JP2016080054A - Work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work vehicle for allowing either A-position support or neutral-position fixation (neutral lock) of a hydraulic external extraction lever to be selected by operating a regulation claw, thus improving the operability thereof.SOLUTION: The work vehicle includes a driving seat mounted on a travel machine body for an operator to ride thereon, and a hydraulic external extraction lever 54 arranged on the lateral side of the driving seat so that the hydraulic external extraction lever 54 is operated to supply oil from a hydraulic external extraction mechanism to external hydraulic equipment. The hydraulic external extraction lever 54 is operated for switching a hydraulic external extraction valve for the hydraulic external extraction mechanism between an A position and a neutral position. A regulation claw 63a capable of locking the hydraulic external extraction lever 54 is provided on either the A position or the neutral position of the hydraulic external extraction lever 54. The regulation claw 63a is slidably supported by a cover 61 on which the hydraulic external extraction lever 54 is arranged.SELECTED DRAWING: Figure 25

Description

  The present invention relates to a work vehicle such as a farm tractor that pulls a ground work machine such as a tillage work machine or a sowing work machine.

  Conventionally, a link mechanism arranged at the rear part of a farm tractor as a work vehicle, a lift arm and a lift cylinder for moving the link mechanism up and down are provided, and a rotary tiller can be raised and lowered at the rear part of the tractor via the link mechanism. There is a technique to install and till the field. (See Patent Document 1)

JP 2008-037411 A

  For example, when a front loader working machine or the like can be installed and a hydraulic external take-out lever (hydraulic external take-out mechanism) is provided to supply hydraulic fluid to the front loader work machine or the like, the neutral position of the hydraulic external take-out lever is set. Since there is no lock (neutral lock), only the A position switching position is fixed, but the neutral position cannot be locked (neutral lock). The hydraulic external take-out lever at the neutral position is inadvertently switched, and the hydraulic external take-out mechanism Had problems such as malfunctioning.

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

  According to the first aspect of the present invention, an operator seat is mounted on the traveling aircraft body, and an operator sits on the side, and a hydraulic external takeout lever is disposed on the side of the control seat, and the hydraulic external takeout lever is operated. In a work vehicle in which hydraulic oil is supplied from an external hydraulic take-out mechanism to an external hydraulic device, the hydraulic external take-out valve of the hydraulic external take-out mechanism is switched between an A position position and a neutral position by operating the hydraulic external take-out lever. In addition, a restriction pawl capable of locking the hydraulic external take-out lever is provided at either the A position position or the neutral position of the hydraulic external take-out lever, and the restriction pawl can be slid on a cover on which the hydraulic external take-out lever is disposed. It is comprised so that it may support.

  According to a second aspect of the present invention, in the work vehicle according to the first aspect, the hydraulic external take-off mechanism includes a hydraulic external take-off valve capable of switching between three positions, and the position of the A position and the neutral position can be controlled by operating the hydraulic external take-out lever. The structure is such that the hydraulic external take-off valve is switched between the position and the B position, and the restriction claw is formed in a bifurcated claw shape, and the hydraulic external take-out is at any of the A position position, the neutral position and the B position position. The lever is configured to be lockable by the restriction claw.

  According to a third aspect of the present invention, in the work vehicle according to the first aspect, a restriction guide groove is formed in a cover on which the hydraulic external takeout lever is disposed, and an operation protrusion is integrally formed on the restriction claw. An operation protrusion is inserted into the restriction guide groove, and an operation protrusion is provided outside the cover.

  According to the first aspect of the present invention, an operator seat is mounted on the traveling body and an operator sits on the hydraulic seat, and a hydraulic external take-out lever is disposed on the side of the control seat, and the operation of the hydraulic external take-out lever is performed. In a working vehicle for supplying hydraulic oil from a hydraulic external take-out mechanism to an external hydraulic device, a structure in which the hydraulic external take-out valve of the hydraulic external take-out mechanism is switched between an A position position and a neutral position by operating the hydraulic external take-out lever. A regulation claw capable of locking the hydraulic external extraction lever is provided at either the A position position or the neutral position of the hydraulic external extraction lever, and the regulation claw is slid on a cover on which the hydraulic external extraction lever is disposed. Since it is configured so that it can be supported, it can be fixed at the A position or in the neutral position by the control claw operation. You can select one of the neutral lock), thereby improving the operability of the hydraulic outcoupling lever.

  According to the second aspect of the present invention, the hydraulic external take-out mechanism is provided with a hydraulic external take-off valve capable of switching between three positions, and hydraulically moves to the A position position, the neutral position, and the B position position by operating the hydraulic external take-out lever. A structure for switching an external take-off valve, wherein the restriction claw is formed in a bifurcated claw shape, and the hydraulic external take-out lever is moved to any of the A position position, neutral position and B position position by the restriction claw. Since it is configured to be lockable, it is possible to select A-position support, neutral position fixing (neutral lock), or B-position support by one-touch operation of the restriction claw.

  According to a third aspect of the present invention, a restriction guide groove is formed in the cover on which the hydraulic external take-out lever is disposed, and an operation protrusion is integrally formed on the restriction claw, and the operation protrusion is formed in the restriction guide groove. Since the body is fitted and the operation projection is protruded on the outside of the cover, the restriction pawl can be easily supported in the restriction guide groove of the cover that also serves as the lever guide of the hydraulic external takeout lever, It can be configured at a low cost by reducing the number of parts for attaching the regulating claws.

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 left side explanatory drawing of a traveling body. It is right side explanatory drawing of a traveling body. It is a top view of a traveling body. It is the perspective view which looked at the traveling body from the left rear. It is the perspective view which looked at the traveling body from the right rear. It is the expansion perspective view which looked at the traveling body from the left side. It is the expansion perspective view which looked at the traveling body from the right side. It is the perspective view which looked at the traveling body from the left front. It is the perspective view which looked at the traveling body from the right side. 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 left view of a mission case. It is a right view of a mission case. It is a top view of a mission case. It is the perspective view which looked at the rear part upper surface of the mission case from the left front. It is a left sectional view of a mission case. It is the perspective view which looked at the mission case from the left front. It is front sectional drawing of a mission case. It is the perspective view which looked at the rear part of the mission case from the left front. It is a disassembled perspective view of the rear part of a mission case. It is sectional explanatory drawing which decomposed | disassembled the mission case rear part. It is a plane sectional view of a hydraulic operation lever attachment part. It is a plane explanatory view of a hydraulic operation lever attachment part. It is side surface sectional drawing of a hydraulic control lever attaching part. It is a side view of a parking brake lever attaching part. It is a side enlarged view of a parking brake lever attachment part. It is the perspective view which looked at the parking brake lever attachment part from the right front.

  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 8, the traveling machine body 2 of the tractor 1 is supported by a pair of left and right rear wheels 4 as well as a pair of left and right front wheels 3 as a traveling unit. The pair of left and right rear wheels 4 corresponds to the rear traveling unit. A diesel engine 5 (hereinafter simply referred to as an engine) is mounted on the front portion of the traveling machine body 2, and the tractor 1 is configured to travel forward and backward by driving the rear wheel 4 or the front wheel 3 with the engine 5. . 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 front wheel 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 bottom of the cabin 7.

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

  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 part of the mission case 17. The ground work machine is connected to the rear portion of the 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. On the rear side surface of the mission case 17, a PTO shaft 25 for projecting a PTO driving force to a ground working machine such as a rotary tiller is provided to project rearward.

  A flywheel 26 (see FIGS. 4 to 6, 10, and 11) is connected to an output shaft (piston rod) of the engine 5 that protrudes rearward from the rear side surface of the engine 5. A main shaft 27 projecting rearward from the flywheel 26 and a main transmission input shaft 28 projecting forward from the front side of the transmission case 17 are connected via a power transmission shaft 29 having universal shaft joints at both ends. 4 to 6). As shown in FIG. 13, a hydraulic continuously variable transmission 500, a forward / reverse switching mechanism 501, travel transmission gear mechanisms 502, 503, 504, a rear wheel differential gear mechanism 506, and the like are arranged inside the mission case 17. Yes. The rotational power of the engine 5 is transmitted to the main transmission input shaft 28 of the transmission case 17 via the main driving shaft 27 and the power transmission shaft 29, and is shifted by the hydraulic continuously variable transmission 500 and the traveling transmission gear mechanism. Is transmitted to the left and right rear wheels 4 via the rear wheel differential gear mechanism 506.

  The front wheel output shaft 30 projecting forward from the front lower part of the transmission case 17 is transmitted to the front wheel projecting rearward from the front axle case 13 containing the front wheel differential gear mechanism 507 via the front wheel drive shaft 31. The shaft 508 is connected. Transmission power by the hydraulic continuously variable transmission 500 and the traveling transmission gear mechanism (two-wheel drive / four-wheel drive switching mechanism 504) in the mission case 17 is transmitted from the front wheel output shaft 30, the front wheel drive shaft 31, and the front wheel transmission shaft 508 to the front axle. It is configured to be transmitted to the left and right front wheels 3 via a front wheel differential gear mechanism 507 in the case 13.

  Next, the internal structure of the cabin 7 will be described with reference to FIGS. 3, 7 and 8. A steering column 32 is disposed in front of the control seat 8 in the cabin 7. The steering column 32 is erected on the rear side of a 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.

  A pair of left and right brake pedals 35 for braking the traveling machine body 2 are disposed on the lower right side of the steering column 32. On the upper 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 is disposed. On the lower left side of the steering column 32, a clutch pedal 37 for disengaging the outputs of the hydraulic continuously variable transmission 500 (forward low speed hydraulic clutch 537, forward high speed hydraulic clutch 539, reverse hydraulic clutch 541) is disposed. . The master control solenoid valve 635 is turned on by stepping on the clutch pedal 37, and the forward output or the reverse output of the hydraulic continuously variable transmission 500 is cut off (see FIG. 14).

  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 causing the erroneous operation preventing body 38, which is a contact prevention tool, to protrude outward from 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. ing. 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. Left and right side columns 42 are arranged on both left and right sides of the control seat 8. Between the control seat 8 and the left side column 42, a parking brake lever 43 that maintains the left and right rear wheels 4 in a braking state, and an ultra-low speed that forcibly and significantly reduces the forward travel speed (vehicle speed) of the tractor 1 A lever 44 (creep operation lever), a sub-transmission lever 45 that switches the output range of the traveling sub-transmission gear mechanism 503 in the mission case 17, and a PTO transmission lever 46 that switches the driving speed of the PTO shaft 25 are arranged. . A differential lock pedal 47 for turning on and off the differential drive of the left and right rear wheels 4 is disposed below the control seat 8. A reverse PTO lever 48 for performing an operation of driving the PTO shaft 25 in the reverse direction is disposed on the left rear side of the control seat 8 (see FIG. 10).

  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 includes a main transmission lever 50 that increases / decreases the traveling speed of the tractor 1, a dial type work unit position dial 51 (elevating dial) that manually changes and adjusts the height position of a ground work machine such as a rotary tiller. It has. In addition, the armrest 49 is configured to be able to be turned up and rotated in a plurality of stages with the rear end lower part as a fulcrum.

  In the right side column 42, in order from the front side, a throttle lever 52 that sets and holds the rotational speed of the engine 5, and a PTO clutch switch 53 that interrupts power transmission from the PTO shaft 25 to a work machine such as a rotary tiller A plurality of hydraulic operation levers 54 (SCV levers) for switching the hydraulic external take-off valve 430 (see FIG. 14) arranged on the upper surface side of the mission case 17 are arranged. Here, the hydraulic external take-off valve 430 is for controlling supply of hydraulic oil to hydraulic equipment of a work machine such as a front loader that is retrofitted to the tractor 1. In the embodiment, four hydraulic operation levers 54 are arranged in accordance with the number of hydraulic external take-out valves (four stations).

  Furthermore, as shown in FIGS. 9 to 12, left and right front support bases 96 that support the front side of the cabin 7 and left and right rear support bases 97 that support the rear part of the cabin 7 are provided. The front support 96 is bolted to the front and rear intermediate portions of the outer side surfaces of the left and right aircraft frames 15, and the front bottom of the cabin 7 is anti-vibrated on the upper surface of the front support 96 via the anti-vibration rubber body 98. The rear support base 97 is bolted to the middle portion of the left and right widths of the upper surfaces of the left and right rear axle cases 19 that are horizontally extended in the left-right direction, and the vibration-proof rubber body 99 is attached to the upper surface side of the rear support base 97. The rear bottom portion of the cabin 7 is supported by vibration isolation. That is, the diesel engine 5 and the cabin 7 are supported by the traveling machine body 2 (the engine frame 14, the machine frame 15, and the rear axle case 19, which are integrally connected) via the plurality of vibration-proof rubber bodies. . Further, as shown in FIGS. 4 and 5, etc., the rear support base 97 is disposed on the upper surface side of the rear axle case 19, and the steady bracket 101 is disposed on the lower surface side of the rear axle case 19. The fastening bracket 101 is fastened with bolts, and both ends of the steady rod body 103 with turnbuckles that can be expanded and contracted are connected to the middle portion of the lower link 23 and the steady bracket 101 that extend in the front-rear direction. The horizontal vibration of 23 is prevented.

  Next, the diesel engine 5 and the engine room structure under the hood 6 will be described with reference to FIGS. The diesel engine 5 has a cylinder head mounted on a cylinder block having a built-in engine output shaft and piston, and is connected to an air cleaner 221 via a turbocharger 211 on the right side surface of the diesel engine 5 (cylinder head). And an EGR device 210 that recirculates a part of the exhaust gas from the exhaust manifold 204, and a part of the exhaust gas discharged to the exhaust manifold 204 is returned to the intake manifold 203. The maximum combustion temperature during high-load operation is lowered, and NOx (nitrogen oxide) emissions from the diesel engine 5 are reduced. On the other hand, the exhaust manifold 204 connected to the tail pipe 229 and the turbocharger 211 are arranged on the left side surface of the diesel engine 5 (cylinder head). That is, the intake manifold 203 and the exhaust manifold 204 are distributed and arranged on the left and right side surfaces along the engine output shaft in the engine 5. A cooling fan 206 is disposed on the front side of the diesel engine 5 (cylinder block).

  In addition, as shown in FIGS. 4 to 8 and the like, the diesel engine 5 includes a continuously regenerative exhaust gas purifying device 224 (DPF) disposed on the upper surface side of the diesel engine 5 (above the exhaust manifold 204). A tail pipe 229 is connected to the exhaust side of the purification device 224. The exhaust gas purifying device 224 removes particulate matter (PM) in the exhaust gas discharged from the engine 5 through the tail pipe 229 to the outside of the machine, and at the same time, carbon monoxide (CO) and carbonization in the exhaust gas. Hydrogen (HC) is configured to be reduced.

  Furthermore, as shown in FIGS. 1 to 3 and the like, the bonnet 6 has a front grill 231 at the front lower side, and covers the upper surface side and the front surface side of the engine room 200. Side engine covers 232 formed of a perforated plate are arranged on the lower left and right sides of the bonnet 6 to cover the left and right sides of the engine room 200. That is, the hood 6 and the engine cover 232 cover the front, upper, and left and right sides of the diesel engine 5.

  Further, as shown in FIGS. 4 to 8, a radiator 235 having a fan shroud 234 attached to the back side is erected on the engine frame 14 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. An air cleaner 221 is disposed above the front surface of the radiator 235. In addition to the above intercooler, an oil cooler, a fuel cooler, and the like are installed on the front side of the radiator 235.

  On the other hand, as shown in FIGS. 9 to 12 and the like, the pair of left and right body frames 15 are connected by a support beam frame 236. The support beam frame 236 is bolted to the left and right airframe frames 15 and is erected on the front end portions (rear side of the engine 5) of the left and right airframe frames 15, and the rear engine legs 237 having vibration-proof rubber bodies. The rear part of the diesel engine 5 is connected to the upper surface of the support beam frame 236 via As shown in FIGS. 1, 2, 4, 5, 11, and 12, left and right front engine legs 238 having anti-vibration rubber bodies are provided in the middle of the pair of left and right engine frames 14. The left and right side surfaces of the front part of the diesel engine 5 are connected to each other. That is, the front side of the diesel engine 5 is supported on the engine frame 14 by vibration isolation, and the rear part of the diesel engine 5 is supported on the front end sides of the pair of left and right body frames 15 via the support beam frame 236.

  Next, with reference to FIGS. 4-12, the attachment structure of the mission case 17, the hydraulic lifting mechanism 22, and the three-point link mechanism 111 will be described. The transmission case 17 includes a front transmission case 112 having a main transmission input shaft 28 and the like, a rear transmission case 113 having a rear axle case 19 and the like, and a front side of the rear transmission case 113 on the rear side of the front transmission case 112. An intermediate case 114 to be connected is provided. 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. The transmission case 17 is integrally connected to form the rear part of the traveling machine body 2, and the front transmission case 112 or the power transmission shaft 29 is disposed between the left and right machine body frames 15, so that the front transmission case is provided. 112 and the like are protected. The left and right rear axle cases 19 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 transmission case 17 is divided into the three parts of the front transmission case 112, the intermediate case 114, and the rear transmission case 113, parts such as shafts and gears are provided in each case 112-114. , The three parts of the front transmission case 112, the intermediate case 114, and the rear transmission case 113 can be assembled. Therefore, the assembly of the mission case 17 can be performed accurately and efficiently.

  The left and right rear axle cases 19 are attached to the left and right sides of the rear transmission case 113, and the middle of the high-rigidity structure connecting 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. Since the case 114 is connected, 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 and the like are installed. Maintenance or repair work such as replacement of the shaft and gear in the front transmission case 112 can be performed. Therefore, the frequency of the disassembling work for removing the entire mission case 17 from the tractor 1 can be remarkably reduced, and the workability at the time of maintenance and repair can be improved.

  Further, while the intermediate case 114 and the rear transmission case 113 are made of cast iron, and 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 axle cases 19 are made. The rear transmission case 113 to which the two are connected 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 transmission case 17 as a whole while sufficiently securing the rigidity of the traveling machine body 2.

  On the other hand, as shown in FIGS. 4 to 12, 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 like, and the upper surface of the rear transmission case 113 of the transmission case 17. 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.

  7, 8, 10, etc., 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.

  Next, the internal structure of the mission case 17 and the power transmission system of the tractor 1 will be described with reference to FIGS. The transmission case 17 includes a front transmission case 112 having a main transmission input shaft 28 and the like, a rear transmission case 113 having a rear axle case 19 and the like, and a front side of the rear transmission case 113 connected to the rear side of the front transmission case 112. An intermediate case 114 is provided. The mission case 17 is formed in a hollow box shape as a whole.

  A front lid member 491 is disposed on the front surface of the mission case 17, that is, on the front surface of the front transmission case 112. The front lid member 491 is detachably fastened to the front surface of the front transmission case 112 with a plurality of bolts. A rear cover member 492 is disposed on the rear surface of the transmission case 17, that is, on the rear surface of the rear transmission case 113. The rear cover member 492 is detachably fastened to the rear surface of the rear transmission case with a plurality of bolts. An intermediate partition wall 493 that partitions the front transmission case 112 and the intermediate case 114 is integrally formed on the front side in the intermediate case 114. A rear partition wall 494 that partitions the inside of the rear transmission case 113 forward and backward is integrally formed in the middle part of the rear transmission case 113.

  Therefore, the inside of the mission case 17 is divided into three chambers, a front chamber 495, a rear chamber 496, and an intermediate chamber 497, by the middle and rear partition walls 493 and 494. A space between the front lid member 491 and the intermediate partition wall 493 in the transmission case 17 (inside the front transmission case 112) is a front chamber 495. A rear chamber 496 is formed between the rear lid member 492 and the rear partition wall 494 (inside the rear side of the rear transmission case 113). A space between the intermediate partition wall 493 and the rear partition wall 494 (inside the intermediate case 114 and the front side of the rear transmission case 113) is an intermediate chamber 497. The front chamber 495, the intermediate chamber 497, and the rear chamber 496 communicate with each other by cutting out part of the partition walls 493 and 494 so that the hydraulic oil (lubricating oil) in the chambers 495 to 497 can move to each other. doing.

  In the front chamber 495 (in the front transmission case 112) of the transmission case 17, a mechanical creep transmission gear mechanism 502 that shifts rotational power via the hydraulic continuously variable transmission 500 and a forward / reverse switching mechanism 501 described later. In addition, a traveling auxiliary transmission gear mechanism 503 and a two-wheel drive / four-wheel drive switching mechanism 504 for switching between the two-wheel drive and the four-wheel drive of the front and rear wheels 3, 4 are arranged. A forward / reverse switching mechanism 501 is provided in the intermediate chamber 497 of the mission case 17 (inside the intermediate case 114 and the front of the rear transmission case 113) to switch the rotational power from the hydraulic continuously variable transmission 500 in the forward or reverse direction. ing. After transmitting the rotational power from the engine 5 to the PTO shaft 25 by appropriately shifting and transmitting the rotational power via the creep transmission gear mechanism 502 or the traveling auxiliary transmission gear mechanism 503 to the left and right rear wheels 4. A wheel differential gear mechanism 506 is disposed. 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 work case hydraulic pump 481 that is driven by the rotational power of the engine 5 and a pump case 480 that houses the traveling hydraulic pump 482 are attached to the front portion of the left outer surface of the rear transmission case 113.

  As shown in FIGS. 4 to 6, a flywheel 26 is connected to an output shaft (crankshaft) of the engine 5 projecting rearward from the rear side surface of the engine 5. A main transmission input shaft 28 projecting forward from the front side (front cover member 491) of the transmission case 17 is connected to a main driving shaft 27 projecting rearward from the flywheel 26 via a power transmission shaft 29 having universal joints at both ends. It is connected. The rotational power of the engine 5 is transmitted to the main transmission input shaft 28 of the transmission case 17 (front transmission case 112) via the main driving shaft 27 and the power transmission shaft 29, and the hydraulic continuously variable transmission 500 and the creep transmission gear mechanism. After being shifted by 502 or the traveling auxiliary transmission gear mechanism 503, it is transmitted to the rear wheel differential gear mechanism 506 to drive the left and right rear wheels 4. Shift power via the creep transmission gear mechanism 502 or the traveling auxiliary transmission gear mechanism 503 is transmitted from the two-wheel drive and four-wheel drive switching mechanism 504 to the front axle via the front wheel output shaft 30, the front wheel drive shaft 31, and the front wheel transmission shaft 508. It is transmitted to the front-wheel differential gear mechanism 507 in the case 13 so as to drive the left and right front wheels 3.

  The main transmission input shaft 28 protruding forward from the front lid member 491 extends in the front-rear direction from the front transmission case 112 to the intermediate case 114 (from the front chamber 495 to the intermediate chamber 497). A midway portion before and after the main transmission input shaft 28 is rotatably supported by the intermediate partition wall 493. The rear end side of the main transmission input shaft 28 is rotatably supported by an intermediate auxiliary plate 498 that is detachably fastened to the front surface side (intermediate chamber 497 side) of the rear partition wall 494. The intermediate auxiliary plate 498 and the rear partition wall 494 are arranged so that a gap in the front-rear direction is left between the two plates 498 and 494. From the front transmission case 112 to the intermediate case 114 (from the front chamber 495 to the intermediate chamber 497), an input transmission shaft 511 for transmitting power from the main transmission input shaft 28 is arranged in parallel with the main transmission input shaft 28. . In the front transmission case 112 (in the front chamber 495), a hydraulic continuously variable transmission 500 is disposed via an input transmission shaft 511. The front side of the hydraulic continuously variable transmission 500 is attached to the inner surface side of the front lid member 491 that detachably closes the front opening of the front transmission case 112. The rear end side of the input transmission shaft 511 is rotatably supported by the intermediate auxiliary plate 498 and the rear partition wall 494.

  The hydraulic continuously variable transmission 500 in the front chamber 495 is an inline type in which a main transmission output shaft 512 is concentrically disposed on an input transmission shaft 511. A cylindrical main transmission output shaft 512 is fitted in a portion of the input transmission shaft 511 in the intermediate chamber 497. The front end side of the main transmission output shaft 512 passes through the intermediate partition wall 493 and is rotatably supported on the intermediate partition wall 493. The rear end side of the main transmission output shaft 512 is rotatably supported by the intermediate auxiliary plate 498. Therefore, the rear end side that is the input side of the input transmission shaft 511 protrudes rearward from the rear end of the main transmission output shaft 512. A main transmission input gear 513 is fitted on the rear end side of the main transmission input shaft 28 (between the intermediate auxiliary plate 498 and the rear partition wall 494) so as not to be relatively rotatable. An input transmission gear 514 that always meshes with the main transmission input gear 513 is fixed to the rear end side of the input transmission shaft 511 (between the intermediate auxiliary plate 498 and the rear partition wall 494). Accordingly, the rotational power of the main transmission input shaft 28 is transmitted to the hydraulic continuously variable transmission 500 via the main transmission input gear 513, the input transmission gear 514, and the input transmission 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 hydraulic 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 input transmission 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 input transmission shaft 511 is linked to the pump swash plate 523. In the embodiment, the main transmission hydraulic cylinder 524 is assembled inside the front lid member 491 on which the front portion of the hydraulic continuously variable transmission 500 is supported, and the front lid member 491 and the hydraulic continuously variable transmission 500 are combined into one member. As a unit. By changing the inclination angle of the pump swash plate 523 by driving the main transmission hydraulic cylinder 524, the amount of hydraulic oil supplied from the hydraulic pump unit 521 to the hydraulic motor unit 522 is changed and adjusted, and the main variable speed transmission 500 of the hydraulic continuously variable transmission 500 is changed. A speed change operation is performed.

  That is, 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 input transmission shaft 511 is changed accordingly. The pump swash plate 523 of the embodiment has a range between a maximum tilt angle of one (forward rotation) and a maximum tilt angle of the other (reverse rotation) with a neutral angle of the tilt angle of substantially zero (before and after including zero). When the vehicle speed of the traveling machine body 2 is the lowest, when the vehicle speed of the traveling machine body 2 is the medium speed, the swash plate inclination angle near the maximum reverse rotation is set to the stop state. The swash plate angle is set to an inclination angle near substantially zero, and is set to the swash plate inclination angle near the maximum of forward rotation when the vehicle speed of the traveling machine body 2 is the highest. Note that when the vehicle speed of the traveling machine body 2 is near the minimum (swash plate inclination angle near the maximum of reverse rotation), the starting force or the low-speed traveling force of the traveling machine body 2 can be easily secured.

  When the inclination angle of the pump swash plate 523 is substantially zero (neutral angle), the hydraulic motor unit 522 is not driven by the hydraulic pump unit 521, and the main transmission output shaft 512 rotates at substantially the same rotational speed as the input transmission shaft 511. To do. When the pump swash plate 523 is tilted in one direction (positive tilt angle) with respect to the axis of the input transmission shaft 511, the hydraulic pump unit 521 activates the hydraulic motor unit 522 at a higher speed than the input transmission shaft 511. The main transmission output shaft 512 rotates at a high rotational speed. For this reason, the rotational speed of the hydraulic motor unit 522 is added to the rotational speed of the input transmission shaft 511 and transmitted to the main transmission output shaft 512. As a result, the shift power (vehicle speed) from the main shift output shaft 512 is changed in proportion to the tilt angle (positive tilt angle) of the pump swash plate 523 within a range of rotation speed higher than the rotation speed of the input transmission shaft 511. Is done. When the pump swash plate 523 is positive and has an inclination angle near the maximum, the traveling machine body 2 reaches the maximum vehicle speed.

  When the pump swash plate 523 is tilted in the other direction (negative tilt angle) with respect to the axis of the input transmission shaft 511, the hydraulic pump unit 521 decelerates (reverses) the hydraulic motor unit 522, and the input transmission shaft The main transmission output shaft 512 rotates at a rotational speed lower than 511. For this reason, the rotational speed of the hydraulic motor unit 522 is subtracted from the rotational speed of the input transmission shaft 511 and transmitted to the main transmission output shaft 512. As a result, the speed change power from the main speed change output shaft 512 is changed in proportion to the inclination angle (negative inclination angle) of the pump swash plate 523 within the range of the rotation speed lower than the rotation speed of the input transmission shaft 511. When the pump swash plate 523 is negative and has an inclination angle near the maximum, the traveling machine body 2 has the minimum vehicle speed.

  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 main transmission input shaft 28 via a flat gear mechanism 485 so that power can be transmitted. A lubricating oil pump 518 is provided between the intermediate auxiliary plate 498 and the rear partition wall 494 to supply hydraulic oil for lubrication to the hydraulic 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 input transmission 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, which is a forward high-speed gear mechanism, and a low-speed gear pair 525, which is a forward low-speed gear mechanism, are disposed at a location in the intermediate chamber 497 of the main transmission input shaft 28 (on the rear side of the main transmission input shaft 28). doing. 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 main transmission input shaft 28, and a carrier 532 that rotatably supports a plurality of planetary gears 533 on the same radius. And a ring gear 534 having inner teeth on the inner peripheral surface. The sun gear 531 and the ring gear 534 are rotatably fitted on the main transmission input shaft 28. The carrier 532 is fitted to the main transmission input 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 main transmission input shaft 28. The input-side low-speed gear 527 and the output-side low-speed gear 528 constituting the low-speed gear pair 525 have an integral structure, and can rotate between the planetary gear mechanism 526 and the main transmission input gear 513 of the main transmission input shaft 28. It is pivotally supported.

  In the intermediate chamber 497 of the transmission case 17 (inside the intermediate case 114 and the front side of the rear transmission case 113), the main transmission input shaft 28, the input transmission shaft 511, the travel relay shaft 535 extending in parallel with the main transmission output shaft 512, and A travel transmission shaft 536 is disposed. The front end side of the travel relay shaft 535 is rotatably supported by the intermediate partition wall 493. A rear end side of the travel relay shaft 535 is rotatably supported on the intermediate auxiliary plate 498. The front end side of the traveling transmission shaft 536 is rotatably supported by the intermediate partition wall 493. The rear end side of the travel transmission shaft 536 is rotatably supported by the intermediate auxiliary plate 498.

  A forward / reverse switching mechanism 501 is provided on the travel relay shaft 535. 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 main transmission input 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 main transmission input 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 travel relay shaft 535 via the low speed gear pair 525 or the planetary gear mechanism 526, and the power is transmitted from the travel relay shaft 535 to the travel 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 driving force from the main transmission output shaft 512 is substantially zero (the main clutch disengaged state). )become.

  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 front chamber 495 of the transmission case (in the front transmission case 112), 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 are arranged. Yes. In this case, a travel counter shaft 545 extending coaxially with the travel transmission shaft 536 is disposed in the front chamber 495 (in the front transmission case 112). A sub-transmission shaft 546 extending in parallel with the travel counter shaft 545 is disposed from the front transmission case 112 to the rear transmission case 113 (from the front chamber 495 through the intermediate chamber 497 to the rear chamber 496). The front end side of the travel counter shaft 545 is rotatably supported by the front lid member 491. The rear end side of the travel counter shaft 545 is rotatably supported by the intermediate partition wall 493. The front end side of the auxiliary transmission shaft 546 is rotatably supported by the front lid member 491. The middle part of the auxiliary transmission shaft 546 is rotatably supported by the intermediate partition wall 493. The rear end side of the auxiliary transmission shaft 546 is rotatably supported by the intermediate auxiliary plate 498 and the rear partition wall 494.

  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 is pivotally supported on the intermediate partition wall 493 while being connected to the travel transmission shaft 536 so as to rotate integrally therewith. The creep gear 548 is fitted on the travel counter shaft 545 so as not to be relatively rotatable. 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 in a portion of the auxiliary transmission shaft 546 in the front chamber 495 (front transmission case 112). 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.

  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. A relatively low speed travel driving force is output from the travel transmission shaft 536 to the front wheel 3 and the rear wheel 4 via the travel counter shaft 545 and the auxiliary transmission shaft 546. The ultra-low speed lever 44 and the auxiliary transmission lever 45 are interlocked and connected via a check mechanism (not shown) so that the auxiliary transmission lever 45 cannot be operated to the high speed side when the ultra-low speed lever 44 is engaged. It is composed.

  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. And a low-speed traveling driving force is output from the traveling transmission shaft 536 to the front wheels 3 and the rear wheels 4 via the traveling counter shaft 545 and the auxiliary transmission shaft 546. 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. And a high-speed travel driving force is output from the travel transmission shaft 536 to the front wheels 3 and the rear wheels 4 via the travel counter shaft 545 and the auxiliary transmission shaft 546.

  The rear end side of the auxiliary transmission shaft 546 passes through the rear partition wall 494 and extends into the rear chamber 496. A pinion 558 is provided at the rear end of the auxiliary transmission shaft 546. Further, in the rear chamber 496 (inside the rear side of the rear transmission case 113), a rear wheel differential gear mechanism 506 for transmitting the driving force to the left and right rear wheels 4 is disposed. The rear wheel differential gear mechanism 506 includes a ring gear 559 that meshes with the pinion 558 of the auxiliary transmission shaft 546, a differential gear case 560 provided in the ring gear 559, and a pair of differential output shafts 561 that extend in the left-right direction. Yes. A differential output shaft 561 is connected to the rear axle 20 via a final gear 562 and the like. The rear wheel 4 is attached to the front end side of the rear axle 20.

  Brake mechanisms 563 are arranged on the left and right differential output shafts 561, respectively. The brake mechanism 563 brakes the left and right rear wheels 4 by two systems, that is, operation of the brake pedal 35 and automatic control. That is, each brake mechanism 563 brakes the corresponding left or right or both differential output shafts 561 by depressing the left or right brake pedal 35, and the corresponding left or right rear wheel. 4 is configured to brake. When the steering angle of the steering wheel 9 is equal to or greater than a predetermined angle, the brake cylinder 630 (see FIG. 14) is actuated by the switching operation of the autobrake solenoid valve 631 (see FIG. 14) with respect to the rear wheel 4 on the inside of the turn. The brake mechanism 563 for the rear wheel 4 is configured to automatically perform a braking operation (so-called autobrake operation works). For this reason, the tractor 1 can easily execute a small turning turn such as a U-turn (direction change at a headland in a field).

  The rear wheel differential gear mechanism 506 is provided with a differential lock mechanism 585 that stops the differential between the left and right rear wheels 4 (the left and right differential output shafts 561 are always driven at a constant speed). When the differential lock pin (not shown) constituting the differential lock mechanism 585 is engaged with the differential gear of the differential gear case 560 by the depression operation of the differential lock pedal 47, the differential gear is fixed to the differential gear case 560, and the differential gear The right and left differential output shafts 561 (left and right rear wheels 4) are driven at a constant speed.

  Next, the switching structure between the two-wheel drive and the four-wheel drive of the front and rear wheels 3 and 4 executed through the two-wheel drive and four-wheel drive switching mechanism 504 will be described. A two-wheel drive / four-wheel drive switching mechanism 504 is disposed in the front chamber 495 (front transmission case 112) of the mission case. In this case, a front wheel input shaft 568 and a front wheel output shaft 30 extending in parallel with the travel counter shaft 545 and the auxiliary transmission shaft 546 are disposed in the front chamber 495 (in the front transmission case 112). A driven gear 569 fitted to the front wheel input shaft 568 so as to be relatively non-rotatable is always meshed with a main gear 569 fitted so as to be relatively non-rotatable on the front end side of the auxiliary transmission shaft 546. A double-speed relay gear 571 and a four-wheel drive relay gear 572 are fitted to the front wheel input shaft 568 so as not to rotate relative to each other on both sides of the driven gear 570.

  A two-wheel drive / four-wheel drive switching mechanism 504 is provided on the front wheel output shaft 30. That is, the front wheel output shaft 30 is fitted with a double speed gear 574 connected by a wet multi-plate type double-speed hydraulic clutch 573 and a four-wheel drive gear 576 connected by a wet multi-plate type four-wheel hydraulic clutch 575. doing. The double speed relay gear 571 of the front wheel input shaft 568 is always meshed with the double speed gear 574 of the front wheel output shaft 30, and the four-wheel drive relay gear 572 is meshed with the four-wheel gear 576.

  When a drive changeover switch or a drive changeover lever (not shown) is operated to the four-wheel drive side, the four-wheel drive hydraulic clutch 575 enters a power connection state, and the front wheel output shaft 30 and the four-wheel drive gear 576 are connected so as not to be relatively rotatable. Then, as a result of the rotational power being transmitted from the auxiliary transmission shaft 546 to the front wheel output shaft 30 via the front wheel input shaft 568 and the four-wheel drive gear 576, the tractor 1 is a four-wheeled vehicle driven by the front wheel 3 together with the rear wheel 4. It becomes a driving state. Further, when the steering angle becomes equal to or greater than a predetermined angle by operating the steering handle 9 to make a U-turn or the like, the double speed hydraulic clutch 573 is automatically connected to the power, and the front wheel output shaft 30 and the double speed gear 574 are connected so as not to be relatively rotatable. Is done. Then, the rotational power is transmitted from the auxiliary transmission shaft 546 to the front wheel output shaft 30 via the front wheel input shaft 568 and the double speed gear 574, so that the rotational speed of the front wheel 3 by the rotational power via the four-wheel drive gear 576 is increased. The front wheel 3 is driven at a high speed about twice as high.

  Power is transmitted to the front wheels 3 through the front wheel transmission shaft 508 projecting rearward from the front axle case 13 and the front wheel output shaft 30 projecting forward from the lower front surface of the transmission case 17 (front lid member 491). The front wheel drive shaft 31 is connected. In the front axle case 13, a front wheel differential gear mechanism 507 that transmits a driving force to the left and right front wheels 3 is disposed. The front wheel differential gear mechanism 507 includes a ring gear 578 that meshes with a pinion 577 provided on the front end side of the front wheel transmission shaft 508, a differential gear case 579 provided on the ring gear 578, and a pair of differential output shafts 580 extending in the left-right direction. And. A differential output shaft 580 is connected to the front axle 16 via a final gear 581 or the like. The front wheel 3 is attached to the front end side of the front axle 16. A steering hydraulic cylinder 622 (see FIG. 14) for power steering is provided on the outer surface of the front axle case 13 to change the traveling direction of the front wheel 3 to the left and right by the steering operation of the steering handle 9.

  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. A PTO transmission mechanism 505 that transmits power from the engine 5 to the PTO shaft 25 is disposed in the rear chamber 496 of the transmission case 17 (inside the rear side of the rear transmission case 113). In this case, a PTO input shaft 591 extending coaxially with the main transmission input shaft 28 is connected to the rear end side of the main transmission input shaft 28 via a PTO hydraulic clutch 590 for power transmission interruption. The PTO input shaft 591 is disposed in the rear chamber 496. In the rear chamber 496, a PTO transmission shaft 592, a PTO counter shaft 593, and a PTO shaft 25 extending in parallel with the PTO input shaft 591 are disposed. The PTO shaft 25 protrudes rearward from the rear lid member 492. 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 28 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 28 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. By operating the reverse PTO lever 48 in reverse with the PTO shift lever 46 in a neutral operation, 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. doing.

  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 607 and the PTO output gear 608 are transmitted. Is transmitted to the PTO shaft 25. The PTO speed change lever 46 and the reverse direction PTO lever 48 are interlocked and connected via a check mechanism (not shown), and the reverse speed PTO lever 48 cannot be operated to enter the reverse direction when the PTO speed change lever 46 is changed to a speed other than neutral. It is configured as follows.

  When the reverse rotation PTO lever 48 is operated for reverse rotation, the reverse shifter gear 598 is engaged with the PTO reverse rotation gear 607, and the rotational power of the PTO input shaft 591 is transmitted to the PTO counter shaft 593 via the reverse rotation shifter gear 598 and the PTO reverse rotation 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 607 and the PTO output gear 608.

  In the rear transmission case 113, a longitudinal longitudinal vehicle speed tuning shaft 564 extending in parallel with the auxiliary transmission shaft 546 is disposed from the intermediate chamber 497 to the rear chamber 496. A vehicle speed tuning input gear 565 is fitted on the front end side of the vehicle speed tuning shaft 564 so as not to be relatively rotatable. The vehicle speed tuning input gear 565 is always meshed with a power branch gear 566 that is fitted in a position in the intermediate chamber 497 of the auxiliary transmission shaft 546 so as not to be relatively rotatable. A vehicle speed tuning output gear 610 that is rotatably fitted to the front side of the PTO output gear 608 in the PTO shaft 25 is always meshed with a vehicle speed tuning relay gear 609 fixed to the rear end portion of the vehicle speed tuning shaft 564. . A vehicle speed tuning shifter 611 is spline-fitted between the vehicle speed tuning output gear 610 and the PTO output gear 608 of the PTO shaft 25 so as not to be relatively rotatable and slidable in the axial direction. By entering and operating a PTO vehicle speed tuning lever (not shown), the vehicle speed tuning shifter 611 slides and the vehicle speed tuning output gear 610 is connected to the PTO shaft 25. As a result, the vehicle speed tuning output from the auxiliary transmission shaft 546 via the vehicle speed tuning shaft 564 is transmitted to the PTO shaft 25.

  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 mission case 17 is used as a working oil tank, and the working oil in the mission case 17 is supplied to the working machine hydraulic pump 481 and the traveling hydraulic pump 482. The traveling hydraulic pump 482 is connected to the steering hydraulic cylinder 622 for power steering by the steering handle 9 via the control valve mechanism 621 for power steering, and the hydraulic pump 521 and the hydraulic motor 522 of the hydraulic continuously variable transmission 500. Is connected to a closed loop oil passage 623 connecting the two. 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 a main transmission hydraulic switching valve 624 for the main transmission hydraulic cylinder 524 of the hydraulic continuously variable transmission 500, a double speed hydraulic switching valve 625 for the double speed hydraulic clutch 573, and a four-wheel drive for the four-wheel hydraulic clutch 575. The hydraulic switching valve 626 is connected to a PTO clutch electromagnetic valve 627 for the PTO hydraulic clutch 590 and a switching valve 628 operated thereby.

  Further, the traveling hydraulic pump 482 includes left and right autobrake solenoid valves 631 as switching valves that actuate a pair of left and right autobrake brake cylinders 630, and a forward low speed clutch solenoid valve 632 that actuates a forward low speed hydraulic clutch 537. A forward high-speed clutch electromagnetic valve 633 for operating the forward high-speed hydraulic clutch 539, a reverse clutch electromagnetic valve 634 for operating the reverse hydraulic clutch 541, and a master control electromagnetic valve 635 for controlling the supply of hydraulic oil to the clutch electromagnetic valves. And connected to.

  The work machine hydraulic pump 481 is configured to provide a tread (distance between wheels) between a plurality of hydraulic external extraction valves 430 arranged on the upper surface of the hydraulic lifting mechanism 22 on the rear side of the upper surface of the mission case 17 and the left and right rear wheels 4. Left and right tread adjustment solenoid valves 646 that control the supply of hydraulic oil to the right and left tread adjustment hydraulic cylinders 645, and a tilt control solenoid valve 647 that controls the supply of hydraulic oil to the horizontal cylinder 122 provided on the right lift rod 121 , An ascending oil pressure switching valve 648 and a descending oil pressure switching valve 649 for controlling the supply of hydraulic oil to the hydraulic lift cylinder 117 in the hydraulic lifting mechanism 22, an ascending control electromagnetic valve 650 for switching the ascending oil pressure switching valve 648, and a descending oil pressure The switching valve 649 is connected to a lowering control electromagnetic valve 651 for operating.

  When the left and right tread adjustment solenoid valves 646 are switched and driven with the left and right rear wheels 4 jacked up and floating from the ground, the left and right tread adjustment hydraulic cylinders 645 expand and contract to move the left and right rear axle cases 19 left and right. It is expanded and contracted in the direction (see FIGS. 6 and 14). As a result, the tread between the left and right rear wheels 4 becomes longer or shorter. 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 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. When the raising hydraulic switching valve is switched by the raising control solenoid valve or the lowering hydraulic switching valve is switched by the lowering control solenoid valve, the hydraulic lift cylinder 117 expands and contracts, and both the lift arm 120 and the left and right lower links 23 are moved together. 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.

  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 lubricating portion of the input transmission shaft 511 that supports the hydraulic continuously variable transmission 500. A forward low speed clutch hydraulic pressure switching valve 642 that supplies hydraulic oil to the lubricating portion of the forward low speed hydraulic clutch 537, a forward high speed clutch hydraulic pressure switching valve 643 that supplies hydraulic oil to the lubricating portion of the forward high speed hydraulic clutch 539, and a reverse hydraulic clutch. It connects with the reverse clutch hydraulic pressure switching valve 644 which supplies hydraulic oil to the lubrication part of 541. 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.

  Next, the mounting structure of the hydraulic operation lever 54 will be described with reference to FIGS. 8 and 25 to 27. The operation lever fulcrum bracket body 56 is bolted to the upper surface of the right fender frame 55 of the cabin 7. An operation lever fulcrum shaft 57 is provided on the operation lever fulcrum bracket body 56. A boss body 58 at the base end of the hydraulic operation lever 54 is pivotally supported on the operation lever fulcrum shaft 57. The hydraulic operation lever 54 is erected and supported on the upper surface of the right fender frame 55 via the operation lever fulcrum shaft 57 so as to be rotatable. A hydraulic operating arm 59 is provided on the boss body 58, and the hydraulic operating arm 59 is connected to a spool shaft of a hydraulic external take-off valve 430 having a three-position switching structure via a hydraulic operating wire 60 so that the hydraulic operating arm serves as a hydraulic external take-out lever. By operating the lever 54, the hydraulic external take-off valve 430 is switched to the A position position, the neutral position, and the B position position.

  Further, the right side column 42 is fixed on the upper surface of the right fender frame 55. A hydraulic operation guide cover body 61 is provided on the upper surface side of the right side column 42. An operation portion on the upper end side of the hydraulic operation lever 54 is projected from the upper surface side of the hydraulic operation guide cover body 61 via a lever guide groove 61a. On the other hand, the slide guide body 62 is fixed to the lower surface side of the hydraulic operation guide cover body 61. The regulating body 63 is slidably supported between the lower surface of the hydraulic operation guide cover body 61 and the upper surface of the slide guide body 62 and supported. The restriction body 63 is provided with a claw-shaped restriction claw 63a bifurcated, and the hydraulic operation lever 54 can be locked by the restriction claw 63a at any one of the A position position, the neutral position, and the B position position.

  A restriction guide groove 61 b is formed in the hydraulic operation guide cover body 61. An operation projection 63b is integrally formed on the regulation body 63 on which the regulation claw 63a is formed. The operation protrusion 63b is fitted into the restriction guide groove 61b, and the operation protrusion 63b is protruded outward from the upper surface of the hydraulic operation guide cover body 61. With the operator operating the hydraulic operation lever 54 to any of the A position position, neutral position, and B position position, the operator operates the operation protrusion 63b to place a bifurcated claw-shaped restriction claw in the lever guide groove 61a. The hydraulic operation lever 54 is configured to be maintained at the operation position of any one of the position position, the neutral position, and the B position position. Even if an operating force that moves from one of the position position, the neutral position, or the B position position to another operation position acts on the hydraulic operation lever 54, the two-prong claw shape that rushes into the lever guide groove 61a. The hydraulic operation lever 54 comes into contact with the distal end of the regulation claw 63a to prevent the hydraulic operation lever 54 from moving to another operation position.

  As shown in FIGS. 1, 8, 14, and 22 to 27, an operator seat 8 is mounted on the traveling machine body 2 and an operator sits on the side of the operator seat 8 as a hydraulic external takeout lever. In a work vehicle in which hydraulic fluid is supplied from the hydraulic external take-off mechanism (hydraulic external take-off valve 430) to an external hydraulic device by operating the hydraulic control lever 54, the hydraulic control lever 54 is operated. The hydraulic external take-off valve 430 of the hydraulic external take-out mechanism is switched between the A position position and the neutral position, and a restriction that allows the hydraulic operation lever 54 to be locked to either the A position position or the neutral position of the hydraulic operation lever 54. The claw 63a is provided, and the regulation claw 63a is slidably supported on the hydraulic operation guide cover body 61 as a cover on which the hydraulic operation lever 54 is disposed. It is configured to be. Therefore, either the A position support or the neutral position fixing (neutral lock) can be selected by operating the restricting claw 63a, and the operability of the hydraulic operation lever 54 can be improved.

  As shown in FIGS. 14 and 22 to 27, the hydraulic external take-out mechanism is provided with a hydraulic external take-off valve 430 capable of switching between three positions, and the A position position, the neutral position, and the B position position can be operated by operating the hydraulic operation lever 54. The hydraulic external take-off valve 430 is switched to a bifurcated claw shape with a regulating claw 63a, and the hydraulic operating lever 54 is placed in one of the A position position, neutral position and B position position. It can be locked with. Accordingly, the A position support, the neutral position fixing (neutral lock), or the B position support can be selected by a one-touch operation of the restriction claw 63a.

  As shown in FIGS. 22 to 27, a restriction guide groove 61b is formed in the hydraulic operation guide cover body 61 in which the hydraulic operation lever 54 is disposed, and an operation protrusion 63b is formed integrally with the restriction claw 63a, thereby restricting the guide. An operation protrusion is inserted into the groove 61b, and an operation protrusion 63b is provided outside the hydraulic operation guide cover body 61. Therefore, the restricting claw 63a can be easily supported in the restricting guide groove 61b of the cover that also serves as the lever guide of the hydraulic operation lever 54, and the number of parts for attaching the restricting claw 63a can be reduced and configured at low cost.

  Next, a parking brake operation structure such as the parking brake lever 43 will be described with reference to FIGS. 8 to 10 and FIGS. 28 to 30. Left and right brake mechanisms 563 for braking the left and right rear wheels 4 and left and right brake operation arms 65 for braking the left and right brake mechanisms 563 are provided (see FIGS. 9 and 10). The left and right brake operation arms 65 are connected to the left and right brake pedals 35 via the left and right brake operation rods 66, and the operator depresses one of the left and right brake pedals 35 to operate either one or both of the left and right brake pedals 35. The brake mechanism 563 is braked to brake either the left or right or both rear wheels 4.

  Further, the operation lever fulcrum frame body 68 is bolted to the upper surface of the seat frame body 67 of the cabin 7. The base end sides of the ultra-low speed lever 44, the auxiliary transmission lever 45, and the PTO transmission lever 46 are pivotally supported on the fulcrum shafts of the operation lever fulcrum frame body 68 so that they can be tilted in the front-rear direction, and the left side column 42 The operation lever fulcrum frame body 68 is covered and the operation portions of the ultra-low speed lever 44, the auxiliary transmission lever 45, and the PTO transmission lever 46 are projected from the upper surface side of the left side column 42. The control seat 8 is placed on the upper surface of the seat frame body 67 of the cabin 7.

  Further, the parking brake frame body 71 is erected on the upper surface of the seat frame body 67 adjacent to the operation lever fulcrum frame body 68. The parking brake frame body 71 is detachably bolted to the upper surface of the seat frame body 67, and the brake lever fulcrum frame body 72 is fastened to the parking brake frame body 71 with a bolt 73. A base end side of the parking brake lever 43 is pivotally supported on the brake lever fulcrum frame body 72 via a brake lever fulcrum shaft 74 so as to be rotatable. The parking brake lever 43 is releasably locked to the braking position or the non-braking position on the brake lever fulcrum frame body 72, and the parking brake lever 43 is supported at the braking position or the non-braking position.

  In addition, one end side of the left and right parking brake wires 75 is connected to the left and right brake operation arms 65, the other end side of the left and right parking brake wires 75 is connected to both end sides of the equalizer body 76, and the middle of the equalizer body 76 is connected. The other end side of the equalizer wire 77 is connected to the parking brake lever 43 via the wire linkage link 78. That is, an equalizer body 76 and an equalizer wire 77 for connecting the left and right brake operation arms 65 to a single parking brake lever 43 are provided, and the operating force of the single parking brake lever 43 is determined by the left and right brake operation arms. It is comprised so that it may act on 65 substantially equally.

  On the other hand, the parking brake cover body 79 covers the upper part of the parking brake frame body 71, and the parking brake frame body 71 and the brake lever fulcrum are located between the right side surface (side surface of the body) of the left side column 42 and the left side surface of the parking brake cover body 79. A parking brake operation mechanism 81 such as a frame body 72, an equalizer body 76, and an outer receptacle 80 of the left and right parking brake wires 75 is disposed. The parking brake cover body 79 is detachably disposed on the upper surface of the seat frame body 67 via the mounting bracket 82 and the like. That is, as shown in FIG. 30 and the like, the parking brake lever 43 is disposed on the upper surface of the seat frame body 67 between the control seat 8 and the left side column 42 through the parking brake cover body 79 among the upper surface of the seat frame body 67. The

  As shown in FIGS. 1, 8 to 10, and 28 to 30, the left and right brake operations for braking the left and right rear wheels 4 as well as arranging the rear wheels 4 as the left and right traveling wheels on the left and right of the traveling machine body 2. A work vehicle including an arm 65 and a parking brake operation mechanism 81 for braking the left and right brake operation arms 65 is provided with a single parking brake lever 43 in the parking brake operation mechanism 81, and includes a parking brake. An equalizer body 76 for connecting the left and right brake operation arms 65 to the lever 43 and an equalizer wire 77 as a brake wire are provided so that the operation force of the parking brake lever 43 acts on the left and right brake operation arms 65 substantially equally. It is composed. Accordingly, the left and right equal braking force can be generated by the equalizer body 76 and the equalizer wire 77, the assembly or maintenance work of the parking brake operating mechanism 81 can be simplified, and the left and right rear can be operated by operating the parking brake lever 43. The wheel 4 and the like can be properly braked, and the parking brake function can be improved.

  As shown in FIGS. 28 to 30, the parking brake frame body 71 as the support bracket is detachably disposed at the mounting position of the operation lever fulcrum frame body 68 as the lever box of the left side column 42, and the parking brake frame body 71 is attached to the parking brake frame body 71. The parking brake lever 43 is assembled. Accordingly, the parking brake operation mechanism 81 can be configured in the parking brake lever 43 unit structure centering on the parking brake frame body 71 and the like, the assembly workability of the parking brake operation mechanism 81 can be simplified, and the parking brake lever 43 mounting parts The number can be reduced and configured at low cost.

  As shown in FIGS. 28 to 30, one end side of the left and right parking brake wires 75 is connected to the left and right brake operation arms 65, and the other end side of the left and right parking brake wires 75 is connected to both end sides of the equalizer body 76. One end side of the equalizer wire 77 is connected to the middle of the equalizer body 76, and the other end side of the equalizer wire 77 is connected to the parking brake lever 43. Accordingly, the parking brake operation mechanism 81 can be simplified, and the parking brake operation mechanism 81 can be installed compactly on the side of the driver seat 8 and the assembly adjustment of the parking brake operation mechanism 81 can be simplified, and the parking brake operation mechanism 81 The maintenance workability of 81 can be improved.

2 Traveling machine body 54 Hydraulic operation lever (hydraulic external takeout lever)
61 Hydraulic operation guide cover (cover)
61b Restriction guide groove 63a Restriction claw 63b Operation protrusion 430 Hydraulic external extraction valve (hydraulic external extraction mechanism)

Claims (3)

A pilot seat is installed on the traveling machine body, and an operator sits, and a hydraulic external take-out lever is arranged on the side of the control seat, and an external hydraulic device is operated from the hydraulic external take-out mechanism by operating the hydraulic external take-out lever. In a work vehicle that supplies hydraulic oil to
By operating the hydraulic external take-out lever, the hydraulic external take-off valve of the hydraulic external take-off mechanism is switched between the A position position and the neutral position, and either the A position position or the neutral position of the hydraulic external take-out lever is set. A work vehicle comprising a restriction claw capable of locking the hydraulic external takeout lever, and slidably supporting the restriction claw on a cover on which the hydraulic external takeout lever is arranged.   The hydraulic external take-off mechanism is provided with a hydraulic external take-off valve capable of switching between three positions, and the hydraulic external take-out valve is switched to an A position position, a neutral position and a B position position by operation of the hydraulic external take-out lever, The regulation claw is formed in a bifurcated claw shape, and the hydraulic external takeout lever can be locked by the regulation claw at any of the A position position, the neutral position, and the B position position. The work vehicle according to claim 1.   A restriction guide groove is formed in the cover on which the hydraulic external take-out lever is disposed, and an operation protrusion is integrally formed on the restriction claw, and the operation protrusion is fitted into the restriction guide groove, and is formed outside the cover. The work vehicle according to claim 1, further comprising an operation protrusion.

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