JP2016016841A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work vehicle in which a tread can be easily changed.SOLUTION: A work vehicle comprises: a traveling machine body on which an engine is mounted; a truck frame which is arranged at the lower part of the traveling machine; and a traveling crawler 125 which is mounted through a drive wheel body 116 and a follower wheel body 123 to the truck frame. A link support body 118 is attached to a rear axle case 19 in which rotational power is transmitted to the drive wheel body 116. The truck frame is longitudinally swingably connected through a pair of link members 120 in a fore-and-aft direction with the link support body 118. Each of the link members 120 is constituted capable of being replaced with each other by reversing front and back to be connected with the link support body 118.SELECTED DRAWING: Figure 9

Description

  The present invention relates to a work vehicle such as a tractor in which left and right traveling crawlers are installed at the rear of a traveling machine body on which an engine or the like is mounted.

  The left and right traveling crawlers are installed at the rear part of the traveling machine body in a work vehicle such as a tractor, that is, the left and right front wheels are installed at the front part of the traveling machine body, and the left and right traveling crawlers are installed at the rear part of the traveling machine body. This is described in Patent Documents 1 to 3 as prior art.

  In the prior art, the rear axle is pivotally supported on the rear axle case of the traveling machine body, and the drive wheel body is attached to the rear axle, while the track frame extending in the front-rear direction is disposed in a portion below the rear axle case, A structure in which a traveling crawler is mounted on a track frame, and a single swing is provided with a midway portion in the front-rear direction of the track frame disposed on a traveling machine body side such as a rear axle case or the like at a position below the rear axle by an appropriate distance. The track frame is pivotally mounted on a fulcrum shaft so that the front and rear portions of the track frame are moved up and down in opposite directions. A traveling crawler is wound around the driving wheel body in a substantially triangular shape across the front driven wheel body provided on the front end side of the track frame, the rear driven wheel body provided on the rear end side, and the driving wheel body. The traveling machine body is moved forward or backward by rotating.

Japanese Patent Laid-Open No. 10-45051 JP 2004-217054 A JP 2006-96199 A

  By the way, when using a work vehicle such as a tractor in the field, the tread distance between the left and right traveling crawlers is adjusted according to the width of the streak spacing because the streak spacing (crest width) varies depending on the crop. It will be necessary to change. In this regard, as a conventional tread changing structure, there is one in which an axle case is configured to be extendable and contractable by hydraulic pressure or the like. However, the expansion / contraction structure of the axle case by hydraulic pressure or the like is easy to change the tread, but has a problem that the structure is extremely complicated, resulting in an increase in size, weight, and cost.

  The present invention seeks to provide a work vehicle such as a tractor that has been improved by examining these current conditions.

  According to a first aspect of the present invention, there is provided a work vehicle comprising: a traveling machine body equipped with an engine; a track frame provided at a lower portion of the traveling machine body; and a traveling crawler attached to the track frame via a driving wheel body and a driven wheel body. A link support is attached to a rear axle case that transmits rotational power to the drive wheel body, and the track frame is connected to the link support via a pair of front and rear link members so as to be able to swing back and forth. The link member is configured so that it can be replaced with the link support by inverting the front and back.

  According to a second aspect of the present invention, in the work vehicle according to the first aspect, the driving wheel body can be reversed and replaced with respect to the left and right outermost portions of the rear axle case.

  According to the first aspect of the present invention, there is provided a traveling machine body on which an engine is mounted, a track frame provided at a lower portion of the traveling machine body, and a traveling crawler mounted on the track frame via a driving wheel body and a driven wheel body. In this work vehicle, a link support is attached to a rear axle case that transmits rotational power to the drive wheel body, and the track frame is connected to the link support through a pair of front and rear links so as to be able to swing back and forth. In addition, since both the link members are reversed so that they can be replaced with the link support, even if a complicated tread changing structure is not adopted, the left and right traveling crawlers can be changed by replacing both the front and rear link members. You can easily change the tread. The tread changing structure between the left and right traveling crawlers can be reduced in weight and can be provided at low cost.

  According to the invention of claim 2, the driving wheel body is configured to be able to be replaced by reversing the front and back with respect to the left and right outermost portions of the rear axle case. The tread change of the traveling crawler can be set in multiple stages, making it easy to deal with specification changes.

It is a side view of a tractor showing an embodiment. It is the same top view. It is a side view of a rear crawler device. It is a side view around a track frame. It is an isolation | separation perspective view which shows the attachment structure of a rear part crawler apparatus. It is a separation perspective view showing the attachment structure of the link support to the rear axle case. It is a separate perspective view which shows the axial support structure of a link support body and a link member. It is the expansion perspective view which looked at the link support body from the front right diagonal lower side. It is a back sectional view of a rear crawler device of standard specifications. It is back surface explanatory drawing which shows the detailed structure of a driving wheel body. It is a back sectional view of a rear crawler device of narrow specification. It is back surface explanatory drawing which shows the detailed structure of a driving wheel body. It is an expanded sectional view which shows the axial support structure of a link member.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, taking a tractor as a work vehicle as an example.

  First, an outline of the tractor 1 will be described with reference to FIGS. The tractor 1 of the embodiment includes a traveling machine body 2, a pair of left and right front wheels 3 that support the front part of the traveling machine body 2, and a pair of left and right rear crawler devices 4 that support the rear part of the traveling machine body 2. A pair of left and right rear crawler devices 4 as well as a pair of left and right front wheels 3 constitutes a traveling portion. By driving the rear crawler device 4 and the front wheels 3 with a common rail type diesel engine 5 (hereinafter simply referred to as an engine) as a power source mounted on the front part of the traveling machine body 2, the tractor 1 travels forward and backward. It is composed. The engine 5 is covered with a bonnet 6. A cabin 7 is installed on the upper surface of the traveling machine body 2, and in the cabin 7, a steering seat 8 and a steering handle (round handle) that moves the steering direction of the front wheel 3 left and right by steering. 9 are arranged. Steps 10 on which the operator gets on and off are provided at the left and right lower portions of the cabin 7. A fuel tank 11 that supplies fuel to the engine 5 is provided below the bottom of the cabin 7.

  The traveling machine body 2 includes an engine frame 14 having a front bumper 12 and a front axle case 13, and left and right machine body frames 15 detachably fixed to a rear portion of the engine frame 14. A front axle 16 is rotatably protruded outward from the left and right ends of the front axle case 13. The front wheels 3 are attached to the left and right ends of the front axle case 13 via the front axle 16. A transmission case 17 is connected to the rear part of the body frame 15 for appropriately changing the rotational power from the engine 5 and transmitting it to the front wheels 3 and the rear crawler device 4. A tank frame 18 having a rectangular frame plate shape in a bottom view projecting outward in the left and right directions is bolted to the lower surface sides of the left and right body frames 15 and the mission case 17. The fuel tank 11 of the embodiment is divided into left and right. The left and right fuel tanks 11 are distributed and mounted on the upper surface side of the left and right projecting portions of the tank frame 18. Left and right rear axle cases 19 are mounted on the left and right outer surfaces of the mission case 17 so as to protrude outward. Left and right rear axle cases 20 are rotatably inserted in the left and right rear axle cases 19. The rear crawler device 4 is connected to the transmission case 17 via the rear axle 20. The upper part of the left and right rear crawler devices 4 is covered with left and right rear fenders 21.

  A hydraulic lifting mechanism 22 that lifts and lowers a working machine such as a rotary tiller is detachably attached to the rear upper surface of the mission case 17. A work machine such as a rotary tiller is connected to the rear portion of the transmission case 17 via a three-point link mechanism including a pair of left and right lower links 23 and a top link 24. On the rear side surface of the mission case 17, a PTO shaft 25 that projects a PTO driving force to a working machine such as a rotary tiller is provided to project rearward.

  A flywheel 26 is attached to an engine output shaft (not shown) projecting rearward from the rear side surface of the engine 5. A main shaft 27 projecting rearward from the flywheel 26 and a main transmission input shaft 28 projecting forward from the front side of the transmission case 17 are connected via a power transmission shaft 29 having universal shaft joints at both ends. (See FIG. 1). In the transmission case 17, a hydraulic continuously variable transmission, a forward / reverse switching mechanism, a traveling auxiliary transmission gear mechanism, and a differential gear mechanism for rear wheels are arranged. The rotational power of the engine 5 is transmitted to the main transmission input shaft 28 of the transmission case 17 via the main driving shaft 27 and the power transmission shaft 29, and is appropriately shifted by the hydraulic continuously variable transmission and the traveling auxiliary transmission gear mechanism. Then, the speed change power is transmitted to the left and right rear crawler devices 4 via the rear wheel differential gear mechanism.

  The front wheel output shaft 30 projecting forward from the lower front portion of the transmission case 17 projects rearward from the front axle case 13 containing a front wheel differential gear mechanism (not shown) via a front wheel drive shaft 31. A front wheel transmission shaft (not shown) is connected. Transmission power by the hydraulic continuously variable transmission and the traveling auxiliary transmission gear mechanism in the transmission case 17 is transmitted from the front wheel output shaft 30, the front wheel drive shaft 31, and the front wheel transmission shaft to the front wheel differential gear mechanism in the front axle case 13. Is transmitted to the left and right front wheels 3 via.

  Next, the internal structure of the cabin 7 will be described with reference to FIGS. 1 and 2. A steering column 32 is disposed in front of the control seat 8 in the cabin 7. The steering column 32 is erected in a state of being embedded in the back side of the dashboard 33 disposed on the front side inside the cabin 7. A steering handle 9 having a substantially round shape in plan view is attached to the upper end side of the handle shaft that protrudes upward from the upper surface of the steering column 32.

  On the right side of the steering column 32, there is a one-touch lift lever 34 for forcibly moving a working machine such as a rotary tiller to the highest position or the lowest position, and a pair of left and right brake pedals 35 for braking the traveling machine body 2. And are arranged. On the left side of the steering column 32, a forward / reverse switching lever 36 (reverser lever) for switching the traveling direction of the traveling machine body 2 between forward and reverse and a power transmission clutch (not shown) are disconnected. A clutch pedal 37 is provided.

  An erroneous operation preventing body 38 (reverser guard) extending along the forward / reverse switching lever 36 is disposed on the left side of the steering column 32 and below the forward / reverse switching lever 36. By disposing an erroneous operation prevention body 38 as a contact preventer below the forward / reverse switching lever 36, the operator is prevented from inadvertently contacting the forward / reverse switching lever 36 when getting on and off the tractor 1. An operation display panel 39 incorporating a liquid crystal panel is provided on the upper rear side of the dashboard 33.

  An accelerator pedal 41 that controls the rotational speed or the vehicle speed of the engine 5 is disposed on the right side of the steering column 32 in the floor plate 40 in front of the control seat 8 in the cabin 7. Note that substantially the entire top surface of the floor plate 40 is formed as a flat surface. Side columns 42 are arranged on both the left and right sides of the control seat 8. Between the control seat 8 and the left side column 42, the parking brake lever 43 for executing the operation of maintaining the left and right rear crawler devices 4 in a braking state and the traveling speed (vehicle speed) of the tractor 1 are forcibly set. An extremely low speed lever 44 (creep lever) that greatly reduces, a sub transmission lever 45 for switching the output range of the traveling sub transmission gear mechanism in the mission case 17, and a PTO for switching the driving speed of the PTO shaft 25 A shift lever 46 is arranged. A differential lock pedal 47 for turning on and off the differential drive of the left and right rear crawler devices 4 is disposed below the control seat 8. A reverse PTO lever 48 that performs an operation of driving the PTO shaft 25 in the reverse direction is disposed on the left rear side of the control seat 8.

  Between the control seat 8 and the left side column 42, an armrest 49 for placing the arm and elbow of the operator seated on the control seat 8 is provided. The armrest 49 is configured separately from the control seat 8 and has a main transmission lever 50 that increases and decreases the traveling speed of the tractor 1 and a dial type that manually changes and adjusts the height position of a work machine such as a rotary tiller. A working part position dial 51 (elevating dial) is provided. In addition, the armrest 49 is configured to be able to be turned up and rotated in a plurality of stages with the rear end lower part as a fulcrum.

  The left side column 42 includes, in order from the front side, a throttle lever 52 that sets and maintains the rotational speed of the engine 5, and a PTO clutch switch 53 that performs intermittent operation of power transmission from the PTO shaft 25 to a working machine such as a rotary tiller. A plurality of hydraulic operation levers 54 (SCV levers) for switching the hydraulic external take-off valves (sub-control valves, not shown) arranged on the upper surface side of the mission case 17 are arranged. Here, the hydraulic external take-off valve is for supplying and controlling hydraulic oil to another work machine such as a front loader retrofitted to the tractor 1. In the embodiment, four hydraulic operation levers 54 are arranged in accordance with the number of hydraulic external take-out valves (four stations).

  Although illustration is omitted, the left and right lower sides of the front portion of the cabin 7 are connected to front support bases attached to the left and right body frames 15 via front vibration isolating rubber bodies as vibration isolating members. Further, the lower left and right sides of the rear portion of the cabin 7 are connected to a rear support 97 attached to the left and right rear axle cases 19 via a rear vibration isolation rubber body 99 as a vibration isolation member (FIGS. 3 to 3). 6). Accordingly, the traveling machine body 2 supports the cabin 7 in a vibration-proof manner via the plurality of vibration-proof rubber bodies 99.

  Next, the structure of the rear crawler device 4 will be described with reference to FIGS. A rear crawler device 4 is detachably attached to the traveling machine body 2 via a rear axle case 19 projecting outwardly on the left and right outer surfaces of the mission case 17. In this case, as shown in FIGS. 3 to 5, the front end side of the rear axle 20 that is pivotally supported by the rear axle case 19 is protruded outward in the left-right direction, and the drive wheel body 116 is attached to the front end side of the rear axle 20. . A track frame 117 extending in the front-rear direction is disposed below the rear axle case 19. A link support 118 is detachably fastened to the rear axle case 19. The link support 118 includes a front link member 119 on the front side across the rear axle 20 and a rear link member 120 on the rear side. A track frame 117 is connected to the link support 118 via a pair of front and rear link members 119 and 120 so as to be swingable back and forth. That is, the link support body 118 (also referred to as the traveling machine body 2), the pair of front and rear link members 119 and 120, and the track frame 117 form a four-bar link structure.

  As shown in FIGS. 1 and 3 to 5, a front driven wheel body 121 is attached to the front end side of the track frame 117 via a tension adjusting mechanism 122. A rear driven wheel body 123 is attached to the rear end side of the track frame 117 via a bifurcated rear arm 124. The rear driven wheel body 123 is rotatably supported on the rear end side of the bifurcated rear arm 124. A driving crawler 125 made of synthetic rubber as a crawler belt is wound around the three members of the driving wheel body 116, the front driven wheel body 121, and the rear driven wheel body 23 in a substantially triangular shape. The driving wheel body 116 (rear axle 20) is rotated forward and backward at an appropriate speed, and the traveling crawler 125 is driven to rotate forward and backward so that the traveling machine body 2 travels forward and backward.

  The track frame 117 includes a plurality of rolling wheels 126 and a crawler guide body 141. In this case, a plurality of rolling wheels 126 (three in the embodiment, front and rear) are rotatably provided on the track frame 117. The crawler guide body 141 is for preventing the traveling crawler 125 from coming off in the left-right direction, and for holding down a plurality of metal cores (not shown) embedded in the traveling crawler 125 at equal intervals, and is fastened to the track frame 117. ing. On the inner peripheral surface of the traveling crawler 125 between the front driven wheel body 121 and the rear driven wheel body 123 (the inner peripheral surface on the grounding side of the traveling crawler 125), the rolling wheel 126 group and the crawler guide body 141 are provided. Contact. The grounding side of the traveling crawler 25 is configured to be landed and supported by the group of rolling wheels 126 and the crawler guide body 141.

  As shown in FIGS. 3 and 4, a pair of front and rear upper swing support shafts 127 and 128 are connected to the link support 118. The front and rear upper swing support shafts 127 and 128 extend in parallel with the rear axle 20. The front and rear upper swing support shafts 127 and 128 pivotally support upper end side boss portions 119a and 120a of the front and rear link members 119 and 120, respectively. The track frame 117 is connected with front and rear lower swinging support shafts 130 and 131. The lower boss 119 b of the front link member 119 is connected to the track frame 117 so as to be rotatable by the front lower swing support shaft 130. The front lower swing support shaft 130 is positioned in front of the front upper swing support shaft 127, and the front link member 119 is tilted forward and supported downward. A lower boss 120 b of the rear link member 120 is connected to the track frame 117 so as to be rotatable by a rear lower swing support shaft 131. The rear lower swing support shaft 131 is positioned rearward of the rear upper swing support shaft 128, and the rear link member 120 is supported while being inclined obliquely downward and rearward.

  As shown in FIGS. 1, 3, and 4, the pair of front and rear link members 119 and 120 in a side view are in a shape of spreading toward each other. Further, when viewed from the side, the front and rear upper swing support shafts 127 and 128 are located in a region on the inner peripheral side of the traveling crawler 125 and the inner peripheral side of the driving wheel body 116, and the front and rear lower swing support shafts 130 and 131. Is located in a region on the inner peripheral side of the traveling crawler 125 and on the outer peripheral side of the driving wheel body 116. As shown in FIG. 3, the traveling crawler 125 is substantially triangular in that the distance Df from the vertical line passing through the rear axle 20 to the front driven wheel body 121 is larger than the distance Db from the vertical line to the rear driven wheel body 123. Stretched in shape.

  In the above configuration, when the tractor 1 travels forward, the traveling crawler 125 receives the forward reaction force from the ground, whereby the track frame 117 moves forward with respect to the traveling machine body 2, and the traveling crawler 125 is in a forwardly raised posture. Tilt. That is, when the track frame 117 moves in the forward direction with respect to the traveling machine body 2, the front link member 119 rotates in a direction in which the angle of inclination from the horizontal plane becomes smaller (the direction of falling) with the front upper swing support shaft 127 as a fulcrum. Move. The rear link member 120 rotates about the rear upper swing support shaft 128 as a fulcrum in a direction in which the inclination angle from the horizontal plane increases (direction to stand up). As a result, the traveling crawler 125 moves forward while being inclined upward.

  On the other hand, when the tractor 1 is caused to travel backward, the traveling crawler 125 receives the reverse reaction force from the ground, whereby the track frame 117 moves backward with respect to the traveling machine body 2 and the traveling crawler 125 tilts to the forward lowered posture. That is, when the track frame 117 moves rearward with respect to the traveling machine body 2, the front link member 119 is in a direction in which the inclination angle from the horizontal plane increases (the standing direction) with the front upper swing support shaft 127 as a fulcrum. Rotate. The rear link member 120 rotates in a direction in which the angle of inclination from the horizontal plane becomes smaller (a direction to fall) with the rear upper swing support shaft 128 as a fulcrum. As a result, the traveling crawler 125 tilts forward and moves backward.

  When driving the crawler 125 on the inside of the turn is interrupted and turning left or right, if the vehicle is moving forward, the crawler 125 on the inside of the turn may be inclined forward and backward. If this is the case, the traveling crawler 125 on the inside of the turn is inclined upward.

  Front and rear as stoppers for restricting rearward rotation of the front link member 119 with the front upper swing support shaft 127 as a fulcrum and forward rotation of the rear link member 120 with the rear upper swing support shaft 128 as a fulcrum, respectively. Restriction pins 134 and 135 are provided on the link support 118. Front and rear restricting pins 134 and 135 are disposed between the front and rear upper swing support shafts 127 and 128 in the link support 118. A range in which the lower end side of the front link member 119 rotates backward with the front upper swing support shaft 127 as a fulcrum is set by the front restriction pin 134. A range in which the lower end side of the rear link member 120 rotates forward with the rear upper swing support shaft 128 as a fulcrum is set by the rear restriction pin 135. The forward and backward movement of the traveling crawler 125 relative to the traveling machine body 2 is limited by the front and rear restricting pins 134 and 135.

  When the pitching operation (forward tilting operation) is performed so that the front portion of the traveling machine body 2 is lowered, the front link member 119 has a direction in which the inclination angle from the horizontal plane decreases (the direction in which the front link member 119 tilts) with the front lower swing support shaft 130 as a fulcrum. To turn. On the other hand, the rear link member 120 rotates in the direction in which the inclination angle with respect to the horizontal plane increases (direction to stand up) with the rear lower swing support shaft 131 as a fulcrum. As a result, the traveling crawler 125 is supported in a forwardly raised posture with respect to the traveling machine body 2.

  When the pitching operation (backward tilting operation) is performed so that the front part of the traveling machine body 2 is raised, the front link member 119 has a direction in which the inclination angle from the horizontal plane increases with the front lower swing support shaft 130 as a fulcrum (direction to stand up). ). On the other hand, the rear link member 120 rotates in the direction in which the inclination angle from the horizontal plane becomes smaller (the direction in which it falls) with the rear lower swing support shaft 131 as a fulcrum. As a result, the traveling crawler 125 is supported in a forwardly lowered posture with respect to the traveling machine body 2.

  By the way, in the four-bar link structure constituted by the link support 118, the pair of front and rear link members 119 and 120, and the track frame 117, the "instant center" when the track frame 117 as one side moves in the longitudinal direction. Is located at the intersection of the virtual extension line of the front link member 119 and the virtual extension line of the rear link member 120. The track frame 117 moves in the longitudinal direction around the “instantaneous center” that is the intersection point.

  In this case, since the front and rear link members 119 and 120 are located in a divergent shape, the “instantaneous center” moves to the rear side of the aircraft when the traveling aircraft 2 is pitched forward and the traveling aircraft 2 rises forward. When the pitching operation is performed, the aircraft moves forward. That is, the “instantaneous center” is held at a height that is close to the height of the rear axle 20. For this reason, when the traveling machine body 2 performs the pitching operation, the distance that the traveling machine body 2 moves back and forth with respect to the track frame 117 can be significantly reduced as compared with the longitudinal movement distance of the prior art.

  Next, the mounting structure of the track frame 117, the link members 119 and 120, and the link support 118 will be described with reference to FIGS. A link support 118 is provided in the middle of the left and right sides of the rear axle case 19. The link support 118 according to the embodiment is configured so as to be separated from the upper and lower sides with the rear axle case 19 in between. The rear support base 97 located on the upper surface side of the rear axle case 19 and a connecting stay 149 made of a flat steel plate, and the rear axle. A downwardly opening box-shaped link block 150 made of a steel plate located on the lower surface side of the case 19 is provided. The rear axle case 19 is sandwiched from above and below by the rear support base 97 and the connecting stay 149 and the link block 150, and the rear support base 97, the connecting stay 149 and the link block 150 are provided with a plurality of long screw bolts 151 (six in the embodiment). The link block 150 is suspended and supported by the rear axle case 19 by being screwed and fixed from above.

  In the embodiment, four long screw bolts 151 are passed through the bottom plate of the rear support base 97 from above, and each long screw bolt 151 is screwed into a bolt hole 152 formed in the top plate 150 a of the link block 150. In addition, long screw bolts 151 are also passed through the connecting stay 149 from both the front and rear ends, and the long screw bolts 151 are screwed into bolt holes 152 formed in the top plate 150 a of the link block 150. The bolt holes 152 of the embodiment are formed in a total of six, three side by side on the front side of the top plate 150a of the link block 150 and three side by side on the rear side.

  A plurality of vertical grooves 153 arranged in the left-right direction are formed on the front and rear surfaces of the rear axle case 19. In the state where the rear support base 97 and the connecting stay 149 and the link block 150 are fastened by the long screw bolts 151, the shaft portions of the long screw bolts 151 are fitted into the vertical grooves 153. By fitting the shafts of the long screw bolts 151 into the vertical grooves 153, the lateral support 97 and the link block 150 are prevented from being laterally displaced with respect to the rear axle case 19.

  On the top plate 150a of the link block 150, a plurality of positioning projections 154 (two in the embodiment) are provided so as to protrude upward at a location overlapping the lower surface of the rear axle case 19. The positioning projection 154 of the top plate 150a of the link block 150 is inserted into a positioning hole (not shown) formed on the lower surface side of the rear axle case 19 to define the position of the link block 150 with respect to the rear axle case 19, and the rear portion The support base 97, the connecting stay 149, and the link block 150 are fastened by the long screw bolts 151. In the embodiment, the rear support 97 and the connecting stay 149 are separated from each other. For this reason, even in the wheel specification tractor 1 (the rear crawler device 4 is replaced with the rear wheel), the rear support base 97 can be used as it is as a member for supporting the vibration damping of the cabin 7. Further, in the tractor 1 having the specification without the cabin 7 (the rops frame specification), the rear support 97 can be shared as a member for supporting the rops frame (safety frame). Parts are shared between tractors 1 with different specifications, contributing to cost reduction.

  Front and rear restricting pins 134 and 135 are bridged between the left and right side plates 150b and 150c of the link block 150. The longitudinal both ends of the regulating pins 134 and 135 are fixed by welding to the left and right side plates 150b and 150c of the corresponding link block 150, respectively. One end side of each regulation pin 134, 135 penetrates the left and right side plates 150b of the link block 150, and a bolt hole 156 is formed in the protruding end surface of each regulation pin 134, 135.

  The front and rear upper swing support shafts 127, 150 b and 150 c of the link block 150, upper boss portions 119 a and 120 a of the front and rear link members 119 and 120, and thrust washers 157 (may also be referred to as spacers). The front and rear upper swing support shafts 127 and 128 are pivotally supported by the left and right side plates 150b and 150c of the link block 150 so as to be rotatable. A shaft pressing plate 158 is welded and fixed to one end of the front and rear upper swinging support shafts 127 and 128 facing left and right. The upper swinging support shafts 127 and 128 are held so that they cannot be removed from the left and right sides by screwing bolts 159 inserted into the shaft pressing plate 158 inward in the left and right directions into the bolt holes 156 of the restricting pins 134 and 135.

  As shown in detail in FIG. 13, a pair of left and right sliding bearings 167 are fitted into upper boss portions 119 a and 120 a of the front and rear link members 119 and 120. Left and right sliding bearings 167 are fitted on the upper swinging support shafts 127 and 128 inserted into the upper end boss portions 119a and 120a of the link members 119 and 120, respectively. An oil seal 168 is fitted between the sliding bearing 167 and the thrust washer 157 on both opening edge sides of the upper end side boss portions 119a, 120a of the link members 119, 120. The oil seal 168 is fitted on the upper swing support shafts 127 and 128. Chamfered portions 169 are formed on both end sides in the longitudinal direction of the upper end boss portions 119a and 120a of the link members 119 and 120, respectively. An O-ring 170 is fitted between the chamfered portion and the thrust washer 157.

  If comprised in this way, between the upper end side boss | hub part 119a, 120a of each link member 119,120 and each upper rocking | fluctuation spindle 127,128 can be sealed with a simple structure, and each upper rocking | fluctuation spindle 127,128 is sealed. The lubricity and durability can be improved. Since the thrust washer 157 and the O-ring 170 are sandwiched between the left and right side plates 150b and 150c of the link block 150 and the upper end boss portions 119a and 120a of the link members 119 and 120, the presence of the thrust washer 157 and the O-ring 170 It is possible to effectively prevent foreign matters such as muddy water from entering through the gap between the link block 150 having a welded integrated structure and the upper boss portions 119a and 120a of the link members 119 and 120. It is possible to easily prevent dust from entering between the upper end side boss portions 119a and 120a of the link members 119 and 120 and the upper swing support shafts 127 and 128, respectively. When inserting the thrust washer 157 between the left and right side plates 150b, 150c of the link block 150 and the upper end side boss portions 119a, 120a of the link members 119, 120, the O-ring 170 is also interposed together with the thrust washer 157. Due to the presence of the ring 170, the metal contact pressure between the left and right side plates 150b, 150c and the upper end side boss portions 119a, 120a and the thrust washer 157 can be appropriately adjusted, and the high durability of the thrust washer 157 can be realized.

  In the assembly operation, the front and rear link members 119 and 120, the thrust washer 157, and the front and rear upper swing support shafts 127 and 128 are attached to the link block 150, and the link block 150 is configured as a unit. Then, the rear support base 97 and the connection stay 149 are brought into contact with the upper surface side of the rear axle case 19, and the unit structure link block 150 is brought into contact with the lower surface side of the rear axle case 19, so that the rear support base 97 and the connection stay are connected. 149 and the link block 150 are screwed and fixed from above with a plurality of long screw bolts 151. As a result, the front and rear link members 119 and 120 are assembled to the rear axle case 19 via the link support 118.

  As shown in FIGS. 6 to 8, the top plate 150a of the link block 150 extends further inward in the left-right direction than the side plates 150c on the left and right inner sides. A pair of front and rear reinforcing plates 150d are arranged at the corners between the extending side of the top plate 150a and the side plates 150c on the left and right inner sides. Both reinforcing plates 150d are welded and fixed to the extending side of the top plate 150a and the left and right side plates 150c. Further, a steady bracket 144 is fixed to the extended side of the top plate 150a by welding. A turnbuckle type check chain body 145 as a stabilizer is attached to the steady rest bracket 144 in a state in which a working machine such as a rotary tiller (the left and right lower links 23) is allowed to slightly swing left and right (see FIG. 1 and FIG. 2). A base end side of the check chain body 145 is connected to the middle part of each lower link 23 by a pin 146, and a front end side of the check chain body 145 is detachably connected to the steady bracket 144 by a pin 147.

  Next, a connection structure between the track frame 117 and the front and rear link members 119 and 120 will be described with reference to FIGS. The base end sides of the front and rear lower swing support shafts 130 and 131 are pivotally supported by lower end side boss portions 119b and 120b of the front and rear link members 119 and 120, respectively. In the front and rear lower swinging support shafts 130 and 131, the front end sides projecting outward from the lower end side boss portions 119b and 120b of the front and rear link members 119 and 120 have a tapered shape. Bolt holes 161 are formed in both longitudinal ends of the front and rear lower swing support shafts 130 and 131. On the upper surface side of the track frame 117 extending in the front-rear direction, a bearing cylinder 162 opened to the left and right is fixed by welding. Tapered tips of the front and rear lower pivot shafts 130 and 131 with thrust washers 164 fitted therein are inserted into the shaft holes 163 of the bearing cylinder 162. A substantially semicircular disk-shaped shaft holding plate 165 is brought into contact with both longitudinal end faces of the front and rear lower swing support shafts 131 and bolts 166 inserted through the shaft holding plate 165 are attached to the front and rear lower swing support shafts 130, 131. By screwing into a bolt hole 161 formed on each end face of 131, each of the lower swing support shafts 130 and 131 is held so as not to be left and right.

  Next, the detailed structure of the drive wheel body 116 will be described with reference to FIGS. The drive wheel body 116 includes an annular rim body 171 connected to the front end side of the rear axle 20 that protrudes left and right outward from the rear axle case 19, and an annular outer ring body 172 connected to the outer peripheral side of the rim body 171. I have. The inner periphery side of the rim body 171 is fastened to the front end side of the rear axle 20 with a bolt 173, and the inner periphery side of the outer peripheral ring body 172 is fastened to the outer periphery side of the rim body 171 with a bolt 174.

  The outer peripheral ring body 172 includes an annular base portion 175 as a whole and a bifurcated sprocket tooth portion 176 projecting radially outward from the base portion 175. Sprocket tooth portions 176 are provided at equal intervals on the outer peripheral side of the drive wheel body 116, that is, in the entire region of the base portion 175. The outer peripheral ring body 172 of the embodiment is configured to be divided into about a quarter of the same circumference (divided into four partial ring bodies). The driving wheel bodies 116 are configured by arranging the end faces in the radial direction of the partial ring bodies 172a in an annular shape and fastening the bases 175 of the partial ring bodies 172a to the outer peripheral edge side of the rim body 171 with bolts 174. . The four partial ring bodies 172a can be attached to and detached from the rim body 171 independently.

  Next, the tread changing structure of the rear crawler device 4 will be described with reference to FIGS. FIGS. 9 and 10 are examples in which the standard traveling crawler 125 described in the embodiments is mounted, and FIGS. 11 and 21 are narrower in width than the standard traveling crawler 125. This is an example in which a traveling crawler 125 having specifications is attached. In the embodiment, both the link members 119 and 120 are reversed so that they can be replaced with the link support 118 (link block 150), and the left and right outermost portions of the rear axle case 19, that is, the left and right sides from the rear axle case 19 are arranged. The driving wheel body 116 is configured to be replaceable by reversing the driving wheel body 116 with respect to the front end side of the rear axle 20 protruding outward. Here, reversing the front and back means that the front and rear link members 119, 120 and the driving wheel body 116 (more specifically, the outer ring body 172) are on the left and right outer sides (left side in FIGS. 9 to 12) and the left and right inner sides (FIGS. 9 to 12 on the left side).

  As shown in FIGS. 9 to 12, the upper end boss portions 119a and 120a and the lower end side boss portions 119b and 120b of the link members 119 and 120 are displaced from each other to the left and right, and both boss portions 119a and 119b (120a , 120b) has an inclined shape with respect to the vertical line when viewed from the front or the back. Therefore, when the standard traveling crawler 125 is mounted, the lower end boss portions 119b and 120b of the link members 119 and 120 protrude outward in the left and right directions from the upper end boss portions 119a and 120a. When the narrow-width traveling crawler 125 is attached, the lower end boss portions 119b and 120b of the link members 119 and 120 protrude inward in the left-right direction from the upper end boss portions 119a and 120a.

  Further, in the driving wheel body 116, the base 175 and the sprocket tooth portion 176 of the outer peripheral ring body 172 are displaced in the left and right directions, and the connecting portion 177 that connects the base portion 175 and the sprocket tooth portion 176 is seen from the front view or the rear view. The shape is inclined with respect to the vertical line. For this reason, when the standard traveling crawler 125 is attached, the base 175 of the outer peripheral ring body 172 is the left and right center line of the standard traveling crawler 125 (in the embodiment, the driving wheel body 116 and the front and rear driven wheel bodies 121 and 123). Of the left and right width center line L1). When the traveling crawler 125 with a narrow specification is mounted, the base 175 of the outer peripheral ring body 172 is the center line of the lateral width of the traveling crawler 125 with a narrow specification (in the embodiment, the driving wheel body 116 and the front and rear driven wheel bodies 121 and 123). It is located on the left and right outside of the left and right width center line L2. In both the standard specification and the narrow specification, the left and right width center lines L1 and L2 of the driving wheel body 116 and the front and rear driven wheel bodies 121 and 123 coincide with the left and right width center line of the traveling crawler 125.

  When both the link members 119, 120 and the driving wheel body 116 are reversed, the left and right width center lines of the driving wheel body 116 and the front and rear driven wheel bodies 121, 123 are switched from the standard specification L1 to the narrow specification L2. The tread between the left and right rear crawler devices 4 is changed by the difference ΔE between the left and right width center line L1 of the standard specification and the left and right width center line L2 of the narrow specification. That is, the tread between the left and right rear crawler devices 4 can be easily changed simply by attaching both the link members 119 and 120 and the drive wheel body 116 so as to be reversed. In this case, it is possible to change the tread between the left and right rear crawler devices 4 without changing the traveling crawler 125 (for example, the standard specification or the narrow specification). It goes without saying that the tread between the left and right rear crawler devices 4 can be further changed in multiple stages if the driving wheel body 116 is reversed not only to the outer ring body 172 but also to the rim body 171.

  As is apparent from the above description and FIGS. 9 to 12, the traveling machine body 2 on which the engine 5 is mounted, the track frame 117 provided at the lower part of the traveling machine body 2, and the driving wheel body 116 and the slave wheel on the track frame 117. In a work vehicle equipped with a traveling crawler 125 mounted via a moving wheel body 121, 123, a link support 118 is attached to a rear axle case 19 that transmits rotational power to the driving wheel body 116, and the track frame 117 is The link support 118 is connected to the link support 118 via a pair of link members 119 and 120 so as to be able to swing back and forth, and both the link members 119 and 120 are reversed so that they can be replaced with the link support 118. Even if a complicated tread changing structure is not used, the left and right link members 119 and 120 can be replaced by changing the left and right. The tread between the travel crawler 125 can be easily changed. The tread changing structure between the left and right traveling crawlers 125 can be reduced in weight and can be provided at low cost.

  In addition, since the driving wheel body 116 is configured to be reversible by reversing the front and rear sides with respect to the left and right outermost portions of the rear axle case 19, the common parts can be used for the left and right traveling crawlers 125 without using dedicated parts. Tread changes can be set in multiple stages, making it easy to deal with specification changes.

  As is clear from the above description and FIGS. 3 to 8, the traveling machine body 2 on which the engine 5 is mounted, the track frame 117 provided at the lower part of the traveling machine body 2, the driving wheel body 116 and the slave wheel on the track frame 117. In a work vehicle equipped with a traveling crawler 125 mounted via a moving wheel body 121, 123, a link support 118 is attached to a rear axle case 19 that transmits rotational power to the driving wheel body 116, and the track frame 117 is The link support 118 is connected to the link support 118 via a pair of link members 119 and 120 so as to be swingable back and forth, and the link support 118, the pair of front and rear link members 119 and 120, and the track frame 117 are formed into a four-bar link structure. On the other hand, the link support 118 is configured to be vertically separated with the rear axle case 19 in between, Since the lower link support 118 is fastened to the rear axle case 19 by bolts 151 from above, the forward and backward inclined posture of the traveling crawler 125 is greatly changed by the parallel link approximate operation of the four-bar link structure. Can be prevented. In addition, it is possible to prevent a significant variation in the ground resistance of the traveling crawler 125, and to reduce the risk of field disturbance and meandering. Furthermore, it is possible to reduce the number of assembling steps and the assembling time of the link support member 118 separated vertically.

  Further, as shown in FIG. 13, since the O-ring 170 and the thrust washer 157 are fitted on both ends of the link members 119, 120 on the upper swing fulcrum shafts 127, 128 side, the link members The space between the upper swing support shafts 127 and 128 can be sealed with a simple structure, and the lubricity and durability of the upper swing support shafts 127 and 128 can be improved. Since the thrust washer 157 and the O-ring 170 are sandwiched between the link support 118 and the link members 119 and 120, the presence of the thrust washer 157 and the O-ring 170 It is possible to effectively prevent foreign matters such as muddy water from entering through the gaps between the link members 119 and 120. It is possible to easily prevent dust from entering between the link members 119 and 120 and the upper swing support shafts 127 and 128. When the thrust washer 157 is inserted between the link support 118 and each of the link members 119 and 120, the O-ring 170 is interposed together with the thrust washer 157. The metal contact pressure between the link support 118 and each of the link members 119 and 120 and the thrust washer 157 can be adjusted appropriately, and high durability of the thrust washer 157 can be realized.

  The configuration of each unit is not limited to the illustrated embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the traveling crawler 125 described so far in the embodiment is a traveling crawler 125 of a standard specification or a narrow specification, but is not limited thereto, and is combined with a traveling crawler 125 of other specifications such as an offset specification, It is also possible to change the tread between the crawler devices 4. What is necessary is just to determine the combination with the driving | running | working crawler 125 according to an agricultural field situation or work content.

8 Engine 11 Traveling machine body 12 Front wheel 15 Rear axle 17 Track frame 18 Flange member 19 Front link member 20 Rear link member 21 Front driven wheel body 23 Rear driven wheel body 25 Traveling crawler 26 Rolling wheel 27 Front upper swing support shaft 28 Rear Upper swing support shaft 30 Front lower swing support shaft 31 Rear lower swing support shaft 32 Spacer body 85 Spacer flange 86 Rim body

Claims (2)

In a work vehicle comprising a traveling machine body equipped with an engine, a track frame provided at a lower portion of the traveling machine body, and a traveling crawler mounted on the track frame via a driving wheel body and a driven wheel body,
A link support is attached to a rear axle case that transmits rotational power to the drive wheel body, and the track frame is connected to the link support through a pair of front and rear link members so as to be able to swing back and forth. It is configured so that it can be replaced with the link support by inverting the front and back.
Work vehicle. The drive wheel body is configured to be replaceable by inverting the driving wheel body with respect to the left and right outermost portions of the rear axle case.
The work vehicle according to claim 1.

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