Construction machinery travel system

Abstract

By preventing damage to the idler wheel, operational efficiency at the site can be improved. [Solution] The side frame 7 is provided with an outer and inner position sandwiching the idler wheel 13. The lower load reduction mechanism 21 and upper load reduction mechanism 26 are provided as load reduction mechanisms that elastically contact the track 15 when the track 15 comes into contact with the annular contact surface 13B which is the outer surface of the idler wheel 13, thereby biasing the track 15 in the direction of the outer circumference of the idler wheel 13. This prevents damage to the track 15 due to collision.

Description

Technical Field

[0001] The present disclosure relates to a traveling device of a construction machine provided in a lower traveling body such as a hydraulic excavator.

Background Art

[0002] Crawler-type construction machines such as hydraulic excavators and bulldozers have a track frame on the lower side of the vehicle body, and traveling devices for traveling the construction machine are provided on both the left and right sides of the track frame.

[0003] The left and right traveling devices include side frames that are located on both sides in the left-right direction of the vehicle body and extend in the front-rear direction, drive wheels provided at the first end in the longitudinal direction (front-rear direction) of the side frames, idler wheels provided at the second end in the longitudinal direction of the side frames, and a crawler belt that is wound around in a circumferential direction between the drive wheels and the idler wheels so as to be rotatable in the front-rear direction.

[0004] In addition, the crawler belt includes a plurality of pairs of track links that are arranged at intervals in the left-right direction and are connected in an endless manner in the circumferential direction, and a plurality of tread plates that are formed of plate bodies extending in the left-right direction and have the middle portion in the left-right direction of the inner surface attached to the plurality of pairs of track links.

[0005] Here, since the traveling device has a structure in which the crawler belt continuously circulates around the drive wheels and the idler wheels, wear occurs at the portions where the drive wheels, the idler wheels, and the crawler belt contact. And, the components constituting the traveling device need to be replaced due to wear, but the larger the load on the contacting portion, the shorter the replacement cycle tends to be. As a result, the construction machine has an increased frequency of component replacement work and a reduced operating efficiency at the site. Moreover, for large construction machines, a large amount of cost and labor are required both when the work is stopped and when the work is restarted. Further, a large amount of cost and labor are required even when large components are replaced.

[0006] Therefore, it is desirable to extend the lifespan of construction machinery by suppressing wear on the components of the running gear. One example of a method to extend the lifespan (suppress wear) of large components is to harden the outer surface of the idler wheel, which the track contacts, by heat treatment to improve wear resistance.

[0007] Furthermore, the running gear applies a biasing force to press the idler wheel against the track in order to provide the appropriate tension to the track (Patent Document 1). In this case, the idler wheel repeatedly collides with the track link, making it more susceptible to deformation and damage compared to other parts. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Utility Model Publication No. 2-63286 [Overview of the project] [Problems that the invention aims to solve]

[0009] Incidentally, in conventional technology, the outer surface of the idler wheel, which the track contacts, is hardened by heat treatment to improve wear resistance. On the other hand, if the outer surface of the idler wheel is hardened by heat treatment, there is a risk that repeated collisions with the track link may cause damage such as cracks.

[0010] An object of one embodiment of the present invention is to provide a running gear for construction machinery that can prevent damage to the idler wheel even when the idler wheel is hardened by heat treatment, thereby improving operational efficiency on site. [Means for solving the problem]

[0011] One embodiment of the present invention is a running gear for a construction machine comprising: side frames located on both sides of the vehicle body in the left-right direction and extending in the front-rear direction; a drive wheel provided at a first end in the longitudinal direction of the side frame; an idler wheel provided at a second end in the longitudinal direction of the side frame; and a track belt wound around the drive wheel and the idler wheel so as to be circumferential in the front-rear direction, wherein a load reduction mechanism is provided at the outer and inner positions of the side frame that sandwich the idler wheel, and elastically contacts the track belt when the track belt contacts the outer circumferential surface of the idler wheel, thereby biasing the track belt toward the outer circumferential direction of the idler wheel. [Effects of the Invention]

[0012] According to one embodiment of the present invention, even when the idler wheel of a construction machine is hardened by heat treatment, damage to the idler wheel can be prevented, and the operational efficiency at the site can be improved. [Brief explanation of the drawing]

[0013] [Figure 1] This is a left side view of a hydraulic excavator equipped with a traveling device according to the first embodiment of the present invention. [Figure 2] This is a left side view showing the lower running body equipped with a running gear. [Figure 3] This is a plan view showing the lower traveling body equipped with a traveling mechanism. [Figure 4] Figure 2 is a left side view showing a portion of the side frame, idler wheel, track, and load reduction mechanism. [Figure 5] This is a disassembled perspective view of the track. [Figure 6] This is a cross-sectional view taken from the direction indicated by the arrow VI-VI in Figure 4. [Figure 7] Figure 4 is a left side view showing the load reduction mechanism. [Figure 8] The arrows in Figure 7 show the load reduction mechanism from the direction indicated by arrows VIII-VIII. [Figure 9] This is a cross-sectional view of the running gear in a state where the tracks are tilted due to traveling on an incline, taken from the same position as in Figure 4. [Figure 10]Left side view showing the load reduction mechanism according to the second embodiment together with a part of the side frame, the idler wheel, and the crawler belt. [Figure 11] Cross-sectional view taken in the direction of arrow XI-XI in FIG. 10. **Modes for Carrying Out the Invention**

[0014] Hereinafter, as a traveling device of a construction machine according to an embodiment of the present invention, a traveling device of a hydraulic excavator will be taken as an example and described in detail according to the accompanying drawings. In this embodiment, the traveling direction of the hydraulic excavator is defined as the front-rear direction, and the lateral direction orthogonal to the traveling direction of the hydraulic excavator is defined as the left-right direction for explanation.

[0015] FIGS. 1 to 9 show the first embodiment of the present invention. The feature of the first embodiment is that the load reduction mechanism is provided at the second end in the longitudinal direction of the side frame.

[0016] In FIG. 1, a hydraulic excavator 1 as a construction machine includes a self-propelled crawler-type lower traveling body 2, an upper revolving body 3 rotatably mounted on the lower traveling body 2, and a working device 4 rotatably provided on the front side of the upper revolving body 3. The lower traveling body 2 and the upper revolving body 3 constitute the vehicle body. The hydraulic excavator 1 performs earth and sand excavation work and the like by rotating the working device 4 while rotating the upper revolving body 3.

[0017] As shown in FIGS. 2 and 3, the lower traveling body 2 has a track frame 5 as a base. The track frame 5 includes a center frame 6 on which the upper revolving body 3 is rotatably mounted, and left and right side frames 7 provided on both the left and right sides of the center frame 6 sandwiching the center frame 6. Traveling devices 11 described later are provided on the left and right side frames 7, respectively.

[0018] The side frame 7 is formed as a sheet metal structure extending in the front-to-rear direction, which is the direction of travel. Specifically, the side frame 7 is formed in a rectangular tubular shape having an upper surface portion 7A and a lower surface portion 7B. A bracket 7C is provided at the first end of the side frame 7 in the front-to-rear direction, and a drive motor (not shown) that drives the drive wheels 12 is attached to this bracket 7C.

[0019] On the other hand, the second end of the side frame 7 in the front-rear direction is divided into an outer part 7D and an inner part 7E in the left-right direction. Between the outer part 7D and the inner part 7E, a freewheel 13, described later, is rotatably positioned around an axis extending in the left-right direction. The lower surface 7B of the outer part 7D and the lower surface 7B of the inner part 7E are each fitted with a lower load reduction mechanism 21, described later. In addition, the upper surface 7A of the outer part 7D and the upper surface 7A of the inner part 7E are each fitted with an upper load reduction mechanism 26, described later.

[0020] In this configuration, the track frame 5, during normal driving, has its second end facing forward and its first end facing backward.

[0021] Next, the configuration and operation of the travel device 11 of the hydraulic excavator 1 according to the first embodiment will be described in detail.

[0022] The running gear 11 is used to move the hydraulic excavator 1 and is formed as a crawler-type running gear. The running gear 11 consists of the drive wheels 12, idler wheels 13, tracks 15, lower load reduction mechanism 21, and upper load reduction mechanism 26, which will be described later.

[0023] The drive wheel 12 is located at the first end of the side frame 7 in the longitudinal direction. Specifically, the drive wheel 12 is attached to a bracket 7C located at the first end of the side frame 7 via a drive motor. The drive wheel 12 is formed as a circular sprocket having multiple teeth around its circumference.

[0024] The drive wheel 12 is then rotated by a motor (electric motor, hydraulic motor, etc.), causing its teeth to engage with the bushings 17 of the track 15 (described later) and push it in a circumferential direction. This allows the drive wheel 12 to cause the track 15 to rotate and drive the lower vehicle 2.

[0025] The idler wheel 13 is located at the second end of the side frame 7. The idler wheel 13 guides the track 15 so that the front portion of the rotating track 15 does not shift in the left-right direction, and is rotatably mounted on the side frame 7.

[0026] The idler wheel 13 is formed as a disc with a diameter larger than the vertical dimension of the side frame 7. An axle portion 14 is provided at the center of the idler wheel 13 so as to extend in the left-right direction. The idler wheel 13 is rotatable around the axle portion 14.

[0027] As shown in Figure 6, the outer circumference of the idler wheel 13 (the outer circumference in the outer or radial direction) has a large-diameter annular protrusion 13A in the center in the thickness direction (left-right direction), and annular contact surfaces 13B on both sides of the annular protrusion 13A. The annular contact surfaces 13B contact (abut) the contact surfaces 16C of the track links 16 that make up the track 15. At this time, the annular protrusion 13A is positioned between the left and right track links 16, so that the idler wheel 13 can guide the track 15 without shifting in the left-right direction.

[0028] The track 15 is wrapped between the drive wheel 12 and the idler wheel 13. Driven by the drive wheel 12, the track 15 rotates between the drive wheel 12 and the idler wheel 13, causing the hydraulic excavator 1 to move. The track 15 is composed of track links 16, bushings 17, connecting pins 18, and track plates 19, which will be described later.

[0029] The track links 16 are arranged in pairs so as to sandwich the drive wheels 12 from left to right. Furthermore, as shown in Figures 4 and 5, multiple pairs of track links 16 are connected endlessly by inserting connecting pins 18 (described later) between adjacent track links 16 in the direction of travel. The pair of track links 16, that is, the left track link 16 and the right track link 16, have a symmetrical shape in the left-right direction and face each other with a constant distance between them in the left-right direction.

[0030] Each pair of track links 16 is formed as an oval-shaped plate with the circumferential direction of the track 15 being the longitudinal direction. The first longitudinal end of the track link 16 is the outer link portion 16A, and the second longitudinal end is the inner link portion 16B.

[0031] The inner width dimension between the outer link portions 16A of a pair of track links 16 is set to be larger than the outer width dimension between the inner link portions 16B of a pair of track links 16. This allows the inner link portions 16B of adjacent track links 16 to be overlapped between the outer link portions 16A of a pair of track links 16. When the outer link portions 16A and inner link portions 16B are overlapping in the left-right direction, the pin insertion hole 16D and the bush insertion hole 16E, described later, are arranged coaxially.

[0032] Furthermore, the side of each track link 16 opposite to the side attached to the track plate 19 is the contact surface 16C. As shown in Figure 4, the contact surface 16C comes into contact with (strikes against) the annular contact surface 13B of the idler wheel 13 when the connected track links 16 rotate around the idler wheel 13.

[0033] The outer link portion 16A of the pair of track links 16 is provided with a pin insertion hole 16D that penetrates from side to side, into which a connecting pin 18 is inserted. On the other hand, the inner link portion 16B of the pair of track links 16 has a bush insertion hole 16E into which a bush 17 is inserted.

[0034] The bush 17 is provided between a pair of track links 16 that face each other in the left-right direction. The bush 17 is formed as a cylindrical (tubular) body extending in the left-right direction. The bush 17 is press-fitted into the bush insertion holes 16E of the pair of track links 16 that face each other at both ends. As a result, the pair of track links 16 are connected between their inner link portions 16B by the bush 17. A connecting pin 18 is rotatably inserted through the inner circumference of the cylindrical bush 17.

[0035] The connecting pin 18 is cylindrical in shape, with its axial middle portion inserted through the inner circumference of the bush 17. Both ends of the connecting pin 18 are press-fitted into pin insertion holes 16D provided in the outer link portions 16A of the pair of track links 16.

[0036] Therefore, when connecting a pair of adjacent track links 16 using a connecting pin 18, the inner link portion 16B of the adjacent pair of track links 16 is placed between the outer link portions 16A of the pair of track links 16, thereby coaxially arranging the pin insertion hole 16D and the bush insertion hole 16E (bush 17). In this state, the connecting pin 18 is inserted into the bush 17, while both ends of the connecting pin 18 are inserted into the pin insertion hole 16D.

[0037] As a result, the connecting pin 18 can rotatably connect the outer link portion 16A of a pair of track links 16 to the inner link portion 16B of an adjacent pair of track links 16. By continuing this connecting structure with the connecting pin 18, multiple pairs of track links 16 can be connected in an endless manner.

[0038] Multiple track plates 19 are attached one to each pair of track links 16. The track plates 19 are formed as metal plates extending in the left-right direction. As shown in Figure 5, the middle portion of the inner surface 19A of the multiple track plates 19, which is located on the inside when wound up, is attached to multiple pairs of track links 16 using track plate bolts 20.

[0039] Next, the configuration and effects of the lower load reduction mechanism 21 and the upper load reduction mechanism 26, which are characteristic features of the first embodiment, will be described in detail.

[0040] The lower load reduction mechanism 21, which serves as a load reduction mechanism, is provided at the second end of the side frame 7 in the longitudinal direction. More specifically, the lower load reduction mechanism 21 is provided on the lower surface 7B of the outer part 7D at the outer position sandwiching the idler wheel 13 and on the lower surface 7B of the inner part 7E at the inner position. Furthermore, the lower load reduction mechanism 21 extends downward toward the track 15 from the lower surface 7B of the outer part 7D and the lower surface 7B of the inner part 7E.

[0041] The lower load reduction mechanism 21 reduces the load acting on the idler wheel 13 by elastically contacting the track 15 when the track link 16 of the track 15 comes into contact with the annular contact surface 13B, which is the outer surface of the idler wheel 13, thereby biasing the track 15 in the outer circumferential direction of the idler wheel 13.

[0042] The lower load reduction mechanism 21 includes a base portion 22 attached to the lower surface portion 7B of the outer portion 7D and the lower surface portion 7B of the inner portion 7E of the side frame 7, a rotating portion 23 that contacts the inner surface 19A of the track plate 19 of the track 15 and is rotatable in the circumferential direction of the track 15, and a biasing portion 24 provided between the base portion 22 and the rotating portion 23, which biases the rotating portion 23 toward the inner surface 19A of the track plate 19.

[0043] The base 22 is formed as a step-shaped block and is interchangeably (detachably) attached to the lower surface 7B of the outer part 7D and the lower surface 7B of the inner part 7E using mounting bolts 25. Here, the base 22 (lower load reduction mechanism 21) is positioned at the tip of the outer part 7D and the tip of the inner part 7E, for example, so that the track 15 rises from a horizontal state parallel to the ground along the contour of the idler wheel 13 and slopes upwards to the inner surface 19A of the track plate 19. In other words, the base 22 (lower load reduction mechanism 21) is positioned on the second end side (opposite side from the drive wheel 12) of the rotation center of the idler wheel 13.

[0044] The rotating part 23 is rotatable in the circumferential direction of the track 15. In other words, the rotating part 23 is rotatable about an axis extending in the left-right direction as its center of rotation. Even when the rotating part 23 is pressed against the track plate 19, it does not interfere with the circumferential movement of the track 15.

[0045] Furthermore, the surface hardness of the outer surface of the rotating part 23 that contacts the track plate 19 is set to a value lower than the surface hardness of the inner surface 19A of the track plate 19. Therefore, the track plate 19 is less prone to wear than the rotating part 23, which are in contact with each other. As a result, the rotating part 23, which is small and easy to replace, can be the target of replacement due to wear, compared to the large and numerous track plates 19, thereby improving work efficiency.

[0046] The biasing unit 24 allows the rotating unit 23 to move only in the vertical direction, while biasing the rotating unit 23 downward toward the track plate 19, which is on the outer circumference of the idler wheel 13. Therefore, if the track plate 19 collides with the rotating unit 23 from below, the biasing unit 24 can reduce the load during the collision by moving the rotating unit 23 upward. This reduction of the load during the collision by the biasing unit 24 functions before the track link 16 of the track 15 comes into contact with the annular contact surface 13B of the idler wheel 13, thus reducing the load acting from the track 15 to the idler wheel 13.

[0047] Furthermore, when the track 15 is tilted, for example, as shown in Figure 9, with the inner side higher and the outer side lower in the left-right direction, the load on the idler wheel 13 increases on the inner side of the track 15 closer to the side frame 7, and decreases on the outer side of the track 15 further away from the side frame 7. In this case, the inner biasing portion 24 compresses significantly, generating a large biasing force (repulsive force), thereby reducing the load acting on the idler wheel 13 from the inner side of the track 15. On the other hand, the outer biasing portion 24 extends significantly, allowing the rotating portion 23 to always be in contact with the track plate 19. This allows the inner and outer rotating portions 23 to wear at the same rate, and the timing of replacement can be synchronized.

[0048] The upper load reduction mechanism 26, which serves as a load reduction mechanism, is provided at the second end of the side frame 7 in the longitudinal direction. More specifically, the upper load reduction mechanism 26 is provided on the upper surface 7A of the outer part 7D at the outer position sandwiching the idler wheel 13 and on the upper surface 7A of the inner part 7E at the inner position. Furthermore, the upper load reduction mechanism 26 extends upward from the upper surface 7A of the outer part 7D and the upper surface 7A of the inner part 7E toward the track 15.

[0049] The upper load reduction mechanism 26 reduces the load acting on the idler wheel 13 by elastically contacting the track 15 when the track link 16 of the track 15 comes into contact with the annular contact surface 13B, which is the outer surface of the idler wheel 13, thereby biasing the track 15 in the outer circumferential direction of the idler wheel 13.

[0050] The upper load reduction mechanism 26, like the lower load reduction mechanism 21, includes a base 22 attached to the upper surface 7A of the outer part 7D and the upper surface 7A of the inner part 7E of the side frame 7, a rotating part 23 that contacts the inner surface 19A of the track plate 19 of the track 15 and is rotatable in the circumferential direction of the track 15, and a biasing part 24 provided between the base 22 and the rotating part 23, which biases the rotating part 23 toward the inner surface 19A of the track plate 19.

[0051] Next, we will describe the effects of the lower load reduction mechanism 21 and upper load reduction mechanism 26 configured in this way. When the track 15 is positioned around the idler wheel 13, the contact surface 16C of the track link 16 constituting the track 15 approaches or comes into contact with the annular contact surface 13B, which is the outer surface of the idler wheel 13. In this state, if the track 15 moves vertically over rocks or steps, the track link 16 of the track 15 may collide with the annular contact surface 13B of the idler wheel 13, potentially causing wear or damage at the point of collision.

[0052] In this case, when the track 15 is positioned around the idler wheel 13, the lower load reduction mechanism 21 brings the rotating part 23 into contact with the inner surface 19A of the track plate 19, and presses the rotating part 23 against the inner surface 19A with the biasing part 24. As a result, the lower load reduction mechanism 21 can absorb and reduce the load when the track 15 contacts the idler wheel 13 from below using the biasing part 24. Furthermore, since the lower load reduction mechanism 21 is positioned on both the left and right sides of the idler wheel 13, when the track 15 is tilted in the left-right direction, the repulsive force from the biasing part 24 can be increased closer to the idler wheel 13 to suppress collisions. In addition, on the side further away from the idler wheel 13, the rotating part 23 can always be in contact with the track plate 19.

[0053] Furthermore, similar to the lower load reduction mechanism 21, when the track 15 is positioned around the idler wheel 13, the upper load reduction mechanism 26 brings the rotating part 23 into contact with the inner surface 19A of the track plate 19 and presses the rotating part 23 against the inner surface 19A with the biasing part 24. As a result, the upper load reduction mechanism 26 can absorb and reduce the load when the track 15 contacts the idler wheel 13 from above using the biasing part 24. Also, since the upper load reduction mechanism 26 is positioned on both the left and right sides of the idler wheel 13, when the track 15 is tilted in the left or right direction, the repulsive force from the biasing part 24 can be increased closer to the idler wheel 13 to suppress collisions. Furthermore, on the side further away from the idler wheel 13, the rotating part 23 can always be in contact with the track plate 19.

[0054] Thus, according to the first embodiment, a lower load reduction mechanism 21 and an upper load reduction mechanism 26 are provided at the outer and inner positions of the side frame 7 that sandwich the idler wheel 13. These mechanisms elastically contact the track 15 when the track 15 comes into contact with the annular contact surface 13B which is the outer circumferential surface of the idler wheel 13, thereby biasing the track 15 in the direction of the outer circumference of the idler wheel 13.

[0055] Therefore, even if the outer circumference of the idler wheel 13 is hardened by heat treatment to suppress wear of the idler wheel 13, the lower load reduction mechanism 21 and the upper load reduction mechanism 26 can reduce the load when the track 15 contacts the idler wheel 13. This improves the wear resistance of the idler wheel 13 and prevents damage to the idler wheel 13. As a result, the hydraulic excavator 1 can improve its operational efficiency on site.

[0056] The lower load reduction mechanism 21 and the upper load reduction mechanism 26 are provided on the outer part 7D and the inner part 7E of the second end in the longitudinal direction of the side frame 7. As a result, the lower load reduction mechanism 21 and the upper load reduction mechanism 26 can reduce the load when the track 15 comes into contact with the idler wheel 13 when the vehicle is running with the second end in the longitudinal direction of the side frame 7 facing forward.

[0057] The track 15 comprises multiple pairs of track links 16, each pair spaced apart in the left-right direction and endlessly connected in the circumferential direction, and multiple track plates 19, each consisting of a plate extending in the left-right direction, with the middle portion of its inner surface 19A in the left-right direction attached to the multiple pairs of track links 16. The lower load reduction mechanism 21 and the upper load reduction mechanism 26 each comprise a base 22 attached to the side frame 7, a rotating part 23 that contacts the inner surface 19A of the track plate 19 and is rotatable in the circumferential direction of the track 15, and a biasing part 24 provided between the base 22 and the rotating part 23, which biases the rotating part 23 toward the inner surface 19A of the track plate 19.

[0058] As a result, the lower load reduction mechanism 21 and the upper load reduction mechanism 26 can reduce the load acting on the idler wheel 13 from the track 15 with a simple configuration. Furthermore, the lower load reduction mechanism 21 and the upper load reduction mechanism 26 can be easily replaced by simply attaching and detaching the base 22 to the side frame 7.

[0059] Furthermore, the load reduction mechanism consists of a lower load reduction mechanism 21 extending downward from the lower surface portion 7B of the side frame 7 toward the track 15, and an upper load reduction mechanism 26 extending upward from the upper surface portion 7A of the side frame 7 toward the track 15. Therefore, the load reduction mechanism can reduce the load when the track 15 contacts the idler wheel 13 from below by the lower load reduction mechanism 21, and can reduce the load when the track 15 contacts the idler wheel 13 from above by the upper load reduction mechanism 26.

[0060] Next, Figures 10 and 11 show a second embodiment of the present invention. The characteristic of the second embodiment is that the load reduction mechanism is provided on the idler wheel. In the second embodiment, the same reference numerals are used for the same components as in the first embodiment, and their descriptions are omitted.

[0061] In Figures 10 and 11, the running gear 31 according to the second embodiment is composed of the drive wheels 12 and tracks 15 of the first embodiment, and the idler wheels 32 and load reduction mechanism 33 described later.

[0062] The idler wheel 32 is formed as a large-diameter disc, similar to the idler wheel 13 in the first embodiment. Its outer circumference has an annular protrusion 32A in the center in the thickness direction, and annular contact surfaces 32B on both sides of the annular protrusion 13A. However, the idler wheel 32 in the second embodiment differs from the idler wheel 13 in that it is provided with a plurality of mounting portions 32C on its side surface.

[0063] The idler wheel 32 is provided with mounting portions 32C that protrude outward from the left and right sides in the left and right directions. Multiple mounting portions 32C are provided continuously in the circumferential direction, for example, in eight locations (eight pieces), forming an arc with the shaft portion 14 as the center. In other words, eight flat mounting portions 32C are provided by forming the outer surface of the cylindrical body into a regular octagon. Note that the mounting portions may be divided into one by one in the circumferential direction, and there may be seven or fewer, or nine or more.

[0064] The load reduction mechanism 33 is provided on the idler wheel 32. More specifically, the load reduction mechanism 33 is located on the left and right sides of the idler wheel 32 and is attached to eight mounting points 32C. Each of the eight load reduction mechanisms 33 comprises a base 34 attached to the mounting points 32C, a rotating part 35 that contacts the contact surface 16C of the track link 16 and is rotatable in the circumferential direction of the track 15, and a biasing part 36 provided between the base 34 and the rotating part 35, which biases the rotating part 35 toward the contact surface 16C of the track link 16. Thus, the load reduction mechanism 33 is provided on the eight mounting points 32C such that the rotating part 35 moves radially around the idler wheel 32.

[0065] The base portion 34 is attached to the mounting portion 32C in a replaceable (detachable) manner using mounting bolts 37. Furthermore, the surface hardness of the outer surface of the rotating portion 35 that contacts the track link 16 is set to a value lower than the surface hardness of the contact surface 16C of the track link 16.

[0066] The load reduction mechanism 33 reduces the load acting on the idler wheel 32 by elastically contacting the track link 16 of the track 15 when the track link 16 of the track 15 comes into contact with the annular contact surface 32B, which is the outer surface of the idler wheel 32, thereby biasing the track 15 in the outer circumferential direction of the idler wheel 32.

[0067] Thus, the same effects and advantages as those of the first embodiment can be obtained in the second embodiment configured in this way.

[0068] In each embodiment, the travel devices 11 and 31 of a hydraulic excavator 1 are used as examples to describe the travel device of the construction machinery. However, the present invention is not limited to these, and may be applied to travel devices of hydraulic cranes, bulldozers, and the like, for example. [Explanation of Symbols]

[0069] 1. Hydraulic excavator (construction machinery) 2. Lower running body (vehicle body) 3. Upper rotating body (vehicle body) 7 Side Frames 7A Top part (upper part) 7B Bottom part (lower part) 7C Bracket (First End) 7D Outer part (2nd end) 7E Inner part (2nd end) 11,31 Running gear 12 drive wheels 13,32 Idle Wheel 13B, 32B Annular contact surface (outer surface) 15 Tracks 16 Track Links 16C contact surface 19 Tracks 19A Inside surface 21. Lower load reduction mechanism (load reduction mechanism) 22,34 base 23,35 Rotating part 24,36 biasing section 26. Upper load reduction mechanism (load reduction mechanism) 33 Load reduction mechanism 32C Mounting section

Claims

1. Side frames located on both sides of the vehicle body in the left-right direction and extending in the front-rear direction, A drive wheel provided at the first end in the longitudinal direction of the side frame, A freewheel is provided at the second end in the longitudinal direction of the side frame, A track is wound between the drive wheel and the idler wheel so as to be able to rotate in the front-rear direction, In a traveling device for a construction machine, A running gear for a construction machine, characterized in that a load reduction mechanism is provided at the outer and inner positions of the side frame that sandwich the idler wheel, which elastically contacts the track when the track contacts the outer surface of the idler wheel, thereby biasing the track in the outer direction of the idler wheel.

2. In the traveling device for construction machinery according to claim 1, The load reduction mechanism is provided at the second end in the longitudinal direction of the side frame, characterized in that it is a traveling device for construction machinery.

3. In the traveling device for construction machinery according to claim 2, The aforementioned track is, Multiple pairs of track links, each pair spaced apart in the left-right direction and endlessly connected in the circumferential direction, It consists of multiple track plates that extend in the left-right direction, with the middle portion of the inner surface in the left-right direction attached to the multiple pairs of track links, Equipped with, The aforementioned load reduction mechanism is The base attached to the side frame, A rotating part that contacts the inner surface of the track plate and is rotatable in the circumferential direction of the track, A biasing portion is provided between the base portion and the rotating portion, and biases the rotating portion toward the inner surface of the track plate, A travel device for construction machinery, characterized by being equipped with the following features.

4. In the traveling device for construction machinery according to claim 2, The aforementioned load reduction mechanism is A lower load reduction mechanism extending downward from the lower part of the side frame toward the track, An upper load reduction mechanism extending upward from the upper part of the side frame toward the track, A travel device for construction machinery, characterized by being composed of the following.

5. In the traveling device for construction machinery according to claim 1, The load reduction mechanism is provided on the idler wheel, characterized in that it is a running gear for a construction machine.

6. In the traveling device for construction machinery according to claim 5, The idler wheel is provided with mounting portions that protrude outward from the left-right side surfaces in the left-right direction. The aforementioned track is, Multiple pairs of track links, each pair spaced apart in the left-right direction and endlessly connected in the circumferential direction, It consists of multiple track plates that extend in the left-right direction, with the middle portion of the inner surface in the left-right direction attached to the multiple pairs of track links, Equipped with, The aforementioned load reduction mechanism is The base attached to the aforementioned mounting portion, A rotating part that contacts the aforementioned track link and is rotatable in the circumferential direction of the track, A biasing portion is provided between the base portion and the rotating portion, and biases the rotating portion toward the track link, A travel device for construction machinery, characterized by being equipped with the following features.

7. In the traveling device for construction machinery according to claim 6, The mounting portion is provided at multiple locations continuously in the circumferential direction of the idler wheel. The load reduction mechanism is provided at the multiple mounting points such that the rotating part moves in the radial direction of the idler wheel, and is a running gear for a construction machine.

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