Track linking device

Abstract

A track link (21) has a through hole (21a) with a first notch (21b) provided on the inner peripheral surface of the through hole (21a). A master pin (22) is inserted into the through hole (21a) of the track link (21) and has a second notch (22b) on the outer peripheral surface. A knock pin (25) is disposed in a first recess (24), which is configured from the first notch (21b) and the second notch (22b) and has an opening at an end part of the through hole (21a), with one end surface (25a) on the opening side. A snap ring (26) is C-shaped and is disposed either with a gap from, or in contact with, the one end surface (25a) of the knock pin (25). The track link (21) is disposed within a rotation trajectory (RT) in the circumferential direction of the snap ring (26), and has a rotation restriction part (RL) that restricts the rotation range of the snap ring (26).

Description

Track linkage device

[0001] The present disclosure relates to a track linkage.

[0002] Hydraulic excavators, bulldozers, and the like are known as work machines that have tracks. The tracks include a track link chain in which multiple track links are connected. When the tracks are detached from the traveling device, the track link chain is released. One method for releasing the track link chain is to remove the master pin that connects the track links from the track links.

[0003] A technique for releasing the connection between track links using a master pin is described, for example, in Japanese Patent Application Laid-Open No. 2013-244783 (Patent Document 1). In Patent Document 1, a knock pin is inserted into a recess formed by a notch in the track link and a notch in the master pin to prevent the master pin from rotating along with the track link. A snap ring is attached to the outer periphery of the master pin to prevent the knock pin from coming out of the recess.

[0004] JP 2013-244783 A

[0005] However, with the configuration described in Patent Document 1, the snap ring rotates circumferentially relative to the master pin due to vibrations during operation (including travel) of the work machine. This rotation could cause weaker parts of the snap ring to move to positions where they are subjected to an unbalanced load. For this reason, greater durability is required of the track linkage device.

[0006] An object of the present disclosure is to provide a track coupling device that is highly durable.

[0007] The track coupling device disclosed herein is for coupling a plurality of track links to form an endless track, and includes track links, a master pin, a knock pin, and a snap ring. The track link has a pin through hole and a first notch on the inner peripheral surface of the pin through hole. The master pin is inserted into the pin through hole of the track link and has a second notch on the outer peripheral surface. The knock pin is composed of the first notch and the second notch and is disposed in a first recess having an opening at an end of the pin through hole, with one end surface facing the opening. The snap ring has a C-shape and is disposed on one end surface of the knock pin with a gap therebetween or in contact with the one end surface. The track link is disposed within the circumferential rotation path of the snap ring and has a rotation limiting portion that limits the rotation range of the snap ring.

[0008] According to the present disclosure, a track coupling device with excellent durability can be realized.

[0009] 1 is a perspective view schematically illustrating a configuration of a work machine according to an embodiment of the present disclosure. FIG. 1 is a side view schematically illustrating a configuration of a running body in the work machine of FIG. 1. FIG. 2 is a partially exploded perspective view schematically illustrating a configuration of a track included in the running body of FIG. 2. FIG. 2 is an enlarged view of the track at P1 portion in FIG. 2. FIG. 4 is an enlarged view of the periphery of the master pin in FIG. 4. FIG. 4 is a partial cross-sectional view taken along line VI-VI in FIG. 4. FIG. 6 is an enlarged view of the track link etc. at P2 portion in FIG. 6. FIG. 5 is a perspective view taken along the cross section taken along line VIII-VIII in FIG. 5. FIG. 8 is a perspective view of the track link etc. with the master pin, snap ring, and knock pin omitted from FIG. 8. FIG. 11 is a view for explaining a rotation limiting portion. FIG. 12 is a view showing the configuration of a modified example in which a circumferential groove for engaging a snap ring is provided on the inner circumferential surface of the pin through hole of the track link. FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. 11. FIG. 13 is a view for explaining a problem with a track coupling device of a comparative example.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the specification and drawings, identical or corresponding components are designated by the same reference numerals, and redundant description will not be repeated. In addition, in the drawings, configurations may be omitted or simplified for the sake of convenience. Furthermore, at least some of the embodiments and modified examples may be combined with each other in any desired manner.

[0011] <Configuration of Work Machine> The configuration of a work machine according to one embodiment of the present disclosure will be described below. A hydraulic excavator will be described below as an example of a work machine to which the concepts of the present disclosure can be applied, but the present disclosure can also be applied to work machines having tracks other than hydraulic excavators, such as bulldozers.

[0012] Fig. 1 is a diagram schematically illustrating the configuration of a work machine according to one embodiment of the present disclosure. As shown in Fig. 1, the work machine (hydraulic excavator) 1 of this embodiment mainly includes a running body 2, a revolving body 3, and a working implement 4. The running body 2 is configured such that a pair of left and right tracks 10 are rotationally driven to cause the work machine (hydraulic excavator) 1 to travel. The revolving body 3 is rotatably mounted on the running body 2. The working implement 4 is rotatably supported on the front side of the revolving body 3. The working implement 4 includes, for example, a boom, an arm, a bucket, a hydraulic cylinder, etc.

[0013] The main body of the work machine is mainly composed of the running body 2 and the rotating body 3. The rotating body 3 has a cab 5 on the front left side (front side of the vehicle) and an engine room 6 that houses the engine and a counterweight 7 on the rear side (rear side of the vehicle). Here, the front, rear, and left and right of the vehicle are determined based on the operator seated in the cab 5.

[0014] As shown in Figure 2, the running body 2 mainly has a track 10, a slewing device 11, a track frame 12, an idler 13, a drive wheel (sprocket) 14, a carrier wheel 15, and a carrier wheel 16.

[0015] The crawler belt 10 has a crawler belt link chain 20 and track shoes 30 attached to the crawler belt link chain 20. The slewing device 11 is configured to be able to slew the slewing unit 3 (FIG. 1) and is provided at the upper end of the running unit 2. The track frames 12 are provided on both sides of a center frame that serves as a mounting base for the slewing device 11, and extend in the fore-and-aft direction of the vehicle.

[0016] The idler wheels 13 are rotatably mounted on the front end of the track frame 12, and the drive wheels 14 are rotatably mounted on the rear end of the track frame 12. A plurality of carrier wheels 15 are mounted on the upper surface of the track frame 12, and a plurality of carrier wheels 16 are mounted on the lower surface of the track frame 12. A climbing ladder 17 may also be attached to the running body 2. Note that the climbing ladder 17 is not shown in FIG. 1.

[0017] The crawler belt 10 is wound around an idler wheel 13 and a drive wheel 14. The crawler belt 10 is supported by an upper roller 15 and a lower roller 16 disposed between the idler wheel 13 and the drive wheel 14. The crawler belt link chain 20 is engaged with the drive wheel 14 and driven, thereby rotating the track plate 30. In this way, the crawler belt 10 is driven to rotate. This allows the running body 2 to self-propel.

[0018] <Configuration of Track> Figure 3 is a partially exploded perspective view showing the schematic configuration of the track included in the running body of Figure 2. As shown in Figure 3, the track 10 has a track link chain 20 and a plurality of track shoes 30. The track link chain 20 mainly has a track link 21, a master pin 22, a knock pin 25, a snap ring 26, a track pin 34, a track bushing 41, and a seal ring 42.

[0019] The crawler belt 10 is formed into a ring shape by connecting a plurality of crawler belt links 21 endlessly. A crawler shoe 30 is fixed to the ground contact surface (outer surface) of each of the plurality of crawler belt links 21. A bolt 43 is inserted from the outer surface side of the crawler belt 30 into a through hole provided in the crawler belt plate 30 and the crawler belt link 21. A nut 44 is screwed onto the tip of the bolt 43 on the non-ground contact surface (inner surface) side of the crawler belt link 21. The bolt 43 and the nut 44 secure the crawler belt 30 to the ground contact surface of the crawler belt link 21.

[0020] The plurality of crawler belt links 21 included in the crawler belt link chain 20 have a pair of crawler belt links 21 (a first crawler belt link 211 and a second crawler belt link 212) facing each other in the crawler belt width direction X. The crawler belt width direction X is a direction perpendicular to the extension direction Y in which the crawler belt 10 extends endlessly and is the longitudinal direction of the crawler belt plate 30. The first crawler belt link 211 and the second crawler belt link 212 are arranged parallel to and spaced apart from each other in the crawler belt width direction X. The first crawler belt link 211 and the second crawler belt link 212 are formed symmetrically. A common crawler belt plate 30 is fixed to the first crawler belt link 211 and the second crawler belt link 212.

[0021] A plurality of first crawler belt links 211 are arranged in a row along the extension direction Y. Each of the plurality of first crawler belt links 211 arranged in a row has the same shape as each other. Furthermore, a plurality of second crawler belt links 212 are arranged in a row along the extension direction Y. Each of the plurality of second crawler belt links 212 arranged in a row has the same shape as each other. As a result, the plurality of crawler belt links 21 are arranged in two rows: a row consisting of the plurality of first crawler belt links 211 and a row consisting of the plurality of second crawler belt links 212.

[0022] Adjacent crawler belt links 21 in the same row are arranged so that the pin through-hole 21a of one crawler belt link 21 communicates with the bushing through-hole 21c of the other crawler belt link 21. A cylindrical crawler belt bushing 41 is press-fitted into the bushing through-hole 21c of one crawler belt link 21. A crawler belt pin 34 is inserted into the crawler belt bushing 41 and press-fitted into the pin through-hole 21a of the other crawler belt link 21. In this way, the crawler belt links 21 lined up in the row are connected to each other.

[0023] A common crawler belt pin 34 is press-fitted into each pin through-hole 21a of the first crawler belt link 211 and the second crawler belt link 212 that face each other in the crawler belt width direction X. A common crawler belt bushing 41 is press-fitted into each bushing through-hole 21c of the first crawler belt link 211 and the second crawler belt link 212 that face each other in the crawler belt width direction X. In this way, the two rows of crawler belt links 21 are connected to each other by the crawler belt pins 34 and the crawler belt bushings 41.

[0024] As shown in FIG. 6, a seal ring 42 is disposed between the crawler belt link 21 and the end of the crawler belt bushing 41 into which the crawler belt pin 34 is inserted.

[0025] The plurality of crawler links 21 are pivotally supported by crawler pins 34 and rotatably connected to one another to form a belt-shaped crawler link chain 20. This belt-shaped crawler link chain 20 is made into an endless loop by connecting the crawler links 21 at both ends. The crawler link connecting device includes the crawler links 21 at the ends of the belt-shaped crawler link chain 20, and is a device for connecting the crawler links 21 at both ends to make the crawler link chain 20 into an endless loop. The pin that connects the crawler links 21 at both ends of the belt-shaped crawler link chain 20 to form an endless chain is called a master pin 22.

[0026] <Crawler Track Linking Device> Next, the crawler track linking device according to this embodiment will be described with reference to FIGS.

[0027] Fig. 4 is an enlarged view showing the crawler belt at part P1 in Fig. 2. Fig. 5 is an enlarged view of the periphery of the master pin in Fig. 4. Fig. 6 is a partial cross-sectional view taken along line VI-VI in Fig. 4. Fig. 7 is an enlarged view showing the crawler belt link and the like at part P2 in Fig. 6.

[0028] As shown in FIG. 3 , the track connection device of this embodiment has a track link 21 , a master pin 22 , a knock pin 25 , and a snap ring 26 .

[0029] As shown in Figure 6, the crawler belt link 21 has one end E1, the other end E2, and an inclined portion IP. The inclined portion IP is disposed between the one end E1 and the other end E2 and connects the one end E1 and the other end E2. The crawler belt link 21 has a pin through hole 21a formed in the one end E1. The crawler belt link 21 has a bushing through hole 21c formed in the other end E2.

[0030] Among the plurality of crawler belt links 21 arranged in the same row, one end E1 of one crawler belt link 21 and the other end E2 of the other crawler belt link 21 are arranged so as to be aligned in the crawler belt width direction X. As a result, the pin through hole 21 a of one crawler belt link 21 and the bushing through hole 21 c of the other crawler belt link 21 are communicated with each other.

[0031] A crawler belt bushing 41 is press-fitted into the bushing through-hole 21c of the other crawler belt link 21. The crawler belt bushing 41 is formed to mesh with the teeth of the drive wheel (sprocket) 14. A seal ring 42 is disposed between the end of the crawler belt bushing 41 and one end E1 of one crawler belt link 21. The crawler belt bushing 41 has a cylindrical shape. The seal ring 42 has an annular shape. The seal ring 42 is disposed in a circumferential groove 21f provided in one end E1 of the crawler belt link 21.

[0032] Master pin 22 is inserted through crawler belt bushing 41 and seal ring 42. Master pin 22 is inserted through pin through hole 21a of one crawler belt link 21 and bushing through hole 21c of the other crawler belt link 21.

[0033] 7, the crawler link 21 has a first notch 21b on the inner peripheral surface of the pin through hole 21a. The first notch 21b is formed to connect to the second recess 21e. The first notch 21b extends from the second recess 21e along the direction of the central axis A of the pin through hole 21a (axis A direction). The first notch 21b has the shape of a portion of a substantial cylinder (for example, a semi-cylindrical shape).

[0034] Central axis A is an imaginary straight line that passes through the center of cylindrical pin through hole 21 a and extends in the axial direction of pin through hole 21 a. When master pin 22 is inserted into pin through hole 21 a, central axis A passes through the center of cylindrical master pin 22 and extends in the axial direction of master pin 22.

[0035] Master pin 22 is a cylindrical component. Master pin 22 has second notch 22b and circumferential groove 22c on outer peripheral surface 22a. Second notch 22b is formed at the end of master pin 22 in track width direction X. Second notch 22b extends from the end of master pin 22 along axis A of master pin 22. Second notch 22b has the shape of a portion of a substantial cylinder (for example, a semi-cylindrical shape).

[0036] When master pin 22 is inserted into pin through hole 21a, first notch 21b and second notch 22b face each other. First notch 21b and second notch 22b form first recess 24. First recess 24 has a cylindrical internal space. First recess 24 has an opening at the end of pin through hole 21a in track width direction X. Central axis B of first recess 24 is parallel to axis A of pin through hole 21a. First recess 24 is a portion into which knock pin 25 is inserted.

[0037] Knock pin 25 prevents master pin 22 from rotating along with crawler belt link 21. Knock pin 25 has, for example, a cylindrical shape. Knock pin 25 is disposed in first recess 24. Knock pin 25 has the same cross-sectional shape perpendicular to axis B from one end to the other end in the direction of axis B. The height of knock pin 25 is greater than the diameter. In other words, the longitudinal direction of knock pin 25 is the direction of axis B.

[0038] When knock pin 25 is placed in first recess 24, one end surface 25a of knock pin 25 is located on the opening side of first recess 24. The length of knock pin 25 is shorter than the depth (length in the direction of axis A) of first recess 24. Because central axis B of knock pin 25 is parallel to central axis A, the direction in which knock pin 25 is inserted into or removed from first recess 24 is the same as the direction in which master pin 22 is inserted into or removed from pin through hole 21a.

[0039] Circumferential groove 22c is provided in an annular shape around the entire circumference of outer peripheral surface 22a of master pin 22. Circumferential groove 22c intersects with second notch 22b. Circumferential groove 22c is a portion into which snap ring 26 is fitted. Snap ring 26 prevents knock pin 25 from slipping out of second notch 22b.

[0040] As shown in Figure 4, snap ring 26 has a C-shape. Snap ring 26 is annular, with a notch formed in one portion thereof. The diameter of snap ring 26 is expanded by widening this notch, for example with pliers. Snap ring 26 is fitted onto the outer peripheral surface of master pin 22 in its expanded diameter state.

[0041] As shown in Figure 7, snap ring 26 is attached to the outer peripheral surface of master pin 22 and fitted into circumferential groove 22c of master pin 22. Snap ring 26 is separated from one end surface 25a of knock pin 25 with a gap therebetween, but may also be in contact with one end surface 25a of knock pin 25. Snap ring 26 is positioned in the direction in which knock pin 25 comes out of first recess 24. As a result, as shown in Figures 4 and 5, when the track connection device is viewed from the track width direction X (as viewed from the direction of axis A), snap ring 26 overlaps knock pin 25. As a result, snap ring 26 prevents knock pin 25 from coming out of first recess 24.

[0042] One snap ring 26 may be fitted in one circumferential groove 22c, or a plurality of snap rings 26 may be fitted in one circumferential groove 22c.

[0043] The knock pin 25 is intermediately fitted into the first recess 24. This makes it difficult for the knock pin 25 to come out of the first recess 24 because it presses against the inner peripheral surface of the first recess 24. The outer peripheral surface of the knock pin 25 is in continuous contact with the first recess 24 over the entire circumference.

[0044] On the other hand, the snap ring 26 prevents the knock pin 25 from slipping out of the first recess 24. Therefore, the fit between the knock pin 25 and the first recess 24 may be a clearance fit. In this case, the knock pin 25 can be easily removed from the first recess 24 by removing the snap ring 26.

[0045] As shown in Fig. 6, the knock pin 25 is preferably disposed on the bushing through-hole 21c side of the pin through-hole 21a in a single crawler belt link 21. The crawler belt link 21 can be formed thicker on the bushing through-hole 21c side of the pin through-hole 21a than on the opposite side of the bushing through-hole 21c side. Therefore, by disposing the first notch 21b for inserting the knock pin 25 on the bushing through-hole 21c side of the pin through-hole 21a, stress acting on the first crawler belt link 21 can be suppressed. For the reasons described above, it is preferable to provide the first notch 21b in a position closest to the bushing through-hole 21c side of the pin through-hole 21a.

[0046] The end of track pin 34 is press-fit into pin through hole 21a and firmly fixed thereto by an interference fit. Track pin 34 is press-fit into pin through hole 21a with, for example, 160 kN (kilonewtons). In contrast, in the track coupling device of this embodiment, the end of master pin 22 is press-fit into pin through hole 21a with a force smaller than that of track pin 34, and is engaged with an intermediate fit rather than an interference fit. Here, intermediate fit refers to a fit in which the maximum allowable pin diameter of master pin 22 is larger than the minimum allowable hole diameter of pin through hole 21a and the minimum allowable pin diameter is smaller than the maximum allowable hole diameter. An intermediate fit is also called a snug fit. In other words, master pin 22 is fixed to an extent that it does not move due to the fit between outer peripheral surface 22a and the inner peripheral surface of pin through hole 21a. Master pin 22 is press-fit into pin through hole 21a with, for example, 16 kN. The end of master pin 22 may be loosely fitted into pin through hole 21 a. From the standpoint of ease of attachment and detachment of master pin 22, it is more preferable that the end of master pin 22 be loosely fitted into pin through hole 21 a.

[0047] 6 , in the track belt connection device of the present embodiment, knock pin 25 and snap ring 26 may be disposed only on one end side of master pin 22 in track belt width direction X. Alternatively, knock pin 25 and snap ring 26 may be disposed on both one end side and the other end side of master pin 22 in track belt width direction X.

[0048] Furthermore, in the track belt connection device of this embodiment, the shape of knock pin 25 is not limited to a cylinder. Knock pin 25 may be, for example, a truncated cone. In this case, first recess 24 formed by first notch 21 b of track belt link 21 and second notch 22 b of master pin 22 has a shape corresponding to the shape of knock pin 25.

[0049] The track coupling device of this embodiment may be provided on at least one side (the pin through hole 21 a side) of the track link 21 in the extension direction Y, but may also be provided on both sides (the pin through hole 21 a side and the bushing through hole 21 c side) of the track link 21. Furthermore, the track coupling device of this embodiment may be provided on at least one track link 21, but may also be provided on multiple track links 21 that constitute the track link chain 20.

[0050] <Rotation Limiting Section> Next, the rotation limiting section of the track coupling device of this embodiment will be described with reference to FIGS. 5 and 8 to 10. FIG.

[0051] Fig. 8 is a perspective view taken along the cross section of line VIII-VIII in Fig. 5. Fig. 9 is a perspective view of the crawler belt link and the like, with the master pin, snap ring, and knock pin omitted from Fig. 8. Fig. 10 is a view for explaining the rotation limiting portion.

[0052] As shown in Fig. 5, the track coupling device of this embodiment has a rotation limiting portion RL. The rotation limiting portion RL is disposed within a rotation locus RT in the circumferential direction of the snap ring 26 and limits the rotation range (rotation angle) of the snap ring 26. When viewed from the direction of the axis A, the rotation locus RT is an area sandwiched between a circumscribing circle RT1 and an inscribing circle RT2 of the snap ring 26. The circumscribing circle RT1 is a circle centered on the central axis A and tangent to the outermost diameter portion of the snap ring 26. The inscribing circle RT2 is a circle centered on the central axis A and tangent to the innermost diameter portion of the snap ring 26.

[0053] The snap ring 26 has a ring portion 26a and a pair of flange portions 26b. The ring portion 26a has a C-shape. The ring portion 26a has an annular shape with a partial cutout. The ring portion 26a has a first peripheral end and a second peripheral end in the circumferential direction.

[0054] The pair of flanges 26b includes a first flange 26b1 and a second flange 26b2. The first flange 26b1 is connected to a first peripheral end of the ring portion 26a. The first flange 26b1 protrudes from the first peripheral end of the ring portion 26a toward the outer periphery of the ring portion 26a. The second flange 26b2 is connected to a second peripheral end of the ring portion 26a. The second flange 26b2 protrudes from the second peripheral end of the ring portion 26a toward the outer periphery of the ring portion 26a.

[0055] First flange 26b1 and second flange 26b2 each have pliers engagement portion 26c. Pliers engagement portion 26c is a portion that engages pliers with snap ring 26 when attaching or detaching snap ring 26 to or from master pin 22. Pliers are a tool with a tip shape that can be opened and closed. Pliers engagement portion 26c is, for example, a through hole provided in each of first flange 26b1 and second flange 26b2. The through hole serving as pliers engagement portion 26c may be, for example, circular or may be polygonal, such as rectangular.

[0056] The circumferential direction of snap ring 26 is the direction of rotation when snap ring 26 is rotated about central axis A while attached to master pin 22. Furthermore, the circumferential rotation locus RT of snap ring 26 is the locus followed by ring portion 26a and pair of flange portions 26b of snap ring 26 when snap ring 26 is rotated about central axis A while attached to master pin 22.

[0057] When viewed from the direction of axis A, second recess 21e is provided between crawler belt link 21 and master pin 22. In this embodiment, second recess 21e is formed in crawler belt link 21. That is, crawler belt link 21 has second recess 21e. Second recess 21e has small diameter recess 21ea and large diameter recess 21eb. Rotation limiting portion RL is formed, for example, by the wall surface of large diameter recess 21eb.

[0058] 8 and 9, the small diameter recess 21ea surrounds (for example, the entire circumference of) the pin through hole 21a at the end of the pin through hole 21a. The small diameter recess 21ea is connected to the entire outer periphery of the pin through hole 21a. The small diameter recess 21ea has a bottom surface B1. The bottom surface B1 serves as a receiving surface for the snap ring 26.

[0059] 5, the large diameter recess 21eb is connected to the small diameter recess 21ea. The large diameter recess 21eb is disposed on the outer periphery of the small diameter recess 21ea. The large diameter recess 21eb is located on the track shoe 30 side of the small diameter recess 21ea. In other words, the large diameter recess 21eb is connected to the portion of the small diameter recess 21ea that is closest to the track shoe 30.

[0060] The portion of master pin 22 opposite to track shoe 30 is the portion that meshes with drive wheel (sprocket) 14, etc., and is therefore prone to load. Furthermore, because extension direction Y is the direction in which crawler belt 10 is driven to rotate, loads are also likely to be applied to the portion of master pin 22 in extension direction Y. By arranging large diameter recess 21eb closer to track shoe 30 than small diameter recess 21ea, large diameter recess 21eb can be arranged in a position on crawler belt link 21 where loads are less likely to be applied.

[0061] The large diameter recess 21eb has a first outer peripheral wall OW1. The first outer peripheral wall OW1 has a portion that is a first distance Da away from the central axis A. The first outer peripheral wall OW1 has an arc portion whose radius is the distance Da from the central axis A. The first distance Da is greater than the distance Dc from the central axis A to the outermost diameter portion of the snap ring 26. The outermost diameter portion of the snap ring 26 is, for example, the outer peripheral end of the flange portion 26b.

[0062] The small diameter recess 21ea has a second outer peripheral wall OW2. The second outer peripheral wall OW2 has a portion that is a second distance Db away from the central axis A. The second outer peripheral wall OW2 has an arc portion whose radius is the distance Db from the central axis A. The second distance Db is shorter than the distance Dc from the central axis A to the outermost diameter portion of the snap ring 26.

[0063] The ring portion 26a of the snap ring 26 has a portion located within the small diameter recess 26a and a portion located within the circumferential groove 22c when viewed from the direction of the axis A. The pair of flange portions 26b of the snap ring 26 are located within the large diameter recess 26b when viewed from the direction of the axis A. The pliers engagement portion 26c provided on each of the pair of flange portions 26b has a portion located within the large diameter recess 26b when viewed from the direction of the axis A.

[0064] The rotation limiting portion RL is formed by, for example, the wall surface of the large-diameter recess 21eb. When the snap ring 26 rotates a predetermined angle in the circumferential direction about the central axis A, the flange 26b of the snap ring 26 interferes with the wall surface of the large-diameter recess 21eb. In this way, the wall surface of the large-diameter recess 21eb limits the rotation range (rotation angle) of the snap ring 26.

[0065] 8 and 9, large diameter recess 21eb is formed deeper than small diameter recess 21ea in the direction of axis A. Therefore, bottom surface B2 of large diameter recess 21eb is located on the surface side of crawler belt link 21 opposite to the surface on which second recess 21e is provided, relative to bottom surface B1 of small diameter recess 21ea.

[0066] The small diameter recess 21ea has a bottom surface B1 provided with a first notch 21b for inserting the knock pin 25. Therefore, the end of the first notch 21b in the direction of the axis A opens into the bottom surface B1 of the small diameter recess 21ea.

[0067] A bottom surface B1 of the small diameter recess 21ea serves as a receiving surface for the ring portion 26a. A bottom surface B2 of the large diameter recess 21eb is separated from the flange portion 26b of the snap ring 26 with a gap in the axial direction A.

[0068] In the above embodiment, the rotation limiting portion RL is configured by the wall surface of the large-diameter recess 21eb, but the rotation limiting portion RL is not limited to this. As shown in FIG. 10 , the rotation limiting portion RL may be any type that is disposed within the circumferential rotation locus RT of the snap ring 26 and limits the rotation range of the snap ring 26.

[0069] The rotation limiting portion RL may be a recessed portion or a protruding portion. The rotation limiting portion RL may be formed integrally with the crawler belt link 21, or may be formed separately from the crawler belt link 21.

[0070] The rotation limiting portion RL may have a first rotation limiting portion RL1 located between the first flange 26b1 and the knock pin 25 in the rotational direction R1 of the snap ring 26 when viewed from the direction of the axis A. The rotation limiting portion RL may have a second rotation limiting portion RL2 located between the second flange 26b2 and the knock pin 25 in the rotational direction R2 of the snap ring 26 when viewed from the direction of the axis A. The rotation limiting portion RL may have a third rotation limiting portion RL3 located between the first flange 26b1 and the second flange 26b2 when viewed from the direction of the axis A. The rotation limiting portion RL may have the first rotation limiting portion RL1, the second rotation limiting portion RL2, and the third rotation limiting portion RL3 each independently or in any combination.

[0071] If the rotation limiting portion RL3 is provided, when the snap ring 26 rotates in the circumferential direction, the first flange 26b1 or the second flange 26b2 comes into contact with the rotation limiting portion RL3, thereby stopping the rotation of the snap ring 26. At this time, a force acts in the direction in which the snap ring 26 opens. Therefore, in terms of durability, it is more preferable to provide at least one of the rotation limiting portions RL1 and RL2 outside the C-shaped opening of the snap ring 20, rather than at the opening.

[0072] <Method for Uncoupling the Track Link Chain 20> Next, a method for uncoupling the track 10 using the track link chain 20 according to this embodiment will be described.

[0073] 3 and 6 , in the track belt connection device of this embodiment, connection is released by pulling master pin 22 out of pin through hole 21 a in each of first track belt link 211 and second track belt link 212 and out of adjacent bushing through hole 21 c in each of first track belt link 211 and second track belt link 212. This causes endless annular track belt 10 to become belt-like.

[0074] The track coupling device of this embodiment is released in the following procedure. First, C-shaped notch of snap ring 26 is widened, for example, with pliers. This widens the diameter of ring portion 26 a of snap ring 26, and snap ring 26 is removed from circumferential groove 22 c of master pin 22, and then removed from master pin 22.

[0075] Next, knock pin 25 is removed from first recess 24. In this state, master pin 22 is pulled out from either first crawler belt link 211 or second crawler belt link 212. This releases the connection of crawler belt 10 by the crawler belt connection device.

[0076] Furthermore, when reconnecting track belt 10, the connection can be achieved by reversing the above-described procedure. First, master pin 22 is inserted into pin through hole 21a of each of first track belt link 211 and second track belt link 212 and into adjacent bushing through hole 21c of each of first track belt link 211 and second track belt link 212. At this time, master pin 22 is inserted into track bushing 41 press-fitted into bushing through hole 21c. Seal ring 42 is disposed between the end face of track belt bushing 41 and track belt link 21. Master pin 22 is positioned so that second notch 22b of master pin 22 and first notch 21b of track belt link 21 form cylindrical first recess 24.

[0077] Next, knock pin 25 is inserted into first recess 24. Knock pin 25 is inserted into first recess 24 so as to provide, for example, an intermediate fit or a clearance fit. Thereafter, snap ring 26 is expanded in diameter, for example with pliers, and fitted into circumferential groove 22c of master pin 22. In this way, snap ring 26 is attached to master pin 22, and crawler belt 10 is connected. Since crawler belt 10 can be connected and disconnected without using a press in this way, the workability of attaching and detaching crawler belt 10 can be improved.

[0078] Note that it is possible to pull out master pin 22 by removing snap ring 26 on only one side, without removing snap rings 26 on both ends of one master pin 22. Therefore, by removing snap ring 26 on only one side of one master pin 22, the connection of crawler belt 10 may be released.

[0079] <Modification> Next, a configuration of a modification of the present disclosure will be described with reference to FIGS. 11 and 12. FIG.

[0080] Fig. 11 is a diagram showing the configuration of a modified example in which a circumferential groove for retaining a snap ring is provided on the inner circumferential surface of the pin through hole of the crawler belt link, and Fig. 12 is a cross-sectional view taken along line XII-XII in Fig. 11.

[0081] 1 to 10, circumferential groove 22c for retaining a snap ring is provided on the outer periphery of master pin 22, but as in the modified example shown in Figures 11 and 12, circumferential groove 21d (Figure 12) for retaining a snap ring may be provided on the inner circumferential surface of pin through hole 21a of crawler link 21. In this modified example, there is no circumferential groove on the outer periphery of master pin 22, where stress may concentrate, and therefore the reliability of master pin 22 is improved.

[0082] As shown in FIG. 11 , in this modification as well, the crawler belt link 21 is disposed within the circumferential rotation locus RT of the snap ring 26 and has a rotation limiting portion RL that limits the rotation range of the snap ring 26.

[0083] A second recess 21e is provided between crawler belt link 21 and master pin 22. Second recess 21e has small diameter recess 21ea and large diameter recess 21eb. Small diameter recess 21ea is formed by annular notch 22d of master pin 22 and pin through hole 21a of crawler belt link 21. Annular notch 22d is provided annularly around the entire circumference of master pin 22 at the end of master pin 22. The inner circumferential surface of small diameter recess 21ea is formed by the outer circumferential surface of master pin 22. The outer circumferential surface of small diameter recess 21ea is formed by the circumferential surface of pin through hole 21a. Therefore, the outer circumferential surface of small diameter recess 21ea has the same diameter as the circumferential surface of pin through hole 21a.

[0084] The large diameter recess 21eb is connected to the small diameter recess 21ea. The large diameter recess 21eb is disposed on the outer peripheral side of a portion of the small diameter recess 21ea when viewed from the central axis A. The large diameter recess 21eb is located on the track shoe 30 side of the small diameter recess 21ea. In other words, the large diameter recess 21eb is connected to the portion of the small diameter recess 21ea that is closest to the track shoe 30.

[0085] The large diameter recess 21eb has a first outer peripheral wall OW1. The first outer peripheral wall OW1 has a portion that is a first distance Da away from the central axis A. The first distance Da is greater than the distance Dc from the central axis A to the outermost diameter portion of the snap ring 26. The outermost diameter portion of the snap ring 26 is, for example, the outer peripheral edge of the flange portion 26b.

[0086] The small diameter recess 21ea has a second outer peripheral wall OW2. The second outer peripheral wall OW2 is spaced a second distance Db from the central axis A. The second distance Db is smaller than the distance Dc from the central axis A to the outermost diameter portion of the snap ring 26.

[0087] When viewed from the direction of axis A, the ring portion 26a of the snap ring 26 has a portion that is located within the small diameter recess 26a and a portion that is located within the circumferential groove 21d of the crawler belt link 21. When viewed from the direction of axis A, the pair of flange portions 26b of the snap ring 26 are located within the large diameter recess 26b. When viewed from the direction of axis A, the pliers engagement portion 26c provided on each of the pair of flange portions 26b has a portion that is located within the large diameter recess 26b.

[0088] The rotation limiting portion RL is formed by, for example, the wall surface of the large-diameter recess 21eb. When the snap ring 26 rotates a predetermined angle in the circumferential direction about the central axis A, the flange 26b of the snap ring 26 interferes with the wall surface of the large-diameter recess 21eb. In this way, the wall surface of the large-diameter recess 21eb limits the rotation range (rotation angle) of the snap ring 26.

[0089] As shown in FIG. 12, in this modification, the bottom surface of annular notch 22d provided in master pin 22 serves as a receiving surface for snap ring 26.

[0090] The configurations of the modified examples other than those described above are almost the same as the configurations of the embodiment shown in Figures 1 to 10, so the components of the modified examples that are the same as the components of the embodiment are given the same symbols and their descriptions will not be repeated.

[0091] 11 , when the snap ring 26 rotates in the circumferential direction, the first flange 26b1 or the second flange 26b2 comes into contact with the rotation limiting portion RL1 or RL2, thereby stopping the rotation of the snap ring 26. At this time, a force acts in the direction of closing the snap ring 26. Therefore, in terms of durability, it is more preferable to provide a rotation limiting portion at a position corresponding to the rotation limiting portion RL3 shown in FIG. 10 (the C-shaped opening of the snap ring 20) than to provide at least one of the rotation limiting portion RL1 and the rotation limiting portion RL2 on the outside of the C-shaped opening of the snap ring 20.

[0092] <Effects> Next, the effects of the crawler belt connecting device of this embodiment will be described.

[0093] FIG. 13 is a diagram illustrating a problem with a track coupling device of a comparative example. In the comparative example shown in FIG. 13 , vibrations during operation of work machine 1 cause snap ring 26 to rotate circumferentially about central axis A relative to master pin 22. This rotation may cause the connection between ring portion 26 a and flange portion 26 b of snap ring 26 to be positioned directly above knock pin 25 (in the direction of axis A of knock pin 25). Knock pin 25 may move in the direction of axis A. In this case, the movement of knock pin 25 in the direction of axis A causes knock pin 25 to collide with the vicinity of the connection between ring portion 26 a and flange portion 26 b. The connection between ring portion 26 a and flange portion 26 b is likely to have lower strength than other portions of snap ring 26. Therefore, if knock pin 25 collides with the vicinity of the connection between ring portion 26 a and flange portion 26 b, snap ring 26 may be damaged. If the snap ring 26 is damaged, the snap ring 26 will no longer be able to prevent the knock pin 25 from coming out, causing the knock pin 25 to fall off. For this reason, improved durability is required for crawler belt connecting devices.

[0094] In contrast, according to this embodiment, as shown in Figure 5, crawler belt link 21 is disposed within circumferential rotation locus RT of snap ring 26, and has rotation limiting portion RL within the rotation range of snap ring 26. This limits the circumferential rotation of snap ring 26 relative to master pin 22, thereby preventing weak portions of snap ring 26 from moving to positions where an unbalanced load is applied and causing breakage. This makes it possible to realize a track belt connection device with excellent durability.

[0095] 3 , according to the track belt connection device of this embodiment, snap ring 26 has a C-shape, which allows snap ring 26 to be easily attached to and detached from master pin 22 or track belt link 21. Furthermore, unlike ordinary track belt pins, master pin 22 is not fixed to track belt link 21 by an interference fit, so master pin 22 can be attached to and detached from track belt link 21 relatively easily by attaching and detaching snap ring 26. Therefore, master pin 22 can be attached to and detached from track belt link 21 without using a press machine. This improves the workability of attaching and detaching track belt 10.

[0096] Furthermore, knock pin 25 is disposed in first recess 24 formed by first notch 21b of crawler belt link 21 and second notch 22b of master pin 22. This allows knock pin 25 to come into surface contact with first notch 21b and second notch 22b within first recess 24. Therefore, master pin 22 is fixed and unable to rotate relative to crawler belt link 21, even though the fit is an intermediate fit or a clearance fit. Furthermore, knock pin 25 is prevented from making partial contact with first notch 21b and second notch 22b. This prevents first recess 24 from being worn away. This prevents a gap from being formed between knock pin 25 and first recess 24, thereby preventing master pin 22 from falling off from crawler belt link 21.

[0097] Furthermore, snap ring 26 is provided at a position that blocks the path of knock pin 25 from coming out of first recessed portion 24. Therefore, snap ring 26 prevents knock pin 25 from coming out of first recessed portion 24. Therefore, knock pin 25 is prevented from coming out of first recessed portion 24, and master pin 22 is prevented from rotating relatively with respect to crawler belt link 21.

[0098] 5 , the rotation limiting portion RL includes a first rotation limiting portion RL1 and a second rotation limiting portion RL2. The first rotation limiting portion RL1 is located between the first flange 26b1 and the knock pin 25 in the first circumferential direction R1 of the snap ring 26. The second rotation limiting portion RL2 is located between the second flange 26b2 and the knock pin 25 in the second circumferential direction R2 of the snap ring 26. This prevents both the connection between the first flange 26b1 and the ring portion 26a and the connection between the second flange 26b2 and the ring portion 26a from being located directly above the knock pin 25 (in the direction of the axis A of the knock pin 25). This prevents weaker portions of the snap ring 26 from moving to positions where an offset load is applied and causing damage.

[0099] 5, the second recess 21e has a large diameter recess 21eb having a first outer peripheral wall OW1 that is farther from the central axis A than the distance Dc from the central axis A to the outermost diameter portion of the snap ring 26, and a small diameter recess 21ea having a second outer peripheral wall OW2 that is closer to the central axis A than the distance Dc. The outermost diameter portion of the snap ring 26 is located within the large diameter recess 21eb. This allows the outermost diameter portion of the snap ring 26 to move only within the large diameter recess 21eb and cannot move into the small diameter recess 21ea.

[0100] 5, at least a portion of each of first flange portion 26b1 and second flange portion 26b2 of snap ring 26 is disposed within large diameter recess 21eb. At least a portion of ring portion 26a is disposed within small diameter recess 21ea. This allows first flange portion 26b1 and second flange portion 26b2 to move only within large diameter recess 21eb and cannot move into small diameter recess 21ea. Because rotation of snap ring 26 relative to master pin 22 is restricted in this manner, a weak portion of snap ring 26 is prevented from moving to a position where an unbalanced load is applied and causing damage.

[0101] 8 and 9, the pliers engaging portions 26c of the first and second flanges 26b1 and 26b2 each have a portion located within the large-diameter recess 21eb that is deeper than the small-diameter recess 21ea, making it easier to engage the pliers with the pliers engaging portions 26c.

[0102] 5 , according to this embodiment, outer peripheral wall OW1 of large diameter recess 21eb limits the range of movement of pliers engaging portion 26c when snap ring 26 is attached to or detached from master pin 22. This makes it possible to prevent snap ring 26 from being deformed by excessively expanding its diameter when snap ring 26 is attached or detached.

[0103] 8, in this embodiment, bottom surface B1 of small diameter recess 21ea is configured to serve as a receiving surface for ring portion 26a of snap ring 26, which deforms when snap ring 26 is attached to or detached from master pin 22. In this way, ring portion 26a can be received by bottom surface B1 of small diameter recess 21ea, thereby preventing an unbalanced load from being applied to ring portion 26a.

[0104] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0105] REFERENCE SIGNS LIST 1 Work machine, 2 Traveling body, 3 Swing body, 4 Work machine, 5 Cab, 6 Engine room, 7 Counterweight, 10 Track, 11 Swing device, 12 Track frame, 13 Idler wheel, 14 Drive wheel, 15 Upper roller, 16 Lower roller, 17 Lift ladder, 20 Track link chain, 21 Track link, 211 First track link, 212 Second track link, 21a Pin through hole, 21b First notch, 21c Bush through hole, 21d, 22c Circumferential groove, 21e Second recess, 21ea Small diameter recess, 21eb Large diameter recess, 22 Master pin, 22a Outer circumferential surface, 22b Second notch, 22d Annular notch, 24 First recess, 25 Knock pin, 25a One end surface, 26 Snap ring, 26a ring portion, 26b flange portion, 26b1 first flange portion, 26b2 second flange portion, 26c pliers engagement portion, 30 track shoe, 34 track pin, 41 track bushing, 42 seal ring, 43 bolt, 44 nut, A, B central axis, B1, B2 bottom surface, E1 one end portion, E2 other end portion, IP inclined portion, OW1 first outer peripheral wall, OW2 second outer peripheral wall, RL rotation limiting portion, RL1 first rotation limiting portion, RL2 second rotation limiting portion, RL3 third rotation limiting portion, RT rotation trajectory.

Claims

1. A track connection device for connecting a plurality of track links to form an endless track, comprising: a track link having a pin through hole and a first notch on an inner peripheral surface of the pin through hole; a master pin inserted into the pin through hole of the track link and having a second notch on its outer peripheral surface; a knock pin consisting of the first notch and the second notch and disposed in a first recess having an opening at an end of the pin through hole, with one end face facing the opening; a C-shaped snap ring disposed on the one end face of the knock pin with a gap therebetween or in contact with the one end face; and a rotation limiting portion disposed within the circumferential rotation trajectory of the snap ring and limiting the rotation range of the snap ring.

2. A track coupling device as described in claim 1, wherein the snap ring has a C-shaped ring portion and first and second flange portions at first and second circumferential ends of the ring portion, respectively, which protrude radially outward beyond the ring portion, and the rotation limiting portion has a first rotation limiting portion located between the first flange portion and the knock pin in a first direction in the circumferential direction of the snap ring, and a second rotation limiting portion located between the second flange portion and the knock pin in a second direction that is the opposite direction to the first direction in the circumferential direction of the snap ring.

3. A track coupling device as described in claim 1, wherein a second recess is provided between the track link and the master pin, the second recess having a large diameter recess having a first outer peripheral wall farther from the central axis than the distance from the central axis of the pin through hole to the outermost diameter portion of the snap ring, and a small diameter recess having a second outer peripheral wall closer to the central axis than said distance, and the outermost diameter portion of the snap ring is located within the large diameter recess.

4. A track coupling device as described in claim 3, wherein the snap ring has a C-shaped ring portion, and first and second flange portions at first and second peripheral ends of the ring portion which protrude radially outward beyond the ring portion, and at least a portion of the first and second flange portions are disposed within the large diameter recess, and at least a portion of the ring portion is disposed within the small diameter recess.

5. A track belt connection device as set forth in claim 4, wherein said large diameter recess is formed deeper than said small diameter recess, and said snap ring has a pliers engagement portion on each of said first flange portion and said second flange portion, said pliers engagement portion having a portion located within said large diameter recess.

6. A track belt connecting device as set forth in claim 5, wherein said first outer peripheral wall of said large diameter recess limits the movable range of said pliers engagement portion when said snap ring is attached to or detached from said master pin.

7. A track belt connecting device as set forth in claim 5 or claim 6, wherein a bottom surface of said small diameter recess is configured to serve as a receiving surface for said ring portion of said snap ring that deforms when said snap ring is attached to or detached from said master pin.

Images