JP2017070260A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve higher efficiency of a transmission route and improved operability while ensuring weight and cost saving in a work vehicle such as a tractor.SOLUTION: A lifting mechanism 22 comprises: a lifting cylinder 117 for lifting a linkage 111; a lifting valve mechanism 652 for supplying a hydraulic fluid to the lifting cylinder 117 to raise a cylinder rod 125; and a double-acting valve mechanism 431 for supplying the hydraulic fluid to the lifting cylinder 117 to have the cylinder rod 125 descend. The lifting valve mechanism 652 is arranged on the top surface in the rear of a transmission case for direct advance 17, and the double-acting valve mechanism 431 is arranged on one lateral side in the rear of the transmission case for direct advance 17.SELECTED DRAWING: Figure 18

Description

  For example, the present invention relates to a work vehicle such as a farm work machine such as a tractor or a combiner, or a special work machine such as a crane truck or a backhoe.

  2. Description of the Related Art Conventionally, a work vehicle such as a farm vehicle such as a tractor or a combiner or a construction machine such as a crawler crane has been provided with two hydraulic continuously variable transmissions (HST) to which power from an engine is transmitted. Some types of continuously variable transmissions output straight power and turning power based on engine output. The applicant of the present application previously proposed a work vehicle in Patent Document 1 that can turn by combining the straight power and the turning power output from each of the two hydraulic continuously variable transmissions with the left and right planetary gear mechanisms. ing.

  In addition, some conventional work vehicles include a transmission case that transmits power from an engine and a hydraulic mechanical transmission (HMT) that has higher transmission efficiency than a hydraulic continuously variable transmission. The applicant of the present application has previously made a series-type (in-line type) hydraulic mechanical transmission in which the hydraulic pump and the hydraulic motor are arranged in series so that the input shaft of the hydraulic pump and the output shaft of the hydraulic motor are positioned concentrically. Is proposed in Patent Document 2.

  In an inline type hydraulic mechanical transmission, an output shaft is fitted on an input shaft to which power is transmitted from an engine so as to be relatively rotatable. Further, a hydraulic pump, a cylinder block, and a hydraulic motor are fitted on the input shaft. The cylinder block alone serves as both a hydraulic pump and a hydraulic motor, and power is transmitted from the hydraulic motor to the output shaft. For this reason, unlike a general hydraulic mechanical transmission, an in-line type hydraulic mechanical transmission can output a combination of hydraulic shift power and engine power without interposing a planetary gear mechanism. It has the advantage that transmission efficiency can be obtained.

  Further, as a conventional technique, a lifting device for a working machine has been proposed that uses only a hydraulic cylinder of a double-acting piston, but has a function equivalent to that of a hydraulic cylinder formed with a single-acting piston. (See Patent Document 3).

JP 2002-059753 A Japanese Patent Laying-Open No. 2005-083497 JP 2008-028104 A

  Incidentally, in order to mount the hydraulic mechanical transmission in Patent Document 2 on a medium-sized or large work vehicle, it is necessary to increase the output of the hydraulic mechanical transmission. In order to increase the output of the hydraulic mechanical transmission, for example, the capacity of the hydraulic mechanical transmission can be increased. However, simply increasing the capacity of the hydraulic mechanical transmission not only increases the size of the hydraulic mechanical transmission itself but increases the manufacturing cost, but also sacrifices the power transmission efficiency (especially in the low load range). There was a problem.

  Further, even when the mechanism in Patent Document 1 is mounted on a large work vehicle, the mechanism becomes larger with the increase in output of the hydraulic continuously variable transmission, which not only increases the weight of the work vehicle but also transmits power. Since the efficiency is lower than that of the hydraulic mechanical transmission, the speed change range (main speed change range) in the straight direction is limited.

  Further, in the hydraulic circuit of Patent Document 3, although the piston used for the lifting device of the working machine can be operated by switching between the single-action operation and the double-action operation, the working vehicle including the double-action piston and the single-action type When a plurality of vehicle types are manufactured using the same traveling machine body instead of using common parts with a work vehicle including a piston, an assembly process may be complicated. Therefore, the assembly work of the work vehicle including the double-acting piston becomes independent, which not only increases the work cost, but also requires the assembly work to be changed for each vehicle type, which places a heavy load on the assembly work and maintenance work.

  This invention makes it a technical subject to provide the working vehicle which examined and improved the above present condition.

  A work vehicle according to the present invention includes a traveling machine body on which an engine is mounted, a link mechanism that mounts the work machine on the traveling machine body, and an elevating mechanism that moves the link mechanism up and down. A part of the traveling machine body is used as a transmission case. In the working vehicle configured as described above, the elevating mechanism includes an elevating cylinder that elevates and lowers the link mechanism, an elevating valve that supplies hydraulic oil to the elevating cylinder and raises the cylinder rod, and supplies hydraulic oil to the elevating cylinder. And a double-acting valve for lowering the cylinder rod. The elevating valve is disposed on the rear upper surface of the transmission case, and the double-acting valve is disposed on one rear surface of the transmission case.

  In the work vehicle, a hydraulic pump that is driven by power through the transmission mechanism in the transmission case is attached to the rear side surface of the transmission case, and the hydraulic pump and the double-acting valve are connected by hydraulic piping. It is good.

  In the work vehicle, the elevating mechanism further includes a horizontal cylinder that changes a right and left tilt angle of a work machine supported by the link mechanism, and a horizontal control valve that operates the horizontal cylinder, and the rear of the transmission case. On the top surface, the horizontal control valve is disposed behind the elevating valve, and a hydraulic external take-off valve is disposed behind the horizontal control valve for switching operation oil to and from a hydraulically-driven working machine that is detachably attached to the traveling machine body. The hydraulic external take-out valve and the horizontal control valve may be connected to the double-acting valve by hydraulic piping.

  In the work vehicle, the traveling unit is a crawler, and a frame rear connection body connected to a rear part of a track frame having the crawlers crawled on the left and right of the transmission case is connected to the left and right of the transmission case, and the frame rear part is connected. It is good also as what supports the back of a control part with a body side surface, and supports the double-acting valve with the front of the frame rear part connecting body.

  In the work vehicle, a crawler and a wheel are configured to be selectable as the traveling unit, and when the traveling unit is a wheel, a rear accelerator case for driving a rear wheel is connected to the left and right of the transmission case, The rear part of the control part may be supported above the rear axle case.

  According to the present invention, hydraulic equipment parts related to the lifting mechanism provided in the mission case can be arranged together to form a unit, assembly and maintenance work of the mission case and lifting mechanism can be easily simplified, and the assembly of the mission case is easy. It can be improved. In addition, a lifting valve is supported on the rear upper surface of the mission case and a double-acting valve is arranged on one side of the rear of the mission case, so that the lifting mechanism can be installed compactly behind the mission case and the hydraulic piping can be simplified. Can reduce the complexity.

  According to the present invention, when a double-acting valve mechanism is additionally installed as an elevating mechanism, each component of the elevating mechanism is arranged behind the transmission case, so that each hydraulic pipe connected to the double-acting valve can be shortened. In addition, the complexity of the piping installation work can be eliminated. In addition, parts of the lifting mechanism that are capable of single-acting operation other than double-acting valves are installed together on the top surface of the mission case, while double-acting valves that also allow double-acting operation are installed on the side of the mission case. It is installed in. Therefore, when assembling a work vehicle equipped with a mechanism with a single-action operation using only a lift valve as a lifting mechanism and a work vehicle equipped with a mechanism capable of double-action operation with a double-action valve, each assembly is performed. It is possible to prevent errors in work.

  According to the present invention, the double-acting valve is supported by the mission case that is a part of the traveling machine body and is a highly rigid part together with the control unit. Moreover, since the frame rear connector is a member that is also connected to the track frame, the double-acting valve is supported in a stable state. By supporting the double-acting valve mechanism on the frame rear coupling body, the unit can be configured together with the frame rear coupling body as a unit for adding a double-action function, so that the assembly work can be made more efficient.

  According to the present invention, it is possible to select a crawler and a wheel as a traveling portion, and in a multi-type work vehicle, not only can a straight traveling mission case be used as a common part, but also the assembly workability can be improved and the cost can be reduced.

It is a left view of a tractor. It is a right view of a tractor. It is a top view of a tractor. It is a right view of a traveling body. It is a left view of a traveling body. It is a top view of a traveling body. It is the perspective view seen from the right rear of a traveling machine body. It is the perspective view seen from the right front of the traveling body. It is the perspective view seen from the left front of the traveling body. It is the perspective view seen from the left rear of a traveling machine body. It is a plane explanatory view of a control seat part. It is a perspective view which shows the connection structure of a brake mechanism and a brake pedal. It is a skeleton figure of the power transmission system of a tractor. It is a hydraulic circuit diagram of a tractor. It is a top view which shows the piping path | route of the hydraulic piping in a tractor. It is a left view of the mission case for going straight. It is a top view of the mission case for straight advance. It is a back expansion perspective view of a traveling machine body. It is a perspective view which shows the structure of the left fuel tank periphery. It is a disassembled perspective view which shows the structure of a rear housing periphery. It is the perspective view seen from the lower side which shows the structure of a link mechanism and a tank frame. It is a bottom enlarged view which shows the structure of a link mechanism. It is a top view of the traveling body which shows each composition at the time of making a run part into a crawler and a wheel. It is a rear view of the traveling body which shows each when a traveling part is made into a crawler and a wheel. It is the schematic explaining operation | movement of a double acting valve.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings for a farm tractor. As shown in FIGS. 1 to 10, the traveling machine body 2 of the tractor 1 is supported by a pair of left and right traveling crawlers 3 as traveling portions. A diesel engine 5 (hereinafter simply referred to as an engine) is mounted on the front of the traveling machine body 2, and the traveling crawler 3 is driven by the engine 5 so that the tractor 1 travels forward and backward. The engine 5 is covered with a bonnet 6. A cabin 7 is installed on the upper surface of the traveling machine body 2. Inside the cabin 7, a steering seat 8 and a steering handle 9 for steering the traveling crawler 3 are arranged. Steps 10 on which the operator gets on and off are provided on the left and right outer sides of the cabin 7. A fuel tank 11 for supplying fuel to the engine 5 is provided below the left and right sides of the cabin 7. The fuel tank 11 is covered with left and right rear fenders 21. A battery 817 that supplies power to the front of the fuel tank 11 is provided on the left side of the cabin 7, and is covered with the left rear fender 21 together with the fuel tank 11.

  As shown in FIGS. 1 to 10, the traveling machine body 2 includes an engine frame 14 having a front bumper 12 and a turning mission case 13, and left and right machine body frames 15 detachably fixed to a rear portion of the engine frame 14. ing. The axle 16 is rotatably projected outwardly from the left and right ends of the turning mission case 13, and axle cases 90 covering the axle 16 are provided on both the left and right sides of the turning mission case 13. Sprockets 62 are attached to the left and right ends of the turning mission case 13 via axles 16. The rear part of the body frame 15 is connected to a straight traveling mission case 17 for appropriately changing the rotational power from the engine 5 and transmitting it to the sprocket 62.

  A hydraulic lifting mechanism 22 that lifts and lowers a ground working machine (not shown) such as a rotary tiller is detachably attached to the rear portion of the straight traveling case 17. The ground work machine is connected to the rear part of the straight traveling transmission case 17 via a three-point link mechanism 111 including a pair of left and right lower links 23 and a top link 24. A PTO shaft 25 for transmitting a PTO driving force to a working machine such as a rotary tiller is provided on the rear side surface of the straight traveling case 17 so as to protrude rearward.

  A pair of left and right engine frames (front frame) 14 has a front end side inner surface connected to the left and right outer surfaces of the frame connecting member 12a, and the front bumper 12 is fixed in front of the frame connecting member 12a. The frame connecting member 12a is made of a rectangular metal casting, and the diesel engine 5 is supported on the engine frame 14 installed by the frame connecting member 12a. A frame bottom plate 233 is installed on the upper edges of the left and right engine frames 14 and the upper surface of the frame connecting member 12a so as to cover the upper front side of the engine frame 14. An under cover 296 that covers the lower side of the turning mission case 13 is installed on the lower edge of the engine frame 14 from the front end of the engine frame 14 toward the rear. The under cover 296 has its front end connected to the lower surface of the frame connecting member 12a, while its left and right side edges are connected to the left and right engine frames 14, respectively.

  A radiator 235 having a fan shroud 234 attached to the back side is erected on the frame bottom plate 233 so as to be positioned on the front side of the engine 5. The fan shroud 234 surrounds the outer peripheral side of the cooling fan 206 and allows the radiator 235 and the cooling fan 206 to communicate with each other. A rectangular frame-shaped frame 226 is erected on the frame plate 233 on the front side of the radiator 235. An intercooler 220, an oil cooler 274, a condenser 275, and the like are installed in the frame frame 226. An air cleaner 221 is installed above the front surface of the frame frame 226, and a fuel cooler below the air cleaner 221. 273 is installed.

  The front end sides of the left and right airframe frames 15 are connected to the rear end sides of the left and right engine frames 14, and the left and right airframe frames 15 are arranged so as to sandwich the left and right engine frames 14. A support beam frame 236 is connected to the middle part of the pair of left and right body frames 15. The body frame 15 has a front end connected to the rear end of the engine frame 14, a midway portion connected to the end face (outer side face) of the support beam frame 236, and a rear end connected to the straight traveling mission case 17. The support beam frame 236 is bolted to the left and right airframe frames 15 to mount the left and right airframe frames 15, and the engine support frame 237 is mounted on the upper surface thereof. The engine support frame 237 has a shape that surrounds the flywheel 26 of the diesel engine 5 together with the support beam frame 236 by fastening the lower end surface of the engine support frame 237 with the upper surface of the support beam frame 236.

  As shown in FIGS. 1 to 10, the diesel engine 5 has a cylinder head mounted on a cylinder block containing an engine output shaft 5a (see FIG. 12) and a piston, and an intake manifold is disposed on the right side of the cylinder head. On the other hand, an exhaust manifold is arranged on the left side of the cylinder head. That is, the intake manifold and the exhaust manifold are distributed and arranged on both side surfaces along the engine output shaft 5a in the engine 5. The cooling fan 206 is disposed on the front surface of the cylinder block in the diesel engine 5, while the flywheel 26 is disposed on the rear surface of the cylinder block. That is, the flywheel 26 and the cooling fan 206 are arranged separately on both side surfaces of the engine 5 that intersect the engine output shaft 5a.

  A flywheel 26 is attached to the rear end of the output shaft (piston rod) 5a (see FIG. 12) of the engine 5 protruding rearward from the rear side surface of the engine 5. A main shaft 27 projecting rearward from the flywheel 26 and an input counter shaft 28 projecting forward from the front side of the straight traveling mission case 17 are connected via a power transmission shaft 29 having universal shaft joints at both ends. . The straight output shaft 30 that protrudes forward from the lower front portion of the straight transmission case 17 has a linear input counter that protrudes backward from the turning mission case 13 via a power transmission shaft 31 having universal joints at both ends. The shaft 508 is connected. The front end of the output shaft (piston rod) 5a of the engine 5 protruding forward from the front side surface of the engine 5 protrudes rearward from the turning mission case 13 via a power transmission shaft 711 having universal joints at both ends. The turning input counter shaft 712 is connected.

  Front engine legs (engine mounts) 238 having anti-vibration rubber are respectively bolted to the left and right side surfaces of the cylinder block of the engine 5. The engine legs 238 are bolted to the upper portions of the engine support brackets 298 connected to the outside of the midway part of the pair of left and right engine frames 14. The diesel engine 5 is sandwiched between the engine frames 14 by a pair of left and right engine legs 238 to support the front side of the diesel engine 5. In the diesel engine 5, the upper part of the rear flywheel housing 60 is connected to the upper surface of the engine support frame 237 via an engine leg (engine mount) 240 having vibration-proof rubber. The rear surface of the diesel engine 5 is connected to the front end sides of the pair of left and right body frames 15 via the support beam frame 236, the engine support frame 237, and the engine legs 240, and the diesel engine 5 is rearward at the front end of the body frame 15 The side is supported.

  As shown in FIGS. 1 to 10, left and right track frames 61 are arranged on the lower surface side of the traveling machine body 2. The track frame 61 extends in the front-rear direction and is provided in a pair of left and right sides, and is positioned on both outer sides of the engine frame 14 and the body frame 15. The left and right track frames 61 are connected to the engine frame 14 and the body frame 15 by a lower frame 67 extending in the left-right direction. The front ends of the left and right track frames 61 are connected to axle cases 90 provided on both left and right sides of the turning mission case 13. On the outside of each of the left and right track frames 61, a step 10a on which the operator gets on and off is provided.

  The left and right central portions of the lower frame 67 are fixed to the rear side surface of the engine frame 14 via a connection bracket 72. The left and right ends of a beam frame 68 extending in the left-right direction are connected to the middle part of the left and right track frames 61 in the front-rear direction. Rear beams 73 projecting inward at the rear of the left and right track frames 61 are connected to rear housings 74 fixed to the left and right side surfaces of the straight traveling mission case 17 so that the rear part of the track frame 61 is connected to the left and right side surfaces of the transmission case 17. Fix it.

  The track frame 61 includes a drive sprocket 62 that transmits the power of the engine 5 to the traveling crawler 3, a tension roller 63 that maintains the tension of the traveling crawler 3, and a plurality of track rollers that hold the ground side of the traveling crawler 3 in a grounded state. 64 and an intermediate roller 65 that holds the non-grounding side of the traveling crawler 3. The driving sprocket 62 supports the front side of the traveling crawler 3, the tension roller 63 supports the rear side of the traveling crawler 3, the track roller 64 supports the grounding side of the traveling crawler 3, and the intermediate roller 65 supports the non-traveling crawler 3. Support the ground side. The tension roller 63 is rotatably supported by a rear end of a tension frame 69 configured to be extendable and retractable rearward from the rear end of the track frame 61. The track roller 64 is rotatably supported on the front and back of an equalizer frame 71 supported on the lower part of the track frame 61 so as to be swingable back and forth.

  Further, a front dozer 80 can be mounted on the front portion of the tractor 1. A pair of left and right dozer brackets 81 are fixed to the front side surface of the engine frame 14, the axle case 90, and the lower frame 67, and a U-shaped (U-shaped) support arm 83 of the front dozer 80 in the plan view is The dozer bracket 81 is pivotally supported so as to be detachable on the outside (machine outside). The left and right dozer brackets 81 have a front end inside (machine inside) connected to the side surfaces of the left and right engine frames 14, a rear end lower side connected to the upper surface of a middle part of the lower frame 67, and a midway part in the middle of the axle case 90. It is connected so that it can be held up and down. The dozer bracket 81 can be secured to the three bodies of the engine frame 14, the axle case 90, and the lower frame 67, thereby ensuring the strength to withstand heavy work by the front dozer 80.

  The front dozer 80 includes a pair of left and right connecting frames 82 that are bolted to the outside (machine outside) of each of the pair of left and right dozer brackets 81. The end is pivotally supported at the front lower part of the left and right connecting frames 82 so as to be rotatable up and down. A pair of left and right lifting cylinders 85 are interposed between the front upper portion of the left and right support frames 82 and the front end portions of the left and right upper surfaces of the support arm 83 so that the support arms 83 can be raised and lowered by extending and retracting the lifting cylinders 85.

  A blade 84 is provided at the front end of the support arm 83 via a blade attachment body 88. A blade mounting body 88 is pivotally supported at the left and right center of the support arm 83 so as to be rotatable left and right, and the blade 84 is supported on the front surface of the blade mounting body 88 so as to be tiltable. An inclined cylinder 87 is interposed between the upper left and right central portions of the blade 84 and the left and right sides of the blade mounting body 88, and the blade 54 can be tilted by extending and contracting the inclined cylinder 87. A pair of left and right angle cylinders 86 are interposed between the left and right rear portions of the support arm 83 and the left and right sides of the blade mounting body 88. The left and right angle cylinders 86 are expanded and contracted in opposite directions to move the blade mounting body 88 left and right. It can be rotated. Thus, the blade 84 can be moved up and down, tilted forward and backward, and tilted up and down.

  As shown in FIGS. 1 to 10, the cabin 7 that covers the control seat 8 on the traveling machine body 2 includes a cabin frame 300 that forms a framework. The cabin frame 300 includes a pair of left and right front columns 301 positioned in front of the control seat 8, a pair of left and right rear columns 302 positioned behind the control seat 8, and a front beam that connects between the upper ends of the front columns 301. A member 303, a rear beam member 304 for connecting the upper ends of the rear columns 302, and a left and right side beam member 305 for connecting the upper ends of the front columns 301 and the rear columns 302 arranged in the front-rear direction. It is a box frame. A roof body 306 is detachably attached to the upper end side of the cabin frame 301, that is, on a rectangular frame constituted by the front beam member 303, the rear beam member 304, and the left and right side beam members 305.

  The left and right outer end sides of the front lower plate member 307 extending inward in the left-right direction are connected to the lower end side of each front column 301. A vertically long board support plate 901 that fixes and supports the dashboard 33 is connected to the left and right inner ends of the left and right front lower plate members 307, and the board support plate 901 is erected between the left and right front columns 301. On the other hand, a rear intermediate beam member 309 extending in parallel with the rear beam member 304 is connected between the lower ends of the left and right rear columns 302. The rear intermediate beam member 309 is connected to the upper ends of a pair of left and right rear lower frames 310 extending downward.

  End portions in the longitudinal direction of the bottom frame 311 extending in the front-rear direction are connected to the front lower plate 307 and the lower end side of the rear lower frame 310 aligned in the front-rear direction. The floor plate 40 is stretched on the upper surface side of the left and right bottom frames 311, the dashboard 33 is erected on the front end side of the floor plate 40, and the steering handle 9 is installed on the rear surface side of the dashboard 33 via the steering column 32. . A brake pedal 35 and the like are disposed on the front upper surface side of the floor board 40, and the control seat 8 is attached to the rear upper surface side of the floor board 40.

  The cabin 7 is supported by the traveling machine body 2 via left and right front support tables 96 and left and right rear support tables 97. A front support 96 is bolted to the front end of the left and right machine frame 15 and the front bottom of the cabin 7 is supported on the upper surface of the front support 96 via a vibration isolating rubber member 98. doing. Further, a rear support base 97 is bolted to the outer side surface of the rear housing 74 provided on the left and right of the straight traveling mission case 17, and the rear side of the cabin 7 is provided on the upper surface side of the rear support base 97 via a vibration isolating rubber body 99. Anti-vibration support for the bottom. Accordingly, the cabin 7 is supported by the traveling machine body 2 in a vibration-proof manner via the plurality of vibration-proof rubber bodies 98 and 99.

  The tank frame 18 is fixed to the upper surfaces of the left and right rear support bases 97 and supported by the rear housing 74 via the rear support bases 97. That is, the pair of left and right tank frames 18 are fixed to the traveling machine body 2 by being distributed to the left and right sides of the cabin 7 at a position above the crawler 3. In each of the left and right tank frames 18, two supporting pillar frames 290 are provided upright on a tank mounting plate 289 on which the fuel tank 11 is placed. The supporting column frame 290 is provided on the cabin 7 side, and the fuel tank 11 is installed on the upper surface of the tank mounting plate 289 and on the outer side (outside of the machine) from the supporting column frame 290. Then, by fixing the other end of the band 286 having one end connected to the upper end of the support column frame 290 to the tank mounting plate 290, the two front and rear portions of the fuel tank 11 are placed on the tank mounting plate 289 by the band 286. Bonded and fixed.

  A battery 817 is installed on one of the left and right tank frames 18 (in this embodiment, the left tank frame 18). The battery 817 is installed in front of the fuel tank 11, and a battery mounting plate 291 is extended in front of the tank mounting plate 289 of the tank frame 18. The lower side of the battery mounting plate 291 is connected to a reinforcing frame 292 that is connected to the front side surface of the rear support 97, and the battery 291 is supported with high rigidity.

  The fuel tank 11 and the battery 817 mounted on the left and right tank frames 18 are covered with a rear fender 21 below the cabin 7, and the rear fender 21 functions as a tank cover. One of the left and right rear fenders 21 (in this embodiment, the left rear fender 21) is configured to cover the battery 817 together with the fuel tank 11, and a battery opening is provided on the front side surface where the battery 817 is installed. A door 21a is provided. The battery opening door 21a is provided at a front position corresponding to the battery 817, and is opened rearward and outward by a hinge member also received inside the rear fender 21. By opening the battery opening door 21a, the battery 817 installation position of the rear fender 21 can be greatly opened, so that various maintenance work including replacement of the battery 817 is facilitated.

  The left and right fuel tanks 11 that are installed to be divided into left and right below the cabin 7 are communicated with the fuel communication pipe 281 at the front lower side, and one of the left and right fuel tanks 11 (in this embodiment, the right fuel tank). A refueling port 283 is provided above the tank 11). As a result, the fuel supplied from the fuel filler port 283 to one fuel tank 11 is also supplied to the other fuel tank 11 through the fuel communication pipe 281.

  In addition, one of the left and right rear fenders 21 (in the present embodiment, the right rear fender 21) includes a refueling open door 21b at a position on the upper rear side and corresponding to the refueling port 283. The refueling open door 21 b is opened rearward and outward by a hinge member also received inside the rear fender 21. Accordingly, even when the refueling open door 21b is opened, the refueling open door 21b does not collide when the cabin 7 door is opened. Furthermore, by arranging the fuel filler opening 283 and the battery 817 on the left and right sides of the fuel tank 11, not only can the opening area of the rear fender 21 be suppressed and the strength can be prevented, but also the operator can easily identify the doors 21a and 21b. Become.

  Breather hoses 331 and 332 that release the inside of the fuel tank 11 to the atmosphere are piped up to the rear upper side along the cabin frame 300. Specifically, breather hoses 331 that connect the upper surfaces of the left and right fuel tanks 11 extend to the left and right along the rear intermediate beam member 309. The breather hose 331 is connected to the breather hose 332 connected to the upper surface of one fuel tank 11 (in the embodiment, the right fuel tank 11) below the connecting portion between the rear strut 302 and the rear intermediate beam member 309. Air in the tank 11 is merged by breather hoses 331 and 332. The breather hose 332 extends upward along the rear strut 302 from the connection position with the breather hose 331. The upper end of the breather hose 331 is embedded in the roof body 306 to prevent rainwater from entering the breather hose 331 and to prevent rainwater from entering the fuel tank 11.

  An oil / water separator 215 and an auxiliary fuel pump 216 for supplying the fuel in the fuel tank 11 to the diesel engine 5 are arranged on a tank frame 18 on which one of the left and right fuel tanks 11 is mounted. In the present embodiment, the fuel filter 217 is disposed on the right side of the engine 5, and the oil / water separator 215 and the auxiliary fuel pump 216 are fixed to the right tank frame 18. That is, since the battery 817 is also installed in the left tank frame 18, not only can the oil / water separator 215 and the auxiliary fuel pump 216 be effectively arranged in the right tank frame 18 having a large installation space, but also the same side as the fuel filter 217. In addition, the oil / water separator 215 and the auxiliary fuel pump 216 can be arranged to improve the efficiency of the piping work of the fuel supply path. The oil / water separator 215 is suspended and supported by the rear support column frame 290 of the tank frame 18, while the auxiliary fuel pump 216 is mounted and fixed on the upper surface of the tank mounting plate 289 on the front side of the fuel tank 11. Yes.

  As shown in FIGS. 1 to 10, the hydraulic lifting mechanism 22 is provided with lift fulcrums on the left and right hydraulic lift cylinders 117 that are controlled by operation of the working unit position dial 51 and the upper lid of the transmission case 17. Left and right lift arms 120 that pivotally support the base end side through a shaft so as to be rotatable, and left and right lift rods 121 that connect the left and right lift arms 120 to the left and right lower links 23 are provided. A part of the right lift rod 121 is formed by a horizontal cylinder 122 for hydraulic control, and the length of the right lift rod 121 is configured to be adjustable by the horizontal cylinder 122. When the ground work machine is supported by the top link 24 and the left and right lower links 23, the piston of the horizontal cylinder 122 is expanded and contracted to change the length of the right lift rod 121. The angle is configured to change.

  Next, the internal structure of the cabin 7 will be described with reference to FIGS. 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, a brake pedal 35 for performing a braking operation on the traveling machine body 2 is disposed. 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. A parking brake lever 43 for holding the brake pedal 35 in the depressed position is disposed on the rear side of the steering column 32. On the right side of the steering column 32, a work implement lifting lever 963 for operating the lifting operation of the hydraulic lifting mechanism 22 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 for controlling the rotational speed of the engine 5 or the vehicle speed is arranged on the right side of the steering column 32 on 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, an ultra-low speed lever 44 (creep lever) for forcibly and greatly reducing the traveling speed (vehicle speed) of the tractor 1 and a traveling sub-shift in the straight traveling mission case 17 are provided. An auxiliary transmission lever 45 for switching the output range of the gear mechanism and a PTO transmission lever 46 for switching the drive speed of the PTO shaft 25 are arranged.

  Between the control seat 8 and the right side column 42, an armrest 49 for placing an arm or elbow of an 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 ground working machine such as a rotary tiller. Working part position dial 51 (elevating dial). Note that the armrest 49 is configured to be able to be turned up and rotated in a plurality of stages with the rear end lower portion as a fulcrum. In the present embodiment, the vehicle speed of the traveling machine body 2 increases when the main transmission lever 50 is tilted forward, while the vehicle speed of the traveling machine body 2 decreases when the main transmission lever 50 is tilted backward. The main transmission lever 50 is provided with a work implement elevating switch 964 that designates the vertical movement of the hydraulic lifting mechanism 22 by tilting up and down on the front surface, and the hydraulic lifting mechanism 22 is moved up and down on the side surface on the control seat 89 side. A lift adjustment switch 965 for fine adjustment is provided.

  The right side column 42 has, in order from the front side, an operation monitor 55 having a touch panel function and capable of commanding each part of the tractor 1, a throttle lever 52 for setting and maintaining the rotational speed of the engine 5, and the PTO shaft 25. A plurality of hydraulic control levers for switching between a PTO clutch switch 53 for intermittently transmitting power to a working machine such as a rotary tiller and a hydraulic external take-off valve 430 disposed on the upper surface side of the straight traveling mission case 17 54 (SCV lever) and a single-acting switch 56 for switching the actuating double-acting valve mechanism 431 disposed on the front surface of the rear housing 74. Here, the hydraulic external take-off valve 430 is for controlling supply of hydraulic oil to hydraulic equipment of another work machine such as a front loader retrofitted to the tractor 1. The double-acting valve mechanism 431 is for operating the lift cylinder 117 in a double-acting manner by operating together with the elevating valve mechanism 652 disposed on the upper surface side of the straight traveling mission case 17.

  Next, the relationship between the brake pedal 35 and the brake mechanism 751 will be described mainly with reference to FIG. In front of the steering column 32, a brake pedal support bracket 916 that supports the brake pedal shaft 755 is fixed to the back surface of the board support plate (air cut plate) 901 (the control seat 8 side). The base end boss portion 35a of the brake pedal 35 is fitted on the brake pedal shaft 755, and the base end boss portion 35a of the brake pedal 35 is connected so as to rotate integrally with the brake pedal shaft 755. A pedal shaft arm 756 protruding forward is fixed to both ends of the brake pedal shaft 755, and the pedal shaft arm 756 rotates together with the brake pedal shaft 755.

  A pair of left and right brake operation shafts 757 are supported on the left and right lower sides of a board support plate (air cut plate) 901. A link boss body 758 connected to the brake arm 752 of the brake mechanism 751 in the turning mission case 13 is rotatably fitted to the left brake operation shaft 757. A link arm 759 projecting from the outer peripheral surface of the link boss body 758 has a two-stage expansion / contraction that makes the braking operation of the brake mechanism 751 stepwise and the lower end of a vertically long link rod 762 connected to the left pedal shaft arm 756. The upper end of the link body 763 is connected. The lower end of the two-stage telescopic link body 763 is connected to the tip of the link arm 767 at the rear end of the brake rod 766. The brake rod 766 is supported by link support brackets 764 and 765 fixed to the engine frame 14 and extends in the front-rear direction. The link arm 768 at the front end of the brake rod 766 is connected to the brake arm 752 of the brake mechanism 751 in the turning mission case 13 via the connecting plate 753.

  That is, the left end of the brake pedal shaft 755 is connected to the brake arm 752 of the brake mechanism 751 via the link rod 762, the two-stage telescopic link body 763, and the brake rod 766. Therefore, as the brake pedal shaft 755 rotates as the brake pedal 35 is depressed, the brake arm 752 can be rotated, and the braking operation by the brake mechanism 751 can be executed. At this time, when the two-stage telescopic link body 763 acts, the amount of stepping for sudden braking is larger (the brake mechanism 751) than when the amount of stepping for adjusting the traveling speed is small (the play area of the brake mechanism 751). The braking force applied to the brake pedal 35 is increased in the braking region).

  A link boss body 760 having a link arm 761 is rotatably fitted to the right brake operation shaft 757. The upper end of a two-stage telescopic link body 769 for stepping on the brake pedal 35 is connected to the right pedal shaft arm 756, and the link arm 761 projecting from the outer peripheral surface of the link boss body 760 has two stages. The lower end of the telescopic link body 769 is connected. When the brake operation shaft 757 is rotated according to the depression of the brake pedal 35, the two-stage telescopic link body 769 acts, so that the amount of depression for adjusting the traveling speed is small (play area of the brake mechanism 751). Thus, when the amount of stepping on the sudden brake is large (braking region by the brake mechanism 751), the depression force on the brake pedal 35 increases.

  Next, the internal structure of the straight traveling mission case 17 and the turning mission case 13 and the power transmission system of the tractor 1 will be described mainly with reference to FIGS. In the front chamber of the straight traveling case 17, there are a hydraulic mechanical continuously variable transmission 500 for straight traveling, a mechanical creep transmission gear mechanism 502 for shifting rotational power via a forward / reverse switching mechanism 501, which will be described later, and a traveling auxiliary gear. A transmission gear mechanism 503 is disposed. A forward / reverse switching mechanism 501 that switches the rotational power from the hydraulic mechanical continuously variable transmission 500 in the forward or reverse direction is disposed in the intermediate chamber of the transmission case 17 for straight travel. A PTO transmission mechanism 505 that appropriately changes the rotational power from the engine 5 and transmits it to the PTO shaft 25 is disposed in the rear chamber of the straight traveling mission case 17. The creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503 correspond to a traveling transmission gear mechanism that multi-shifts the transmission output via the forward / reverse switching mechanism 501. A pump case 480 accommodating a working machine hydraulic pump 481 driven by the rotational power of the engine 5 and a traveling hydraulic pump 482 is attached to the front part of the right outer surface of the straight traveling case 17.

  A flywheel 26 is directly connected to an output shaft 5a of the engine 5 that protrudes rearward from the rear side surface of the engine 5. An input counter shaft 28 projecting forward from the front side of the straight traveling mission case 17 is connected to a main driving shaft 27 projecting rearward from the flywheel 26 through a power transmission shaft 29 having universal joints at both ends. The rotational power of the engine 5 is transmitted to the input counter shaft 28 of the straight traveling mission case 17 via the main driving shaft 27 and the power transmission shaft 29, and the hydraulic mechanical continuously variable transmission 500 and the creep transmission gear mechanism 502 or the traveling auxiliary gear The speed is appropriately changed by the transmission gear mechanism 503. The speed change power via the creep speed change gear mechanism 502 or the travel auxiliary speed change gear mechanism 503 is transmitted to the gear mechanism in the turning mission case 13 via the front output shaft 30, the power transmission shaft 31, and the straight travel input counter shaft 508. Is done.

  In a straight-forward hydraulic mechanical continuously variable transmission (HMT) 500, a main transmission output shaft 512 is concentrically disposed on a main transmission input shaft 511, and a hydraulic pump unit 521, a cylinder block, and a hydraulic motor unit 522 are arranged in series. Are in-line type (in-line type). A main transmission input gear 513 is fitted on the rear end side of the input counter shaft 28 so as not to be relatively rotatable. An input transmission gear 514 that is always meshed with the main transmission input gear 513 is fixed to the rear end side of the main transmission input shaft 511. Accordingly, the rotational power of the input counter shaft 28 is transmitted to the hydraulic mechanical continuously variable transmission 500 via the main transmission input gear 513, the input transmission gear 514, and the main transmission input shaft 511. A main transmission high-speed gear 516, a main transmission reverse gear 517, and a main transmission low-speed gear 515 are fitted on the main transmission output shaft 512 so as not to rotate relative to each other for traveling output. The input side of the main transmission input shaft 511 and the output side of the main transmission output shaft 512 are located on the same side (both rear as viewed from the hydraulic mechanical continuously variable transmission 500).

  The hydraulic mechanical continuously variable transmission 500 includes a variable displacement hydraulic pump unit 521 and a constant displacement hydraulic motor unit 522 that is operated by high-pressure hydraulic oil discharged from the hydraulic pump unit 521. The hydraulic pump unit 521 is provided with a pump swash plate 523 that can change the inclination angle with respect to the axis of the main transmission input shaft 511 and adjust the amount of hydraulic oil supplied. A main transmission hydraulic cylinder 524 that changes and adjusts the inclination angle of the pump swash plate 523 with respect to the axis of the main transmission input shaft 511 is linked to the pump swash plate 523. In the embodiment, the main transmission hydraulic cylinder 524 is assembled to the hydraulic mechanical continuously variable transmission 500 and unitized as one member.

  When the main transmission hydraulic cylinder 524 is driven in proportion to the operation amount of the main transmission lever 50, the inclination angle of the pump swash plate 523 with respect to the axis of the main transmission input shaft 511 is changed accordingly. The pump swash plate 523 of the embodiment is angle-adjusted in a range between one (positive) maximum inclination angle and the other (negative) maximum inclination angle with a neutral angle of substantially zero inclination (before and after including zero) interposed therebetween. It is possible to set an angle that is inclined to one of the two times when the vehicle speed of the traveling machine body 2 is the lowest (in this case, an inclination angle that is negative and near the maximum).

  When the inclination angle of the pump swash plate 523 is substantially zero (neutral angle), the hydraulic pump unit 521 does not push and pull the input side plunger group. Although the cylinder block rotates in the same direction and substantially the same rotational speed as the main transmission input shaft 511, there is no hydraulic oil supply from the hydraulic pump unit 521, so the output side plunger group of the cylinder block and thus the hydraulic motor unit 522 are not driven. The main transmission output shaft 512 rotates at substantially the same rotational speed as the main transmission input shaft 511.

  When the pump swash plate 523 is tilted in one direction (which may be referred to as a positive tilt angle or a forward tilt angle) with respect to the axis line of the main transmission input shaft 511, the hydraulic pump unit 521 is configured as an input side plunger group. Is pushed and pulled to supply hydraulic oil to the hydraulic motor unit 522, and the hydraulic motor unit 522 is rotated in the same direction as the main transmission input shaft 511 via the output side plunger group of the cylinder block. At this time, because the cylinder block rotates in the same direction and substantially the same rotational speed as the main transmission input shaft 511, the main transmission output shaft 512 rotates at a higher rotational speed than the main transmission input shaft 511. That is, the rotational speed of the hydraulic motor unit 522 is added to the rotational speed of the main transmission input shaft 511 (also referred to as the rotational speed of the cylinder block) and transmitted to the main transmission output shaft 512. As a result, in the range of the rotational speed higher than the rotational speed of the main transmission input shaft 511, the main transmission output is proportional to the inclination angle of the pump swash plate 523 (which may be referred to as a positive inclination angle or a forward rotation inclination angle). The speed change power of the shaft 512 is changed. When the pump swash plate 523 is positive and has an inclination angle near the maximum, the main transmission output shaft 512 rotates at a high speed, but the traveling machine body 2 has an intermediate speed corresponding to the intermediate speed from the lowest speed (substantially zero) to the highest speed. Become.

  When the pump swash plate 523 is inclined in the other direction (which may be referred to as a negative inclination angle or a reverse inclination angle) with respect to the axis line of the main transmission input shaft 511, the hydraulic pump unit 521 causes the input-side plunger group to move. The hydraulic oil is supplied to the hydraulic motor unit 522 by pushing and pulling, and the hydraulic motor unit 522 is rotated in the direction opposite to the main transmission input shaft 511 via the output side plunger group of the cylinder block. At this time, the cylinder block rotates in the same direction and substantially the same rotational speed as the main transmission input shaft 511, so that the main transmission output shaft 512 rotates at a lower rotational speed than the main transmission input shaft 511. That is, the rotational speed of the hydraulic motor unit 522 is subtracted from the rotational speed of the main transmission input shaft 511 (which may be referred to as the rotational speed of the cylinder block) and transmitted to the main transmission output shaft 512. As a result, the main transmission output shaft is proportional to the tilt angle of the pump swash plate 523 (which may be referred to as a negative tilt angle or a reverse tilt angle) within a range of rotational speed lower than the rotational speed of the main shift input shaft 511. The shifting power of 512 is changed. When the pump swash plate 523 is negative and has an inclination angle near the maximum, the main transmission output shaft 512 is at the lowest speed (substantially zero).

  A pump drive gear 484 is fitted on the pump drive shaft 483 that drives both the working machine and traveling hydraulic pumps 481 and 482 so as not to be relatively rotatable. The pump drive gear 484 connects the main transmission input gear 513 of the input countershaft 28 via a flat gear mechanism 485 so that power can be transmitted. The straight traveling mission case 17 includes a lubricating oil pump 518 that supplies hydraulic oil to the hydraulic mechanical continuously variable transmission 500, the forward / reverse switching mechanism 501 and the like. The pump gear 520 fixed to the pump shaft 519 of the lubricating oil pump 518 is always meshed with the input transmission gear 514 of the main transmission input shaft 511. Therefore, the working machine and traveling hydraulic pumps 481 and 482 and the lubricating oil pump 518 are driven by the rotational power of the engine 5.

  Next, a forward / backward switching structure executed via the forward / reverse switching mechanism 501 will be described. A planetary gear mechanism 526 that is a forward high-speed gear mechanism and a low-speed gear pair 525 that is a forward low-speed gear mechanism are disposed on the rear side of the input counter shaft 28. The planetary gear mechanism 526 includes a sun gear 531 that rotates integrally with an input-side transmission gear 529 that is rotatably supported on the input counter shaft 28, a carrier 532 that rotatably supports a plurality of planetary gears 533 on the same radius, In addition, a ring gear 534 having internal teeth on the inner peripheral surface is provided. The sun gear 531 and the ring gear 534 are rotatably fitted on the input counter shaft 28. The carrier 532 is fitted on the input counter shaft 28 so as not to be relatively rotatable. The sun gear 531 meshes with each planetary gear 533 of the carrier 532 from the inside of the radius. Further, the inner teeth of the ring gear 534 mesh with the planetary gears 533 from the radially outer side. An output side transmission gear 530 that rotates integrally with the ring gear 534 is also rotatably supported on the input counter shaft 28. The input-side low-speed gear 527 and the output-side low-speed gear 528 constituting the low-speed gear pair 525 are integrated, and can rotate between the planetary gear mechanism 526 and the main transmission input gear 513 in the input counter shaft 28. It is pivotally supported.

  In the straight traveling mission case 17, an input counter shaft 28, a main transmission input shaft 511, and a traveling relay shaft 535 extending in parallel with the main transmission output shaft 512 and a traveling transmission shaft 536 are arranged. A forward / reverse switching mechanism 501 is provided on a travel relay shaft 535 serving as a transmission shaft. That is, the traveling relay shaft 535 has a forward high-speed gear 540 coupled by a wet multi-plate forward high-speed hydraulic clutch 539, a reverse gear 542 coupled by a wet multi-plate reverse hydraulic clutch 541, and a wet multi-plate. A forward low-speed gear 538 connected by a forward low-speed hydraulic clutch 537 of the mold is fitted. A travel relay gear 543 is fitted between the forward high speed hydraulic clutch 539 and the reverse gear 542 in the travel relay shaft 535 so as not to be relatively rotatable. A travel transmission gear 544 that always meshes with the travel relay gear 543 is fitted to the travel transmission shaft 536 so as not to be relatively rotatable. The main transmission low speed gear 515 of the main transmission output shaft 512 is always meshed with the input low speed gear 527 of the low speed gear pair 525 on the input counter shaft 28 side, and the output low speed gear 528 is always meshed with the forward low speed gear 538. The main transmission high speed gear 516 of the main transmission output shaft 512 is always meshed with the input transmission gear 529 of the planetary gear mechanism 526 on the input counter shaft 28 side, and the output transmission gear 530 is always meshed with the forward high speed gear 540. A main transmission reverse gear 517 of the main transmission output shaft 512 is always meshed with the reverse gear 542.

  When the forward / reverse switching lever 36 is operated to the forward side, the forward low-speed hydraulic clutch 537 or the forward high-speed hydraulic clutch 539 is in a power connection state, and the forward low-speed gear 538 or forward high-speed gear 540 and the travel relay shaft 535 are connected to each other so as not to be relatively rotatable. Is done. As a result, forward low-speed or high-speed rotational power is transmitted from the main transmission output shaft 512 to the travel relay shaft 535 via the low-speed gear pair 525 or the planetary gear mechanism 526, and power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536. Communicated. When the forward / reverse switching lever 36 is operated to the reverse side, the reverse hydraulic clutch 541 enters a power connection state, and the reverse gear 542 and the travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, the reverse rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the main transmission reverse gear 517 and the reverse gear 542, and the motive power is transmitted from the traveling relay shaft 535 to the traveling transmission shaft 536.

  Note that which of the forward low-speed hydraulic clutch 537 and the forward high-speed hydraulic clutch 539 is in the power connection state by the forward operation of the forward / reverse switching lever 36 is determined according to the operation amount of the main transmission lever 50. When the forward / reverse switching lever 36 is in the neutral position, all the hydraulic clutches 537, 539, and 541 are in the power cut state, and the traveling drive force from the main transmission output shaft 512 is substantially zero (the main clutch disengaged state). )become. On the other hand, when the main transmission lever 50 is neutrally operated regardless of the operation state of the forward / reverse switching lever 36, the pump swash plate 523 is negative and has a maximum inclination angle (reverse rotation inclination angle) by driving the main transmission hydraulic cylinder 524. Thus, the main transmission output shaft 512 and the travel relay shaft 535 are in the lowest speed rotation state (substantially zero). As a result, the vehicle speed of the tractor 1 becomes substantially zero.

  When the main transmission lever 50 is operated from the neutral to the intermediate speed while the forward / reverse switching lever 36 is operated to the forward side, the pump swash plate 523 is negative and maximum when the main transmission hydraulic cylinder 524 is driven. The shift power from the hydraulic motor unit 522 to the main transmission output shaft 512 is changed from approximately zero by changing from a nearby tilt angle (reverse tilt angle) to a positive and maximum tilt angle (forward tilt angle) through zero. Increase to high speed. At this time, the forward low-speed hydraulic clutch 537 is in a power connection state, and the forward low-speed gear 538 or the forward high-speed gear 540 and the travel relay shaft 535 are connected so as not to be relatively rotatable. As a result, the forward low-speed rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the low-speed gear pair 525, and the traveling relay shaft 535 is rotated at the lowest speed by the increased power to the main transmission output shaft 512. It changes from the state to the forward intermediate speed rotation state. Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536.

  When the main transmission lever 50 is operated from the intermediate speed to the maximum speed while the forward / reverse switching lever 36 is operated to the forward side, the inclination angle is positive and near the maximum by driving the main transmission hydraulic cylinder 524. (Forward rotation tilt angle) changes from zero to a negative and maximum tilt angle (reverse rotation tilt angle) through zero, and the pump swash plate 523 shifts the shift power from the hydraulic motor unit 522 to the main shift output shaft 512 from a high speed. Decelerate to almost zero. At this time, the forward high speed hydraulic clutch 539 is in a power connection state, and the forward high speed gear 540 and the travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, forward high speed rotational power is transmitted from the main transmission output shaft 512 to the travel relay shaft 535 via the planetary gear mechanism 526. That is, after the power from the engine 5 and the deceleration power to the main transmission output shaft 512 are combined in the planetary gear mechanism 526, the travel relay shaft 535 is moved from the forward intermediate speed rotation state to the forward maximum speed rotation state by the combined power. Change. Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536. The traveling machine body 2 has the highest speed.

  When the main transmission lever 50 is operated from the neutral side to the acceleration side while the forward / reverse switching lever 36 is operated to the reverse side, the pump swash plate 523 is negative by the drive of the main transmission hydraulic cylinder 524 and the inclination angle near the maximum is reached. It changes from (reverse rotation tilt angle) to a positive and near-maximum tilt angle (forward rotation tilt angle) through zero, and the shift power from the hydraulic motor unit 522 to the main shift output shaft 512 is increased from substantially zero to high speed. Let At this time, the reverse hydraulic clutch 541 is in a power connection state, and the reverse gear 542 and the travel relay shaft 535 are coupled so as not to be relatively rotatable. As a result, the reverse rotational power is transmitted from the main transmission output shaft 512 to the traveling relay shaft 535 via the main transmission reverse gear 517 and the reverse gear 542, and the traveling relay shaft 535 is driven by the increased power to the main transmission output shaft 512. Changes from the lowest speed rotation state to the reverse high speed rotation state. Then, power is transmitted from the travel relay shaft 535 to the travel transmission shaft 536.

  Next, an ultra-low speed, low-speed and high-speed switching structure executed through the creep transmission gear mechanism 502 and the traveling auxiliary transmission gear mechanism 503, which are traveling transmission gear mechanisms, will be described. In the straight transmission case 17, a mechanical creep transmission gear mechanism 502 and a traveling auxiliary transmission gear mechanism 503 for shifting rotational power via the forward / reverse switching mechanism 501, and a traveling counter that extends coaxially with the traveling transmission shaft 536. A shaft 545 and an auxiliary transmission shaft 546 extending in parallel with the travel counter shaft 545 are disposed.

  A transmission gear 547 and a creep gear 548 are provided on the rear side of the travel counter shaft 545. The transmission gear 547 is rotatably fitted to the travel counter shaft 545 and connected to the travel transmission shaft 536 so as to rotate integrally. The creep gear 548 is rotatably fitted on the travel counter shaft 545. A creep shifter 549 is spline-fitted between the transmission gear 547 and the creep gear 548 of the travel counter shaft 545 so as not to be relatively rotatable and slidable in the axial direction. The creep shifter 549 slides by turning the ultra low speed lever 44 on and off, and the transmission gear 547 and the creep gear 548 are alternatively connected to the travel counter shaft 545. A reduction gear pair 550 is rotatably fitted to a portion of the auxiliary transmission shaft 546 in the front chamber. The input side reduction gear 551 and the output side reduction gear 552 constituting the reduction gear pair 550 have an integral structure, and the transmission gear 547 of the travel counter shaft 545 always meshes with the input side reduction gear 551 of the auxiliary transmission shaft 546, The creep gear 548 is always meshed with the output side reduction gear 552.

  A low speed relay gear 553 and a high speed relay gear 554 are provided on the front side of the travel counter shaft 545. The low speed relay gear 553 is fixed to the travel counter shaft 545. The high-speed relay gear 554 is fitted on the travel counter shaft 545 so as not to be relatively rotatable. A low-speed gear 555 that meshes with the low-speed relay gear 553 and a high-speed gear 556 that meshes with the high-speed relay gear 554 are rotatably fitted on the auxiliary transmission shaft 546 on the front side of the reduction gear pair 550. A sub-transmission shifter 557 is spline-fitted between the low-speed gear 555 and the high-speed gear 556 in the sub-transmission shaft 546 so as not to be relatively rotatable and slidable in the axial direction. By operating the sub transmission lever 45, the sub transmission shifter 557 slides and the low speed gear 555 and the high speed gear 556 are alternatively connected to the sub transmission shaft 546.

  Further, a straight traveling relay shaft 568 and a straight traveling output shaft 30 that extend in parallel with the travel counter shaft 545 and the auxiliary transmission shaft 546 are arranged. The driven gear 569 fitted so as to be relatively non-rotatable with the straight-traveling relay shaft 568 is always meshed with the main driving gear 569 fitted so as not to be relatively rotatable on the front end side of the auxiliary transmission shaft 546. A straight travel relay gear 582 that is fitted to the rear end side of the straight travel relay shaft 568 so as not to be relatively rotatable, and a straight travel output gear 583 that is fitted to the straight travel output shaft 30 so as not to be relatively rotatable are always meshed. The main drive gear 569 of the subtransmission shaft 546, the driven gear 570 and the rectilinear relay gear 582 of the rectilinear relay shaft 568, and the rectilinear output gear 583 of the rectilinear output shaft 30 are used to linearly rotate the subtransmission shaft 456. A straight output gear mechanism 509 for transmitting power to the output shaft 30 is configured.

  In the embodiment, when the super low speed lever 44 is turned on and the sub transmission lever 45 is operated to the low speed side, the creep gear 548 is connected to the travel counter shaft 545 so as not to be relatively rotatable, and the low speed gear 555 is connected to the sub transmission shaft 546. It is connected so that it cannot rotate relative to the traveling transmission shaft 536, travel counter shaft 545, auxiliary transmission shaft 546, and straight traveling relay shaft 568. Is output.

  When the super low speed lever 44 is turned off and the sub transmission lever 45 is operated to the low speed side, the transmission gear 547 is connected to the travel counter shaft 545 so as not to rotate relative to it, and the low speed gear 555 cannot be rotated relative to the sub transmission shaft 546. To the transmission case 13 through the traveling transmission shaft 536, the traveling counter shaft 545, the sub-transmission shaft 546, the straight traveling relay shaft 568, and the like. Is done.

  When the super low speed lever 44 is turned off and the sub transmission lever 45 is operated to the high speed side, the transmission gear 547 is connected to the travel counter shaft 545 so as not to rotate relative to it, and the high speed gear 556 cannot be rotated relative to the sub transmission shaft 546. The traveling drive shaft 536 outputs a traveling drive force at a higher speed than the straight traveling output shaft 30 to the turning mission case 13 via the traveling transmission shaft 536, the traveling counter shaft 545, the auxiliary transmission shaft 546, the straight traveling relay shaft 568, and the like. The

  A straight transmission input countershaft 508 that protrudes backward from the turning mission case 13 and a straight output shaft 30 that protrudes forward from the lower front portion of the straight transmission case 17 are connected by a power transmission shaft 31. The turning mission case 13 includes a turning hydraulic continuously variable transmission (HST) 701 for appropriately changing the rotational power from the engine 5, and an output rotation from the hydraulic continuously variable transmission 701 to the left and right traveling crawlers 3 ( A differential gear mechanism 702 that transmits to the sprocket 62), and a pair of left and right planetary gear mechanisms 703 that combine the rotational power from the differential gear mechanism 702 and the rotational power from the straight traveling mission case 17.

  In the hydraulic continuously variable transmission 701, a pair of hydraulic pump units 704 and a hydraulic motor unit 705 are arranged in parallel, and the power transmitted to the pump shaft 706 is transferred from the hydraulic pump unit 704 to the hydraulic motor unit 705. The hydraulic oil is fed appropriately. A charge pump 707 for supplying hydraulic oil to the hydraulic pump 704 and the hydraulic motor 705 is attached to the pump shaft 706. The turning hydraulic continuously variable transmission mechanism 701 changes the discharge angle and discharge amount of the hydraulic oil to the hydraulic motor unit 705 by changing and adjusting the inclination angle of the pump swash plate 708 in the hydraulic pump unit 704, thereby changing the hydraulic pressure. The motor shaft 709 protruding from the motor 705 is configured to arbitrarily adjust the rotation direction and the number of rotations.

  In the turning mission case 13, the turning input counter shaft 712 is arranged in parallel with the pump shaft 706 of the hydraulic pump unit 704, and the turning input gear 713 is fitted on the turning input counter shaft 712 so as not to be relatively rotatable. ing. Between the turning input counter shaft 712 and the pump shaft 706, a turning relay shaft 714 is arranged in parallel with the turning input counter shaft 712 and the pump shaft 706, and the turning is always meshed with the turning input gear 713. The relay gear 715 is fitted on the turning relay shaft 714 so as not to rotate relative to the pivot shaft 714. A pump input gear 710 that is always meshed with the turning relay gear 715 is fitted to the pump shaft 706 so as not to be relatively rotatable, and the rotational power transmitted from the engine 5 transmitted to the turning input counter shaft 712 is turned. It is transmitted to the pump shaft 706 via the relay shaft 714 for use.

  In the turning mission case 13, a differential gear mechanism 702 is configured by a bevel gear mechanism in which a pair of left and right side gears 717 are engaged with both sides of a pinion gear 716 that is fitted to the rear end of the motor shaft 709 so as not to be relatively rotatable. Yes. In addition, the differential gear mechanism 702 has a pair of left and right turning output shafts 718 each having a side gear 717 fitted at one end thereof so as not to rotate relative to each other. A turning output gear 719 for transmitting power to the pair of left and right planetary gear mechanisms 703 is fitted to the other end of each of the pair of left and right turning output shafts 718 so as not to be relatively rotatable.

  Rotational power (turning rotational power) from the hydraulic motor unit 705 output from the motor shaft 709 is branched into forward and reverse rotational power by the differential gear mechanism 702 and left and right via a pair of left and right turning output shafts 718. This is transmitted to the pair of planetary gear mechanisms 703. That is, in the differential gear mechanism 702, the reverse rotation power is transmitted to the left planetary gear mechanism 703 through the left turning output shaft 718 fitted with the left side gear 717, while the right side gear 717 is fitted. It is transmitted to the right planetary gear mechanism 703 as forward rotation power through the right turning output shaft 718.

  In the turning mission case 13, a brake mechanism 751 that interlocks with the operation of the brake pedal 35 is provided on the straight input counter shaft 508 to which the rotational power from the straight traveling mission case 17 is transmitted. Then, the linear input gear 720 is fitted to the front end of the linear input counter shaft 508 so as not to be relatively rotatable. Further, the straight travel relay shaft 721 is arranged in parallel with the straight travel input counter shaft 508, and the straight travel relay gear 722 that is always meshed with the straight travel input gear 720 is not rotatable relative to the straight travel relay shaft 721. It is fitted.

  A bevel gear mechanism is provided in which a ring gear 724 is engaged with a pinion gear 723 that is fitted to the rear end of the linear relay shaft 721 so as not to be relatively rotatable. The ring gear 724 cannot be relatively rotated on a straight output shaft 725 that is extended to the left and right. It is put on. Both ends of the straight output shaft 725 are connected to a pair of left and right planetary gear mechanisms 703, respectively. The rotational power (straight forward rotational power) from the straight traveling mission case 17 input to the straight traveling input counter shaft 508 is transmitted to the pair of left and right planetary gear mechanisms 703 via the straight traveling output shaft 725. In addition, the brake mechanism 751 performs a braking operation in accordance with the operation of the brake pedal 35, so that the rotational power of the straight output shaft 725 is attenuated or stopped.

  Each of the left and right planetary gear mechanisms 703 rotates one sun gear 726, a plurality of planet gears 727 engaged with the sun gear 726, a ring gear 728 engaged with the turning output gear 719, and a plurality of planet gears 727 on the same circumference. And a carrier 729 which can be arranged. The carriers 729 of the left and right planetary gear mechanisms 703 are arranged on the same axis so as to face each other with an appropriate interval. The left and right sun gears 726 are fixed to both ends of a straight output shaft 725 in which a ring gear 724 is fitted in the middle.

  The left and right ring gears 728 are rotatably fitted to the straight output shaft 725, and the external teeth on the outer peripheral surface thereof are engaged with the left and right turning output gears 719 to be connected to the turning output shaft 718. ing. A carrier 729 fixed to the ring gear 728 rotatably supports the planetary gear 727. The left and right carriers 729 are rotatably fitted to the left and right differential output shafts 730. The left and right output transmission gears 731 that rotate together with the left and right planetary gears 727 mesh with the left and right differential input gears 732 that are non-rotatably fitted to the left and right differential output shafts 730. doing. The left and right differential output shafts 730 are connected to the left and right relay shafts 735 via relay gears 733 and 734, and the left and right relay shafts 735 are connected to the left and right axles 16 via final gears 736 and 737. ing.

  Each of the left and right planetary gear mechanisms 703 receives rotational power from the straight traveling mission case 17 via the straight traveling relay shaft 721 and the straight traveling output shaft 725, and rotates the sun gear 726 at the same rotational speed in the same direction. . That is, the left and right sun gears 726 receive the rotational power from the straight traveling mission case 17 as straight forward rotation, and transmit it to the differential output shaft 730 through the planetary gear 727 and the output side transmission gear 731. Therefore, the rotational power transmitted from the straight traveling mission case 17 to the left and right planetary gear mechanisms 703 is transmitted from the left and right axles 16 to the drive sprockets 62 at the same rotational speed in the same direction, and the left and right traveling crawlers 3 are transmitted to the same. Driven at the same number of rotations in the direction, the traveling machine body 1 moves straight (forward, backward).

  On the other hand, the left and right planetary gear mechanisms 703 receive rotational power from the hydraulic motor unit 705 via the differential gear mechanism 702 and the turning output shaft 718, and cause the ring gear 728 to rotate in the opposite directions at the same rotational speed. Rotate. That is, the left and right ring gears 728 receive the rotational power from the hydraulic motor unit 705 as turning rotation, and the carrier 729 causes the turning rotation to be superimposed on the straight rotation from the sun gear 726 to rotate the planetary gear 727 and the output side transmission gear 731. . As a result, the rotational power obtained by adding the rotational rotation to the straight rotation is transmitted to one of the left and right differential output shafts 730 via the planetary gear 727 and the output side transmission gear 731. Rotational power obtained by subtracting the turning rotation from the rectilinear rotation is transmitted through the planetary gear 727 and the output side transmission gear 731.

  The speed change outputs from the linear input counter shaft 508 and the motor shaft 709 are transmitted to the drive sprockets 62 of the left and right traveling crawlers 3 via the left and right planetary gear mechanisms 703, respectively, so that the vehicle speed (traveling speed) of the traveling machine body 2 is increased. ) And the direction of travel is determined. That is, when the rotational power from the straight traveling mission case 17 is input to the straight traveling input counter shaft 508 with the hydraulic motor portion 705 of the hydraulic continuously variable transmission 701 stopped and the left and right ring gears 728 stationary and fixed. The rotation of the input counter shaft 508 for straight travel is transmitted to the left and right sun gears 71 at the same left and right rotational speed, the left and right traveling crawlers 3 are driven at the same rotational speed in the same direction, and the traveling machine body 2 travels straight.

  Conversely, when the hydraulic motor unit 705 of the hydraulic continuously variable transmission 701 is driven in a state where the rotation of the transmission case 17 for the straight traveling is stopped by the straight output shaft 30 and the left and right sun gears 71 are stationary, the motor shaft 709 is driven. Rotational power from the left ring gear 728 rotates forward (reverse), and the right ring gear 728 rotates reverse (forward). As a result, one of the drive sprockets 62 of the left and right traveling crawlers 3 is rotated forward, the other is rotated backward, and the traveling machine body 2 is turned on the spot (revolution turning spin turn).

  Further, the left and right traveling crawlers 3 are driven by driving the left and right ring gears 728 by turning the hydraulic motor portion 705 of the hydraulic continuously variable transmission 701 while driving the left and right sun gears 726 by rotating straight from the transmission case 17 for straight traveling. The traveling body 2 turns left or right (U-turn) with a turning radius larger than the belief turning radius while moving forward or backward. The turning radius at this time is determined according to the speed difference between the left and right traveling crawlers 3.

  Next, the drive speed switching structure (three forward rotations and one reverse rotation) of the PTO shaft 25 executed via the PTO transmission mechanism 505 will be described. The straight traveling mission case 17 is provided with a PTO transmission mechanism 505 that transmits power from the engine 5 to the PTO shaft 25. In this case, a PTO input shaft 591 extending coaxially with the main transmission input shaft 511 is connected to the rear end side of the main transmission input shaft 511 via a PTO hydraulic clutch 590 for power transmission interruption. Further, the straight traveling mission case 17 is provided with a PTO transmission shaft 592, a PTO counter shaft 593, and a PTO shaft 25 extending in parallel with the PTO input shaft 591. The PTO shaft 25 protrudes rearward from the rear surface of the straight traveling mission case 17.

  When the power connection operation is performed on the PTO clutch switch 53, the PTO hydraulic clutch 590 is in a power connection state, and the main transmission input shaft 511 and the PTO input shaft 591 are coupled so as not to be relatively rotatable. As a result, rotational power is transmitted from the main transmission input shaft 511 toward the PTO input shaft 591.

  The PTO input shaft 591 is provided with a medium speed input gear 597, a low speed input gear 595, a high speed input gear 596, and a reverse shifter gear 598 in order from the front side. The medium-speed input gear 597, the low-speed input gear 595, and the high-speed input gear 596 are fitted on the PTO input shaft 591 so as not to be relatively rotatable. The reverse shifter gear 598 is spline-fitted to the PTO input shaft 591 so as not to rotate relative to the PTO input shaft 591 and to be slidable in the axial direction.

  On the other hand, the PTO transmission shaft 592 is rotatably fitted with a PTO medium speed gear 601 that meshes with the medium speed input gear 597, a PTO low speed gear 599 that meshes with the low speed input gear 595, and a PTO high speed gear 600 that meshes with the high speed input gear 596. doing. A pair of front and rear PTO transmission shifters 602 and 603 are spline-fitted to the PTO transmission shaft 592 so as not to be relatively rotatable and to be slidable in the axial direction. The first PTO shift shifter 602 is disposed between the PTO medium speed gear 601 and the PTO low speed gear 599. The second PTO speed shifter 603 is disposed on the rear end side with respect to the PTO high speed gear 600. The pair of front and rear PTO shift shifters 602 and 603 are configured to slide in the axial direction in conjunction with the operation of the PTO shift lever 46. A PTO transmission gear 604 is fixed between the PTO low-speed gear 599 and the PTO high-speed gear 600 in the PTO transmission shaft 592.

  The PTO counter shaft 593 has a PTO counter gear 605 that meshes with the PTO transmission gear 604, a PTO relay gear 606 that meshes with a PTO output gear 608 that is non-rotatably fitted to the PTO shaft 25, and a PTO reverse gear 607. It is impossible to fit. When the sub-PTO lever 48 is engaged with the PTO speed change lever 46 in a neutral state, the reverse shifter gear 598 slides and the reverse shifter gear 598 meshes with the PTO reverse gear 607 of the PTO counter shaft 593. ing.

  When the PTO speed change lever 46 is operated to shift, the pair of front and rear PTO speed shifters 602 and 603 slide along the PTO speed change shaft 592, and the PTO low speed gear 595, the PTO medium speed gear 597, and the PTO high speed gear 596 become the PTO speed change shaft. 592 is alternatively connected. As a result, the low-speed to high-speed PTO shift outputs are transmitted from the PTO shift shaft 592 to the PTO counter shaft 593 via the PTO transmission gear 604 and the PTO counter gear 605, and further, the PTO relay gear 606 and the PTO output gear 608 are transmitted. Is transmitted to the PTO shaft 25.

  When the sub PTO lever 48 is turned on and operated, the reverse shifter gear 598 is engaged with the PTO reverse gear 607, and the rotational power of the PTO input shaft 591 is transmitted to the PTO counter shaft 593 via the reverse shifter gear 598 and the PTO reverse gear 607. Then, the reverse PTO shift output is transmitted from the PTO counter shaft 593 to the PTO shaft 25 via the PTO relay gear 606 and the PTO output gear 608.

  Next, the hydraulic circuit 620 structure of the tractor 1 will be described with reference to FIG. The hydraulic circuit 620 of the tractor 1 includes a working machine hydraulic pump 481 and a traveling hydraulic pump 482 that are driven by the rotational power of the engine 5. In the embodiment, the straight traveling mission case 17 is used as a hydraulic oil tank, and the working oil (lubricating oil) in the straight traveling mission case 17 is passed through two oil filters (suction filters) 656. To the hydraulic pump 481 for traveling and the hydraulic pump 482 for traveling. The traveling hydraulic pump 482 is connected via an oil filter (line filter) 487 to a closed loop oil passage 623 that connects the hydraulic pump 521 and the hydraulic motor 522 in the straight-forward hydraulic mechanical continuously variable transmission 500. While the engine 5 is being driven, the hydraulic oil from the traveling hydraulic pump 482 is always replenished to the closed loop oil passage 623.

  The traveling hydraulic pump 482 includes an oil filter (line filter) 487, a main transmission hydraulic pressure switching valve 624 for the main transmission hydraulic cylinder 524 of the hydraulic mechanical continuously variable transmission 500, and a PTO clutch for the PTO hydraulic clutch 590. The solenoid valve 627 and the switching valve 628 operated thereby are connected. Further, the traveling hydraulic pump 482 includes a forward low speed clutch electromagnetic valve 632 that operates the forward low speed hydraulic clutch 537, a forward high speed clutch electromagnetic valve 633 that operates the forward high speed hydraulic clutch 539, and a reverse clutch that operates the reverse hydraulic clutch 541. The solenoid valve 634 is connected to a master control solenoid valve 635 that controls the supply of hydraulic oil to the clutch solenoid valves 632 to 634.

  In addition, the work machine hydraulic pump 481 includes a plurality of hydraulic external take-off valves 430 arranged on the upper surface of the hydraulic lifting mechanism 22 on the rear side of the upper surface of the straight traveling mission case 17, and a hydraulic lift cylinder in the hydraulic lifting mechanism 22. 117 Double-acting control electromagnetic valve 432 for controlling hydraulic oil supply to the lower side, tilt control electromagnetic valve 647 for controlling hydraulic oil supply to the horizontal cylinder 122 provided on the right lift rod 121, and hydraulic pressure in the hydraulic lifting mechanism 22 The rising hydraulic pressure switching valve 648 and the lowering hydraulic pressure switching valve 649 for controlling the hydraulic oil supply to the lower side of the lift cylinder 117, the rising control electromagnetic valve 650 for switching the rising hydraulic pressure switching valve 648, and the lowering hydraulic pressure switching valve 649 are operated. It is connected to the lowering control electromagnetic valve 651. The double-acting valve mechanism 431 includes a hydraulic circuit including a double-acting control electromagnetic valve 432, and the ascending / descending valve mechanism 652 includes an ascending hydraulic switching valve 648, a descending hydraulic switching valve 649, an ascending control electromagnetic valve 650, and a descending A hydraulic circuit including a control solenoid valve 651 is used.

  When the tilt control electromagnetic valve 647 is switched and driven, the horizontal cylinder 122 expands and contracts, and the right lower link 23 moves up and down with the lower link pin on the front side as a fulcrum. As a result, the ground work machine tilts to the left and right with respect to the traveling machine body 2 via the left and right lower links 23, and the left and right tilt angles of the ground work machine change. By switching control of the double-acting control electromagnetic valve 432, either a single-acting type or a double-acting type can be selected as a driving method of the hydraulic lift cylinder 117. In other words, the drive system of the hydraulic lift cylinder 117 is set by switching the double-action control electromagnetic valve 432 in accordance with the switching operation of the single-double action switch 56.

  When the hydraulic lift cylinder 117 is driven by a single action, when the rising hydraulic pressure switching valve 648 or the downward hydraulic pressure switching valve 649 is switched, the hydraulic lift cylinder 117 expands and contracts, and the lift arm 120 and both the left and right lower links 23 are both moved. Move up and down. As a result, the ground work machine moves up and down, and the height position of the ground work machine changes. On the other hand, when the hydraulic lift cylinder 117 is driven in a double-acting manner, the hydraulic lift cylinder 117 is expanded and contracted by switching the double-acting control electromagnetic valve 432 and simultaneously switching the upward hydraulic switching valve 648 or the downward hydraulic switching valve 649. Move. Accordingly, the ground work machine can be moved up and down, and when the ground work machine is lowered, the ground work machine is pressurized toward the ground, and the ground work machine can be held in the lowered position.

  As shown in FIG. 25, when the single-acting method is designated or when the lowering operation by the hydraulic lift cylinder 117 is not performed, the double-acting control electromagnetic valve 432 is displaced to the right side, and from the shunt valve 436 Is supplied to the hydraulic external take-off valve 430. At this time, the upper port of the hydraulic lift cylinder 117 is connected to the hydraulic oil tank by the straight traveling mission case 17 via the double-action control electromagnetic valve 432.

  Further, as shown in FIG. 25, after the double-action system is designated by the single-double-action changeover switch 56 (see FIG. 11), the work implement lift lever 963 (see FIG. 11) or the work implement lift switch 964 (see FIG. 11). ) Designates lowering (lowering operation) of the hydraulic lifting mechanism 22, the double-acting control electromagnetic valve 432 is displaced to the left, and hydraulic oil from the diversion valve 436 is supplied to the upper port of the hydraulic lift cylinder 117. . When the double-action system is designated, when the lowering of the hydraulic lift mechanism 22 is adjusted by the lift adjustment switch 965 (see FIG. 11), the double-action control solenoid valve 432 remains displaced to the right, and the hydraulic lift cylinder The upper port 117 is connected to the hydraulic oil tank by the straight traveling mission case 17 via the double-action control solenoid valve 432.

  As shown in FIG. 14, the hydraulic circuit 620 of the tractor 1 includes a charge pump 707 that is driven by the rotational power of the engine 5, and the charge pump 707 is a hydraulic pump 704 in the hydraulic continuously variable transmission 701 for turning. And a closed loop oil passage 740 connecting the hydraulic motor 705 and the hydraulic motor 705. In the embodiment, the straight traveling mission case 17 is used as a hydraulic oil tank, and the hydraulic oil in the straight traveling mission case 17 is supplied to the charge pump 707 via an oil filter (suction filter) 743. During the driving of the engine 5, hydraulic oil from the charge pump 707 is always replenished to the closed loop oil passage 740 via the oil filter (line filter) 744. The hydraulic circuit 620 of the tractor 1 includes a swing hydraulic cylinder 741 that changes the angle of the pump swash plate 708 of the hydraulic pump 702 in the hydraulic continuously variable transmission 701, and a swing hydraulic pressure switching valve 742 for the swing hydraulic cylinder 741.

  The hydraulic circuit 620 of the tractor 1 includes a lubricating oil pump 518 that is driven by the rotational power of the engine 5 in addition to the aforementioned working machine hydraulic pump 481 and traveling hydraulic pump 482. The lubricating oil pump 518 includes a PTO clutch hydraulic pressure switching valve 641 that supplies hydraulic oil (lubricating oil) to the lubricating portion of the PTO hydraulic clutch 590, and a main transmission input shaft 511 that supports the hydraulic mechanical continuously variable transmission 500. The lubrication section, the forward low speed clutch hydraulic pressure switching valve 642 that supplies hydraulic oil (lubricating oil) to the lubrication section of the forward low speed hydraulic clutch 537, and the forward movement that supplies hydraulic oil (lubricating oil) to the lubrication section of the forward high speed hydraulic clutch 539. The high-speed clutch hydraulic pressure switching valve 643 is connected to a reverse clutch hydraulic pressure switching valve 644 that supplies hydraulic oil (lubricating oil) to the lubricating portion of the reverse hydraulic clutch 541. As shown in FIG. 14, the hydraulic circuit 620 includes a relief valve, a flow rate adjustment valve, a check valve, an oil cooler, an oil filter, and the like in addition to the above-described configuration.

  As shown in FIGS. 1 to 10, 12, and 15, the turning mission case 13 includes a turning transmission case 91 containing a hydraulic continuously variable transmission 701, and a pump in the hydraulic continuously variable transmission 701. A relay case 92 having a joint shaft connected to the shaft 706 and the motor shaft 709, and a gear mechanism that receives rotational power from the engine 5 and the straight traveling mission case 17 and outputs rotational power to the axle 16. An output case 93 is included. In the turning transmission case 91, a charge pump 707 is arranged on the front surface, and a turning hydraulic pressure switching valve 742 is arranged on the upper surface thereof. An input / output case 93 is connected to the rear of the turning transmission case 91 via a relay case 92, and an axle case 90 is connected to both sides of the input / output case 93.

  As shown in FIGS. 1 to 10, 12 and 15, oil filters 743 and 744 are provided in front of the turning mission case 13. The oil filters 743 and 744 are suspended and fixed to a filter fixing bracket 459 installed on the left and right upper edges of the frame connecting member 12a that connects the front ends of the left and right engine frames 14. A partition plate 460 is provided above the turning mission case 13 so as to be installed on the left and right engine frames 14.

  Hydraulic pipes 450 to 456 for circulating hydraulic oil to the turning mission case 13 are extended from the straight traveling mission case 17 toward the turning mission case 13. The hydraulic pipes 450 and 456 on the straight traveling mission case 17 side are disposed along the traveling machine body 2 outside the traveling machine body 2 (the engine frame 14 and the machine body frame 15). On the other hand, hydraulic piping 451, 452, 455 on the turning mission case 13 side is disposed inside the traveling machine body 2 and connected to the turning mission case 13 via filters 743, 744 provided inside the traveling machine body 2. Yes.

  The turning mission case 13 includes a rear case (input / output case) 93 that houses a gear mechanism that outputs power to the left and right traveling units (crawlers) 3, and a front case that houses the second continuously variable transmission 701 (turning). And a transmission case 91). A partition plate 460 installed on the traveling machine body 2 (engine frame 14) is provided above the turning mission case 13 and at a connection position between the front case 91 and the rear case 93. The middle of hydraulic piping 451 and 455 is fixed by a partition plate 460, and the filters 743 and 744 are suspended and supported by the traveling machine body 2 (engine frame 14) in front of the turning mission case 13. A relay case 92 having a relay shaft is provided between the turning transmission case 91 and the input / output case 93, and the partition plate 460 is provided in front of the boundary position between the relay case 92 and the input / output case 93. It is done.

  Support brackets 81 that support a working machine (front dozer) 80 mounted in front of the traveling machine body 2 are fixed to the left and right side surfaces of the traveling machine body 2 (engine frame 14). A pair of left and right axle cases 90 connected to both sides of the rear case (input / output case) 93 of the turning mission case 13 are coupled to a pair of left and right support brackets 81, respectively. The hydraulic pipes 451 and 455 are disposed inside the traveling machine body 2 (engine frame 14) at a position overlapping the support bracket in the front-rear direction. In addition, a lower frame 67 that supports the front of the track frame 61 of the traveling crawler 3 is suspended and supported on the lower side of the traveling machine body 2 (engine frame 14) and is connected to the support bracket 81.

  A hydraulic pipe 89a that supplies a part of the hydraulic oil in the straight transmission case 17 to a work machine (front dozer) 80 is provided, a pipe connecting member 89 that connects the hydraulic pipe 89a and the hydraulic pipe 89b, and a hydraulic pipe A work implement valve mechanism 89c that switches the operation oil from entering and exiting the work implement (front dozer) 80 from 89b is fixed to one of the left and right support brackets 81 (in the embodiment, the right support bracket 81). The hydraulic pipe 89b is disposed on the outer side of the traveling machine body 2 and rearward of the support bracket 81 along the traveling machine body 2, and is connected to a hydraulic circuit of a hydraulic external take-out mechanism 430 disposed above the straight traveling mission case 17. Is done.

  Next, the structure of the straight traveling mission case 17 and the mounting structure of each component will be described with reference to FIGS. The straight transmission case 17 includes a front transmission case 112 having a main transmission input shaft 28 and the like, a rear transmission case 113 connected to the rear housing 74, and a front side of the rear transmission case 113 on the rear side of the front transmission case 112. An intermediate case 114 is provided for connecting the two. The rear end portions of the left and right machine body frames 15 are connected to the left and right side surfaces of the intermediate case 114 via the left and right upper and lower machine body connecting shafts 115 and 116. That is, the rear end portions of the left and right airframe frames 15 are connected to the left and right side surfaces of the intermediate case 114 by the two upper airframe connecting shaft bodies 115 and the two lower airframe connecting shaft bodies 116. A straight traveling transmission case 17 is integrally connected to form a rear part of the traveling machine body 2, and a front transmission case 112 or a power transmission shaft 29 is arranged between the left and right machine body frames 15, The transmission case 112 and the like are protected. The left and right rear housings 74 are attached to the left and right sides of the rear transmission case 113 so as to protrude outward. In the embodiment, the intermediate case 114 and the rear transmission case 113 are made of high-rigid cast iron, while the front transmission case 112 is made of aluminum die cast that is lightweight and has good workability.

  According to the above configuration, since the straight transmission case 17 is divided into the front transmission case 112, the intermediate case 114, and the rear case 113, each case 112 to 114 has a shaft, a gear, etc. After the parts are assembled in advance, the front transmission case 112, the intermediate case 114, and the rear transmission case 113 can be assembled. Therefore, the assembly of the straight traveling mission case 17 can be performed accurately and efficiently.

  Further, a left and right rear housing 74 is attached to both the left and right sides of the rear transmission case 113, and an intermediate case having a high rigidity structure that connects the front transmission case 112 and the rear transmission case 113 to the left and right body frames 15 constituting the traveling vehicle body 2. 114, for example, with the intermediate case 114 and the rear transmission case 113 attached to the body frame 15, only the front transmission case 112 is removed and the hydraulic continuously variable transmission 500 or the like is installed. Maintenance or repair work such as replacement of the shaft and gear in the internal transmission case 112 can be performed. Accordingly, the frequency of the disassembling work for removing the entire straight traveling mission case 17 from the tractor 1 can be remarkably reduced, and the workability during maintenance and repair can be improved.

  Further, since the intermediate case 114 and the rear transmission case 113 are made of cast iron, while the front transmission case 112 is made of aluminum die cast, the intermediate case 114 connected to the body frame 15 and the left and right rear housings 74 are provided. The connected rear transmission case 113 can be configured with high rigidity as a strength member constituting the traveling machine body 2. In addition, the front transmission case 112 that is not a strength member can be reduced in weight. Therefore, it is possible to reduce the weight of the traveling case 17 as a whole while sufficiently securing the rigidity of the traveling machine body 2.

  As shown in FIGS. 15 to 17, a pump case 480 is disposed in the front portion of the right outer surface of the rear transmission case 113 in the straight traveling mission case 17. A working machine hydraulic pump 481 and a traveling hydraulic pump 482 are housed in the pump case 480. The suction side of the working machine hydraulic pump 481 and the traveling hydraulic pump 482 is connected to a double oil filter 656 below the pump case 480 in the front portion of the right outer surface of the rear transmission case 113 via a filter bracket 655. ing. The two oil filters 656 are detachably attached to the filter bracket 655. The filter bracket 655 is provided with a suction nozzle 657 extending into the straight traveling mission case 17 (inside the rear transmission case 113). The suction nozzle 657 in the rear transmission case 113 communicates with the two oil filters 656 via the filter bracket 655.

  The working machine and traveling hydraulic pumps 481 and 482 and the two series of oil filters 656 are forward of the rear housing 74 (right rear housing 74 in the embodiment) protruding outward from the rear transmission case 113 in the left-right direction, and It is located below the control seat 8 on the traveling machine body 2 (see FIG. 8). In this way, the working machine and traveling hydraulic pumps 481 and 482 and the two series of oil filters 656 are disposed away from the control seat 8 surrounded by the cabin 7.

  A gear case 486 that houses a flat gear mechanism 485 is provided projecting outward in the left-right direction above the two oil filters 656 in the front portion on the right outer surface of the rear transmission case 113. A pump case 480 is attached to the front side of the gear case 486. A pump drive shaft 483 protruding from the working machine and traveling hydraulic pumps 481 and 482 in the pump case 480 extends into the gear case 486. In the gear case 486, a pump drive gear 484 fixed to the pump drive shaft 483 is connected to the flat gear mechanism 485 so that power can be transmitted (see FIG. 14).

  As shown in FIGS. 15 to 17, a double-acting valve mechanism 431 is provided on the left and right other side portions (the left outer surface side of the rear transmission case 113) located on the opposite side of the pump case 480 etc. in the straight traveling mission case 17. ing. The double-acting valve mechanism 431 is positioned in front of a rear housing 74 (right rear housing 74 in the embodiment) that protrudes left and right outward from the rear transmission case 113 and below the control seat 8 on the traveling machine body 2. doing. That is, the pump case 480 is provided at a position that is distributed to the left and right with the transmission case 17 (rear transmission case 113) for straight travel in between.

  The double-acting valve mechanism 431 is disposed at a position facing the pump case 480 across the straight traveling mission case 17 and is connected to the working machine hydraulic pump 481 in the pump case 480 by hydraulic piping. Therefore, the hydraulic piping 745 that connects the double-acting valve 431 and the work machine hydraulic pump 481 can be shortened to improve the working efficiency in the piping work, and the piping loss in the hydraulic circuit 745 can be reduced.

  The double-acting valve mechanism 431 is mounted on a valve support bracket 433 that is fixed to the front surface of the rear housing 74 that is connected to the rear side portion of the straight traveling mission case 17 (the left outer surface side of the rear transmission case 113). . That is, the valve support bracket 433 is bolted to the front surface of the rear housing 74 projecting to the side (left side) of the straight traveling mission case 17, and the double-acting valve mechanism 431 is bolted to the upper surface of the valve support bracket 433. Has been. Therefore, the double-acting valve mechanism 431 can be supported by the rear housing 74 with high rigidity.

  In addition, the double-acting valve mechanism 431 is disposed together with the hydraulic pumps 481 and 482 and the two oil filters 656 by effectively utilizing a place in front of the rear housing 74, that is, the right and left inner side of the rear traveling unit 3 where it is easy to secure a working space. As a result, the transmission case 17 for straight traveling is made more compact. In addition, since the hydraulic pump 481 and the double-acting valve mechanism 431 are arranged at positions that are distributed to the left and right with the transmission case 17 interposed therebetween, the hydraulic piping connecting the hydraulic pump 481 and the double-acting valve mechanism 431 can be shortened.

  As shown in FIGS. 15 to 17, the front lid member 491 detachably fastened to the front surface of the straight traveling mission case 17, that is, the front surface of the front transmission case 112, has a traveling hydraulic pump 482 that is a hydraulic source and each hydraulic pressure. A part of a hydraulic circuit 620 that connects the clutches 537, 539, and 541 is formed. On the front side of the front lid member 491, the clutch electromagnetic valves 632, 633, 634 and the master control electromagnetic valve 635 are arranged.

  Each clutch solenoid valve 632, 633, 634 and master control solenoid valve 635 are assembled into an oil passage block 660 to form a unit. The clutch solenoid valves 632, 633, 634 and the oil passage block 660 with the master control solenoid valve 635 are detachably fastened to the front side of the front lid member 491. An oil filter (line filter) 487 disposed on the hydraulic oil supply path to the hydraulic mechanical continuously variable transmission 500 is fixed to the front surface of the front lid member 491.

  The transmission case 17 for straight travel includes a PTO hydraulic clutch 590 that interrupts transmission of power to the PTO transmission mechanism 505, a PTO valve that houses a PTO clutch electromagnetic valve 627 that operates the PTO hydraulic clutch 590, and a switching valve 628 (PTO valve). A case 663. As shown in FIGS. 15 to 17, a PTO valve case 663 is disposed on the left outer surface of the straight traveling mission case 17, that is, on the front portion of the left outer surface of the rear transmission case 113, at a position overlapping the PTO hydraulic clutch 590 in a side view. doing. As described above, the work case hydraulic pump 481 driven by the rotational power of the engine 5 and the pump case 480 accommodating the traveling hydraulic pump 482 are attached to the front portion of the right outer surface of the rear transmission case 113. Accordingly, the pump case 480 and the PTO valve case 663 are located on the left and right sides of the rear transmission case 113.

  A PTO valve case 663 provided with PTO valves 627 and 628 is positioned on the left and right side surfaces of the rear case 113 in front of the rear housing 74 and on the opposite side of the hydraulic pumps 481 and 482. The hydraulic pumps 481 and 482 and the PTO valves 627 and 628 are distributed and arranged on the left and right sides of the rear transmission case 113, and an effective use is made of a place that easily secures a work space in front of the rear housing 74. The hydraulic pumps 481 and 482 and the PTO valves 627 and 628 can be arranged efficiently. Furthermore, the PTO valve case 663 is effectively disposed in a space between the straight traveling mission case 17 and the double-acting bubble mechanism 431, and helps to make the straight traveling mission case 17 compact.

  As shown in FIGS. 15 to 18 and the like, the hydraulic lifting mechanism 22 includes left and right hydraulic lift cylinders 117 that are controlled by operation of the working unit position dial 51 and the upper surface of the rear transmission case 113 of the transmission case 17 for straight traveling. The left and right lift arms 120 are connected to the left and right lower links 23, and the left and right lift arms 120 are pivotally supported via a lift fulcrum shaft 119 on an openable and closable upper surface lid 118. Left and right lift rods 121 are provided. A part of the right lift rod 121 is formed by a horizontal cylinder 122 for hydraulic control, and the length of the right lift rod 121 is configured to be adjustable by the horizontal cylinder 122.

  Further, the top link hinge 123 is fixed to the back side of the top cover 118, and the top link 24 is connected to the top link hinge 123 via a hinge pin. When the ground work machine is supported by the top link 24 and the left and right lower links 23, the piston of the horizontal cylinder 122 is expanded and contracted to change the length of the right lift rod 121. The angle is configured to change.

  As shown in FIGS. 15 to 17 and the like, the upper cover 118 installed on the upper surface of the rear transmission case 113 is provided with a lift valve mechanism 652 (a rising hydraulic pressure switching valve 648 and a lowering hydraulic pressure switching valve 649) and an inclination control electromagnetic valve 647. Is arranged. Accordingly, the hydraulic device parts related to the lifting mechanism 22 provided behind the straight traveling mission case 17 can be arranged together on the upper cover 118 to constitute a unit, and the lifting valve mechanism 652 (lifting hydraulic pressure) disposed on the upper surface side of the straight traveling mission case 17 can be configured. The assembly and maintenance work of the switching valve 648, the descending hydraulic pressure switching valve 649) and the tilt control electromagnetic valve 647 can be easily simplified, and the ease of assembling the straight traveling mission case 17 can be improved.

  The lifting mechanism 22 includes left and right lift arms 120 that connect the left and right lift cylinders 117 and the left and right lower links 23 as shown in FIGS. Then, a lift fulcrum shaft 119 as an elevating fulcrum shaft is passed through the rear portion of the top cover 118 in the left-right direction, and the left and right lift arms 120 base end portions are pivotally supported at both left and right ends of the lift fulcrum shaft 119. The left and right lift arms 120 are arranged on the top cover 118 via lift fulcrum shafts 119 as elevating fulcrum shafts. Therefore, the elevating mechanism 22 (elevating valve mechanism 652 and lift arm 120) can be disposed on the upper surface side of the upper cover 118, and the assembly and maintenance work of the elevating mechanism 22 to the straight traveling mission case 17 can be simplified. Further, the elevating valve mechanism 652 is supported on the front portion of the upper surface lid 118, and the lift arm 120 is supported on the rear portion of the upper surface lid 118 via the lift fulcrum shaft 119, so that the straight traveling transmission case 17 (rear transmission case). 113) can be installed compactly on the upper surface side.

  As shown in FIGS. 15 to 17, a valve plate 653 that is hydraulically connected to the lift cylinder 117 via hydraulic piping, and hydraulic proportional valves (a lift control solenoid valve 650 and a lift control solenoid valve 651) as the lift valve mechanism 652 are provided. I have. Then, the valve plate 653 is placed on the upper surface front portion of the upper cover 118, and the lift valve mechanism 652 (the lift control solenoid valve 650 and the drop control solenoid valve 651 as hydraulic proportional valves) is placed on the top surface of the valve plate 653. ing. In addition, an inclination control electromagnetic valve 647 is disposed at the upper rear portion of the upper cover 118. More specifically, an inclination control electromagnetic valve 647 is arranged on the upper surface between the lift valve mechanism 652 and the lift fulcrum shaft 119 in the upper surface front portion of the upper surface lid 118 among the upper surface of the upper surface lid 118.

  Therefore, ascending / descending valve mechanism 652 (rising oil pressure switching valve 648 and descending oil pressure switching valve 649, ascending control solenoid valve 650 and descending control solenoid valve 651) is assembled to top cover 118 via valve plate 653 constituting a hydraulic circuit. In this state, the valve plate 653 can be attached to and detached from the upper surface cover body 118, while the upper surface cover body 118 can be attached to and detached from the upper surface of the transmission case 17 with the valve plate 653 assembled to the upper surface cover body 118. Assembly and maintenance workability of the lift valve mechanism 652 and the tilt control electromagnetic valve 647 can be simplified. In addition, the inclination control electromagnetic valve 647 can be arranged on the upper surface side of the upper surface lid 118 closer to the horizontal cylinder 122, and the hydraulic piping work or maintenance work of the horizontal cylinder 122 and the inclination control electromagnetic valve 647 can be simplified. Can be

  As shown in FIGS. 1 to 6, 10, and 15, hydraulic pressure as a hydraulic external take-out mechanism that supplies hydraulic oil to a hydraulically-driven working machine (front loader working machine, etc.) that is detachably attached to the traveling machine body 2. And an external take-out valve 430. A hydraulic external take-off valve 430 is disposed above the lift fulcrum shaft 119 installation portion in the upper cover 118. Therefore, the hydraulic equipment parts (hydraulic external take-off valve 430) related to the lifting mechanism 22 provided behind the straight traveling mission case 17 can be arranged together on the upper cover 118 to form a unit, and the hydraulic external take out to the straight traveling mission case 17 can be achieved. The assembly and maintenance work of the valve 430 can be easily simplified, and the ease of assembly of the straight traveling mission case 17 can be improved.

  A hydraulic external take-out valve 430 is placed on the upper surface of the upper cover 118 and behind the tilt control electromagnetic valve 647. Accordingly, the upper cover 118 can be attached to and detached from the straight traveling mission case 17 with the hydraulic external take-off valve 430 and the tilt control solenoid valve 647 assembled to the upper cover 118, and the hydraulic external take-out valve 430 and the tilt control solenoid valve can be attached. Assembling and maintenance workability of 647 can be simplified. By arranging the hydraulic external take-off valve 430 at the position where the hydraulic piping at the rearmost part of the upper surface of the straight traveling case 17 is easy, the handling workability of the hydraulic external take-out valve 430 can be improved.

  As shown in FIGS. 15 to 18, the elevating mechanism 22 includes an elevating cylinder 117 that elevates and lowers the link mechanism 111, an elevating valve mechanism 652 that supplies hydraulic oil to the elevating cylinder 117 and raises the cylinder rod 125, and the elevating cylinder 117. And a double-acting valve mechanism 431 for lowering the cylinder rod 125 by supplying hydraulic oil. An elevating valve mechanism 652 is arranged on the rear upper surface of the transmission case 17 (in the embodiment, the upper surface of the top cover 118), and one side of the rear of the transmission case 17 (in the embodiment, on the left side of the rear transmission case 113). A double-acting valve mechanism 431 is disposed at the center.

  Therefore, when the double-acting valve mechanism 431 is additionally attached as the elevating mechanism 22, since each component of the elevating mechanism 22 is disposed behind the straight traveling mission case 17, each hydraulic pressure to be connected to the double-acting valve mechanism 431. Not only can the piping 746-749 be shortened, but the complexity of the piping installation work can be eliminated. In addition, the components of the lifting mechanism 22 other than the double-acting valve mechanism 431 that are capable of single-acting operation are collectively installed on the top cover 118 of the straight traveling mission case 17, while the double-acting operation is also possible. The moving valve mechanism 431 is installed on the side of the rear transmission case 113 of the straight traveling mission case 17. Therefore, when assembling a working vehicle equipped with a mechanism with a single-action operation of only the raising / lowering valve mechanism 652 and a working vehicle with a mechanism capable of a double-action operation provided with the double-action valve mechanism 431 as the lifting mechanism 22. In addition, errors in each assembly operation can be prevented.

  Further, as shown in FIGS. 15 to 18, the lifting mechanism 22 has a horizontal cylinder 122 that changes the right and left tilt angles of the work implement supported by the link mechanism 111, and a tilt control electromagnetic valve that operates the horizontal cylinder 122 (horizontal control Valve) 647. Then, the inclination control electromagnetic valve 647 is disposed behind the elevating valve mechanism 652 on the rear upper surface (in the embodiment, upper surface lid 118 upper surface) of the straight traveling case 17. Further, a hydraulic external take-out valve 430 for switching the operation oil to and from the hydraulic drive work machine that is detachably attached to the traveling machine body 2 is disposed behind the tilt control electromagnetic valve 647. Then, each of the hydraulic external take-out valve 430 and the inclination control electromagnetic valve 647 and the double-acting valve mechanism 431 are connected by hydraulic pipes 747 and 748.

  As shown in FIGS. 18 to 21, a rear housing (frame rear coupling body) 74 coupled to the rear portion of the track frame 61 on which the crawler 3 is tracked is coupled to the left and right of the straight traveling mission case 17. At this time, the rear side of the cabin (control unit) 7 is supported on the side of the rear housing 74 and the double-acting valve mechanism 431 is supported on the front surface of the rear housing 74. A rear beam 72 connected to the rear end of the track frame 61 is connected to the lower surface of the rear housing 74. Accordingly, the double-acting valve mechanism 431 is supported together with the cabin 7 by the straight traveling mission case 17 which is a part of the traveling machine body 2 and is a highly rigid part. Further, since the rear housing 74 is a member that is also connected to the track frame 61, the double-acting valve mechanism 431 is supported in a stable state.

  The rear housing 74 has a valve support bracket 433 bolted to the front side surface, a rear support base 97 bolted to the side surface, and a rear beam 72 bolted to the lower surface. A double-acting valve mechanism 431 is placed and fixed on the upper surface of the valve support bracket 433 fixed to the rear housing 74 in a cantilever manner by bolt fastening. Further, the tank frame 18 and the vibration isolating rubber body 99 are installed on the upper surface of the rear support 97 fixed to the rear housing 74 in a cantilever shape. The fuel tank 11 and the battery 817 are fixed to the tank frame 18, and the cabin frame 300 is connected to the anti-vibration rubber body 99, and not only the rear portion of the cabin 7 but also the fuel tank 11 and A battery 817 is supported.

  The double-acting valve mechanism 431 is also connected to the rear housing 74 by a hydraulic pipe 749. As a result, the hydraulic oil from the double-acting valve mechanism 431 is returned to the straight traveling mission case 17 that is a hydraulic oil tank through the rear housing 74. Therefore, by supporting the double-acting valve mechanism 431 on the rear housing 74 via the valve support bracket 743, the unit can be configured with the rear housing 74 as a unit for adding a double-acting function, so that the ease of assembly can be improved.

  As shown in FIGS. 10, 18, 21, and 22, the link mechanism 111 includes a fulcrum bearing bracket in which the top link 24 is connected to the top link hinge 123 and the lower link 23 is provided on the rear end surface of the rear beam 72. 137 is pivotally supported. Further, both end portions of an anti-sway rod body (vibration restricting body) 103 with turnbuckle that can be expanded and contracted are connected to a chain bracket 101 and a lower link 23 provided on the rear end surface of the rear beam 72.

  Two plate-shaped fulcrum bearing brackets 137 are juxtaposed on the rear end surface of the rear beam 72, and the chain bracket 101 is fixed to the outer side (machine outside) of the fulcrum bearing bracket 137. One of the fulcrum bearing brackets 137 extends rearward from the inner surface (side closer to the straight traveling transmission case 17) of the rear beam 72, and the other extends rearward from the middle portion of the rear end surface of the rear beam 72. The two fulcrum bearing brackets 137 are fixed to the rear surface of the rear beam 72 so as to be parallel to each other. The fulcrum bearing brackets 137 have fulcrum shaft bosses 136 fixed to surfaces facing each other. A gap is provided between the two fulcrum shaft bosses 136, and the base end portion of the lower link 23 is inserted between the fulcrum shaft bosses 136.

  As described above, the fulcrum shaft boss 136 and the fulcrum bearing bracket 137 are fixed to the rear end surface of the rear beam 72. Then, one end side of the lower link fulcrum shaft body 130 is fitted into the fulcrum shaft boss 136, and a shaft stopper plate 138 is fixed to the other end side of the lower link fulcrum shaft body 130. At this time, one end side of the lower link fulcrum shaft body 130 is passed through the fulcrum bearing bracket 137 from the outside of the machine, and one end side of the lower link fulcrum shaft body 130 is fitted to the base end portion of the lower link 23 and the fulcrum shaft boss 136. The shaft stop plate 138 is bolted to the outer surface of the fulcrum bearing bracket 137. That is, the lower link fulcrum shaft body 130 is attached to and detached from the rear beam 72 from the left and right outer sides of the straight traveling case 17 so that the lower link 23 can be attached and detached.

  As shown in FIGS. 10, 18, 21, and 22, the hitch body 131 is fastened to the left and right side plate bodies 132 that are fastened to the outside of the side surface portion of the straight traveling mission case 17 and the bottom surface portion of the straight traveling mission case 17. The bottom plate body 133 is fixed to the left and right ends of the bottom plate body 133, and the lower end sides of the left and right side plate bodies 132 are integrally fixed, and the side and bottom portions of the straight traveling case 17 are surrounded by the hitch body 131. It is configured as follows. Accordingly, it is possible to easily prevent the interference between the rear beam 72 and the hitch body 131 disposed on the left and right side surfaces of the straight traveling mission case 17, and it is possible to easily secure a support load adapted to a large working machine.

  As shown in FIGS. 10, 18, 21 and 22, the left and right lift arms 120 are connected to the straight transmission case 17 via a lift fulcrum shaft 119, and the lift rods are connected to the distal ends of the left and right lift arms 120. The middle of the left and right lower links 23 is connected via 121. A lift cylinder 117 is mounted between the left and right lift arms 120, and the lift cylinder 117 is connected to a cylinder receiver 146 of the hitch body 131 via a cylinder mounting shaft body 147. Accordingly, the left and right lift arms 120 can be arranged on the upper surface side of the straight traveling mission case 17, the lift cylinder 117 can be arranged on the rear surface side of the straight traveling mission case 17, and the left and right side surfaces and the upper and lower surfaces of the rear traveling mission case 17 are effective. It is possible to improve the assembling / disassembling workability of the lifting mechanism 22 while the lifting mechanism 22 can be assembled in a compact manner.

  As shown in FIGS. 10, 18, 21, and 22, the link mechanism 111 is provided at each of the lower links 23 while the middle part of each of the left and right lower links 23 is suspended by the lift rod 121 of the lifting mechanism 22. A lateral swing of the work implement is restricted by a pair of left and right vibration restrictors 103. The vibration regulating body 103 is connected to the lower link 23 at a position where one end is on the front side of the lift rod 121, and the other end is connected to the rear beam 72. Since the vibration restricting body 103 is connected to the rear beam 72 that pivotally supports the lower link 23, the parts for supporting the link mechanism 111 can be shared, and the ease of assembly can be improved. In addition, since the lower link 23 of the link mechanism 111 and the support member of the swing restricting body 103 are configured by a single component, the complexity of adjusting the attachment of the link mechanism 111 can be reduced.

  As shown in FIGS. 10, 18, 21, and 22, one end of the swing restricting body 103 is bolted to the lower link 23 so as to be swingable in the left-right direction at a position on the front side of the lift rod 121. The other end of the swing restricting body 103 is pivotally supported by the chain bracket 101 so as to be rotatable in the left-right direction. The chain bracket 101 extends from the outside of the rear end surface of the rear beam 72 toward the fixed portion of the vibration regulating body 103 in the lower link 23 so as to be parallel to the installation direction of the rocking regulation body 103. Accordingly, the lower link 23 can be connected in the shortest time by the swing restricting body 103, the load applied to the swing restricting body 103 is reduced, the swing of the link mechanism 11 is stabilized, and the swing restricting body 103 is Damage and single life can be prevented.

  A left and right penetrating mounting hole 152 is formed on the rear end side of the chain bracket 101. The left and right outer ends of the lower link fulcrum shaft body 130 face the mounting hole 152 of the chain bracket 101 from the axial center line direction. The inner diameter of the mounting hole 152 is set to a size that allows the lower link fulcrum shaft body 130 to be inserted. That is, the inner diameter of the mounting hole 152 is set larger than the diameter of the lower link fulcrum shaft body 130. A bearing body 153 into which the pivot pin 151 is inserted is detachably fitted in the mounting hole 152. A horizontally long pivot pin 151 with a head is passed through the base end side of the swing regulating body 103 and the bearing body 153 fitted in the mounting hole 152 of the chain bracket 101. A retaining pin for retaining is detachably attached to the protruding end of the pivot pin 151 opposite to the head. The pivot pin 151 is held by a stop pin so as not to be detached from the proximal end side of the swing restricting body 103 and the bearing body 153 of the chain bracket 101. In the state in which the connection between the swing restricting body 103 and the chain bracket 101 is released by removing the locking pin and the pivot pin 151 is pulled out, and the bearing body 153 and the outer cover body 140 are removed, the insertion through the insertion hole 152 in a side view. The left and right outer ends of the lower link fulcrum shaft 130 can be seen.

  That is, if the connection between the swing restricting body 103 and the chain bracket 101 is released and the bearing body 153 and the outer cover body 140 are removed, the lower link fulcrum shaft body 130 can be inserted and removed through the mounting hole 152. Therefore, the lower link 23 can be easily attached to and detached from the straight transmission case 17 (rear beam 72). In addition, when the portion that pivotally supports the pivot pin 151 (the shaft hole portion of the bearing body 153) is worn, it is only necessary to replace the bearing body 153, which can improve the maintenance workability and reduce the maintenance cost. Also contribute to.

  As shown in FIGS. 23 and 24, the rear axle case 19 can be attached to the straight traveling mission case 17 instead of the rear housing 74. That is, a rear axle case 19 in which a rear axle is rotatably inserted is attached to both side surfaces of a rear transmission case 113 of a straight traveling transmission case 17 so as to provide wheels (wheels) 4 instead of the crawler 3 as a traveling portion. At this time, the tractor 1 can be configured as a wheel tractor by attaching the wheel (wheel) 4 to the front axle 16 inserted in the axle case 90 attached to both sides of the turning mission case 13. In this way, the crawler 3 and the wheel 4 can be selected as the traveling unit, and the straight traveling mission case 17 can be a common component in many types of work vehicles.

  In addition, the structure of each part in this invention is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

2 traveling machine body 3 traveling crawler 4 wheel 5 diesel engine 8 control seat 13 turning mission case 17 straight traveling mission case 500 hydraulic mechanical transmission 642 forward low speed clutch hydraulic pressure switching valve 643 forward high speed clutch hydraulic pressure switching valve 644 reverse clutch hydraulic pressure switching valve 701 Hydraulic continuously variable transmission (HST)

Claims (4)

A traveling machine body on which an engine is mounted, a link mechanism that mounts a work machine on the traveling machine body, a lifting mechanism that moves the link mechanism up and down, and a hydraulic pump that is driven by power through the mission mechanism in the mission case. In a work vehicle in which a part of the traveling machine body is configured by a mission case,
The elevating mechanism includes an elevating cylinder that elevates and lowers the link mechanism, a elevating valve that supplies hydraulic oil to the elevating cylinder to raise the cylinder rod, and a complex that lowers the cylinder rod by supplying hydraulic oil to the elevating cylinder. It consists of a dynamic valve and
The raising / lowering valve is disposed on the rear upper surface of the mission case, and the double-acting valve and the hydraulic pump are separately disposed on both rear surfaces of the mission case, and the hydraulic pump and the double-acting valve are connected by hydraulic piping. A working vehicle characterized by that. The elevating mechanism further includes a horizontal cylinder that changes a right and left tilt angle of a work implement supported by the link mechanism, and a horizontal control valve that operates the horizontal cylinder;
On the rear upper surface of the transmission case, the horizontal control valve is disposed behind the elevating valve, and the horizontal control is performed on the hydraulic external take-off valve that switches the operation oil to and from the hydraulically-driven working machine that is detachably attached to the traveling machine body. 2. The work vehicle according to claim 1, wherein the work vehicle is disposed behind the valve, and the hydraulic external take-off valve and the horizontal control valve are respectively connected to the double-acting valve by hydraulic piping. The traveling portion is a crawler, and a frame rear connecting body connected to a rear portion of a track frame on which the crawler is crawled on the left and right of the mission case is connected to the left and right of the mission case,
3. The work vehicle according to claim 1, wherein a rear side of the control unit is supported by a side surface of the frame rear connector, and the double-acting valve is supported by a front surface of the frame rear connector. A crawler and a foil can be selected as the traveling unit,
When the traveling unit is a wheel, a rear axle case for driving a rear wheel is connected to the left and right of the transmission case, and the rear of the control unit is supported above the rear axle case. 3. The work vehicle according to 3.

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