Running device for work vehicle and work vehicle

Abstract

To provide a running device for a work vehicle and the work vehicle, which suppress application of a force to a main shaft member, the force which may deform the main shaft member.SOLUTION: A running device 3 of a work vehicle includes a depress device 41, a support member 45, a pair of coupling members 46, and a breaking mechanism 47. The depress device 41 includes a main shaft member 411 which elongates in a predetermined direction, and depresses a push member 412 to the main shaft member 411 toward one side in the predetermined direction. The support member 45 supports one end portion of the main shaft member 411. The pair of coupling members 46 couples the support member 45 to a fastening member 48. The breaking mechanism 47 applies, when the one coupling member 46 in the pair of coupling member 46 is broken down, a force that breaks down the other coupling member 46 to the other coupling member 46 before a force that deforms the main shaft member 411 is applied to the main shaft member 411.SELECTED DRAWING: Figure 15

Description

[Technical field]

[0001] The present invention relates to a travel device for a work vehicle that is provided with a pressing device that presses a pressing member in a predetermined direction by a main shaft member, and to a work vehicle. [Background technology]

[0002] As a related technique, a (crawler) traveling device is known that is used in a work vehicle such as a combine harvester and includes a tension frame (tension adjustment frame) that can be displaced in the front-rear direction relative to the track frame, and a tension roller (crawler tension adjustment wheel) supported by the tension frame (see, for example, Patent Document 1). In this traveling device, the tension frame includes a main frame that can move in the front-rear direction relative to the track frame, and a wheel support that supports the tension roller. The wheel support is displaceable between a normal connection position where the tension roller is positioned at an adjustment position by the main shaft member (tension adjustment screw shaft), and an abnormal connection position where the tension roller has moved from the adjustment position to the crawler loosening side.

[0003] This traveling device further includes a holding means capable of switching between a non-destructive state in which the wheel body support is held in the normal connection position and a destructive state in which the wheel body support is released from being held in the normal connection position. When the crawler tension acting on the tension roller is less than a set tension, the holding means is in a non-destructive state in which the shear pin is not broken, and when the crawler tension acting on the tension roller is equal to or greater than the set tension, the shear pin breaks and the holding means switches to the destructive state. Thus, when excessive crawler tension acts on the tension roller, the shear pin breaks and the wheel body support is switched to the abnormal connection position, and the tension roller moves to the crawler loosening side, thereby reducing the crawler tension. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-292338 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the configuration of the above-mentioned related art, the load on the shear pin is not stable, and if an excessive external force is applied to the tension roller, for example when the crawler belt goes over a protrusion, a force that causes deformation of the main shaft member may be applied to the main shaft member.

[0006] An object of the present invention is to provide a traveling device for a work vehicle, and a work vehicle in which forces that would deform the main shaft member are unlikely to be applied to the main shaft member. [Means for solving the problem]

[0007] A travel device for a work vehicle according to one aspect of the present invention includes a pressing device, a support member, a pair of connecting members, and a breaking mechanism. The pressing device includes a main shaft member having a length in a predetermined direction, and the main shaft member presses the pressing member in one of the predetermined directions. The support member supports one end of the main shaft member. The pair of connecting members connect the support member to a fixed member. When one of the pair of connecting members breaks, the breaking mechanism applies a force to the other connecting member to break the other connecting member before a force that deforms the main shaft member acts on the main shaft member.

[0008] A work vehicle according to one aspect of the present invention includes a travel device for the work vehicle, and a machine base supported by the travel device so as to be capable of traveling. Effect of the Invention

[0009] According to the present invention, it is possible to provide a travel device for a work vehicle and a work vehicle in which forces that would deform the main shaft member are unlikely to be applied to the main shaft member. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic left side view of a work vehicle according to a first embodiment. [Diagram 2]FIG. 2 is a schematic perspective view of a chassis frame and a traveling device of the work vehicle according to the first embodiment. [Diagram 3] FIG. 3 is a schematic perspective view of a traveling device of the work vehicle according to the first embodiment. [Figure 4] FIG. 4 is a schematic perspective view of a traveling device of the work vehicle according to the first embodiment with the crawlers removed. [Diagram 5] FIG. 5 is a schematic left side view of the travel device of the work vehicle according to the first embodiment. [Figure 6] FIG. 6 is a schematic left side view of the travelling device of the work vehicle according to the first embodiment with the crawler removed. [Figure 7] FIG. 7 is an enlarged perspective view of the periphery of the tension adjustment device for the travelling gear of the work vehicle according to the first embodiment. [Figure 8] FIG. 8 is an enlarged perspective view of the periphery of the tension adjustment device for the travelling gear of the work vehicle according to the first embodiment. [Figure 9] FIG. 9 is an enlarged left side view of the periphery of the tension adjuster for the travelling gear of the work vehicle according to the first embodiment. [Figure 10] FIG. 10 is an enlarged plan view of the periphery of the tension adjuster for the travelling gear of the work vehicle according to the first embodiment. [Figure 11] FIG. 11 is a partially cutaway perspective view of the periphery of a tension adjuster for a traveling device of a work vehicle according to the first embodiment. [Figure 12] FIG. 12 is a cross-sectional view of the periphery of a tension adjustment device for a traveling device of a work vehicle according to the first embodiment. [Figure 13] FIG. 13 is a partially cutaway perspective view of the periphery of a tension adjustment device for a traveling device of a work vehicle according to the first embodiment. [Figure 14] FIG. 14 is a cross-sectional view of the periphery of a tension adjustment device for a traveling device of a work vehicle according to the first embodiment. [Figure 15] FIG. 15 is a cross-sectional view of the periphery of a tension adjuster for a traveling device of a work vehicle according to the first embodiment. [Figure 16] FIG. 16 is a partially cutaway perspective view of the periphery of a tension adjuster for a traveling device of a work vehicle according to the first embodiment. [Figure 17] FIG. 17 is a cross-sectional view of the periphery of a tension adjuster for a traveling device of a work vehicle according to the first embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0012] (Embodiment 1) [1] Overall structure First, the overall configuration of a work vehicle 1 according to this embodiment will be described with reference to FIG.

[0013] In this disclosure, the term "work vehicle" refers to a machine that performs various tasks in a target area F1, such as a farm field, and examples of such tasks include agricultural machines (farm machinery) such as harvesters, tractors, seeders, rice transplanters, spreaders, sprayers, and transplanters. The work vehicle 1 may also be, for example, a construction machine (construction machinery). In this disclosure, "work" refers to a job that the work vehicle 1 performs in the target area F1, and includes, for example, various agricultural tasks such as harvesting, leveling, sowing, fertilizing, spraying pesticides, or planting (rice planting), and various tasks such as construction work.

[0014] In this embodiment, unless otherwise specified, the working vehicle 1 is a machine that performs crop harvesting work in the target area F1, and more specifically, a combine harvester (combine harvester) that performs threshing and sorting in addition to harvesting work will be described as an example. The combine harvester as the working vehicle 1 is mainly used for grain harvesting work, and while moving (traveling) in the target area F1, it harvests crops and harvests the harvested crops. In particular, there are normal (general-purpose) combine harvesters that send the entire harvested crop to a thresher (thresher 12) and self-feeding combine harvesters that send only the tips of the harvested crops to the thresher. In this embodiment, the normal combine harvester will be described as an example of the working vehicle 1. In addition, in this embodiment, as an example, the working vehicle 1 is operated by a person (operator) (including remote operation), but the present invention is not limited to this, and the working vehicle 1 may be an unmanned vehicle that operates by automatic driving.

[0015] The "target area" in the present disclosure is an area in which the work vehicle 1 travels and performs various tasks such as harvesting, leveling, sowing, fertilizing, spraying pesticides, or planting (rice planting), and includes paddy fields, fields, orchards, and pastures. For example, if a paddy field or field in which crops (agricultural products) such as rice, wheat, soybeans, or buckwheat are grown is the target area F1, the crops grown in the target area F1 are agricultural products. Furthermore, if plants are grown in a plantation, the plantation becomes the target area F1, and if trees that become lumber are grown in a forest as in forestry, the forest becomes the target area F1. In this case, the crops grown in the target area F1 are plants or trees. In this embodiment, unless otherwise specified, a case will be described in which the harvest target by the work vehicle 1 is "rice" and the target area F1 is a paddy field as a field in which rice is grown. Furthermore, the target area F1 is not limited to a farm field. For example, if the work vehicle 1 is a construction machine, the site where the construction machine performs work becomes the target area F1.

[0016] In this embodiment, for ease of explanation, the vertical direction when the work vehicle 1 is in a usable state is defined as the up-down direction D1. The front-rear direction D2 and the left-right direction D3 (see FIG. 2) are defined based on the direction as seen by a person (operator) riding on the work vehicle 1 (the driver's unit 16) as a reference. The left side of the left-right direction D3 refers to the left side when the work vehicle 1 is traveling forward (advancing), and the right side of the left-right direction D3 refers to the right side when the work vehicle 1 is traveling forward (advancing). However, these directions are not intended to limit the use direction of the work vehicle 1 (direction during use).

[0017] The work vehicle 1 includes a machine base 2, and a traveling device 3 (of the work vehicle 1). In this embodiment, the work vehicle 1 is a harvesting machine, and therefore further includes a reaping device 11, a threshing device 12, a sorting device 13, a storage device 14, a power device 15, and a driving unit 16. In this embodiment, the work vehicle 1 further includes a control device, a communication terminal, a display device, a fuel tank, a battery, various sensors, and the like.

[0018] The machine base 2 has a chassis frame 21 (see FIG. 2) and constitutes the body of the work vehicle 1. The machine base 2 is equipped with a threshing device 12, a sorting device 13, a storage device 14, a power unit 15, a driving section 16, and the like.

[0019] The traveling device 3 supports the machine base 2 so that it can travel. In other words, the machine base 2, which is equipped with the threshing device 12, the sorting device 13, the storage device 14, the power device 15, the driving unit 16, etc., is supported by the traveling device 3 so that it can move (travel) within the target area F1. The traveling device 3 is a device (car body) that makes the machine base 2 travel. The machine base 2 can move in the forward / backward direction D2 and the left / right direction D3 within the target area F1 by traveling (including turning) on ​​the traveling surface Fs1 using the traveling device 3. The "traveling surface" in this disclosure is a surface (ground) on which the work vehicle 1 travels, and includes a rice field surface, a paved surface, etc. In this embodiment, a case is taken as an example where the farm scene, which is the surface of the target area F1 consisting of a farm field, is the traveling surface Fs1. By providing such a traveling device 3, the work vehicle 1 can perform work (harvesting work) while moving within the target area F1. As an example, the work vehicle 1 may move within the target area F1 from the outside to the inside while turning left, in which case the travel path of the work vehicle 1 will be a counterclockwise spiral path in a plan view.

[0020] Specifically, the traveling device 3 includes a pair of crawlers 31 arranged in the left-right direction D3. As an example, the pair of crawlers 31 includes a hydraulic actuator such as a hydraulic motor, and is driven by power from the power unit 15 in a state in which independent speed changes are possible. Therefore, the machine base 2 is in a forward state moving straight forward when the pair of crawlers 31 are driven at a constant speed in the forward direction, and in a reverse state moving straight backward when the pair of crawlers 31 are driven at a constant speed in the reverse direction. In addition, the machine base 2 is in a forward turning state turning while moving forward when the pair of crawlers 31 are driven at a non-uniform speed in the forward direction, and in a reverse turning state turning while moving backward when the pair of crawlers 31 are driven at a non-uniform speed in the reverse direction. In addition, the machine base 2 is in a pivot turning state when one of the pair of crawlers 31 is stopped and the other is driven, and in a spin turning state when the pair of crawlers 31 are driven at a constant speed in the forward direction and the reverse direction. Furthermore, the machine 2 comes to a stopped state as the driving of the pair of crawlers 31 is stopped.

[0021] A more detailed configuration of the traveling device 3 will be explained in section "[3] Configuration of the traveling device."

[0022] The reaping device 11 reaps crops (rice, as an example, in this embodiment) on a travel surface Fs1 (a field in this embodiment). The reaping device 11 is disposed in front of the machine base 2 of the work vehicle 1 and is coupled to the machine base 2. Here, the reaping device 11 is supported so as to be able to rise and fall with respect to the machine base 2. In other words, the relative height of the reaping device 11 with respect to the machine base 2 is not fixed, but changes as the reaping device 11 is driven to rise and fall.

[0023] The reaping device 11 is equipped with a cutting blade (cutter). In this embodiment, as an example, the reaping device 11 is a reaping device having a cutting width of six rows. The stalks of the crop harvested by the reaping device 11 are transported to the threshing device 12.

[0024] The threshing device 12 performs a threshing process on the crop (culms) harvested by the harvesting device 11. In the threshing process, threshing pieces containing grains are separated from the culms. The threshing pieces fall from the threshing device 12 to a sorting device 13 below.

[0025] The sorting device 13 executes a sorting process to sort grains from the threshed grains that drop from the threshing device 12. The sorting device 13 sorts grains from the threshed grains, for example, by sifting the threshed grains while blowing air obliquely downward onto them.

[0026] The storage device 14 has a grain tank 141, a discharge auger 142, etc. The grain tank 141 stores grains transported from the sorting device 13 by the transport conveyor. In other words, the grains sorted by the sorting device 13 are transported to the grain tank 141 by the transport conveyor and stored in the grain tank 141. The discharge auger 142 discharges the grains in the grain tank 141 to any location around the work vehicle 1.

[0027] The power unit 15 supplies power to the traveling devices 3, the harvesting device 11, the threshing device 12, the sorting device 13, the storage device 14, etc. The power unit 15 has an engine such as a diesel engine as a power source. The power unit 15 may also have a motor (electric motor) as a power source, or may have a hybrid power source including an engine and a motor. The power unit 15 supplies power to each part of the work vehicle 1 by, for example, driving a hydraulic pump with a power source such as an engine, and supplying hydraulic oil from the hydraulic pump to hydraulic actuators (including hydraulic motors, hydraulic cylinders, etc.) of each part of the work vehicle 1.

[0028] The driving unit 16 is provided with a driver's seat where a user (operator) sits, and operation devices such as a steering wheel, various operation levers, and various operation switches operated by the user. In the present embodiment, as an example, the driving unit 16 is a cabin type equipped with a cabin 161, and the user boards the cabin space inside the cabin 161.

[0029] The control device mainly comprises a computer system having one or more processors such as a CPU (Central Processing Unit) and one or more memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and executes various processes (information processing). In this embodiment, since the control device mainly comprises a computer system having one or more processors, the control device is realized by the one or more processors executing a control program for the work vehicle. In this embodiment, the control device is an integrated controller that controls the entire work vehicle 1, and is composed of, for example, an electronic control unit (ECU). However, the control device may be provided separately from the integrated controller.

[0030] [2] Machine configuration Next, the configuration of the base 2 of the work vehicle 1 according to this embodiment will be described in detail with reference to Figs.

[0031] The machine base 2 has a chassis frame 21 as a structure. The chassis frame 21 is a frame that supports the threshing device 12, the sorting device 13, the storage device 14, the power unit 15, the driving unit 16, etc. In FIG. 2, the threshing device 12 and the like mounted on the machine base 2 (chassis frame 21) are omitted. The chassis frame 21 is configured by combining a plurality of frame materials (e.g., metal pipes, etc.). In this embodiment, the chassis frame 21 spreads out in a planar shape along a horizontal plane to form a platform. The threshing device 12, the sorting device 13, the storage device 14, the power unit 15, the driving unit 16, etc. are mounted on the chassis frame 21. The machine base 2 moves together with the chassis frame 21 within the target area F1 by the traveling device 3. Therefore, the chassis frame 21 has sufficient strength (rigidity) to support heavy objects such as the threshing device 12.

[0032] Specifically, the chassis frame 21 has a plurality of frame members, such as a left frame 211, a right frame 212, a front frame 213, a rear frame 214, a pair of vertical frames 215, 216, and three horizontal frames 217, 218, 219. The plurality of frame members constituting the chassis frame 21 are fixed to each other by means of, for example, welding, adhesive bonding, or fastening using fasteners.

[0033] The left frame 211 and the right frame 212 each have a length in the front-rear direction D2. The left frame 211 and the right frame 212 are disposed spaced apart in the left-right direction D3 such that the left frame 211 is located on the left side. The front frame 213 has a length in the left-right direction D3 and connects front portions of the left frame 211 and the right frame 212 to each other. The rear frame 214 has a length in the left-right direction D3 and connects rear portions of the left frame 211 and the right frame 212 to each other. As a result, the left frame 211, the right frame 212, the front frame 213, and the rear frame 214 form a rectangular (oblong) outer frame frame having a length in the front-rear direction D2 in a plan view.

[0034] The pair of vertical frames 215, 216 each have a length in the front-rear direction D2. The pair of vertical frames 215, 216 are disposed between the left frame 211 and the right frame 212, spaced apart in the left-right direction D3, so that the vertical frame 215 is located on the left side. The front ends of the pair of vertical frames 215, 216 are connected to the front frame 213, and the rear ends of the pair of vertical frames 215, 216 are connected to the rear frame 214. The three horizontal frames 217, 218, 219 each have a length in the left-right direction D3. The three horizontal frames 217 to 219 are disposed between the front frame 213 and the rear frame 214, spaced apart in the front-rear direction D2, so that the horizontal frame 217, the horizontal frame 218, and the horizontal frame 219 are arranged in this order from the front. The left ends of the three horizontal frames 217 to 219 are connected to the left frame 211 , and the right ends of the three horizontal frames 217 to 219 are connected to the right frame 212 .

[0035] [3] Configuration of the running gear Next, the configuration of the traveling device 3 of the work vehicle 1 according to this embodiment will be described in detail with reference to Figures 2 to 6. From Figure 3 onwards, the machine base 2 (including the chassis frame 21) and the like are not shown.

[0036] The traveling device 3 has a first traveling body 301 including one of a pair of crawlers 31, and a second traveling body 302 including the other. In this embodiment, of the pair of crawlers 31 arranged side by side in the left-right direction D3, the left crawler 31 is included in the first traveling body 301, and the right crawler 31 is included in the second traveling body 302. In other words, the first traveling body 301 and the second traveling body 302 are arranged side by side in the left-right direction D3.

[0037] The first running body 301 receives power from the power unit 15 and drives one (the left side in this embodiment) of the crawlers 31. The second running body 302 receives power from the power unit 15 and drives the other (the right side in this embodiment) of the crawlers 31. This allows the running device 3 to individually drive the pair of crawlers 31, and realize the above-mentioned forward state, reverse state, forward turning state, reverse turning state, pivot turning state, spin turning state, etc.

[0038] The first running body 301 and the second running body 302 are connected to each other by a connecting member 303. The connecting member 303 is a frame material having a length in the left-right direction D3, and both ends in the longitudinal direction are extended downward, so that the connecting member 303 is generally formed in a U-shape that is open downward as a whole. The left end of the connecting member 303 is connected to the first running body 301, and the right end of the connecting member 303 is connected to the second running body 302. In this embodiment, the traveling device 3 has a pair of connecting members 303 spaced apart in the front-rear direction D2. Therefore, the first running body 301 and the second running body 302 are connected (coupled) to each other by the connecting member 303 at the front end and the rear end, respectively.

[0039] As shown in FIG. 2, the pair of connecting members 303 are joined to the chassis frame 21 of the machine base 2. Specifically, the front connecting member 303 of the pair of connecting members 303 is installed between the front ends of the pair of vertical frames 215, 216 and connects the front ends of the pair of vertical frames 215, 216 to each other. The rear connecting member 303 of the pair of connecting members 303 is installed between the central parts of the pair of vertical frames 215, 216 in the longitudinal direction (front-rear direction D2) and connects the central parts of the pair of vertical frames 215, 216 to each other. In other words, the connecting member 303 is a cross member and is fixed to the chassis frame 21 (the pair of vertical frames 215, 216) by means of, for example, welding, bonding, or fastening using fasteners. As a result, the machine base 2 is supported by the traveling device 3 so as to be capable of traveling.

[0040] Incidentally, the first running body 301 and the second running body 302 have the same structure and are arranged symmetrically in the left-right direction D3. Therefore, unless otherwise specified, the configuration of the traveling device 3 will be described below using the first running body 301 as an example, and the description of the second running body 302 will be omitted, assuming that it has the same (symmetric) configuration as the first running body 301.

[0041] The traveling device 3 (first traveling body 301) has a track frame 32. The track frame 32 has a length in the front-rear direction D2. The track frame 32 is directly or indirectly fixed to the above-mentioned connecting member 303. Specifically, of the pair of connecting members 303, the front connecting member 303 is connected to the front end of the track frame 32, and the rear connecting member 303 is connected to the rear end of the track frame 32. In other words, the traveling device 3 supports the machine base 2 by fixing the track frame 32 to the chassis frame 21 of the machine base 2 via the connecting member 303.

[0042] The track frame 32 is disposed inside the crawler 31 and rotatably supports the crawler 31. Here, the track frame 32 supports the weight of the work vehicle 1 by pressing the contact portion (lower portion) of the crawler 31 with the traveling surface Fs1 against the traveling surface Fs1.

[0043] The traveling device 3 (first traveling body 301) further includes, in addition to the crawler 31 and the track frame 32, a drive sprocket 33, a plurality (two, for example) of carrier rollers (upper rollers) 34, a plurality (six, for example) of track rollers (lower rollers) 35, and a tension roller 36. The drive sprocket 33, the plurality of carrier rollers 34, the plurality of track rollers 35, and the tension roller 36 are directly or indirectly supported by the track frame 32 in a state in which they can rotate about rotation axes extending along the left-right direction D3.

[0044] The crawler 31 is a circularly formed crawler belt made of rubber, metal, or a combination of rubber and metal. The crawler 31 is wound around the outer circumferential surface of a drive sprocket 33, a plurality of carrier rollers 34, a plurality of track rollers 35, and a tension roller 36 supported by a track frame 32 so as to surround them. As a result, the drive sprocket 33, the plurality of carrier rollers 34, the plurality of track rollers 35, and the tension roller 36 contact the inner circumferential surface of the crawler 31 from the inside of the crawler 31, and support the crawler 31.

[0045] The drive sprocket 33 is disposed diagonally upward and forward of the track frame 32. Specifically, the drive sprocket 33 is rotatably supported at the tip end (front end) of a bearing frame 321 extending diagonally upward and forward from the front connecting member 303 (illustration of a support structure for the drive sprocket 33 is omitted). In other words, the drive sprocket 33 is indirectly supported at the front end of the track frame 32 via the connecting member 303 and the bearing frame 321.

[0046] The multiple carrier rollers 34 are disposed above the track frame 32. Specifically, the two carrier rollers 34 are disposed above the track frame 32, spaced apart from each other in the front-rear direction D2. Of the two carrier rollers 34, the front carrier roller 34 is rotatably supported by a support base 322 provided on the upper surface of the track frame 32, and the rear carrier roller 34 is rotatably supported by a guide frame 42 (described below) fixed to the track frame 32. In other words, the multiple carrier rollers 34 are indirectly supported by the track frame 32 via the support base 322 or the guide frame 42.

[0047] The multiple track rollers 35 are disposed below the track frame 32. Specifically, the six track rollers 35 are disposed below the track frame 32, spaced apart in the front-rear direction D2. Of the six track rollers 35, the rearmost track roller 35 is rotatably supported by a bracket 323 (see FIG. 11 ) fixed to the track frame 32, which will be described later, and the remaining five track rollers 35 are directly rotatably supported by the track frame 32. In other words, the multiple track rollers 35 are indirectly or directly supported by the track frame 32 with or without the bracket 323.

[0048] The tension roller 36 is disposed rearward of the track frame 32. Specifically, the tension roller 36 is rotatably supported on the tip end (rear end) of a tension frame 43 (described below) that extends rearward from the rear end of the track frame 32. In other words, the tension roller 36 is indirectly supported on the rear end of the track frame 32 via the tension frame 43.

[0049] The traveling device 3 (first traveling body 301) is equipped with a tension adjustment device 4. The tension adjustment device 4 includes a guide frame 42, a tension frame 43, and a tension roller 36, and is a device for adjusting the tension (tensile force) applied to the crawler 31.

[0050] In the tension adjustment device 4, the tension frame 43 is configured to be movable relative to the track frame 32 in the longitudinal direction of the track frame 32. In this embodiment, the track frame 32 has a length in the front-rear direction D2. That is, the tension frame 43 is displaceable in the front-rear direction D2 relative to the track frame 32. When the tension frame 43 is displaced in the front-rear direction D2, the tension roller 36 supported by the tension frame 43 is also displaced in the front-rear direction D2, and as a result, the tension applied to the crawler 31 changes.

[0051] In this embodiment, as an example, the tension roller 36 is located behind the track frame 32. Therefore, as the tension frame 43 moves backward relative to the track frame 32, the pressing force of the tension roller 36 pressed against the crawler 31 becomes larger (stronger), and the tension acting on the crawler 31 becomes larger (tighter). On the other hand, as the tension frame 43 moves forward relative to the track frame 32, the pressing force of the tension roller 36 pressed against the crawler 31 becomes smaller (weaker), and the tension acting on the crawler 31 becomes smaller (looser).

[0052] A more detailed configuration of the tension adjustment device 4 will be explained in the section "[4] Configuration of the tension adjustment device."

[0053] As described above, the traveling device 3 includes a bearing frame 321, a support base 322, a bracket 323, a guide frame 42, a tension frame 43, etc. as members for supporting the drive sprocket 33, the multiple carrier rollers 34, the multiple track rollers 35 and the tension roller 36.

[0054] With the configuration described above, the traveling device 3 rotates the crawler 31 by driving the drive sprocket 33, which contacts the crawler 31 from the inside, with power from the power unit 15. At this time, the multiple carrier rollers 34, the multiple track rollers 35, and the tension roller 36, which contact the crawler 31 from the inside, rotate (are driven) in accordance with the rotation of the crawler 31. In other words, the traveling device 3 can individually rotate the crawlers 31 of the first traveling body 301 and the second traveling body 302 by driving the drive sprocket 33.

[0055] [4] Configuration of tension adjustment device Next, the configuration of the tension adjustment device 4 of the work vehicle 1 according to this embodiment will be described in detail with reference to Figs.

[0056] The tension adjustment device 4 of the first running body 301 will be described below with reference to the drawings (FIGS. 7 to 17) illustrating the periphery of the tension adjustment device 4 of the first running body 301. As described above, the first running body 301 and the second running body 302 are symmetrical in the left-right direction D3, and therefore the tension adjustment device 4 of the second running body 302 has the same (symmetrical) configuration as the tension adjustment device 4 of the first running body 301, and therefore a description thereof will be omitted.

[0057] Fig. 7 is an enlarged view of the periphery of the tension adjustment device 4 of the first running body 301 in Fig. 4. Fig. 8 is a drawing showing a state in which the carrier roller 34 and the guide frame 42 have been removed in Fig. 7. Fig. 9 is an enlarged view of the periphery of the tension adjustment device 4 of the first running body 301 in a state in which the carrier roller 34 has been removed in Fig. 6, showing a state in which the guide frame 42 is present in the upper part and a state in which the guide frame 42 has been removed in the lower part. Fig. 10 is a plan view of the portion shown in Fig. 9 seen from above, showing a state in which the guide frame 42 is present in the upper part and a state in which the guide frame 42 has been removed in the lower part.

[0058] FIG. 11 is a perspective view showing the tension adjustment device 4 cut along the line A1-A1 in FIG. 10. FIG. 12 is a left side view showing the tension adjustment device 4 cut along the line A1-A1 in FIG. 10, with the upper part showing a state where the tension applied to the crawler 31 is small, and the lower part showing a state where the tension applied to the crawler 31 is large. FIG. 13 is a perspective view showing the tension adjustment device 4 cut along the line A2-A2 in FIG. 9. FIG. 14 is a plan view showing the tension adjustment device 4 cut along the line A2-A2 in FIG. 9. FIG. 15 is a plan view showing the tension adjustment device 4 cut along the line A2-A2 in FIG. 9, with a joining member 46 (see FIG. 7) described later broken, and a partially enlarged view (inside the balloon). FIG. 16 is a perspective view showing the tension adjustment device 4 cut along the line A3-A3 in FIG. 10. Figure 17 is a rear view showing the tension adjustment device 4 broken along the cross section line A3-A3 in Figure 10, with the left side showing the state before the pushing member 412 (see Figure 8) described below rotates, and the right side showing the state after the pushing member 412 has rotated.

[0059] 11 to 17 show partially cutaway views, but hatching (diagonal lines) on the cutaway surfaces will be omitted.

[0060] The guide frame 42 regulates the displacement direction of the tension frame 43. In this embodiment, since the tension frame 43 is displaceable in the front-rear direction D2, the guide frame 42 regulates the movement of the tension frame 43 in directions other than the front-rear direction D2, thereby guiding the movement of the tension frame 43 in the front-rear direction D2. The guide frame 42 is fixed to the track frame 32 directly or indirectly.

[0061] Specifically, the guide frame 42 is a frame member having a length in the front-rear direction D2. The guide frame 42 has a hollow shape, and when the tension frame 43 is inserted therein, the guide frame 42 regulates the displacement direction (movement direction) of the tension frame 43. As an example in the present embodiment, the guide frame 42 is formed in a shape in which the lower surface of the guide frame 42 is open, so that the cross section viewed from one side in the front-rear direction D2 is formed in a substantially C-shape that is open downward.

[0062] The tension frame 43 is combined with the guide frame 42 so as to be displaceable in the front-rear direction D2. Specifically, the tension frame 43 is a frame member having a length in the front-rear direction D2. The tension frame 43 is configured to be displaceable in the front-rear direction D2 by sliding on the inside of the guide frame 42 relative to the guide frame 42.

[0063] In this embodiment, as an example, the tension frame 43 has a pair of side plates 431 (see FIG. 8) and a top plate 432 (see FIG. 8). The pair of side plates 431 are disposed opposite each other in the left-right direction D3, and the top plate 432 is located above the pair of side plates 431 and connects the pair of side plates 431 to each other. In order to show the internal configuration of the tension frame 43, the top plate 432 is shown by an imaginary line (two-dot chain line) in FIG. 8, and the top plate 432 is omitted in FIGS. 9 and 10.

[0064] As shown in FIGS. 7 to 12, in addition to the guide frame 42 and the tension frame 43, the tension adjustment device 4 further includes a pressing device 41, a support member 45, a pair of connecting members 46, and a fixing member 48.

[0065] 8, the pressing device 41 has a main shaft member 411 and a pressing member 412. The main shaft member 411 has a length in a predetermined direction. The pressing device 41 presses the pressing member 412 in one of the predetermined directions with the main shaft member 411. In this embodiment, the predetermined direction which is the longitudinal direction of the main shaft member 411 is the front-rear direction D2, and the "one of the predetermined directions" in which the pressing member 412 is pressed by the main shaft member 411 is the "rearward direction."

[0066] In this embodiment, as an example, the main shaft member 411 is a tension bolt having a length in the front-rear direction D2, and the pressing member 412 is a nut member that screws into the main shaft member 411. The pressing member 412 is prevented from rotating. The main shaft member 411 made of a tension bolt rotates around its central axis, thereby moving the pressing member 412 made of a nut member in parallel in the central axis direction (front-rear direction D2).

[0067] The pressing device 41 presses the tension frame 43 with the pressing member 412. That is, the pressing device 41 is configured to press the pressing member 412 against the tension frame 43 with the main shaft member 411, thereby pressing the tension frame 43 backward. As a result, the tension roller 36 supported by the tension frame 43 is pressed against the crawler 31, and tension can be applied to the crawler 31.

[0068] The support member 45 supports one end (in the longitudinal direction) of the main shaft member 411. In this embodiment, the support member 45 supports the end of the main shaft member 411 opposite to the pressing member 412. In other words, the support member 45 supports the front end of the main shaft member 411 made of a tension bolt. Here, the main shaft member 411 is supported by the support member 45 in a state in which it can only rotate around the central axis, that is, in a state in which translation in the up-down direction D1, the front-rear direction D2, and the left-right direction D3 is restricted.

[0069] Specifically, the support member 45 is a rectangular plate-like member having a length in the left-right direction D3. The support member 45 has a through hole 451 (see FIG. 11) through which the main shaft member 411 penetrates. The front end of the main shaft member 411 penetrates the through hole 451, thereby restricting the movement of the main shaft member 411 relative to the support member 45 in the up-down direction D1 and the left-right direction D3. Furthermore, the main shaft member 411 has a flange portion 413 (see FIG. 11) formed with a partially large diameter, and the flange portion 413 is brought into contact with the periphery of the through hole 451 in the support member 45 from behind, thereby restricting the movement of the main shaft member 411 relative to the support member 45 in the forward direction.

[0070] The fixed member 48 is a member fixed to the truck frame 32. The fixed member 48 is located on the pushing member 412 side, that is, rearward, as viewed from the support member 45. In this embodiment, the fixed member 48 is a rectangular plate-shaped member, and a pair of fixed members 48 are provided corresponding to the pair of connecting members 46. The pair of fixed members 48 are disposed spaced apart in the left-right direction D3.

[0071] The pair of connecting members 46 are members that connect the support member 45 to the fixed member 48. The pair of connecting members 46 are arranged spaced apart in the left-right direction D3. In the present embodiment, as an example, each of the pair of connecting members 46 is a fastener including a bolt 461 (see FIG. 13) and a nut 462 (see FIG. 13). Each connecting member 46 fastens the support member 45 and the fixed member 48 with the bolt 461 and the nut 462, and connects the support member 45 to the fixed member 48.

[0072] Specifically, with the support member 45 overlapped on the front side of the pair of fixing members 48, a bolt 461 inserted from the rear is tightened into a nut 462 located in front of the support member 45, whereby the pair of connecting members 46 fasten the support member 45 and the (pair of) fixing members 48. Here, the bolt 461 penetrates the support member 45 and the fixing member 48 by being inserted through a support hole 452 (see FIG. 15) formed in the support member 45 and a fixing hole 481 (see FIG. 15) formed in the fixing member 48.

[0073] In this manner, when the support member 45 supporting one end of the main shaft member 411 is connected to the fixed member 48 by the pair of connecting members 46, one end of the main shaft member 411 is indirectly supported by the track frame 32 via the support member 45 and the fixed member 48. Therefore, in this state, the main shaft member 411 is restricted from moving at least forward, and the pushing member 412 can be pushed backward relatively to the track frame 32.

[0074] On the other hand, when the pair of connecting members 46 breaks, the connection between the support member 45 and the fixed member 48 is released, and one end of the main shaft member 411 becomes movable forward together with the support member 45. Therefore, in this state, the main shaft member 411 becomes movable forward, and therefore the pushing member 412 cannot be pushed backward relatively to the track frame 32.

[0075] Incidentally, in the traveling device 3 according to this embodiment, as shown in Figs. 7 to 12, at least a part of the tension frame 43 is disposed in a recess 324 provided in one side surface of the track frame 32 along the front-rear direction D2.

[0076] That is, a recess 324 is formed on one side surface (upper surface, lower surface, right side surface, or left side surface) of the track frame 32 along the front-rear direction D2, which is the displacement direction of the tension frame 43. The tension frame 43 is combined with the track frame 32 so that at least a portion of the tension frame 43 fits within the recess 324.

[0077] According to this configuration, at least a portion of the tension frame 43 is embedded in the track frame 32, and external forces acting on the tension frame 43 can be more easily received by the track frame 32. As a result, there is an advantage in that the strength of the support structure (tension frame 43, etc.) for the tension roller 36 can be easily increased.

[0078] Furthermore, by embedding at least a portion of the tension frame 43 in the track frame 32, it is easier to configure the tension adjustment device 4 more compactly than if the tension frame 43 were disposed on the upper surface of the track frame 32.

[0079] Specifically, the recess 324 is provided on the upper surface of the track frame 32, which is one side surface (along the front-rear direction D2 of the track frame 32). In other words, the side surface on which the recess 324 is provided is the upper surface of the track frame 32. This allows the tension frame 43 to be disposed above the track frame 32, and at least a portion of the tension frame 43 can be disposed within the recess 324 without requiring a significant change in the layout of the tension frame 43, etc.

[0080] Furthermore, the recess 324 is open upward and backward. That is, the recess 324 is provided at the rear end of the upper surface of the track frame 32, and is open at least upward and backward. In particular, in this embodiment, the recess 324 is open toward both sides in the left-right direction D3. This configuration makes it easy to suppress a decrease in strength of the track frame 32 caused by providing the recess 324.

[0081] More specifically, in this embodiment, the track frame 32 is formed in a square tube shape, with a cross section viewed from one side in the front-rear direction D2 being a rectangle having a length in the up-down direction D1. A cutout portion 325 (see FIG. 11) of a certain depth is provided from the upper surface side of the rear end portion of the track frame 32, and a recess 324 is formed by covering the cross section of the cutout portion 325 with a cover member 326 (see FIG. 11). Here, the cover member 326 is formed in a substantially L-shape viewed from one side in the left-right direction D3, and covers the entire cross section of the cutout portion 325. In other words, the upper surface of the cover member 326 forms the bottom surface of the recess 324.

[0082] In this embodiment, the tension frame 43 is arranged so that only the lower half thereof fits within the recess 324 having such a configuration. However, it is sufficient that at least a portion of the tension frame 43 is arranged within the recess 324, and the entire tension frame 43 may be arranged within the recess 324.

[0083] Here, in this embodiment, the pushing member 412, which pushes the tension frame 43 in the direction in which the tension roller 36 moves away from the track frame 32, pushes the action part between the center and the upper end in the vertical direction D1 of the tension frame 43. That is, as shown in Figures 8 and 9, since the main shaft member 411 is located above the track frame 32 with the pushing member 412 to the rear, the pushing member 412 pushes a position (action part) above the center in the vertical direction D1 of the tension frame 43, whose lower half is disposed within the recess 324.

[0084] According to this configuration, even if an excessive external force is applied to the tension roller 36, the moment acting on the tension frame 43 can be effectively received by the pressing member 412. Therefore, the strength of the tension frame 43 can be further increased.

[0085] Furthermore, the tension frame 43 is in contact with the bottom surface of the recess 324. The bottom surface of the recess 324 is formed by the upper surface of the cover member 326, and the tension frame 43 slides in the front-rear direction D2 relative to the cover member 326 while in contact with the upper surface of the cover member 326. Therefore, the tension frame 43 is supported by the bottom surface of the recess 324 (the upper surface of the cover member 326), which leads to an increase in the strength of the tension frame 43.

[0086] Moreover, in this embodiment, at least a portion of the guide frame 42 is disposed within the recess 324. Like the tension frame 43, only the lower half of the guide frame 42 is disposed within the recess 324. In this manner, by embedding at least a portion of the guide frame 42 in the track frame 32, it becomes easier to configure the tension adjustment device 4 more compactly than when the guide frame 42 is disposed on the upper surface of the track frame 32. Furthermore, it is sufficient that at least a portion of the guide frame 42 is disposed within the recess 324, and the entire guide frame 42 may be disposed within the recess 324.

[0087] Here, the carrier roller 34 that contacts the crawler 31 from the inside is supported by the guide frame 42. Specifically, the rear carrier roller 34 is rotatably supported by the guide frame 42. Therefore, it is possible to keep the amount of protrusion of the carrier roller 34 from the track frame 32 small.

[0088] In this embodiment, as described above, the rearmost track roller 35 is rotatably supported by the bracket 323 fixed to the track frame 32. The bracket 323 is provided across the lower surface and rear end surface of the track frame 32. That is, the bracket 323 is provided at one end (rear end) of the track frame 32 on the tension roller 36 side in the front-rear direction D2, and supports the track roller 35. The bracket 323 is provided across the side surface (lower surface) and end surface of the track frame 32 opposite the recess 324.

[0089] According to this configuration, the track rollers 35 are supported by utilizing the brackets 323 that are firmly fixed to the track frame 32, which leads to an improvement in the supporting strength of the track rollers 35.

[0090] In this embodiment, a (rear) connecting member 303 is connected to the guide frame 42. In other words, the connecting member 303 connects the guide frame 42 to the machine base 2. Since the guide frame 42 is fixed to the track frame 32, the connecting member 303 is fixed to the track frame 32 via the guide frame 42. With this configuration, the connecting member 303 can be connected to the guide frame 42 instead of the track frame 32 which is thinner than other parts due to the provision of the recess 324, and this makes it easier to ensure the connection strength between the connecting member 303 and the track frame 32.

[0091] 13 to 15, the traveling device 3 according to this embodiment is equipped with a breaking mechanism 47 (see FIG. 13). When one of the pair of connecting members 46 breaks, the breaking mechanism 47 applies a force to the other connecting member 46 to break it before a force that deforms the main shaft member 411 acts on the other connecting member 46.

[0092] In this embodiment, the support member 45 that supports one end of the main shaft member 411 is connected to the fixed member 48 by the pair of connecting members 46, so that when both of the pair of connecting members 46 break, the connection between the support member 45 and the fixed member 48 is released. At this time, the one end of the main shaft member 411 becomes movable forward together with the support member 45, so that the pressing member 412 can no longer be pressed backward relatively against the track frame 32. In other words, the pressing device 41 can no longer press the tension frame 43 backward by the pressing member 412, and tension is no longer applied from the tension roller 36 of the tension adjustment device 4 to the crawler 31.

[0093] According to the breaking mechanism 47, when one of the pair of connecting members 46 breaks, the other connecting member 46 breaks before a force that would deform the main shaft member 411 acts on the main shaft member 411. Therefore, the other connecting member 46 does not break and remains sticky, making it easier to prevent the main shaft member 411 from being deformed by an excessive force acting on it. As a result, there is an advantage that a force that would deform the main shaft member 411 is less likely to be applied to the main shaft member 411. Furthermore, if the main shaft member 411 does not deform, the main shaft member 411 can be reused, and the tension adjustment device 4 can be repaired by simply replacing the pair of connecting members 46.

[0094] Specifically, in this embodiment, the breaking mechanism 47 includes a support member 45 and a fixed member 48. That is, a through hole 451 through which the main shaft member 411 passes is formed in the support member 45, and a gap G1 (see FIG. 14 ) is formed between the main shaft member 411 and the inner peripheral surface of the through hole 451 to avoid interference between the main shaft member 411 and the inner peripheral surface of the through hole 451 when the support member 45 is inclined with respect to the fixed member 48.

[0095] In short, the inner diameter of the through hole 451 is set to be slightly larger than the outer diameter of the main shaft member 411, and a sufficient gap G1 is secured between the inner peripheral surface of the through hole 451 and the outer peripheral surface of the main shaft member 411. Therefore, for example, as shown in Fig. 15, even if one (here, the left) connecting member 46 (bolt 461) breaks and the support member 45 tilts, interference (contact) between the main shaft member 411 and the inner peripheral surface of the through hole 451 can be avoided by this gap G1.

[0096] In other words, when one of the connecting members 46 breaks, the support member 45 receives a reaction force from the crawler 31 via the tension roller 36, the tension frame 43, and the pressing device 41, and may tilt with respect to the fixed member 48. If the main shaft member 411 interferes with the inner peripheral surface of the through hole 451 at this time, this leads to deformation of the main shaft member 411, but the breaking mechanism 47 makes it possible to avoid such interference and thereby avoid deformation of the main shaft member 411. Specifically, if the tilt of the support member 45 is a few degrees (for example, 9 degrees) or less, interference between the main shaft member 411 and the inner peripheral surface of the through hole 451 is avoided.

[0097] Furthermore, the breaking mechanism 47 breaks the connecting member 46 by setting the gap between the inner circumferential surface of the support hole 452 formed in the support member 45 and (the bolt 461 of) the connecting member 46 to be smaller than the gap G1 between the main shaft member 411 and the inner circumferential surface of the through hole 451. That is, for example, as shown in FIG. 15, in a state in which the support member 45 is inclined with respect to the fixing member 48, the central axis of the fixing hole 481 formed in the fixing member 48 and the support hole 452 is bent. At this time, a force for breaking the connecting member 46 (the bolt 461) penetrating the fixing hole 481 and the support hole 452 is applied from the support member 45 and the fixing member 48 to the connecting member 46.

[0098] Thus, in this embodiment, the breaking mechanism 47 breaks the other (i.e., the one that did not break earlier) connecting member 46 by applying at least one of bending stress and shear stress to it. Specifically, by tilting the support member 45, both bending stress and shear stress act on (the bolt 461 of) the connecting member 46 penetrating the fixing hole 481 and the support hole 452 from the support member 45 and the fixing member 48 serving as the breaking mechanism 47. As a result, even if a member having a necessary and sufficient strength is used as the connecting member 46, when one connecting member 46 breaks, the other connecting member 46 is also likely to break actively.

[0099] Moreover, the main shaft member 411 is located between the pair of connecting members 46 in a plan view. In this embodiment, the pair of connecting members 46 are disposed apart from each other in the left-right direction D3, and the main shaft member 411 is located at the center position of the pair of connecting members 46. Therefore, when one connecting member 46 breaks, the amount of displacement of the support member 45 in the vicinity of the other connecting member 46 becomes larger than that of the main shaft member 411, making it easier to actively break the other connecting member 46.

[0100] Furthermore, in this embodiment, the fixing member 48 is fixed to the guide frame 42. That is, the fixing member 48 is indirectly fixed to the track frame 32 by being fixed to the guide frame 42. Therefore, the fixing member 48 is easily and firmly fixed to the track frame 32, and when one connecting member 46 breaks and the support member 45 tilts, a force that breaks the other connecting member 46 is easily generated.

[0101] 16 and 17, a gap G2 is provided between the pressing member 412 and the inner surface of the guide frame 42. The pressing member 412 is a part of the pressing device 41, and is a member that moves inside the guide frame 42 in the front-rear direction D2 and presses the tension frame 43 in a direction in which the tension roller 36 moves away from the track frame 32.

[0102] Specifically, a stop plate 44 is disposed below the pressing member 412 as a member for preventing the pressing member 412 from rotating. The stop plate 44 is fixed to the tension frame 43. Here, the gap between the stop plate 44 and the pressing member 412 is smaller than the gap G2 between the pressing member 412 and the inner surface of the guide frame 42.

[0103] 17, even if the pushing member 412 rotates together with the main shaft member 411 when the main shaft member 411 rotates, the pushing member 412 contacts the stop plate 44 before the guide frame 42, and further rotation is restricted. Therefore, the pushing member 412 and the guide frame 42 maintain a state of not contacting each other (a state in which there is a gap G2). As a result, friction loss caused by the pushing member 412 sliding against the inner surface of the guide frame 42 can be suppressed.

[0104] [5] Variations Below, we will list some modified examples of the embodiment 1. The modified examples explained below can be applied in appropriate combinations.

[0105] The work vehicle 1 is not limited to a normal combine harvester, but may be a head-feeding combine harvester, a harvesting machine other than a combine harvester, or another work vehicle. The harvest target by the work vehicle 1 is not limited to "rice", and is not limited to grains. The driving section 16 is not limited to a cabin type, but may be, for example, a canopy type or a floor type.

[0106] Furthermore, the traveling device 3 is not limited to a crawler type, and may be, for example, a half-crawler type.

[0107] The work vehicle 1 may also be provided with a lifting device that raises and lowers the platform 2 relative to the traveling device 3. In this case, the platform 2 is supported by the lifting device so that it can be raised and lowered relative to the traveling device 3. As a result, the height (vehicle height) of the platform 2 from the traveling surface Fs1 is not fixed, but changes when the lifting device is driven. Here, it is preferable that a pair of lifting devices is provided corresponding to the pair of crawlers 31, and the pair of lifting devices is driven individually. As a result, for example, when the traveling surface Fs1 is inclined so that one of the left and right directions D3 is lowered, the platform 2 can be maintained horizontal by raising the platform 2 with the one lifting device. In this way, the lifting device is used not only for vehicle height adjustment control that changes the height (vehicle height) of the platform 2 from the traveling surface Fs1, but also for automatic level control that corrects the inclination of the platform 2 in the roll direction to maintain the platform 2 horizontal.

[0108] Furthermore, the specific shapes and dimensions of each member of the tension adjustment device 4, such as the guide frame 42 or the tension frame 43, are not limited to the examples shown in the embodiment 1. For example, the recess 324 in which at least a part of the tension frame 43 is disposed is not limited to the top surface of the track frame 32, and may be provided on, for example, the bottom surface, left side surface, or right side surface.

[0109] Moreover, the tension adjustment device 4 of the traveling device 3 needs to include at least two (a pair of) connecting members 46, and may include three or more connecting members 46.

[0110] Moreover, with regard to the configuration of the breaking mechanism 47, the configuration described in the first embodiment is merely one example, and various configurations can be adopted as long as, when one of the pair of connecting members 46 breaks, a force for breaking the other connecting member 46 is applied to the other connecting member 46 before a force for deforming the main shaft member 411 is applied to the other connecting member 46. For example, the breaking mechanism 47 may be configured to apply a shear stress to the connecting members 46 from the edges of both members when the supporting member 45 moves in the up-down direction D1 relative to the fixed member 48, like "scissors."

[0111] [Appendix to the invention] The following will provide an overview of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0112] <Appendix 1> a pressing device including a main shaft member having a length in a predetermined direction, the main shaft member pressing a pressing member in one of the predetermined directions; A support member for supporting one end of the main shaft member; a pair of connecting members that connect the support member to a fixing member; and a breaking mechanism that, when one of the pair of connecting members breaks, applies a force to break the other connecting member to the other connecting member before a force that deforms the main shaft member acts on the other connecting member. Running gear of a work vehicle.

[0113] <Appendix 2> A truck frame having a length in a front-rear direction; A tension frame that is displaceable in a front-rear direction relative to the track frame; A tension roller supported by the tension frame, The pressing device presses the tension frame with the pressing member. 2. A running device for a work vehicle as described in appendix 1.

[0114] <Appendix 3> Further, a guide frame is provided to regulate the displacement direction of the tension frame, The fixing member is fixed to the guide frame. 3. A running device for a work vehicle as described in appendix 2.

[0115] <Appendix 4> The main shaft member is located between the pair of connecting members in a plan view. A travel device for a work vehicle according to any one of claims 1 to 3.

[0116] <Appendix 5> The breaking mechanism applies at least one of a bending stress and a shear stress to the other connecting member. A travel device for a work vehicle according to any one of claims 1 to 4.

[0117] <Appendix 6> the support member has a through hole through which the main shaft member passes, A gap is formed between the main shaft member and the inner peripheral surface of the through hole to avoid interference between the main shaft member and the inner peripheral surface of the through hole when the support member is inclined with respect to the fixed member. 6. A travel device for a work vehicle according to any one of claims 1 to 5.

[0118] <Appendix 7> A travel device for a work vehicle according to any one of appendices 1 to 6; A machine base supported by the traveling device so as to be capable of running. Work vehicle. [Explanation of symbols]

[0119] 1 Work vehicle 2 machines 3 Running gear 32 Truck Frame 36 Tension roller 42 Guide Frame 43 Tension Frame 45 Support member 46 Connecting members 47 Breaking Mechanism 48 Fixing member 41 Pressing device 411 Main shaft parts 412 Push member 451 Through hole G1 Gap D2 Anteroposterior direction

Claims

1. a pressing device including a main shaft member having a length in a predetermined direction, the main shaft member pressing a pressing member in one of the predetermined directions; A support member for supporting one end of the main shaft member; a pair of connecting members that connect the support member to a fixing member; and a breaking mechanism that, when one of the pair of connecting members breaks, applies a force to break the other connecting member to the other connecting member before a force that deforms the main shaft member acts on the other connecting member. Running gear of a work vehicle.

2. A truck frame having a length in a front-rear direction; A tension frame that is displaceable in a front-rear direction relative to the track frame; A tension roller supported by the tension frame, The pressing device presses the tension frame with the pressing member. A travel device for a work vehicle according to claim 1.

3. Further, a guide frame is provided to regulate the displacement direction of the tension frame, The fixing member is fixed to the guide frame. A travel device for a work vehicle according to claim 2.

4. The main shaft member is located between the pair of connecting members in a plan view. A travel device for a work vehicle according to any one of claims 1 to 3.

5. The breaking mechanism applies at least one of a bending stress and a shear stress to the other connecting member. A travel device for a work vehicle according to any one of claims 1 to 3.

6. the support member has a through hole through which the main shaft member passes, Between the main shaft member and the inner peripheral surface of the through hole, a gap is formed to avoid interference between the main shaft member and the inner peripheral surface of the through hole when the support member is inclined with respect to the fixed member. A travel device for a work vehicle according to any one of claims 1 to 3.

7. A travel device for a work vehicle according to any one of claims 1 to 3; A machine base supported by the traveling device so as to be capable of running. Work vehicle.

Images