AU782643B2 - Mounting attachment and bearing system for an industrial earth-boring cutter - Google Patents

Description

S&FRef: 595948

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Smith International, Inc.

16740 Hardy Street Houston Texas 77032 United States of America Peter L. Cariveau Vincent W. Shotton Spruson Ferguson St Martins Tower,Level 31 Market Street Sydney NSW 2000 (CCN 3710000177) Mounting Attachment and Bearing System for an Industrial Earth-boring Cutter The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845c MOUNTING ATIACHMENT AND BEARING SYSTEM

FOR

AN INDUSTRIAL EARTH-BORING

CUTTER

Background of Invention Field of the Invention [0001j The invention relates generally to industrial earth-boring cutters and, more particularly, to the bearing system and attachments therefor for earthboring cutters.

Background Art [0002] Industrial earth-boring cutters, such as the type used in raise bore and shaft-drilling assemblies are well known in the art. An industrial earth-boring cutter 1, as shown in Figure 1, typically comprises a central joirnal assembly 2 on which a cutter body 3 is rotatably mounted. The cutter body 3 typically includes ribs, protuberances, or hard inserts 4 to break up and crush a formation when the cutter body 3 is pressed against and rolled over the formation [0003) The cutter 1 shown in Figure 1 is a raised bore cutter. A ball bearing and roller bearings 11 are disposed between the journal assembly 2 and the cutter body 3 to allow the cutter body 3 to rotate freely with respect to the journal assembly 2. The ball bearing 10 is usually provided to carry axial load, and the one or mo::-e roller bearings 11 are typically provided to carry radial loads. In this confi.iuration the roller bearings 11 are placed around the journal assembly 2 prior to sliding the journal assembly 2 into the cutter body 3. Then the ball bearing 10 is put into place by inserting bearing balls through the ball hole 13 in the journal 2. Once the bearing balls are in place, a ball plug 12 is inserted into the ball loading hole 13 and then a ball plug retainer 14 is inserted into the journal 2 to retain the ball plug 12 in place.

[0004] To prevent damage to the bearing balls of the ball bearing 10 and edges of the ball loading hole 13, cutter designs known in the art have the ball hole 13 placed at 180 degrees from the load bearing zone of the journal assembly 2.

This placement is selected to prevent forcing the bearing balls against the rough edges of the ball loading hole 13 as they pass over the hole 13. If the ball loading hole 13 were positioned in the load bearing zone, the bearing balls would forcibly impact the edges of the ball loading hole 13, probably resulting in metal chips and debris being removed from the journal 2 so as to contaminate the lubricant and eventually destroy the bearings and seals.

[00051 Once assembled, the cutter 1 is typically attached to a rotatable headplate (not shovm) by a support bracket 6 or similar structure. Typically the support bracket 6 includes a base attachable to the rotatable headplate (not shown), and legs 7 on each side of the base extending away from the base.

Each leg 7 includes a yoke 8 at its distal end which is configured to receive and fixably couple to a support shaft 9 of the journal assembly 2 which extends axially outward at each end of the cutter 1.

[0006] For many applications, industrial cutters are limited by the bearing capacity or bearing life. A major cause of bearing failure in industrial cutter systems is spalling of the non-rotating journal bearing surface. Spalling is the flaking off of material from a surface. Spalling of the non-rotating journal bearing surface is the result of a fatigue process caused by the rolling elements as they passed acro:;s the position the journal surface that carries the load. For example, as the rolling elements roll across the journal surface, the surface is repeatedly loaded and unloaded, which initiates subsurface cracks that ultimately cause spalling. When the journal surface spalls, hard steel debris contaminates the lubricant which causes rapid wear and damage to the rest of the operable bearing and seal components which eventually results in bearing failure.

[0007] Ideally, the load-bearing journal surface should be replaced with a new surface before it spalls so that the life of the bearing can be increased. This may be accomplished by rotating the journal during servicing of the cutter to place the previously unloaded journal surface in the load bearing position. One cutter design which allows for rotation of the journal by 180 degrees is shown in Figure 2. However, this design uses cylindrical roller thrust bearings instead of ball bearings. In this design, the ball bearing (shown at 10 in Figure 1) is substituted by a plurality of small roller bearings 20 transversely disposed between the journal assembly 2 and the cutter body 3 along opposed upper and lower paths defined between a projection 21 extending from the journal surface and an internal recess 22 formed in the cutter body 3. Because this design has no ball bearing, concerns regarding the placement of the ball loading hole (13 in Figure 1) are eliminated. Therefore, it is possible to reverse the journal to expose a previously substantially unloaded surface as a replacement surface before significant spalling of the first load-bearing surface takes place.

However, this cutter configuration requires very tight tolerances on four different axial bearing surfaces to maintain good control of axial loading and deflection. A closely toleranced cone bearing sleeve 23 is also necessary to assemble the thrust elements of the bearing. This sleeve 23 greatly restricts the outer bearing diameter, however, which limits radial roller bearing capacity.

[0008] In prior art cutter designs which use ball bearing retention, as previously explained, the ball loading hole is placed 180 degrees from the load zone.

While this configuiation ensures little or no load on the ball loading hole, this design does not allow for rotation of the journal. Therefore, the substantially unloaded surface of the journal bearing in these designs can not be later used during the cutter life. Further, if the journal were rotated, it would put the rough opening of the ball loading hole into a position of maximum radial loading, which would lead to premature bearing failure as described above.

It is desirable to have a simplified cutter which uses ball bearing retention and permits rotation of the journal so that a previously substantially unloaded surface may be subsequently used to carry load while maintaining the ball loading hole in a position outside of the bearing zone so that the life of the bearing may be increased.

Summary of the Invention According to the invention there is provided a rotary cutter mount for an earthboring cutter comprising: a bearing journal adapted to be coupled to a cutter body, the bearing journal having a rotary cutter body rotationally coupled to an exterior bearing surface thereof, a first mounting end of the bearing journal shaped to enable rotationally fixed positioning in a corresponding yoke, the yoke operatively coupled to the body of the earth-boring cutter; a ball race formed in an exterior surface of the bearing journal; and a ball loading passage formed in the bearing journal, the ball loading passage having an exit hole on the ball race, wherein the first mounting end and the corresponding yoke are shaped to allow mounting of the bearing journal in a plurality of rotary orientations, each of the rotary orientations selected such that the exit hole is angularly displaced from a direction of S* 20 maximum radial loading on the bearing journal.

S"Brief Description of the Drawings A preferred embodiment of the invention will be described hereinafter, by way of example only, with reference to the accompanying drawings, in which: o: *Figures 1 and 2 show examples of prior art industrial cutter structures.

oooo S 25 Figure 3 shows an exploded view of one embodiment of a cutter according to the invention.

4 R:\libtt\04015.doc [0013] Figure 4 shows an exploded view of another embodiment of a cutter according to the invention.

[0014] Figure 5 shows one embodiment of a bearing journal according to the invention.

100151 Figure 5B shows one example of possible positions of an exit hole of a ball loading passage for various rotary orientations of a bearing journal according to the invention.

[0016] Figures 6A and 6B show another embodiment of a bearing journal and a corresponding mounting yoke.

[00171 Figures 7A and 7B show another embodiment of a bearing journal and a corresponding mounting yoke.

100181 Figures 8A and 8B show another embodiment of a bearing journal and a corresponding mou ting yoke.

[00191 Figures 9A and 9B show another embodiment of a bearing journal and a corresponding mounting yoke.

(00201 Figures 9C end 9D show examples of other embodiments of a mounting configuration according to the general concept shown in Figures 9A and 9B.

[00211 Figures 10A and 10B show another embodiment of a bearing journal and a corresponding mounting yoke.

[0022] Figures 11A and 11B show another embodiment of a bearing journal and a corresponding mounting yoke.

[00231 Figures 12A and 12B show another embodiment of a bearing journal and a corresponding mounting yoke.

[0024] Figures 13A and 13B show another embodiment of a bearing journal and a corresponding mounting yoke.

[0025] Figuresl4A and 14B show another embodiment of a bearing journal and a corresponding mounting yoke.

Detailed Description [0026] The invention provides a mounting system for an earth-boring cutter or other rotary systemrs having a journal bearing assembly subject to substantially one-sided loading. For example, this mounting system may be used for raised bore cutters, replac.eable cutters on hole openers, underreamers, and reverse reamers used in irenchless utility boring. The invention may provide a substantial increase in bearing life for the rotary system.

[00271 An exploded view of one example of an earth-boring cutter 100 in accordance with the invention is shown in Figure 3. In this example, the cutter 100 comprises a generally cylindrical journal assembly 102. The journal assembly 102 may be an integrally formed member or may comprise a plurality of members coupled together. The journal assembly 102 comprises a journal body 128 preferably having a plurality of recessed bearing rolling paths (not shown) defined thereon.

[0028] The cutter 100 further comprises a generally cylindrical cutter body 103 having a bore that extends axially therethrough for receiving the journal assembly 102 therein. The cutter body 103 may be tapered, as shown, and may include ribs, protrusions, or inserts which contact and cut through earth formations during drilling operations. The cutter body 103 further comprises an inner surface having a plurality of bearing rolling paths 131, 132, and 133 defined thereon and corresponding to the rolling paths (not shown) on the outer surface of the journil body 128.

[0029] A plurality of roller elements 129 are disposed between the cutter body 103 and the journal assembly 102. The roller elements 129 are axially positioned to roll within the corresponding rolling paths (131, 132, 133) between the journal assembly 128 and the cutter body 103 to enable the relative rotation of the cutter body 103 with respect to the journal assembly 102. In accordance with the invention, the rolling elements 129 include at least one set of ball bearings 112 and at least one other set of bearings, such as roller bearings III and .713. The ball bearings 112 are provided primarily to carry axial load. The one: or more other sets of bearings 111, 113 may be provided to carry radial or lateral loads. The one or more other sets of bearings 1 11, 113 may be cylindr-ical, crowned, logarithmic, or tapered roller bearings, or may be ball bearings. In this example, the other set of bearings 111, 113, comprises a set of outer roller bearings 111 and a set of innier roller bearings 113. For ball bearings primarily adapted for axial loading, a large bail race may be used to provide high thrusl capacity and tight control of axial movement. Any type of race selected by one skilled in the art may be used for the ball bearings, for example an angular contact ball race design such as disclosed in U. S. Patent No. 3,762,782 to Rumbarger.

[00301 The other components shown in Figure 3 or the cutter 100 include a lubrication fitting 104, an outer retainig ring 105, an outer seal retainer 107, 0-rings 1.06, 116 anid 119, dowel pins 108 and 115, an outer seal 119, an inner seal 114, an inner retaining ring 117, an inner seal retainer 118, a ball plug 123, a ball plug retainer 124, and a spring pin 125.

[00311 A similar cutter is shown in exploded view in Figure 4. This cutter 100 includes an additiona] set of outer roller bearings at Ill for handling high radial loads. The type, number, and placement of the at least one other set of bearings in accordznce with the invention may be determined by those skilled in the art and is not a limitation on the invention.

10032] Referring to Figure 5, in accordance with the invention, the mounting system for the journal on the cutter allows reorientation of the journal 152 such that the substantially unloaded portions of the journal bearing surface can be reoriented into the load-bearing position, such as when the cutters are serviced, without subjecting the ball loading hole (150 in Figure 5) to maximum radial loading. This may result in a substantial increase in bearing life, To achieve reorientation of the journal for this type of roller retention earth-boring cutter configuration, a ball loading hole 150 must be located so that it is not subject to significant radial o: lateral loading. This is achieved by positioning the exit of the all loading hole 150 away from the load bearing zone, shown at 150A in Figure 5. In the e:nbodiment shown in Figure 5 the ball hole exit 150 on the journal 152 is loc:ted 90 degrees from the position of maximum radial load 150A. This configuration enables the journal 152 to be rotated 180 degrees about the journal a is 154 during service of the cutter (100 in Figure while still orienting the ball loading hole 150 at a position which is about 90 degrees from the from the position of maximum radial load 150A.

[00331 Thus, embodiments of the invention provide both apparatus and methods for reorienting the journal during the servicing of a cutter which may extend the life of the bearing. In some applications, the apparatus and method may effectively double the life of the bearing in comparison to prior art mounting systems. Embodiments of the invention may also be more cost effective and reliable than previous reversible systems. For example, using an integral ball race on the journal 152 and on the cutter body (103 in Figure 3) reduces the design o1 a fewer number of bearing components, which may result in lower manufacturing costs. This may also lead to an improvement in reliability because Ihe number of potential lubricant leak paths is reduced and tolerance stack-up is avoided in the axial direction.

[00341 Material wkch may be used for the roller elements may include any shock resistant tool steel, such as that known by the industrial designation S2 and S5, or chrome alloy steel, such as known by the industrial designation 52A100. These m.terials are only listed here as examples of materials that may be used. Tho;e skilled in the art will appreciate that any other suitable material may be used as without departing from the spirit of the invention.

[00351 As shown in Figure 5, when the cutter is in use, only a portion of the journal 152 is subject to substantial load bearing, this portion being shown generally at 150A. in accordance with the invention, after a first surface on the journal 152 is used the journal 152 may be detached from its mounting and rotated about its a-ds 154. After rotation, the journal 152 is then reattached such that the unworn surface is oriented toward the direction of maximum radial loading 150/A.

[00361 In accordani..e with the invention, the journal assembly is oriented such that the ball hole e,-rdt 150 is at an angle less than 180 degrees from the position on the journal 152 carrying maximum radial load 150A. Preferably, the ball1 hole exit .150 is located between 45 degrees and 135 degrees away from position on the journal 152 carrying the maximum radial load 150A. More preferably, the ball hole exit 150 may be located around 90 degrees away from position on the Jouinal 152 carrying the maximum radial load 1 50A. Locating the ball hole exit 150 respective of the maximum load-bearing position in this way allows for a rotatable or reversible journal system having the benefit of ball bearing retentiorn, wherein the journal 152 can be rotated to expose a new area of journal surface to load bearing prior to significant spalling of the initially load-bearing surface. This may be done to postpone the effects of spalling and increas-ing the life of the bearing.

(0037] In another embodiment shown in Figure 5B, the ball hole exit 150 may be located about 45 degrees away from the maximum radial load-bearing position 1 50A. This positioning of the ball hole exit 150 allows for the journal to be rotated up to three different times in 90 degree increments, which may allow the cutter to be serviced as many as three times before it becomes necessary to replace the journal.

[00381 Those skilled in the art will appreciate that factors such as the load profile for the cutter, the design factors related thereto, and other factors such as the potential for l oad bearing on the edge of the ball hole, the rigidity of the mounting system, and the size of the ball hole should be considered when determining the selected angles at which the ball hole exit 150 is to be oriented during cutter operations.

[0039] To provide a rotatable journal for a cutter in accordance with the invention, a mounting system is required which allows for repositioning and securing in the journal in the selected orientations. In general, the mounting system comprises contoured attachment mechanism disposed at each end of the cutter and rigidly coupled to the journal assembly, and a yoke having a complementary contour for receiving the contoured attachment mechanism and a means for rigidly coupling thereto. One embodiment of a journal mounting system in accordance with the invention is shown in Figures 6A and 6B. In this embodiment, the attachment mechanism comprises a generally octagonal cross-sectioned attachment shaft or pin 64 attachable to the end 153 of the journal assembly 152 in a rotationally fixed manner, such as by bolts, screws, or the like. The pin 64 may alternatively be or a shaft integrally formed with and extending from the journal assembly 152. The external surface of the pin 64 is adapted to fil within corresponding surfaces of a yoke 60. The pin 64 may be retained in the yoke 60 by a bolt or pin such as shown at 68.

100401 An embodiment shown in Figure 6B, includes a threaded hole 65 in the pin 64. A corresponding threaded hole 67 is provided in the yoke 60, such that when the pin 64 is properly oriented in the yoke 60, the holes 65, 67 of the pin 64 and the yoke 60, respectively, align so that a bolt 69 may be passed therethrough to engage the holes 65, 67 and rigidly and removably couple the pin 64 to the yoke [0041J As illustrated in Figures 6A and 6B, after the journal assembly 152 is used in an initial rotary orientation, the journal assembly 152 may then detached from the yoke 60 by removing the bolt 69, and rotated, as shown in Figure 6B. After rotating the journal assembly 152 such that a new bearing surface is oriented in the direction of maximum radial loading (150A in Figure the journal assembly 152 may then be reattached to the yoke 60 in the new rotary orientation. If desired, a second threaded hole (not shown) 90 degrees displaced from the hole 65 shown in Figure 6B may be provided in the pin 64 to enable rotation of the journal assembly 152 in 90 degree increments. In other embodiments, attachment devices other than bolts may be used to attach the pin to the yoke without departing from the scope of the invention, [00421 Another embodiment of a journal mounting device is shown in Figures 7A and 7B. In this embodiment, the mounting device comprises a generally cross-shaped attachment mechanism 74 forming or coupled to the end of the journal 152, and a y'oke 70 having a correspondingly cross-shaped cavity (Figure 7B3) for receiving the cross-shaped attachment mechanism 74 therein.

At least one arm 71, and preferably the opposing arm 71 A as well, of the crossshaped attachment mechanism 74 is provided with a threaded bole penetrating each arm 71, 71A. Corresponding threaded holes 77 are provided in the corresponding shoulders of the yoke 70 as shown in Figure 7B. The journal assembly 152 is then attached to the yoke 70 by engaging bolts 79 in each of the holes 75 in the arms 71, 71A of the cross-shaped attachment mechanism 74 and the corresponding holes 77 in the yoke 70, as particularly shown in Figure 7B.

[00431 In accordance with the invention, after the journal assembly 152 is used in an initial rotary o)rientationl, the journal assembly 152 can then be detached from the yoke 70 by removing the bolts 79, and then rotated 180 degrees to allow substantially unloaded portions of the journal bearing surface to be reoriented into the i aximum load-bearing position (I 50A in Figure After rotation of the Journal assembly 152, the journal assembly 152 is then reattached in the samne manner described above. In other embodiments, a second set of parallel axially aligned threaded holes (not shown) may be p rovided in the other two arms 7113, 71C of the cross-shaped attachment mechanism 74 to enable for rotation of the journal assembly in 90 degree increments.

(00441 Another embodiment of a mounting attachment is shown in Figures 8A and 8B. In this embodiment, the mounting attachment comprises an end of a generally cylindrical shaft 84 which extends at one end of the journal assembly 82. The cylindrical shaft 84 is provided with a plurality of threaded holes form-ed on the end face 84A thereof The mounting attachment further comprises a corresponding attachment yoke 80 having a slot or cutout formed therein whii,.h truncates in a shape adapted to receive the end 80A of the cylindrical shaft 84. therein. The yoke 80 is also provided with a plurality of threaded holes 87 which extend through the wall thereof having the slot When the cylindrical shaft 84 is in a selected rotary orientation in the yoke the threaded holes V7 of the yoke 80 align with the threaded holes 85 in the end of the cylindrijcal shaft 84. The shaft 84 can then be rigidly coupled to the yoke by engaging a pini or bolt 89 in one or more, and preferably all of the aligned holes 85, 87, as shown in Figure 8B.

10045] After the journal assembly 152 is used in an initial rotary orientation, the journal assembly 82 can then be detached from the yoke 80 by removing the b olIts 89. The j ourrnal 152 can th en be rotated by a selected angular amount to enable substantially unloaded portions of the journal bearing surface to be reonented into the inaximur radial load-bearing position (I 50A in Figure Those skilled in the art will appreciate that this type of attachment configuration enablos the journal assembly 152 to be configured to be rotated by any desired amou~nt, such as 90 degrees or 180 degrees. The rotation angles available depend on the positions ofthe mating holes 85, 87. The pattern shown in Figures &A and 8B, which enables 90 degree incremental rotation is only one example of- selected incremental rotation angles. After rotation of the journal assembly 152 to the next desired rotary orientation, the journal 152 is then reattached such that a different journal surface is subjected to the expected maximum radial loail, as shown at 150A in Figure [0046] Another embo~diment of a mounting attachment is shown in Figures 9A and 9B, In this emr.bodiment, a contoured attachment mechanism 94 on the journal assembly 15:1 is configured to mate with a substantially triangular yoke wherein the contoured attachment mechanism 94 and the yoke 90 are coupled by bolts 99 passing through corresponding threaded holes 95, 97 of the contoured attachment mechanism 94 and the yoke 90, as shown in detail in Figure 9B. This configuration enables reorientation of the journal assembly 152 in 180 degree increments to allow substantially unloaded portions of the journal bearing surface to be reoriented into the load-bearing position. The design shown in Figures 9A and 9B could be modified as shown in Figure 9C to enable rotation of the journal assembly (152 in Figure 9A) in 120 degree increments. Another embodiment shown in Figure 9D is adapted to enable rotation of the journal assembly (152 in Figure 9A) in 90 degree intervals.

[0047] Another embodiment of a mounting attachment is shown in Figures and 10B. In this embodiment, a contoured attachment mechanism 204 on the journal assembly 152 is configured to mate with a yoke 200 having a substantially square yoke cavity configuration (200A in Figure 10B) which extends around the sides of the contoured attachment mechanism 204. The contoured attachment mechanism 204 comprises a square-like cross section with beveled corner. The yoke 200 comprises upwardly extending legs which cradle the sides of the.contoured attachment mechanism 204. This embodiment of the yoke 200 has radial recessed corners. The radially recessed corners of the yoke 200 combined with the beveled comers of the contoured attachment mechanism 204 facilitate the insertion and removal of the contoured attachment mechanism 204 from the yoke 200. In this embodiment, the contoured attachment mechanism 204 and yoke 200 each are provided with threaded holes 205, 207 which extend through opposing side surfaces. The contoured attachment mechani.m 204 and yoke 200 may be coupled to each other by engaging a threaded member, such as a bolt 209 in the aligned holes 205, 207 as shown in Figure 10A. This configuration enables reorientation of the journal assembly 152 in 180 degree increments. In other embodiments, the coupling of Figures 10A and 10B may be modified by providing the other set of opposed sides of the contoured attachment mechanism 204 with holes to allow for a rotation of the journal assembly in 90 degree increments.

1 00 48) Another embodiment of a mounting attachment is shown in Figures 11A and I IB. In this embodiment, the contoured attachment mechanism comprises an elongated rectangular rib member 214 coupled to the end of the journal assembly 212 and having a hole 215 radially disposed therethrough.

A

corresponding yoke 210 comprises a slot configured to receive and retain the elongated rib menmber. The yoke 210 also comprises a hole 217 which corresponds in alignment with the threaded hole in the rib member when the rib member is inserted into the slot of the yoke. A member such as a bolt 219 may be used to couple the rib member and the yoke when aligned by threadably engaging in the holes when aligned. This configuration allows for reorientation of the journal assembly 212 by rotating it 180 degrees to allow substantially unloaded portions of the journal bearing surface to be reoriented into the loadbearing position. In other embodiments, this configuration may be modified to allow for a rotation of the journal assembly by a different amount, [0049] Another embodiment of a mounting attachment is shown in Figures 12A and 12B. This attachment mechanism 224 is similar to that shown in Figures and 10B. However in the embodiment of Figures 12A and 12B, the legs of the yoke 220 extend above the contoured attachment member 224 such that holes 227 in the upper portion of the legs of the yoke 220 align with a groove 225 formed along the top surface of the contoured attachment member 224. A pin or bolt 229 which extends through the holes 227 in the yoke 220, engage with the groove 225 in the contoured attachment mechanism 224 member thereby locking the ontoured attachment mechanism 224 in place in the yoke 220.

[0050] Another embodiment of a mounting attachment is shown in Figures 13A and 13B. In this embodiment, the contoured attachment mechanism 234 on the journal assembly 232 comprises a square-shape shaft having holes 235 provided there in. The yoke 235 comprises a generally rectangular shaped structure provided with a corresponding shaped cutout section configured to receive and couple with the square-shaped shaft extending from the journal assembly 232. The contoured attachment mechanism 234 and yoke 230 are provided with corresponding threaded holes 235, 237 such that once the shaft is inserted into the cavity of the yoke 230, a bolt 239 may be engaged therein to couple the contoured attachment member to the yoke. A wedge member 233 is also included in this configuration. The wedge member 233 is configured be placed on top of the contoured attachment mechanism 234 when positioned in the cavity of the yoke 233. The wedge 233 is provided with a threaded hole 231 extending down through the wedge from the upper surface.

A

corresponding threaded hole 237A is provided in the yoke 230 to allow for threadably coupling the wedge to the yoke body to provide additional support for maintaining the ::;haft in place in the yoke.

[0051] Another embodiment of a mounting attachment is shown in Figures 14A and 14B. This attachment mechanism 244 is similar to that shown in Figures 6A and 6B. However, in the embodiment of Figures 14A and 14B the attachment mechanism 244 is a hexagon comprising sides each having substantially the same width. This attachment mechanism 244 couples to the yoke 240 similar to that for the mounting attachment shown in Figures 6A and 6B. However, this rounting attachment allows the journal assembly 242 to be rotated at 60 degree increments.

100521 While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that numerous other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.

Claims (21)

1. A rotary cutter mount for an earth-boring cutter comprising: a bearing journal adapted to be coupled to a cutter body, the bearing journal having a rotary cutter body rotationally coupled to an exterior bearing surface thereof, a first mounting end of the bearing journal shaped to enable rotationally fixed positioning in a corresponding yoke, the yoke operatively coupled to the body of the earth-boring cutter; a ball race formed in an exterior surface of the bearing journal; and a ball loading passage formed in the bearing journal, the ball loading passage having an exit hole on the ball race, wherein the first mounting end and the corresponding yoke are shaped to allow mounting of the bearing journal in a plurality of rotary orientations, each of the rotary orientations selected such that the exit hole is angularly displaced from a direction of maximum radial loading on the bearing journal. is

2. The mount as defined in claim 1 wherein the shape of the first mounting end comprises an octagon.

3. The mount as defined in claim 1 wherein the shape of the first mounting end comprises a substantially regular hexagon.

4. The mount as defined in claim 1 wherein the shape of the first mounting end comprises a cross.

The mount as defined in claim 1 where the shape of the first mounting 25 end comprises a surface adapted to rest on a top of a substantially triangular upper surface of the corresponding yoke. 16 [R:\LIBT]G0401

6. The mount as defined in claim 5 wherein the surface adapted to rest on the top comprises two mating surfaces angularly displaced by 180 degrees.

7. The mount as defined in claim 5 wherein the surface adapted to rest on the top comprises three mating surfaces angularly displaced by 120 degrees.

8. The mount as defined in claim 5 wherein the surface adapted to rest on the top comprises four mating surfaces angularly displaced by 90 degrees.

9. The mount as defined in claim 1 wherein the shape of the first mounting end comprises a cylinder.

The mount as defined in claim 9 wherein an end face of the mounting end comprises holes each for receiving a bolt therein, and the corresponding yoke comprises holes in a face thereof, the holes on the yoke face and on the end face positioned to enable mounting the bearing journal in the plurality of rotary orientations.

11. The mount as defined in claim 10 wherein the plurality of rotary orientations is four in number, each of the four rotary orientations angularly separated by about 90 degrees.

12. The mount as defined in claim 1 wherein the shape of the first mounting end comprises a square.

13. The mount as defined in claim 12 wherein the square comprises radiused coners.

14. The mount as defined in claim 12 wherein the corresponding yoke comprises a locking wedge coupled to an upper surface thereof.

The mount as defined in claim 1 wherein the shape of the first mounting end comprises a flat blad.;.

16. The mount as defined in claim 1 wherein the shape of the first mounting end and the corresponding yoke are selected to provide a selected amount of angular separation between each of the plurality of rotary orientations.

17. The mount as defined in claim 16 wherein the exit hole is positioned with respect to the plurality of rotary orientations such that the exit hole is oriented at least about 45 degrees angularly separated from the direction of maximum radial loading irrespective of the rotary orientation.

18. The mount as defined in claim 16 wherein the selected amount of angular separation is 90 degrees.

19. The mount as defined in claim 16 wherein the selected amount of angular separation is 120 de.grees.

The mount as defined in claim 16 wherein the selected amount of angular separation is 180 degrees.

21. A rotary cutter mount for an earth-boring cutter substantially as hereinbefore described with reference to the accompanying drawings. Dated 8 May, 2002 Smith International, Inc. Patent Attorneys for the Applicant/Nominated Person SPRUSON FERGUSON