs l9 and wings 26 to project downwardly beyond the lower ends of the legs l6 and wings 26. The cutters II have flat parallel ends and central longitudinal openings 26. Peripheral cutting teeth 29 are provided on the cutters I I. The active edges of the teeth 29 taper or converge inwardly toward the central longitudinal axis of the bit. The outer corners of the cutting teeth 29 are bevelled off to be substantially vertical when the teeth come into contact with the formation at the bottom of the bore.

The means H for rotatably supporting the outer cutters II are in the nature of anti-friction bearing means supporting the cutters for rotation about downwardly and inwardly inclined axes. Each bearing means l2 includes a supporting screw or pin 36. The pins 36 are passed outwardly through openings 3| in the wings 26 and their outer portions are threaded in openings 32 in the legs IS. The longitudinal axes of' the openings 3| and 32 are inclined downwardly and inwardly with respect to the vertical axis of the bit. Heads 33 are provided on the inner ends of the pins 36 to engage outwardly against the wings 26. The heads 33 may be of the socket type to receive tools for threading the pins 36. The pins 36 may be secured or locked in place in any suitable manner.

The bearing means I 2 further include thrust washers 34 surrounding the pins 36 and bearing outwardly against the faces 2| of the legs-l6 and thrust washers 35 surrounding the pins 36 and bearing inwardly against the faces 21 of the wings 26. outwardly projecting lugs 36 are provided on the, outer thrust washers 34 and are disposed at the lower ends of the legs I 9. Similar lugs 31 are provided on the inner thrust washers 35 and project inwardly at the lower ends of the wings 26. A race member 36 surrounds each Supporting 'pin 36 between the adjacent thrust washers 34 and 35. The thrust washers 34 and 35 are received in the opposite end portions of the cutter openings 28 and the race members 36 are entirely within the cutter openings substantially intermediate their ends.

The means |2 are in the nature of ball bearing means and races or ball grooves are provided in the internal surfaces of the cutters l I and in the adjacent end portions of the washers 34 and 35 and the race members 38. Two axially spaced ball races or grooves 39 and 46 are provided in the wall of each cutter opening 28. The grooves 39 and 46 are spaced inwardly from the ends of the cutters H and are spaced a suitable distance apart. In accordance with the invention the grooves 39 and 46 are partially cylindrical in transverse cross section and are of substantial depth. The circumferential center lines of the grooves '36 lie in the same planes as the contacting or abutting ends of the outer thrust washers 34 and the outer ends of the race members 36.v In a like manner the circumferential center lines of the grooves 46 in the same planes as the abutting end surfaces of the inner washers 35 and the race members 36.

Partial grooves are provided in the inner corners of the outer thrust washers 34 and the outer corners of the race members 36 and these partial grooves join or register to form ball channels or grooves 4|. The grooves 4| formed in the adjacent corners of the washers 34 and members 36 occur at the split or plane of abutment of the washers and members. The outer thrust washers 34 are considerably larger in diameter than the race members 36 and because of this relationship the grooves 4| have their greater portions in the washers 34. Annular series of balls 42 cooperate with the opposing grooves 36 and 4|. The balls 42 cooperating with the deep grooves 36 in the cutters H and the deep and partially offset grooves 4| eflectively transmit radial thrusts and the heavy outwardly directed end thrusts. The grooves 4| are of such depth that the balls 42 cooperating with them are also operable to transmit inward end thrusts between the cutters II and the inner elements of the bearings.

Ball races or grooves 43 are provided in the inner thrust washers 35 and the race members 36 at their abutting ends. Partial grooves are provided in the inner corners of the race members 36 and partial grooves are provided in the outer corners of the washers 35 and these partial grooves join or register to form the grooves 43. The grooves 43 oppose the grooves 46 in the interiors of the cutters II. The washers 35 are larger in diameter than the race members 36 and the grooves 43 have their greatest portions in the thrust washers 35. balls 44 cooperate with the opposing grooves 46 and 43. The balls 44 are particularly effective in the transmission of the inwardly directing end thrusts between the cutters II and the inner bearing parts. The grooves 46 and the grooves 43 are of such depth that the balls 44 transmit end thrusts in both directions and the radial thrusts between the cutters H and the inner bearing elements. It is to be understood that the spaced series of balls 42 and 44 serve to rotatably support the cutters H and that the walls Annular series of of the cutter openings 26 have proper working clearance with the peripheries of the thrust washers 34 and 35.

Means are provided to prevent rotation of the thrust washers 34 and 35 and the race members 36. The lugs 36 of the washers 34 are secured to the lower ends of the legs I9 by welds 45. In a like manner the lugs 31 of the washers 35 are secured to the lower ends of the wings 26 by welds 46. The race members 36 have axial openings 4'I spaced between their interiors and their peripheries. The thrust washers 34 and 35 are provided with axially extending sockets 46 which are adapted to register with the openings 41. Dowel pins 49 extend through the openings 41 and project into the sockets 46. The welds 45 'to engage against the balls 42.

ber 38 is then inserted in the cutter opening 28 The balls 44 are then introduced into the opposing grooves 48 and 43. A notch 58 is provided in each race member 38 at its inner end to communicate with the groove 43. In assembling the balls 44 in the groove 48 and the portion of the groove 43 in the race member 38 the balls are passed through the notch 58 one at a time. The notch 58 makes it possible to introduce the balls 44 in the deep groove 48 and the portion of the groove 43 in the race member 38. The dowel pin 49 may be carried by the race member 38 to have one end introduced into the socket 48 of the outer washer 34 when the race member is positioned in the opening 28. Following the introduction of the balls 44 in the groove 48 the inner thrust washer 35 is positioned in the opening 28 to engage against the balls 44. The projecting inner portion of the dowel pin 48 is received in the socket 48 of the washer 35 when the washer is arranged in place. The assembly of the cutter II and its bearing elements is introduced between a leg I9 and a wing 26 and the supporting pin 38 is passed outwardly through the opening 3| and the bearing elements to have its outer portion threaded in the opening 32. The lug 36 and the lug 31 may then be welded to the leg I9 and the wing 26, respectively.

The inner cutters I3 and I4 are provided to act on the earth formation at the inner portion of the well bore and are supported on the body I8 through the bearing means I to rotate about a common substantially horizontal axis. The cutters I3 and I4 are in the nature of roller cutters, the cutters I3 being frusto-conical and the cutters I4 being generally cylindrical. The cutter's I3 are considerably longer and larger in diameter than the cutters I4. The cutters I3 preferably have concave outer ends and fiatinner ends. A central longitudinal opening 5| is provided in each cutter I3. The outer portions of the cutter openings 5| are enlarged in diameter. The cutters 3 are provided with peripheral cutting teeth 52. The teeth 52 may be notched,'as illustrated in the drawings, and their active edges are inwardly convergent with respect to the central longitudinal axis of the bit. The cutters I4 have flat parallel ends and central longitudinal openings 53. Axially extending cutting teeth 54 are provided on the cutters I4. The active edges of the teeth 54 may be notched and are substantially horizontal.

The means I5 for rotatably supporting the cutters I3 and I4 is a feature of the invention. In accordance with the invention the cutter mounting means I5 includes a single support member or pin 55 which serves to carry both sets of cutters I3 and I4 and their bearing elements. The pin 55 is substantially horizontal or transverse relative to thevertical axis of the body I8 and extends between the two legs 28. The pin 55 is passed inwardly through an opening 56 in one leg 28, extends through a transverse opening 51 in the web 23 and has an end portion threaded in an opening 58 in the other body leg 28. The pin 55 arranged in this manner has its opposite end portions supported in openings in the body legs 28 and its intermediate portion supported in the opening 51 of the body web 23. A head 58 is provided on the pin 55 and is received in the opening 56. The'cutter supporting pin 55 may be locked against unthreading in any suitable manner. The'pairs of cutters I3 and I4 are arranged between the legs 28 and the web 23 and the pin 55 passes. through the openings of the several cutters. The cutters I3 are positioned adjacent the inner sides of the legs 28 and the cutters M are located between the cutters I3 and the body web 23.

The bearing means I5 includes or provides a plurality of axially spaced races or grooves in openings and are pitched or faced outwardly somewhat toward the legs 28. The bearing means I5 further include a series of race members 63, 64 and 65 in each cutter I3 and thrust washers 66 bearing against the faces 22 of the legs 28 and received in the enlarged outer portions of the cutter openings 5|. The members 63, 64 and 65 are cylindrical and of the same diameter. The inner ends of the inner members 63 lie in the same planes as the inner ends of the cutters I3. The abutting ends of the members 63 and '64 are in the same planes as the circumferential centers of the grooves 68 and the abutting ends of the members 64 and 65 are in the same planes as the circumferential centers ,of the grooves 6|.

Races or grooves 61 are provided in the peripheries of the race members 63 and 64 at their abutting ends and similar grooves 68 are provided in the peripheries of the members 64 and 65 at their abutting ends. The grooves 61 have portions in the members 63 and 64 and the circumferential centers of the races or grooves 68 lie in the same planes as the abutting ends of the members 64 and 65. The grooves 61 and 68 are of substantial depth having an'arc or curvature of approximately 180. The grooves 61 directly oppose the grooves 68 and the grooves 68 directly oppose the grooves 6| Annular series of balls 18 are arranged in the opposing grooves 68 and 61 and annular series of balls 1| are arranged in the opposing grooves 6| and 68.

Due to the depth of the grooves receiving them the balls 18 and 1| are .operable to transmit radial thrusts and end thrusts in both directions between the cutters I3 and the inner bearing elements. The spaced annular series of balls 18 and 1| effectively support the inner portions of the cutters I3 for free rotation.

The thrust washers 66 are shaped to have extensive cooperation with the faces 22 on the legs 28 and to fit in the concave ends of the cutters I3 with suitable clearance. The washers 66 have reduced cylindrical portions extending into the enlarged outer portions of the cutter openings 5| and ball races or grooves 12 are provided in these reduced washer portions and the end parts of the adjacent race members 65 to oppose the grooves 62. The grooves 12 have their larger portions in the washers 66. Annular series of balls 13 are arranged in the opposing grooves 62 and 12. The grooves 62 and 12 are of substantial depth and the balls 13 are operable to transmit the radialthrusts and the end thrusts in both directions between the cutters I3 and the inner bearing parts. To facilitate the assembly of the balls 18 and 1| in the sets of grooves 68 and 61, and 6| and 68, notches 14 are provided in the ends of the members 64 and 65 to communiformed in them. The washers 88 are provided with lugs which project outwardly at the lower ends of the legs 28. Welds l8 secure the lugs I8 to the legs 28 to prevent rotation of the washers 88.

The bearing means l5 further include pairs of race members 11 and 18 in the openings 58 of the cutters M. The members 11 are somewhat longer than the members 18 and have sockets 18 in their inner ends receiving the hoses 28. The members 11 are preferably force-fitted on the bosses 28. In practice the cooperation of the bosses 28 with the sockets I8 holds the members 11 spaced from the faces 25. The racemembers l8 engage against the outer ends of the members 11 and have their outer ends in abutment with the race members 88. The outer ends of the members 18 are in the same planes as the inner ends 01' the cutters I8.

The invention provides a plurality of axially spaced races or grooves in the interior 01' each cutter. H. In the case illustrated there are two grooves 88 and 8| provided in the wall 58 of each cutter II. The grooves 88 and 8| are partially cylindrical and, are of substantial depth.

Partially cylindrical races or grooves 82 are provided in the peripheries of the members 11 and 18st their abutting ends to oppose the grooves 8|. Annular series of balls 88 are arranged in the opposing grooves 8| and 82. The grooves 8| and 82 are of such depth that the balls 88 transmit the end thrusts in both directions, as well as the radial thrusts between the cutters l8 and the inner bearing .parts. Ball races or grooves 85 are provided in the peripheries oi the members 11 adjacent their inner ends to oppose the grooves 88. The races 85 continue to. or are open to the inner ends of the members I1. An-

nular series of balls 88 are arranged in the opposwelded to the body legs .88 are provided in the ing grooves 88 and 85. The balls 88 are operable to transmit the radialthrusts and the outward end thrusts between. the cutters l8 and the inner bearing parts. It will be noted that the race members 11 bear directly on the bosses 28 which are integral parts oi. the body I8 as well as on the supporting pin 55. Notches 8'|- are provided in the outer ends of the members 11 to communicate with their portions of the grooves 82 to fa- :illitate the insertion of the balls 88 in the grooves The invention includes means for preventing the rotation'oi the race members 88, 88, 85, I1 and 18. The thrust washers 88 have their lugs 28 as described above, and are held against rotation by this means. The adjacent race members 88 and 85 have axially extending openings 88 spaced between their peripheries and their internal surfaces. Sockets thrust washers 88 and in the race members 88 and are aligned with the openings 88. Dowel pins 8| are arranged in the openings 88 and have their end portions in cooperation with the sockets 88. The pins 8| are operable to prevent rotation 01' the race members 88, 88 and 85 relative to the. thrust washers 88 which in turn are welded to the body legs 28. Similarly, sockets 88 are provided in the race members IT and I8. Dowel pins 8| are arranged in and cooperate with the sockets 88,,, in such a manner as to prevent rotation of the race members .18 relative to the race members 11 which in turn are secured against rotation by means of their close fitting cooperation with the bosses 24.

areas-u 'icate with the portions of the grooves n and a In assembling a set of cutters l8 and I8 on the body I8 the series of balls 88 is arranged in the inner groove 88 of the cutter I4 and the race member I1 is then arranged in the opening 58 to engage against the balls 88. Balls 88 are then introduced one at a time through the notch 81 into' the groove 8| and the portion of the groove 82 in the race member 11. The dowel pin 8|- maybe carried by the race member 11. Following the introduction of the balls 88 into the groove 8| the race member 18 is positioned in the opening 58 to engage against the balls 88. The projecting outer portion of the dowel pin 8| is received in the socket 88 of the race member 18 when the member is arranged in place. The assembly of the cutter l4 and its bearing elements is introduced between a leg 28 and the web 28 and is moved inwardly until the socket 18-of the race member 11 fully receives the boss 28 of the'web 28. The cutter I8 is then assembled with its bearing elements. The series of balls 18 is arranged in the outer groove 82 of 'the cutter I3 and the thrust washer 88 is then arranged in the enlarged outer portion of the opening 5| to engage against the balls 18. The race member 85 is then arranged in the opening 5| to engage against the balls 18. The balls H are introduced one at a time into the groove 8| and the portion 'of the groove in the race member 85 through the notch 14 in the member 85. The race member 84 is then arranged in the opening 5| to engage against the balls II.

The balls 18 are introduced one at a time through the notch 18 in the race member 84 into the groove 88 and the portion of the groove 81 in the member 88. The dowel pin 8| may be carried in the openings 88 of the race members 88 and 85 to have one end introduced into the socket 88 of the thrust washer 88. Following the introduction of the balls 18 into the groove 88 the inner race member 88 is positioned in the opening 5| to engage against the balls I8. The projecting inner end of the dowel pin 8| is received in the socket 88 of the race member 88 when the race member 88 isarranged in place. The assembly of the cutter I8 and its bearing elements is then introduced between the leg 28 and the cutter I which has been positioned on the web l8 as described above. In a similar manner the second set of cutters I8 and I8 are arranged on the body |8. When the sets of cutters i8 and I4 have been arranged between the legs 28 and'the web 28 and in axial alignment with the opening 51 in the web 28 and the openings 58 and 58 in the legs 28, the pin 55 is passed through the opening 58, the bearing elements of the cutters 8 and I8 and the opening 51 in the web 28 to have its end portion threaded into the opening 58. The lugs 15 may then be welded to the legs.

The means l8 for flushing. the cutters II and I8 and I8 includes ports or openings 82 in the wall of the body |8 communicating with the lower end of the passage l8 and facing downwardly and outwardly between the legs l8 and the web 28 toward the cutters Tubular bushings 88 are inserted in the openings 82 and are welded to the body 8 at 88. The longitudinal openings 85 in the bushings 88 are tapered having downwardly or outwardly convergent walls. Beans or nozzles 88 are removabiy arranged in the openings 85 of the bushings 88. The nozzles 88 have their exteriors tapered to correspond to the taper of the openings 85. The nozzles 88 are inserted downwardly in the openings 85 to seat therein. Fluid discharging openings 81, extend through the nozzles 99. The openings 91 may be downwardly convergent to produce a jetting action. The

streams of fluid under pressure discharged from the nozzle openings 91 impinge against the cutters II to wash their teeth 29. It will be observed that the fluid under pressure passing through the nozzles 99 tends to tighten or at least hold the nozzles in the tapered openings 95. The fluid handling means I6 further includes or provides openings 98 in the body l9 communicating with the lower end of the passage l8 and opening downwardly toward the pairs ,of cutters l3 and I4. The openings 98 may be tapered or of downwardly increasing diameter. Wear preventing bushings 99 are provided in the openings 98. The bushings 99 are adapted to discharge streams of circulation fluid downwardly against the cutters l3 and [4 to flush their teeth 52 and 54. Welds I99 may secure the bushings 99 to the body l9.

In operation the bit body I9 is secured to the lower end of the drilling string and is rotated in the well in the usual manner. ll act on the formation at the outer portion of the bore to cut the bore to size and are supported by the series of balls 42 and 44 for free rotation about downwardly and inwardly inclined axes; The sets or pairs of opposing grooves 39 and 4|, and 49 and 43 are of substantial depth and the balls 42 and 44 have extensive engagement with their walls so that the forces or pressures are well distributed and are materially reduced in intensity. This promotes the long life of the bearings.

The balls 42 and 44 cooperating with their respective grooves are operable to transmit end thrusts in both directions as well as the radial thrusts and thus constitute the sole means for rotatably supporting the cutters II on the inner bearing parts.

rotatable about a common transverse axis to act on the formation at the bottom of the well bore. The cutters l3 are rotatably supported by the annular series of-balls I9, H and 19. Each of these series of balls is operable to transmit the end thrusts in both directions as well as the radial thrusts. The grooves receiving the balls I9, 'II and 19 are of such depth that the balls have extensive engagement with their walls so that the forces are well distributed and the pressures are of less intensity. In a like manner the inner cutters l4 are rotatably supported by spaced series of balls 93 and 86 for free rotation. The cutter mounting means provided by the present invention are long wearing and dependable and assure the free independent rotation of the several cutters for a substantial period.

ing aligned openings, at single support member extending between the legs with its end portions,-

supported in the openings in the legs and its intermediate portion supported in the opening in the web, and sets of roller cutters supported on the member between the legs and web.

The outer cutters The inner cutters i3 and I4 are independently 2. A well bit comprising a body, two substantially diametrically opposite legs projecting from the body, a web projecting from the body and spaced between the legs, the legs and web having aligned openings, a single support member extending between the legs with one end portion threaded in an opening in one leg and its intermediate portion supported in the opening in the web, the other end portion of the member extending through the opening in the other leg, a head on the said other end of the member bearing inwardly against said other leg, and sets of roller cutters rotatably supported on the mem--' ber between the legs and web.

3.. A well bit comprising a body, two substantially diametrically opposite legs projecting from the body, a web projecting from the body and spaced between the legs, the legs and web having aligned'openings, a single support member extending between the legs with one end portion threaded in an opening in one leg and its intermediate portion supported in the opening in the a pin extending between and carried by the supports, a roller cutter having an opening and surrounding the pin, thrust washers on the pin received in the cutter opening and projecting from the ends of the cutter to bear against the supports, a race member on the pin between the washers and having its ends in abutment with the ends of the washers to space them apart, there being spaced annular grooves in the wall of the opening, there being grooves in the peripheries of the washers and the race member at their abutting ends opposing the races of the opening, and series of balls in the said pposing grooves rotatably supporting the cutter.

5. In a rotary well drilling bit, spaced supports, a pin extending between and carried by the supports, 'a roller cutter having an opening and surrounding the pin, thrust washers on the pin received in the cutter opening and projecting from the ends of the cutter to bear against the supports, a race member on the pin between the washers and having its ends in abutment with the ends of the washers, there being spaced annular grooves in the wall of the opening, the washers and race member having aligned axial openings, a pin in the said aligned opening holding the washers and race member against relative rotation, means securing a washer to a support to hold the washer against rotation on the pin, there being grooves in the peripheries of the washers and the race member at their abutting ends opposing the races of the opening, and series of balls in the said opposing grooves rotatably supporting the cutter.

6. A'well bit comprising, a body having spaced legs and a web spaced between the legs, the legs end portions of said members being concave to present annular grooves opposing the grooves in the cutters, and balls in the opposing first and second mentioned grooves rotstably supporting the cutters, the innermost members having sockets receiving the bosses.

'7. A well bit comprising, a body having spaced legs and a web spaced between the legs, the legs and web having aligned openings, a pin extend ing through the openings and supported by the legs and web, bosses on the opposite sides of the web, sets of cutters surrounding the pin between the legs and web, bearing members arranged on the pin with their ends in abutment, the cutters having internal grooves, the abutting end por- JOHN H. HOWARD. ALFRED C. OA'I'LAND.

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