Debris path for mining track utilizing a sealed joint

Abstract

The track chain assembly (126) includes a first track block (200, 200a) including a first pair of lugs (232, 234) defining a gap (236) therebetween and a second track block (200, 200a) including an intermediate lug (230) disposed in the gap (236). The first pair of lugs (232, 234) and the intermediate lug (230) each define a concentric bore (206, 206a) defining an axis of rotation (132) of a pinned joint (138) of the track chain assembly (126), and the concentric bore (206, 206a) of one of the first pair of lugs (232, 234) is in communication with the gap (236) with a first fusion (238) disposed axially between the gap (236) and the concentric bore.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to track blocks for supporting heavy equipment such as hydraulic mining shovels and the like. In particular, the present disclosure relates to track blocks that allow debris or other contaminants to exit a seal used in a pin joint connecting a pair of such track blocks. BACKGROUND

[0002] In various mining applications, track blocks are subjected to heavy loads, requiring the track blocks to be robust. Moreover, dust, rock, debris, and other contaminants can infiltrate various components of a track chain using such track blocks. More particularly, track chains using such track blocks can have pin joints with seals to prevent unwanted loss of lubrication. Contaminants can infiltrate these seals, which can eventually damage the seals or otherwise interfere with the function of the seals, allowing lubricant to leak from the joint. Ultimately, the lack of lubrication can result in scuffing, jamming, or other mechanical problems of the track chain, requiring maintenance of the track chain and downtime of the machine. This is undesirable as it adversely affects the profitability of the economic activity using the machine.

[0003] Chinese Patent No. CN2702902Y discloses a track-driven machine including a track chain having two chain links forming a pin joint. More particularly, a pin and bushing having a seal are provided. At an axial end of the bushing, the bushing has a chamfer on its outer peripheral surface. A similar chamfer is provided on the inner peripheral surface at the axial end of the bushing. The inner chamfer extends axially further than the outer chamfer. The purpose of these chamfers is to facilitate assembly of the pin joint, provide a long service life, and reduce the amount of noise generated by the pin joint as the track chain moves.

[0004] However, this prior art fails to disclose a track block or track chain that helps reduce the likelihood of contaminants infiltrating the seal assembly, etc., of the pin joint of the track chain. SUMMARY

[0005] A track block according to an embodiment of the present disclosure can include a shoe member including a ground engaging surface and defining a track chain travel direction, a lateral direction perpendicular to the track chain travel direction, and a vertical direction perpendicular to both the lateral direction and the track chain travel direction. The shoe member can also define a first lateral end, a second lateral end, a forward end along the track chain travel direction, and a rearward end along the track chain travel direction, a lateral distance from the first lateral end to the second lateral end, and a width along the track chain travel direction from the forward end to the rearward end, the width being less than the lateral distance. A first link member can extend upwardly from the shoe member, the first link member including a first lug member extending from the first link member along a first direction parallel to the track chain travel direction, and a second lug member and a third lug member both extending from the first link member along a second direction opposite the first direction, forming a first fork portion including a first lateral outer surface, a second lateral outer surface, a first lateral inner surface, and a second lateral inner surface. The second lug member defines a first aperture extending laterally through the first lateral outer surface and the first lateral inner surface, forming a first intersection with the first lateral inner surface, the first intersection including a first blend extending from the first lateral inner surface to the first aperture.

[0006] A track block according to another embodiment of the present disclosure can include a shoe member including a ground engaging surface and defining a track chain travel direction, a lateral direction perpendicular to the track chain travel direction, and a vertical direction perpendicular to both the lateral direction and the track chain travel direction. The shoe member can also define a first lateral end, a second lateral end, a forward end along the track chain travel direction, and a rearward end along the track chain travel direction, a lateral distance from the first lateral end to the second lateral end, and a length along the track chain travel direction from the forward end to the rearward end, the length being less than the lateral distance. A first link member can extend upwardly from the shoe member, the first link member including a first top rail surface (e.g., which can be planar), a first lug member extending from the first link member along a first direction parallel to the track chain travel direction, and a second lug member and a third lug member both extending from the first link member along a second direction opposite the first direction. The second lug member and the third lug member can define a first pair of chamfered surfaces laterally opposite and facing one another.

[0007] A track chain assembly according to embodiments of the present disclosure can include a first track block including a first pair of lugs defining a gap therebetween, and a second track block including a middle lug disposed in the gap. The first pair of lugs and the middle lug can each define a concentric bore defining an axis of rotation of a pinned joint of the track chain assembly, and the concentric bore of one of the first pair of lugs is in communication with the gap, wherein a first fusion section is disposed axially between the gap and the concentric bore of one of the first pair of lugs. BRIEF DESCRIPTION OF DRAWINGS

[0008] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the present disclosure and together with the description, serve to explain the principles of the present disclosure. In the drawings:

[0009] Figure 1 A machine in the form of a hydraulic excavator with a chassis that can use a track chain assembly having track blocks constructed in accordance with various embodiments disclosed herein is shown.

[0010] Figure 2 is a perspective view of a portion of the chassis, the track chain assembly, and a track block of Figure 1

[0011] Figure 3 is a cross-sectional view taken along line 3-3 of the track chain assembly including two track blocks of Figure 2 depicting a pinned joint that allows the track chain assembly to be flexible in that the track blocks, along with the debris path, are free to rotate relative to one another, allowing contaminants to exit the seal assembly of the pinned joint.

[0012] Figure 4 is an enlarged detail view of a single instance of the debris path of Figure 3 more clearly showing the debris path.

[0013] Figure 5 is a side cross-sectional view taken along line 5-5 of a single instance of the track block of Figure 2

[0014] Figure 6 is an enlarged detail view of the track block of Figure 2 showing the chamfer(s) that can provide one boundary of the debris path of Figure 4 DETAILED DESCRIPTION

[0015] ​​​Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. In all of the drawings, like reference numerals will be used to designate like or similar parts. In some instances, reference numerals can be indicated in the description by adding the first few digits that are common to the given figure followed by the unique digits identifying the figure in which that component is found along with a letter designation (e.g., 100a, 100b, etc.). It should be understood that the use of a letter immediately following a reference numeral indicates that these features have similar shapes and function, as is often the case when a geometry is mirrored about a plane of symmetry. For ease of explanation in the present description, the letters will generally not be included herein, but can be shown in the drawings to indicate the repetition of features discussed in the written description.

[0016] While the arrangement is shown in connection with a hydraulic excavator, the arrangement disclosed herein has universal applicability in various other types of machines that typically employ track systems as opposed to wheels. The term "machine" can refer to any machine that performs some type of operation associated with an industry such as mining, earthmoving, or any other industry known in the art. For example, the machine can be an excavator, a wheel loader, a cable shovel, or a dragline, among others. Also, one or more implements can be connected to the machine. The implement can be used for various tasks, including, for example, hoisting and loading. Among other uses, the hydraulic excavator can be used to load topsoil and ore into haul trucks during a mining process in various open-pit mining applications.

[0017] Reference Figure 1 A machine 100 can be seen that can use track blocks constructed in accordance with various embodiments of the present disclosure. The machine 100 can include a body 104 having a cab 106 for housing a machine operator. The machine can also include a boom system 108 that is pivotally connected to the body 104 at one end and supports an implement 110 at an opposite distal end. In embodiments, the implement 110 can be any suitable implement, such as a bucket, a blade, a knife, or any other type of suitable device. A control system can be housed in the cab 106 that can be adapted to allow the machine operator to manipulate and articulate the implement 110 for mining, excavating, or any other suitable application.

[0018] The body 104 can be supported on a main frame 112 that is supported on a chassis structure 114. The chassis structure 114 includes a support structure 118 that supports a track system 102 for movement of the machine 100. The track system 102 can include first and second track roller frame assemblies 116 that are spaced apart and adjacent to respective first and second sides of the chassis structure 114. It should be understood that only one of the track roller frame assemblies 116 can be visible in Figure 1

[0019] ​Each of the track roller frame assemblies 116 carries an idler wheel 120, a drive sprocket 122, and a plurality of track guide rollers 124. The drive sprockets 122 are powered in forward and reverse directions by the machine 100 (via a motor such as an internal combustion engine). An endless track chain assembly 126 encircles each drive sprocket 122, idler wheel 120, and track guide roller 124. The track chain assembly 126 includes a plurality of interconnected track blocks 200, also referred to as track chain members. The track guide rollers 124 guide the track blocks 200 as the track chain assembly 126 is driven by the drive sprockets 122.

[0020] Figure 2 A portion of the track chain assembly 126 is shown that includes two blocks 200 that are pivotally connected to one another. Also shown is a track roller 124 that rides on the rail surfaces 202, 202a of the track blocks 200. Thus, the weight of the machine 100 is transmitted through the chassis structure 114 (see Figure 1 ) to the track rollers 124 to the track blocks 200, which transmit the load through their ground engaging surfaces 204 to the ground. The through-slots 136 extend along the track chain travel direction 210, which allows the guide ridges 134 of the track rollers to pass from one track block to the next unimpeded, while providing lateral guidance of the track chain assembly 126.

[0021] Figure 3 A pin pivot connection of a track block 200 to an adjacent track block 200 is depicted, which can be configured similarly or identically to one another so as to form the track chain assembly 126. A pin 152 (which can be part of a clevis pin assembly 128, for example) is shown that is disposed in a hole 206 of a lug member of a link member of the track block 200 (which will be discussed in more detail later), allowing one track block 200 to pivot relative to another. Also shown is a pin retaining bolt assembly 130 that helps prevent the clevis pin assembly 128 from “walking” laterally out of the hole.

[0022] The track chain assembly 126 according to embodiments of the present disclosure can also be referred to as a track chain assembly 126. Figure 3 and 4Characterized as follows. The track chain assembly 126 can include a first track block 200 that includes a first pair of lugs (hereinafter referred to as a second lug 232 and a third lug member 234) that laterally define a gap 236 between the second and third lugs. A second track block 200a can also be provided that includes a middle lug (hereinafter referred to as a first lug 230) that is disposed in the gap 236. The first pair of lugs and the middle lug each define a concentric bore (see, e.g., 206, 206a, 206b) that defines an axis of rotation 132 of a pinned joint 138 of the track chain assembly 126, and the concentric bore (e.g., 206) of one of the first pair of lugs is in communication with the gap 236, with a first blend 238 being disposed axially between the gap 236 and the concentric bore 206 of one of the first pair of lugs.

[0023] As used herein, a "blend" means any transitional surface that connects two adjacent surfaces and can include an arcuate surface (e.g., a radius, an ellipse, a polynomial spline, etc.) or a chamfer (e.g., a conical surface), etc.

[0024] Similarly, the concentric bore 206a of the other of the first pair of lugs can also be in communication with the gap 236, with a second blend 238a being disposed axially between the gap 236 and the concentric bore 206a of the other of the first pair of lugs.

[0025] More particularly, the first blend 238 can be in the form of a first interior chamfer 240 (so-called because it faces laterally toward the gap 236), and the second blend 238a can be in the form of a second interior chamfer 240a. This can not be the case for other embodiments of the present disclosure.

[0026] Each of the concentric bores 206, 206a, 206b can define the same diameter D206 (i.e., within 0.005 inches of each other), but need not do so. When true, and the track chain assembly 126 can further include a bushing pin assembly 128 that is disposed in each of the concentric bores 206, 206a, 206b to help provide the pivotal function of the pinned joint 138.

[0027] To this end, the bushing pin assembly 128 can include a bushing 140 that defines a first bushing chamfer 142 at one of its lateral ends that is in communication with the gap 236, and a second bushing chamfer 142a at the other of its lateral ends. The first bushing chamfer 142 can be parallel to the first interior chamfer 240, and the second bushing chamfer 142a can be parallel to the second interior chamfer 240a. In this case, the chamfers can be symmetrical to each other about a midplane that is disposed laterally between them. This can not be the case for other embodiments of the present disclosure.

[0028] In other embodiments as shown in Figure 4 , a funnel angle 266 can be formed between the first bushing chamfer 142 and the first interior chamfer 240, which diverges toward the gap 236 to help force contaminants away from the seal assembly 150. A similar arrangement can exist for the second bushing chamfer 142a and the second interior chamfer 142a. This funnel angle 266 can be equal to or greater than 10 degrees. As shown, this angle can be in the range of 15.0 degrees to 25.0 degrees (e.g., 20.0 degrees).

[0029] More particularly, the first bushing chamfer 142 can be spaced apart from the first interior chamfer 140 by a minimum distance 144 (see Figure 4 , thereby forming a first debris path 146. A second debris path 146a can be formed by the second interior chamfer 140a and the second bushing chamfer 142a (see Figure 3 ). These paths can allow dust, debris, or other contaminants to exit the pin joint seal.

[0030] With attention Figure 4 , the barrel pin assembly 128 can define a seal receiving void 148 that is in communication with one of the concentric bores (e.g., see 206) and the first debris path 146. The seal assembly 150 can be disposed therein.

[0031] Referring to Figure 3 and Figure 4 , in some embodiments of the disclosure, the ratio of the same diameter D206 of each concentric bore to the minimum distance 144 can be in the range of 15.0 to 30.0 (e.g., 18.0 to 22.0). In this case, the minimum distance 144 can be in the range of 3.0 mm to 7.0 mm (e.g., 5.0 mm). In other embodiments of the disclosure, other ratios and dimensions are possible.

[0032] As best seen in Figure 3 , one of the first pair of lugs (e.g., see 234) can include a shoulder stop surface 242, and the barrel pin assembly 128 can be disposed axially adjacent (e.g., can abut) the shoulder stop surface 242.

[0033] Other components of the barrel pin assembly 128 include a pin 152 or shaft, a first end collar 154 attached to the pin, a second end collar 156 attached to the pin, a first bearing 158 disposed radially and axially between the bushing 140, the pin 152, and the first end collar 154, and a second bearing 158a disposed radially and axially between the bushing 140, the pin 152, and the second end collar 156.

[0034] The bearings can help prevent the seal assembly 150 from being crushed by axial loads (hence they can also be referred to as thrust bearings), while the bushing provides a lubrication pocket 160 to facilitate bushing rotation, and thus one track block 200 rotation relative to the pin and end collar and another track block 200a.

[0035] Reference will now be made to Figure 2 to Figure 6 Details of various embodiments of track blocks that can be used in the construction and / or servicing of track chain assemblies, etc., will now be discussed in detail.

[0036] Such a track block 200 can include a shoe member 208 that includes a ground engaging surface 204 and defines a track chain travel direction 210, a lateral direction 212 that is perpendicular to the track chain travel direction 210, and a vertical direction 214 that is perpendicular to both the lateral direction 212 and the track chain travel direction 210. The shoe member 208 also defines a first lateral end 216, a second lateral end 218, a forward end 220 along the track chain travel direction 210, and a rearward end 222 along the track chain travel direction 210. A lateral distance 224 (see Figure 5 ) can be measured from the first lateral end 216 to the second lateral end 218, and a width 226 (see Figure 2 ) can be measured along the track chain travel direction 210 from the forward end 220 to the rearward end 222, the width being less than the lateral distance 224.

[0037] Referring to Figure 2 , a first link member 228 can extend upwardly from the shoe member 208, the first link member including a first lug member 230 extending from the first link member 228 along a first direction that is parallel to the track chain travel direction 210, a second lug member 232 and a third lug member 234 both extending from the first link member 228 along a second direction that is opposite the first direction, forming a first fork portion 244.

[0038] Referring now to Figure 3 to Figure 6 , this fork portion can include a first lateral outer surface 246, a second lateral outer surface 248, a first lateral inner surface 250, and a second lateral inner surface 252. The second lug member 232 defines a first aperture (see, e.g., 206) that extends laterally through the first lateral outer surface 246 and the first lateral inner surface 250, forming a first intersection with the first lateral inner surface 250, the first intersection including a first fusion 238 that extends from the first lateral inner surface 250 to the first aperture.

[0039] The third lug member 234 can define a third aperture (see, e.g., 206b) extending from the second lateral inner surface 252 toward the second lateral outer surface 248, forming a second intersection with the second lateral inner surface 252, the second intersection including a second blend (see, e.g., 238a) extending from the second lateral inner surface 252 to the third aperture.

[0040] As mentioned herein before, the first blend and the second blend can be in the form of a plurality of chamfers (see, e.g., 240, 240a). In some embodiments of the present disclosure, at least one of the plurality of chamfers can define an acute angle 256 with the lateral direction 212, the acute angle ranging from 30.0 degrees to 60.0 degrees (e.g., can be 45.0 degrees, see 240a). Figure 4 ) In other embodiments of the present disclosure, this angle range can be different.

[0041] Also, the first aperture defines a first diameter (see, e.g., D206 in Figure 6 ), and the first blend can define a first lateral chamfer distance 258. In some embodiments of the present disclosure, the ratio of the first diameter to the first lateral chamfer distance can range from 15.0 to 30.0. In this case, the first lateral chamfer distance 258 can range from 3.0 mm to 7.0 mm (e.g., 5.0 mm). This can not be the case in other embodiments of the present disclosure.

[0042] Referring to Figure 3 , the third lug member 234 can define a first inner side shoulder surface (see, e.g., 242), and the third aperture (see, e.g., 206a) can extend laterally to the first inner side shoulder surface, while a first reduced diameter aperture 262 can extend laterally from the second lateral outer surface 248 to the third aperture. The reduced diameter aperture can be used to press out a cartridge pin assembly when needed for service.

[0043] A track block 200 according to another embodiment of the present disclosure can also be described as follows with reference to Figure 2 to Figure 6 . The first link member 228 can extend upwardly from a shoe member 208 including a first top rail surface 202.

[0044] The second lug member 232 and the third lug member 234 can define a first pair of chamfered surfaces (see, e.g., 240, 240a) laterally opposite and facing each other.

[0045] Additionally, each of the first pair of chamfered surfaces and the second pair of chamfered surfaces can form an acute angle 256 with the lateral direction 212 as mentioned herein before, the acute angle ranging from 30.0 degrees to 60.0 degrees.

[0046] In this case, at least one of the plurality of holes defines a first diameter (e.g., D206), and at least one of the first pair of chamfered surfaces defines a first radial chamfer distance 264. In some embodiments of the present disclosure, the ratio of the first diameter to the first radial chamfer distance can be in the range of 15.0 to 30.0 (e.g., 18.0 to 22.0). When present, the first radial chamfer distance 264 can be in the range of 3.0 mm to 7.0 mm (e.g., 5.0 mm).

[0047] The track block can be a unitary body as shown or an assembly of different components. Generally, the shoe member and the first and second rail members are substantially comprised of a metallic material such as cast iron, steel, gray cast iron, etc.

[0048] In other embodiments of the present disclosure, any of the foregoing features, and their associated dimensions and / or ratios, can vary from what has been shown or mentioned herein.

[0049] Industrial applicability

[0050] In practice, according to any of the embodiments discussed herein, a track chain assembly, track block, or a portion thereof can be sold, manufactured, purchased, etc., and attached to a machine in an aftermarket or original equipment situation. That is, according to embodiments described herein, the machine can be sold with the track chain assembly, track block, and / or a portion thereof, or the machine can be retrofitted, repaired, refurbished to use any of the embodiments discussed herein. Various components including, but not limited to, the track block can be manufactured from any suitable material such as cast iron, gray cast iron, steel, etc.

[0051] As can be seen, by providing a debris path for such contaminants to exit the seal assembly, various embodiments of the track block disclosed herein can reduce the likelihood of the seal assembly and / or the barrel pin assembly becoming soiled by contaminants. This can extend the useful life of a track chain assembly using such a track block before requiring maintenance, thereby increasing the profitability of the economic activity using the track block.

[0052] As used herein, the articles “a” and “an” are intended to include one or more items, and can be used interchangeably with “one or more.” Where only one item is intended, the term “one” or similar language is used. Also, as used herein, the terms “has,” “have,” “having,” “with” or the like are intended to be open-ended terms. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

[0053] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments of devices and assembly methods discussed herein without departing from the scope or spirit of the application. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of various embodiments disclosed herein. For example, the construction and function of some devices can be different than described herein, and certain steps of any method can be omitted, performed in a different order than specifically mentioned, or in some cases simultaneously or in sub-steps. In addition, certain aspects or features of various embodiments can be changed or modified to produce additional embodiments, and features and aspects of various embodiments can supplement or substitute for other features or aspects of other embodiments in order to provide additional embodiments.

[0054] Accordingly, the specification and examples are to be considered exemplary and illustrative only, with the true scope and spirit of the application being indicated by the following claims and their equivalents.

Claims

1. A track chain assembly (126) comprising two track blocks, wherein each track block includes: A shoe-shaped component (208) includes a ground contact surface (204) and defines a track chain travel direction (210), a lateral direction (212) perpendicular to the track chain travel direction (210), and a vertical direction (214) perpendicular to both the lateral direction (212) and the track chain travel direction (210). The shoe-shaped component (208) also defines a first lateral end (216), a second lateral end (218), a front end (220) along the track chain travel direction (210), and a rear end (222) along the track chain travel direction (210), a lateral distance (224) from the first lateral end (216) to the second lateral end (218), and a width (226) along the track chain travel direction (210) from the front end (220) to the rear end (222), the width being less than the lateral distance (224). and A first link member (228) extends upward from the shoe-shaped member (208), and the first link member includes: A first lug member (230) extends from the first link member (228) along a first direction parallel to the track chain travel direction (210); a second lug member (232) and a third lug member (234) both extend from the first link member (228) along a second direction opposite to the first direction to form a first fork portion (244), the first fork portion including a first lateral outer surface (246), a second lateral outer surface (248), a first lateral inner surface (250) and a second lateral inner surface (252), the second lug member (232) and the third lug member (234) defining concentric holes and a gap (236) between the concentric holes; The second lug member (232) defines a first opening (206), which extends laterally through the first lateral outer surface (246) and the first lateral inner surface (250) to form a first intersection with the first lateral inner surface (250). The first intersection includes a first fusion portion (238) extending from the first lateral inner surface (250) to the first opening (206). The first fusion portion (238) is a first internal chamfer (240). The first lug member (230) defines a second opening (206b), the second opening (206b) extending laterally through the first lug member (230); and A push pin assembly is provided in concentric holes in the second lug member (232) and the third lug member (234) of one track block and in the second opening (206b) of the first lug member (230) of another track block to pivotally connect the two track blocks, the push pin assembly including a bushing (140) that defines a first bushing chamfer (142) at its lateral end facing the first opening (206). A funnel-shaped angle (266) is formed between the first bushing chamfer (142) and the first inner chamfer (240) and diverges toward the gap (236).

2. The track chain assembly (126) according to claim 1, wherein the third lug member (234) defines a third opening (206a) extending from the second transverse inner surface (252) toward the second transverse outer surface (248) and forming a second intersection with the second transverse inner surface (252), the second intersection including a second fusion portion (238a) extending from the second transverse inner surface (252) to the third opening (206a).

3. The track chain assembly (126) according to claim 2, wherein the second fusion portion (238a) is a second internal chamfer (240a).

4. The track chain assembly (126) according to claim 3, wherein at least one of the plurality of chamfers defines an angle within the range of 30.0 degrees to 60.0 degrees with respect to the lateral direction (212).

5. The track chain assembly (126) according to claim 4, wherein the angle is 45.0 degrees.

6. The track chain assembly (126) according to claim 4, wherein the first aperture (206) defines a first diameter (D206), and the first fusion portion (238) defines a first lateral chamfer distance (258), and the ratio of the first diameter (D206) to the first lateral chamfer distance (258) is in the range of 15.0 to 30.

0.

7. The track chain assembly (126) according to claim 6, wherein the ratio is in the range of 18.0 to 22.

0.

8. The track chain assembly (126) of claim 6, wherein the first lateral chamfer distance (258) is in the range of 3.0 mm to 7.0 mm, the third lug member (234) defines a first inner shoulder surface (242), the third aperture (206a) extends laterally to the first inner shoulder surface (242), and the first reduced diameter aperture (262) extends laterally from the second lateral outer surface (248) to the third aperture (206a).

9. The track chain assembly (126) according to claim 3, wherein the first inner chamfer (240) and the second inner chamfer (240a) are laterally opposite each other and face each other.

10. The track chain assembly (126) of claim 9, wherein at least one of the concentric holes communicates with at least one of the first internal chamfer (240) and the second internal chamfer (240a) and defines a first diameter (D206), and at least one of the first internal chamfer (240) and the second internal chamfer (240a) defines a first radial chamfer distance (264), and the ratio of the first diameter (D206) to the first radial chamfer distance (264) is in the range of 15.0 to 30.0.

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